360 timing belt tension question | FerrariChat

360 timing belt tension question

Discussion in 'Technical Q&A' started by mrpcar, Apr 5, 2010.

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  1. mrpcar

    mrpcar Formula 3

    May 27, 2007
    1,114
    Chino hills, CA
    Full Name:
    Robin
    sorry, more timing belt tension question. Just wanted to be sure.

    According to the factory workshop manual -

    Compress tensioner towards center of the engine so the lock holes can be lined up on the hydraulic tensioner so locking tool "just a pin" can be inserted.

    Next step, replace belt etc....

    Set tension on the belt around 190-220 MHz range (combined reading from the long stretch section of the belt and from tensioner to the drive gear) , turn crank by hand two times let it sit for two minutes and then ck tension again.

    Once the tension is set to spec. range remove the locking pin from the hydraulic tensioner.

    OK, sounds simple, basically from my understanding of the shop manual the recommended tension setting is set as static without any hydraulic tensioner pressure applied to it, correct?

    Here is what else I am curious about:
    Setting the belt at 190-220MHz tension feels pretty tight already. After running the engine for several minutes I measured the tension again on the belt and the value on both sides of the belt shot up at least 20-40 MHz. I would say the value went up because now there are tension being pushed onto the belt from the hydraulic tensioner.

    Does that sound like too much tension on the belt?
     
  2. away

    away Formula Junior

    Aug 5, 2004
    635
    Lansdale, PA
    Full Name:
    Andrew
    Got me sir but I'd be curious to know myself.
     
  3. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,238
    Frederick, Maryland
    Full Name:
    Brian Brown
    The engine block and cylinder heads are aluminum, which expands a great deal as it changes temperature. This is why you must set the belt tension with the engine cold. Between the expansion of the block and the hyraulic tensioner, I would say that the tension is probably good.

    Perhaps some other people who have checked the tension hot will chime in.

    Brian Brown
    Patrick Ottis Co.
     
  4. mrpcar

    mrpcar Formula 3

    May 27, 2007
    1,114
    Chino hills, CA
    Full Name:
    Robin
    #4 mrpcar, Apr 10, 2010
    Last edited by a moderator: Sep 7, 2017
    I think I finally figured it out. The shop manual was not very clear but I think I now understood the logic it was written in, but please correct me if I still don't get it...

    Procedure to tension the belt: (At this point the new belt is installed)

    Rotate pulley with tool towards the internal part of the engine until lock (pin) is free to slide into the seat of the hydraulic tensioner (damper). So this is the part where you rotate the tensioner with the special two prong tool so it can compress the damper piston in so the little hole on the piston shaft and housing can line up. But supposedly if you followed the belt removal procedure the locking pin is already inserted into the hydraulic damper housing.

    Ensure the distance between the tensioner (damper) and the pulley holder is equal to 1.9 - 2.3mm. (I think this is when the shop manual should have said to stick a feeler gauge with a combined gap that falls into 1.9-2.3mm range in between the pulley holder and the "damper" housing, see picture)

    Below is my own language:
    Adjust the eccentric tensioner so there is tension on the belt, measure with the Clavis tension gauge adjust if necessary. Rotate the crank two times by hand and wait two minutes and check tension again. When tension falls in correct range remove the feeler gauge and the locking pin.

    So right now I meet both specs. Belt tensioned between 190-220 Hz, gap between the pulley holder to the tensioner (damper) housing is between 1.9-2.3mm and I can freely insert the locking pin in and out even after several crack rotations ( I believe this was one of the tensioning recommendations by one of the techs on this board).

    What do you guys think?
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  5. Bjarne360

    Bjarne360 Rookie

    Jul 8, 2015
    2
    I have been wondering about the same thing. This makes sense, but when I remove blade measure goes down too 150 hz. Maybe the tensioner is worn and lazy.
     
