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Gasketed sufaces dry or sealant?

Discussion in 'Boxers/TR/M' started by mexicruiser, Dec 11, 2020.

  1. mexicruiser

    mexicruiser Karting
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    Aug 28, 2012
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    Jon Brinckmann
    I’m at the point of installing the water pump cover and the oil filter base on my BBi, both these parts use a gasket which were pretty hard to clean off but didn’t appear to have any sealant on them. Since these are areas under pressure and not accesible once the engine is in I’m feeling insecure assembling dry. Options I have considered: on the water pump gasket a light coat of hondabond, on the filter base gasket Loctite 515. My concerns: the hondabond may make removal difficult next time? The Loctite 515 is anaerobic sealant not designed to be used on a gasket, it may not dry or not adhere properly. Shellac might seem to be a lowly option on this kind of car. What are the proven choices on these areas guys?
     
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  3. energy88

    energy88 F1 World Champ
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    You are doing the right thing by asking. Hopefully one of the renowned engine builders on here can weigh in on your dilemma. Do you have access to a factory manual that might say?

    FWIW, just yesterday I had a similar question about proper procedure in mounting a rebuilt Quadrajet carburetor on a Chevy engine. The guy I contacted is considered an expert on fuel systems and his response (in my application) was emphatically to not use any sealant. I'm comfortable in reassembling the engine this way due to his expertise in the industry and glad I was able to avoid "noise" from others who may not know as much as they think they do.
     
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  4. turbo-joe

    turbo-joe F1 Veteran

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    on all paper gaskets I always put on some very little hylomar. it is then later much easier to remove the gasket
     
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  5. Extreme1

    Extreme1 Formula Junior

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  6. vincenzo

    vincenzo F1 Rookie

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    Hylomar on the block side of gasket... silicon (hondabond) on the cover side. Ez cleanup next time - gasket comes off with the cover in one piece.
     
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  8. mexicruiser

    mexicruiser Karting
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    Ok, I’ve been thinking long about this and on both parts I will use the loctite 534 if I can find it (Same as 515 but tacky and on a stick applicator) if not I will use the 515.
    I used this product to mate engine and transmission and the instructions didn’t specify a primer was “required” only “recommended if large gaps or cold weather”, I now read elsewhere this primer 7649 is necessary on aluminum parts too! I will have to investigate if this only causes a long curing time (hopefuly) or if there are problems with adhesion (disassemble again).

    The hondabond I would not use on the oil filter base because of the excess silicone causing problems, I found a Hylomar stays gooey and doesn’t fully dry, this can’t be good on a pressurized application where you want to help the gasket stay put, I imagine on the valve covers, carb bases or areas where fluids are splashed (not immersed or pressurized) it is ok.
     
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  9. JohnMH

    JohnMH Formula 3

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    OEM Ferrari gaskets are designed to be installed dry - you never see tubes of workers using sealant in photos taken at the factory (they were not assembling old Jaguars). If you put sealant on them, the gaskets slide around and have a greater propensity to leak. If you just install them dry and torque the fasteners properly and in the correct order they don't leak. The only exception on a TR valve cover is the small dab of Hondabond at the 90 degree corner where surfaces meet at the end of the valve covers. As to my understanding the water pump and oil filter bases are flat seams, gaskets should be installed dry.
     
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  10. mexicruiser

    mexicruiser Karting
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    The crankcase halves and transmission use sealer from the factory, so some tubes are probably around the engine manufacturing area. Keep in mind these parts are no longer fresh out of the machine shop so heat cycles can cause warping and fluids can cause pitting, also gasket removal procedures (very difficult on my engine at least) can all make for a less than perfect seal.
    On the timing case I used hondabond only around the water passages and the rest of the gasket was installed dry, but this part is not immersed in oil and has no pressure.

    My timing cover gasket was not difficult to remove as was the sealer on the transmission, but valve cover and intake gaskets were incredibly hard to remove even with paint remover, makes me wonder if these were perhaps “dressed” with some compound at the factory?
     
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  11. JohnMH

    JohnMH Formula 3

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    The crankcase halves use sealant, but no gaskets. Even dry gaskets stick of left long enough.
     
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  13. mexicruiser

    mexicruiser Karting
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    #10 mexicruiser, Dec 25, 2020
    Last edited: Dec 25, 2020
    I did some research and also some testing and some using, here’s what I learned on the various loctites:
    -I was concerned the 515 I used to mate the engine to transmission wouldn’t dry because I didn’t use primer, (the instructions on the tube where in chinese, literaly)., the instructions on TDS state curing on aluminium is slow and primer should be used. So I ran a test on small the drop gear nut cover. I used four big drops of 515 without primer between the studs and tightened lightly, after a week to allow for the advertised slow curing I was able to separate the cover with no effort and found the 515 to be cured dry between the parts and only what had been squished out was left uncured. It was also very easy to remove the dried sealant using only a wood toothpic. I ran the same test using primer, this time curing was faster and when loosening the nuts a small cracking noise could be heard, still easy to remove the cover and sealant.
    Veredict:
    515 cures without primer if squeezed between aluminium alloy surfaces (no air), squished out sealant remains uncured even if primer is used (important on engine internals).
    If primer is used curing takes place faster, although it could negatively affect flexibility.
    515 cures to a hard plastic and I would probably use 518 or 5188 in applicattions requiring some grade of flexibility or with studs/bolts too far appart.
    515 is not very thick and spreads easy allowing the assembled parts to seat properly even if tightened lightly, this is good if shimming is a concern (like in engine halves) just consider if primer is used assembly time is shorter.
     

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  14. mexicruiser

    mexicruiser Karting
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    Loctite 518, this product is advertised as preferred on aluminium surfaces.
    I did the previous test using 518 and primer, It is very tick and didn’t squish out as easy so if using on light tightening I would be concerned with the parts not seating completely. I checked on the parts the next day, when loosening the nuts a loud crack was heard, cover was easy to remove as was the sealant. This sealant after curing remained a bit more flexible and didn’t easily flake of the parts with the toothpick, so instead I used a paper towel and some gasket remover.
    My opinion: this sealer seems to allow for more movement between the parts after curing as it remains more flexible, but it is very thick so not ideal if shimming is a concern specially in light tightening applications or thick flanges.
    As a gasket dressing it is too difficult to apply because of its viscosity (I used it on the oil filter base and valve covers) and you end up using too much, so the “stick” presentation is probably the best option, if tackiness is desired.
     
  15. mexicruiser

    mexicruiser Karting
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    Along the way I learned that threadlocker behaves the same, so if using threadlocker on “inactive” surfaces a primer is mandatory or no curing takes place. This would apply to bolts that are blackened, zinc coated, anodized, stainless, painted, titanium, so basically all bolts. unless of course they are threaded into bare steel or iron. If bolted onto aluminium alloy used for engines it “could” be fine as long as the alloy material is active (copper), even then curing will be slower so I don’t think it is worth the risk. Never knew.
     
  16. Solid State

    Solid State F1 Veteran
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    I use a gasket sealer on most paper gaskets. The sealer is a spray and just a bit tacky and helps the gasket stay together when removing. Otherwise you will likely be scrapping off old gasket on both sides. The thicker stuff like RTV on gaps and such and also when the first time try without it leaks. Impossible to tell if you will need the thicker stuff as it depends on how the two sides mate up after torquing. RTV tends to make a mess.
     
  17. mexicruiser

    mexicruiser Karting
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    Would you share the name of the spray you are using?
     
  18. Solid State

    Solid State F1 Veteran
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