Maserati V8 engine health questions - comp results & pistons photos | FerrariChat

Maserati V8 engine health questions - comp results & pistons photos

Discussion in 'Maserati' started by jamespeter26, Mar 3, 2021.

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  1. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    64
    Rome, Italy
    Full Name:
    Peter
    Hi all,

    I’d like to share with you a set of data points and get your insights about intriguing findings on my 1982 Maserati Quattroporte III engine.

    I have two really concerning symptoms:
    • The radiator repeatedly goes low on coolant.
    • A chemical test (block test) turned positive for exhaust gases in the cooling system at least once
    I know what you all think at this stage, but please bear with me for the rest of the story.


    Data points

    The engine probably has 80k to 100k km.

    1. Combustion gases in cooling system (block test for gaseous CO2):
    • Positive once (the blue liquid turned yellow as it reacted to gas present in the expansion tank)
    • Inconclusive or negative several times (remained blue or turned green-ish after sucking back air from the outside atmosphere, incl. exhaust gases present in the vicinity)

    2. Coolant pH (acidity test strips)
    • Control sample (fresh coolant): 8.0
    • Radiator neck: 8.0
    • Expansion tank: 8.0
    Note that the coolant in the radiator has about 1000 km on it.

    3. Cooling system vacuum test
    Cooling system holds a vacuum for more than one hour.

    4. Cooling system pressure test
    Cooling system holds a pressure for more than one hour.

    5. Cylinder compression history (values expressed in bar)

    Cylinder 19 Feb 2020 13 Dec 2020 2 Mar 2021
    1 9.3 9.2 10.3
    2 9.0 9.2 10.0
    3 9.7 10.1 10.7
    4 9.3 9.9 10.8
    5 9.0 9.1 9.9
    6 9.7 10.1 10.0
    7 9.0 8.9 9.7
    8 9.7 9.9 10.7

    These are dry compression test with engine warmed up to normal operating temperature. Service manual considers readings above 9 as "normal". All cylinders are within 10% of each other.

    6. Cylinder leak down

    Results pending (test scheduled for next week).

    I did a quick empirical test by just injecting compressed air into cylinders 8, 7 and 5 at TDC on the compression stroke, without any measurement instrument. I could distinctly hear some hissing coming out of the crankcase indicating worn rings. No bubbles in coolant, no hissing through exhaust or intake.

    7. Spark plugs reading

    I replaced spark plugs about 500 km ago.

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    8. Appearance of pistons

    I am concerned about the discoloration on piston n°5.

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    9. Empiricals
    • In the summer of 2020, I found some gray (non-oily) mud under the radiator cap. The mud does not dissolve in water, but it doesn't float like oil, instead it would slowly sediment at the bottom of water. I had a sample tested by Blackstone labs and they think the sediment is non-metallic.
    • This prompted me to flush the coolant. The previous flush had been done by a mechanic a little more than 1 year earlier. Flush done per the manual (especially the bleeding procedure), using correct coolant.
    • The flush cured the gray mud issue, but now I keep getting a "low radiator level" light every time I start the car, after 10-15 minutes of driving. Topping off the coolant will fix it for a few days, then it comes back. I checked the sensor and it works correctly. The sensor is located on the radiator itself, a few centimeters below the filling neck/radiator cap.
    • I started the engine and let it idle for some time with the radiator cap open. The coolant would overflow during engine warm-up (no bubbles) and then upon opening of the thermostat, the level would drop quickly (again without bubbles) and settle at a low enough level for the sensor to detect "low radiator level". Topping up at this stage, still with the engine running, results in a stable coolant level with no bubbles.
    • No coolant leak detected even under UV light. No puddle under the car.
    • The engine never overheats, even when "low" on coolant. The water temperature is actually very cool since the latest coolant flush and barely reaches 70°C. The oil temperature used to be at 80°C when I was using BP6ES spark plugs, now around 90°C with the hotter BP5ES (no difference in water temperature).
    • Engine oil is replaced every 3500 km using Motul semi-synthetic 15W50. I systematically get it lab-tested and they never found any antifreeze in the oil (not even traces). The oil analysis reports are OK and trending north.
    • The engine idles and runs well. No noticeable loss in power output, 0-100 km/h from a standstill is achieved within 10 seconds (better than when I purchased the car). Last weekend I drove 400 km on the highway and reached 170 km/h (don't ask me where) without any issue, the car actually felt it could go up. Minimal vibration at high speed (north of 120 km/h) attributable to a slightly loose differential. With cold weather and if the car has not been used in the past 2 days, I need to crank the engine a little bit before it starts.
    • No smoke whatsoever. Minimal condensation at startup in cold weather, cleared in 5 minutes.