  6. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,114
    Georgia
    Full Name:
    Wade Williams
    You should be able to set the tension when the pin relaxes, and then rotate the engine by hand a few turns and check it. the tension should stay. If it drops or the gap goes away, I replace the tensioner. Also, when I start the job and get the cover off, I look at the tensioner, if it is collapsed, I'll replace it. Mind you, this is just how I do it after years of experience. I am sure there are many correct ways of getting to the number. This is just what I do. For whatever that is worth.
     
    modificator and brian.s like this.
  7. dersark_painclinic

    dersark_painclinic Formula Junior

    Mar 8, 2005
    981
    Glendale, CA
    Full Name:
    Lazik Der Sarkissian
    Robin, there is a video on you tube by an English man mechanic ( Ratarossa) explained step by step the process.
     
    Mimmo Blue likes this.
  8. windsock

    windsock Formula 3
    Rossa Subscribed

    Nov 29, 2006
    1,066
    The tensioners are very slow to react be patient, the tension also needs to be checked at TDC number 1 otherwise the camshaft attempting to turn due to spring load from the valves can affect the readings. The pin should freely move in and out of the alignment holes at 200 hrtz belt tension and this will correspond to a 2mm gap at the tensioner. ensure that you have the updated tensioner and bracket for the LH tensioner, drivers side.
     
    brian.s and fatbillybob like this.
  9. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,294
    socal
    There are many older pro experienced techs around before the hz meter belt tensioning. Do you more experienced techs set to what Ferrari is posting in the WSM or are you using that data plus past experience and coming up with your own frequecnies?
     
  10. brian.s

    brian.s F1 Rookie
    Professional Ferrari Technician

    Nov 3, 2003
    3,806
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    Brian
    Manual specs between 190 and 220 MHz. I try to get right in the 210 range. At this the gap is correct to tensioner body and a pin will easily slide through the tensioner.
     
    2NA likes this.
  11. zstyle

    zstyle Formula Junior

    Jun 28, 2007
    531
    Fountain Hills
    Full Name:
    Jon
    Despite all the talk about about tension of belts, which I have always used the easy-to-slide-pin method, you need to be sure both exhaust cams are dialed correctly. Having a difference in cam variator readings on the SD2/3/X can throw a CEL and also cause poor performance.

    Unfortunately, you cannot dial in the timing pulley/camshaft in a static mode. Then engine must be running to read the value and then shut off to adjust pulley/camshaft. The discussion about what values to dial in to is a larger discussion since it will affect performance slightly. A trained ear can also notice the difference between synced cams and out-of-phase cams.
     
  12. chris GT3RS

    chris GT3RS Rookie

    Sep 26, 2015
    5
     
  13. chris GT3RS

    chris GT3RS Rookie

    Sep 26, 2015
    5
    You guys can’t end a thread like that that’s a cliffhanger.

    so are you inferring that you cannot change belts and set them correctly without the SD computer?

    also you don’t explain how to get the variators to make sure they are at zero and not advanced without the computer either for us regular guys
     
  14. chris GT3RS

    chris GT3RS Rookie

    Sep 26, 2015
    5
     
  15. chris GT3RS

    chris GT3RS Rookie

    Sep 26, 2015
    5
    I’ll say you say you cannot dial in the timing in static mode

    Aldis voice shows a bulletin and talks about putting the dial indicator on top of the valve with the valve covers off and setting it which is probably how they did it when they built the motor, as in no computer
     
  16. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,114
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    Wade Williams
    Bottom line is. If it is in good running order and all you do is swap the belts, then it will still be in good running order. The varitator sync only becomes and issue if you remove the cam pulleys, they have slotted mounting and can not be installed precisely in the same position. You then need to start the engine and check both cam readings and adjust them to not only the same number between the two but the correct number for best performance. That take a diagnostic tool. I use an SDX, It allows me to see both sides of the engine at the same time. I believe this is important and the engine warms it can change slightly. It takes some time to switch sides in the parameter pages with other tools.
     