    10. Antecedents
    • When I purchased the car, the cooling fan fuses were blown. The engine was cooling adequately when driving, but temperature would rise at idle and eventually reach the red area. I never let it overheat under my ownership and of course replaced the fuses the next day, but cannot entirely rule out at least one overheating episodes under PO ownership.
    • Carburetors were also out of tune and on the leaner side when I purchased the car, leading to hot operating temperature (engine oil around 120-130°C, water around 90°C) and some carb popping as some of you helped diagnose. This issue was fixed after my carb rebuild one year ago.
    • I must have driven at least 5000 km before the first symptoms appeared. The car was fine until then.

    Any thoughts? What would be your recommended next steps?
     
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  2. Nembo1777

    Nembo1777 F1 World Champ
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    Nov 4, 2006
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    Marc Sonnery
    Very well presented report.

    Could head porosity be the culprit? It has been known to happen and documenting the best Maserati restoration workshops brought that to light.
     
  3. italiancars

    italiancars F1 Rookie

    Apr 18, 2004
    3,338
    Hershey, PA
    Is it a low coolant light that comes on that tips you off or are you checking it?
     
  4. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    64
    Rome, Italy
    Full Name:
    Peter
    Thanks Marc, that's good to know and I am also suspecting something along those lines. Not being a specialist, it is difficult to tell by myself, but I can only surmise that a "typical" blown HG would cause bi-directional leaks allowing some coolant in the combustion chamber and/or the crankcase, but I have no evidence of that (no steam-cleaned piston or spark plug, no antifreeze in oil). Instead, I am only getting gases in coolant (and not even sure these are combustion byproducts). A hairline crack in the heads might allow combustion gases to escape only at very high pressures (= engine running), but not the other way around. At least that's one of the hypotheses but I'm eager to hear informed opinions or suggestions.

    I am not convinced that I should put the heads just yet, given the compression results and how the car runs, but definitely willing to perform additional tests and investigate the issue.

    It's the fact that I actually run low on coolant on a regular basis, without any external leak that I can find. I constantly have to top off the coolant, it's like a bleed that's never ending. At some point, I guess anyone would start wondering what is going on.

    Also not sure if that's still relevant but here is a picture of the non-oily mud that was under my radiator cap last summer. I also found a decent amount of the same mud at the bottom of the expansion tank (sediment), which I thoroughly cleaned as part of the flush. I haven't found anything like this since the flush, the coolant is actually quite clean now.

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  5. Mexico074

    Mexico074 Formula 3

    Aug 14, 2008
    1,225
    Harriman, TN USA
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    Michael Demyanovich
    Hi jamespeter26...

    What concerns me most is the two items you list under Data Point #1 !!!!!
    Positive once and inconclusive or negative since.... That may not be good...

    Correct me if I am wrong, but the coolant is used for the HVAC heating system, correct?
    Could you be leaking somewhere there? Perhaps there is a valve not operating correctly,
    or the condensor in the dash may have an issue?

    Just guessing here...

    Mike D.
     
  6. thecarnut

    thecarnut F1 Rookie
    Rossa Subscribed

    Apr 22, 2006
    3,008
    Atlanta
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    The Car Nut
    The muddy looking stuff could be the remains of radiator/head gasket sealer pellets, such as Bar's Leaks. Perhaps the PO experienced similar problems and temporarily solved the problem. When you flushed the system the problem returned. Just a theory ..

    Ivan
     
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  7. italiancars

    italiancars F1 Rookie

    Apr 18, 2004
    3,338
    Hershey, PA
    There maybe slight seepage through the just old head gaskets, if the heads have never been off those gaskets are 40 years old.

    the one thing about Series III quattoporte’s is the placement of the water sensor. That was one issue the then President of MNA at the time George Garbutt complained to the factory about in that the difference between the water level being full and what would set off the light was a minimal difference that easily changed once the engine began to warm. Owner would complain, take the car in for warranty service costing MNA money when there was nothing wrong. If they had simply put the sensor a little lower on the radiator a lot of unnecessary warranty claims would not have been submitted.

    The other common issue was what sounded like metallic grinding in the engine that would diminish when warmed up. The is caused by a misalignment of the accessory belts.
     
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  8. 71Satisfaction

    71Satisfaction Formula 3

    Jul 15, 2012
    1,219
    New York and Norway
    Full Name:
    Art
    Buona sera, John,
    This sounds eerily familiar...

    I have a car that would gradually lose coolant with no evidence where it went.
    It would only lose coolant during a period it was being driven.
    No exhaust smoke, no contamination of any other fluids.
    It would not lose coolant for weeks with the car sitting and not being driven.
    I.e. the coolant loss was strictly related to an operating engine.
    I carefully inspected everything but found nothing.
    One day after a short drive, I found a clue in the engine bay.
    A faint but familiar smell of glycol coolant.
    Careful sniffing and observation led me to a tiny bead of coolant on an engine bay frame rail...
    .. and what I also found at the same location was the outlet for the coolant header tank overflow tube.

    Long story short:
    - A faulty coolant tank pressure cap let coolant escape out the overflow tube during the normal expansion phase of the warm up, and deposited it
    "invisibly" on the roadway in dribs and drabs until temperature stabilized at which point it would stop dripping and airflow would eliminate any evidence of it ever having dripped. Upon returning to the garage, the cap would equalize the ensuing cooling-phase vacuum by letting in air as designed, replacing the volume of the lost coolant, and readying the system to be pressurized and expel more coolant each time I drove the car.

    Check if anything is consistent with your QPIII.
    Best,
    - Art
     
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  9. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    64
    Rome, Italy
    Full Name:
    Peter
    Wow, I am truly grateful to all of you for this combination of historical and mechanical insights plus ownership experiences. That's really great!

    Ivan I didn't think about sealer pellets but this makes sense. It would be consistent with the non-oily AND non-metallic nature of this thing. If that's the case, I'm glad I got rid of it. I'd rather know about a HG leak and fix it now. I guess the leakdown results will tell us more about any issue here.

    Point well noted about the HVAC heater core. Most of the symptoms appeared while the valve was (supposedly) closed so in theory no water should be have been flowing through the heater core, but it would be good to rule out this possibility. I will try and bypass the heater core for a couple of weeks and connect the heater hose directly into the return port in a closed-loop fashion and will report on results.

    I am also very intrigued about the possibility of a dysfunctional expansion system as outlined by italiancars and Art. Correct me if I'm wrong but I see a connection between the two: in a correctly-designed system, the sensor should not be triggered under normal operating conditions and the flow to/from the expansion tank should be sufficient to cover for normal expansion, without inducing coolant loss. Italiancars, your point about the misplaced sensor makes perfect sense since I am not experiencing rising temperatures when the sensor is triggered.

    Art, your description is not just consistent with my car, it is EXACTLY what I have been facing. No coolant loss for weeks (sometimes over a month due to COVID), and these mysterious coolant losses while driving. And then one day, after a short drive (10 min), I also found coolant sputtering from the overflow hose and bubbling noise coming from the expansion tank. This is actually the event which prompted me to perform the chemical block test which turned positive, but since I did it when I was in my garage, I continue to suspect that it might be a false positive due to combustion gases from the outside air and not coming from inside the cooling system. Also worth noting that I replaced the expansion tank cap with a new one from Campana about one year ago - it should be correct but perhaps it is faulty.

    What solution did you find for this issue?