  17. RedNeck

    RedNeck F1 Veteran
    BANNED Silver Subscribed

    Jul 8, 2016
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    I am actually pulling my cams this week and I was going to have you replace the variators for me (I have the parts, just not the machine-ability and do not want to risk the "big twist")...so after I re-install the cams and pulleys, is it not enough to put the engine at TDC and then use the factory timing marks to adjust the cams, then tighten up the pulleys, or is that just a "good enough" setup to then have the variators properly sync'ed at a later time?
     
  18. tazandjan

    tazandjan Three Time F1 World Champ
    Lifetime Rossa Owner

    Jul 19, 2008
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    Terry H Phillips
    Those are not timing marks, they are assembly marks to keep you from bending valves during assembly. Not sure if the factory technicians scratched timing marks on the rear of the cams like the V12s or not.
     
  19. RedNeck

    RedNeck F1 Veteran
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    Jul 8, 2016
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    All the info that I’ve read shows the etches on the rear of the camshafts are factory timing marks. If that’s not correct, that would be good info to have...
     
  20. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
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    Mitchell Le
    Assembly marks at the front of the cams near the pulleys. True after-assembly marks are at the rear of the cams. However, unless you have a way to find the TDC Cyl1 that is identical to the factory setting, then it does not matter where the cams are, you are still going to be off.
     
  21. RedNeck

    RedNeck F1 Veteran
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    Jul 8, 2016
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    I have the Hill TDC tool and degree wheel, which I intend on using, but theoretically, If I get the motor to TDC, where the timing marks on the rear of the cams, and then mark the crank and pulleys for reference, that should get it back to the original timing, correct?

    I have done this type of work on other cars, btw. I don't see the real difference, this motor seems pretty straight forward in that aspect..
     
  22. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
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    Mitchell Le
    If you find TDC accurately, and line up all the scribe marks at the back, it should be good enough to run.
     
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  23. Ferrari Tech

    Ferrari Tech Formula 3

    Mar 5, 2010
    1,114
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    Wade Williams
    The marks will get you close enough to start it for sure. There are ways to time the cams based on piston position vs lobe lift. In that way, no degree wheel is needed as it is tight getting one on the engine in the frame. That method will get you very close. The diagnostic check will get the exhaust cams dialed right in so the Motronic is happy. The intake cams are not monitored by Motronic so they will not trigger a CEL.
     
    RedNeck likes this.
  24. Ernieinky

    Ernieinky Rookie

    May 25, 2018
    30
    Full Name:
    Matthew Ernst
    I just did mine according to Aldous timing article. I set the timing as per his article after contacting him and asking if I needed to have a diagnostic scanner to do exhaust cams, he said ‘not needed’ I also changed out my heat exchanger, water pump, belts, tensioners, tensioner bearings, thermostat, spark plugs as well as send my injectors off for cleaning. Started the car after and it jumped to life, happy as ricotta cheese in a cannoli...


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    RedNeck likes this.
  25. 26street

    26street Formula Junior

    Jan 30, 2021
    343
    Westchester New York
    Full Name:
    Mark k
    I kinda lost track of the original question lol
    The factory install procedure is for new belt replacement this is why there is a rest period between checking adjustments it allows for stretch, the tensioner and idle bearing ,
    my opinion should be replace the cost is cheap Insurance and you are there already
    If you have no performance issues or engine codes setting the cams pulleys for sync really should not be a concern but having a look at them would not hurt
    I would do a before and after comparison if you have the proper equipment to do so (scan tool,dial indicators,etc)
    The only other alternative to a scan tools,etc is using a lab scope with 4 Channel capability back probe the cams sensors and crank sensor all signals have a synchronization tooth which the ECM uses for ignition and fuel timing
    And that’s what you are seeing on the scan tools
    Working with scopes takes getting used too but is more accurate and finding a tech who really knows is hard
    Anyway good luck if the car is running good and no lights on the dash —— drive and enjoy put those dead dinosaurs to work——


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