    Next steps for me this weekend will be:
    1. Try bypassing the HVAC heater core and see if that makes any difference
    2. Replacing the hose from radiator neck to expansion tank - if partially clogged for some reason, that could prevent proper functioning of the expansion system
    3. Try a couple of expansion/contraction cycles with the radiator cap closed and the expansion tank cap removed. That should confirm whether my expansion tank cap is faulty.
    4. Re-do a chemical block test (with a different tool for good measure)
     
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  10. 71Satisfaction

    71Satisfaction Formula 3

    Jul 15, 2012
    1,219
    New York and Norway
    Full Name:
    Art
    I replaced the "weak" coolant tank cap with a new one because the old cap allowed coolant to escape at a lower-than-specified pressure.
    And during my inspection of everything, I noticed cracks in the original plastic coolant expansion tank. Cracks were primarily at the base of the hose outlet necks. So I replaced it too, with a new tank.
    This was all done at once, and solved the problem,
    - Art
     
  11. redfred84

    redfred84 Formula Junior

    Dec 24, 2010
    570
    SF Bay Area, USA
    Great news! Thanks for the follow up!
     
  12. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    64
    Rome, Italy
    Full Name:
    Peter
    Thanks Art, that's good to know. Unfortunately I can now confirm that the issue I'm experiencing is different. I measured the relief valve opening pressure and can confirm that it opens at exactly 0.50 bar. This test was performed by disconnecting the overflow hose from the radiator neck and injecting compressed air into the expansion tank with a calibrated pressure regulator. At 0.45 bar no water is being pushed out, at 0.50 I start getting water on the floor. So apparently the system is tight and the cap is working correctly.

    Leakdown results are finally here... and I really don't know what to think. Below is % leakdown per cylinder. I did the test myself at TDC on compression stroke, with an input pressure of 80 psi using a professional air compressor. Cylinders are listed following firing order.

    1 - 6%
    8 - 5%
    4 - 6%
    2 - 6%
    7 - 5%
    3 - 4%
    6 - 6%
    5 - 5%

    I'm not quite sure about the accuracy of my leakdown tester (calibration-wise), so the numbers may be off a little bit. Actually, considering that this engine has nearly 80k kilometers, they are likely off and I was expecting them to be above 10%.

    This being said, I have no doubt about at least three things:
    1. The results were very consistent from cylinder to cylinder, as there was very little variation in gauge readings and leak noise pitch
    2. All cylinders are leaking through piston rings - a hissing noise was distinctly audible from the oil cap, crankcase gases vent hose and dipstick tube, with small variations in pitch between cylinders in accordance with gauge readings
    3. Most importantly, no cylinder caused bubbling in the radiator when performing the test

    I also performed a new block test which came out inconclusive again (light blue/green). But I am increasingly doubting the validity of these block tests, because from my observations, coolant briefly expands upon start-up, and then the cooling system enters into vacuum as water is pumped from the radiator into the engine. I always have to be careful at that stage to avoid sucking outside air through the block tester, due to vacuum inside the cooling system. Whenever I open the radiator cap while the engine is running, air is aspirated into the radiator. As such I will never be able to rule out the possibility that this air is contaminated by exhaust gases (mine or someone else's), and that these exhaust gases make the block test turn falsely positive when they are eventually pushed out of the radiator due to coolant expansion.

    Which leaves me with: *unknown* presence of CO2 in cooling system, good compression and leakdown results, and yet, coolant which keeps running low on every single drive.
     
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  13. italiancars

    italiancars F1 Rookie

    Apr 18, 2004
    3,338
    Hershey, PA
    here’s something to check. Had a problem of constantly losing coolant in a Mondial. A friend with-a Mondial had the same issue. Replaced the cap ordered from Ferrari still would lose coolant. I don’t remember where I heard it, but i was told to measure the distance from the base of the cap to the seal, then measure the neck of the tank. Apparently Ferrari had superseded the original cap part number with the cap from a Testarossa and changed the tank during production to use Testarossa cap. Upon measuring, it turned out cap neck was something like an 1/8 or 1/16 (I forget the amount) of an inch deeper than the cap. While the cap appeared to fit properly, there was enough of a gap that would allow coolant to escape.
     
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  14. JL350

    JL350 Karting

    Jan 20, 2013
    204
    Number 1 spark plug looks cleaner than the others, any water getting into the cylinder can turn to steam and clean the spark plug. It could be a small leak that only opens up when the engine is at operating temperature and pressure, first guess is head gasket, but could be anywhere where the coolant can evaporate on a hot engine, ie around the water pump etc.

    Leak down and compression numbers are pretty consistent which is a good sign.

    I am assuming that the radiator cap, hoses and thermostat are all in good working order.

    Is it possible to safely do a pressure test on the coolant system when it is at operating temperature?
     
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  15. 71Satisfaction

    71Satisfaction Formula 3

    Jul 15, 2012
    1,219
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    Art
    Agree.

    I'm not wiling to let the coolant system off the hook, mostly because it's not ruled out, and it's quick to check. Even if the cap meets spec, there could be enough pressure somewhere to eject the coolant from a different failure point whilst driving.

    It could be the tank, or filler, or cracked hose, pump seal, or some other fault and finding its way out of the coolant system even within specified pressures - leaks which are extraneous to the engine internals and cylinder heads.

    - Has the engine been started from cold, with full coolant, and warmed up good and hot sitting in one place, even disconnecting a cooling fan to get the temperature up hot, see if any coolant is left on the ground under the car? It's a very simple low-tech approach to see if the coolant is coming out somewhere when cycling from cold to hot. You can even mimic a driving cycle by shutting it down when hot, let it cool overnight without intervention, start it up and get it hot again, maybe try 2-3 cycles, checking for physical coolant on the ground.. Then after 2-3 cycles, check the coolant level.. See if it dropped with no coolant on the ground.. Even try the sniff test, see if you can detect the odor.

    Cheers,
    - Art
     
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  16. staatsof

    staatsof Nine Time F1 World Champ
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    Mar 13, 2005
    91,358
    Fuggetaboutitland
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    Bob
    It does sound like you were getting combustion gasses into the coolant.
    I've had this happen with three cars.
    The first was my Bora which was low miles 3K and it had been sitting in a museum for 10 years.
    No evidence of coolant out of the exhaust.
    I was losing coolant very gradually.
    I tried the blue test liquid and got no conclusive results. Now I no longer trust that method.
    But I did put a pressure gauge on the cooling system and it spiked when I accelerated.
    I didn't have access to a smog machine and wish I had.
    I pulled the heads , cleaned everything and with new properly torqued head gaskets the issue disappeared.
    Coolant breaks down in small pocket areas when left for a long time WO circulation and we could see the trace line failures on the old gaskets.
    So I concluded that while coolant wasn't leaking into the oil or combustion chambers the high pressure gasses were getting into the coolant under high pressure in the combustion chamber.
    This was dirtying the coolant and pushing some out of the overflow tank.

    The second car is my 99 7.4L Suburban which I still own and it still has this problem. It's gotten gradually worse over the years,. I bought it in 2005 with 80K miles on it. It now has 150K.
    I didn't know I had a real problem for a lot of years but I finally did confirm with a smog machine that combustion gases were getting into the cooling system. I ended up with a small leak in the radiator near the top of the core. So no matter how often I filled the system it would drop down to that level and the car ran just fine. When I replaced all the AC componentry 5 years ago I also put in a new radiator but I run with an open system, unpressured and I only need to fill it a little bit now every so often.

    It's not worth it to me to pull the heads on that motor with all those miles and I'd have to pay someone to do it. So I live with it. Those are brutally rugged vehicles but just not worth enough money for an expensive repair.

    The third was my Espada. Same deal as the Bora. It really needs new head gaskets. The compression numbers are great, no coolant in the exhaust or oil but it runs a bit hot in the summers and pushes coolant out of the reservoir tank.

    Too bad you weren't able to utilize a smog sniffer. There may be places that can do a pressure test on your heads but it probably won't be at operating temps or a pressure anywhere near that of a combustion chamber. I've run into that issue with the cooling reservoir on my modern Jag. Zero leaks under pressure when out of the car but it still weeps coolant, not badly just enough to smell when actually operating.

    Cars can be challenging no? :D

     
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  17. Froggie

    Froggie Formula Junior

    Sep 27, 2017
    476
    Belgium
    Full Name:
    Serge
    So, head gasket(s) would be the culprit(s)?
     
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  18. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    64
    Rome, Italy
    Full Name:
    Peter
    Hi all,

    Again sincere thanks to all of you for stepping in and for all your ideas and advices. That has been really helpful and I’m happy to report that we are making real progress!
    My 2 main working hypotheses at this stage are:
    1. Cooling system malfunction somewhere
    2. Head gasket or other combustion chamber problems

    I’ve been following all of your advices and new results seem to narrow down around hypothesis #1. Art you are right to call out the coolant system.
    @italiancars – you were right to mention your non-sealing Mondial cap. Upon closer inspection I found out that my radiator neck cap, albeit new and original from Campana, wouldn’t seal correctly. Enough to let some air in and out, and even some coolant. For now I tightened it by bending the metal tabs to make it fit tighter on the radiator neck and it now seals correctly, and ordered a new cap.

    I also did 2 new tests and that’s where things are starting to get interesting.

    1. Cooling system pressure with engine running
    I put a pressure gauge inline between the radiator and expansion tank and started the engine. Here is a recording of the test incl. idling and part-throttle. This was a cold start:
    .
    Unlike Bob, the pressure doesn’t spike when accelerating. Instead, it decreases upon acceleration and is back to normal at idle. This is clearly visible from the video. The decrease in pressure could be caused by a restriction in the return circuit, whereby coolant doesn’t flow from the engine to the radiator as fast as it is pumped from the radiator into the engine. The difference could cause a small drop in pressure which might be enough to suck air from any leaking point, like my non-sealing radiator cap.
    I don’t know what could be causing this restriction (if there’s a restriction) – perhaps a partially clogged thermostat due to the same debris that I found? If stuck open, even partially, that would also explain why the water temperature barely exceeds 65-70 degrees Celsius.

    2. Cooling system pressure test at operating temperature
    This was done using an adaptor fitted in place of the expansion tank cap to inject compressed air into the system. As specified in the service manual, I used a pressure of 1 bar and did several rounds. Again a recording of the test

    As shown in the video, the pressure drops very slowly, at a rate of about 0.005 bar per minute.
    @JL350, I assumed that by “safely” you meant I should remove all spark plugs in the event water would leak into the cylinders, to avoid hydrostatic lock. At least that’s what I did and took the opportunity to take before/after pictures of the pistons with my borescope, to look for any signs of water in there. Also reviewed the color of spark plugs (which made me think I definitely need to adjust air-fuel richness again).
    I’m not posting the 16 pistons photos here because that would be laborious, but I can confirm that I did not find any water in the cylinders after the pressure test.
    At 1 bar, there was a little bit of water dripping from the lower radiator hose, next to the A/C compressor. Initially the radiator neck cap was also hissing, but after tightening it, I no longer had air coming out from there. I also increased the pressure to 1.25 bar for a minute, and this caused additional hissing out of the upper radiator hose.
    No coolant leak in cylinders or around head gaskets, no cracked or leaking expansion tank, no leak around water pump.

    I don’t know if these sealing issues are enough to cause the issue I’ve been experiencing, but they clearly need to be fixed before further investigation. I have an order underway with:
    • New upper and lower radiator hoses from MIE
    • New thermostat & O-ring from MIE
    • New radiator neck cap from MIE
    • Small water hoses between thermostat housing and intake manifold/water pump
    • T-bolt clamps to seal all that
    Next step for me will be to replace these parts and check again. I’ll report on this next week because I am away this weekend.
    Would you recommend using a light coat of of dressing/sealant on the inner wall of radiator hoses/fittings (e.g. Hylomar)? Or should I avoid that kind of things?

    Again thank you so much to all who participate in this thread. It is really enlightening to hear your experiences and ideas.


    Spark plugs (NGK BP5ES - from left to right: 8, 7, 6, 5, 4, 3, 2, 1)

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    Pressure testing the cooling system

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  19. JL350

    JL350 Karting

    Jan 20, 2013
    204
    Peter my comment on safety was more about hot coolant and care with pressurising the system. Temporary installations can fail if not done with care, and boiling liquid splashed on an arm or face hurts like hell.

    Looks like you have found a list of culprits that all could be the source of the problem so touch wood, you should get closure soon enough. I don’t have experience with the sealants but would avoid using them in the first instance in case it is masking some other issue. Normally they are not used or needed if mating surfaces for the hoses are in good condition and not pitted and corroded. If there was corrosion damage then the sealant would only be a temporary solution anyway.
     
  20. 71Satisfaction

    71Satisfaction Formula 3

    Jul 15, 2012
    1,219
    New York and Norway
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    Art
    That was a clever idea to pressurize the cooling circuit, and you got some useful results - leaks, hissing, and the obvious one:
    - Dripping from the bottom radiator hose..

    I've used coolant-compatible non-hardening sealants and gasket dressing on coolant components like flanges, gaskets, necks & hoses before and what's nice is it makes them easier to pull apart in a non-destructive way.. Corrosion damage at various alloy necks can indeed be headaches.
    Keep us informed!
    - Art
     
  21. staatsof

    staatsof Nine Time F1 World Champ
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    Mar 13, 2005
    91,358
    Fuggetaboutitland
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    Bob
    A friend of mine and Bora owner who was also a car nut and engineer turned me on to this stuff. His company was in the pump and then vacuum pump business and now they make coolant system tools for Snap On and other automotive tool suppliers. It protects and helps to seal at those spots where the coolant never circulates, goes bad and corrodes under hoses near the clamps. There needs to be a ridge on the neck though. It's very slippery stuff.

    https://www.usalab.com/dow-corning-high-vacuum-grease/?action=select&sku=DOWCOR&device=c&keyword=&campaign=359065554&adgroup=pla-4586063000580586&msclkid=7b7045393af4141fd1752568f5ce364a&utm_source=bing&utm_medium=cpc&utm_campaign=**LP%20Shop%20-%20Consumables&utm_term=4586063000580586&utm_content=24403%20%7C%20Dow%20Corning%20High%20Vacuum%20Grease%20%7C%20%2429.95
     
  22. italiancars

    italiancars F1 Rookie

    Apr 18, 2004
    3,338
    Hershey, PA
    I remember having a conversation with George Garbutt the President of Maserati Automobiles (North America) during the era when these cars were new. While it was related to Khamsins, Ghiblis etc. it concerned a drop in coolant flow under acceleration. According to George the issue is related to the large hoses, while they appear to be in great shape, what happens is the inner wall separates from the hose causing an obstruction in the flow of the coolant. Even under examination the hose seems to be in tact, but the pressure in the system under acceleration causes it to collapse. Then returning to normal at idle.
     
  23. staatsof

    staatsof Nine Time F1 World Champ
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    Mar 13, 2005
    91,358
    Fuggetaboutitland
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    Bob
    There are coiled springs that you insert to prevent this. I have them on the suction side near the water pump on my Bora. That's for hoses in good shape!
     
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  24. jamespeter26

    jamespeter26 Karting

    May 9, 2019
    64
    Rome, Italy
    Full Name:
    Peter
    That's interesting and good to know that the issue is known and has been reported for other cars of the same period. I'll be examining these hoses closely then. Because even if I fix the leaks, that won't solve the problem of drop in pressure/flow under acceleration. I am already going to replace the thermostat and hoses and also considering taking the radiator out to have it reverse-flushed. I'll keep all of you posted about the results.

    Thanks also to Bob, Art and JL350 for your replies and suggestions. I will see if there's any corrosion when removing the hoses but I may end up be using a light coat of dressing if that's not harmful. That combined with T-bolt clamps should ensure a good seal all around.
     
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  25. staatsof

    staatsof Nine Time F1 World Champ
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    Mar 13, 2005
    91,358
    Fuggetaboutitland
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    Bob
    The old V8's water pump impeller is a straight vane design which is highly efficient. My old friend's family I mentioned was in the pump business since the 1920's . Jacuzzi family. Mostly farming well pumps. The hot tub business came much later after they sold the business.

    He had a problem with his Bora cavitating under hard acceleration and when it was hot out it would spew coolant sometimes. I never had that issue. He engineered a curved vane solution by adapting an impeller from a Mercedes 6.9. Those don't cavitate as much. Personally I think that's an issue specific to the Bora due to the radiator being so far from the engine. But it might also explain your drop in pressure.

    I've always used ordinary SS screw style clamps and have never had any issues. If you have a lot of corrosion pitting on the inlet/outlet necks of the water pump, radiator or any other cooling nipples maybe you should repair/replace those. The vacuum grease I mentioned won't seal those up but it will help[ to prevent corrosion. USE VERY LITTLE.
     

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