355 - F355 cambelt tensioner bearing premature failure | FerrariChat

355 F355 cambelt tensioner bearing premature failure

Discussion in '348/355' started by ewn355, Nov 28, 2021.

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  1. ewn355

    ewn355 Rookie

    Jan 19, 2014
    16
    Shortly after (< 2000 km, 1 year) the last engine out (cambelt) service for my F355 M2.7 the engine started to generate a squealing noise. I traced the noise to the front right side of the engine. I initially suspected the aux belt tensioner bearing, so I replaced this bearing, but the noise was still there. I inspected the tensioner bearing for the left side cam belt with an endoscope camera from underneath the car and found the bearing to be in very good condition (visually). I was not able to access the right-side tensioner bearing using this approach, but I was (over)confident that it was fine since the left-side one apparently was in good condition. The receipt from the garage that carried out the cambelt service indicated that the cambelt tensioner bearings were replaced. At the time, I was thinking that it might be a water pump bearing or a hydraulic tensioner on its way out and kept driving the car while keeping a close eye (ear) on the noise to see if it developed further.

    This summer, 6 years (7000 km) after the last engine out service, I performed an engine out service in my own garage and I was particularly interested to see if I could locate the origin of the squealing noise. Yes, it was still squealing. I got the engine out and removed the right-side cam belt cover. I was perplexed to see that the right-side tensioner bearing had left a thick streak of grease all over the inside of the cam belt cover. It looked like the bearing had puked out most of its grease, probably quite soon after it was put in operation. The two tensioner bearings were marked: SKF, ITALY M, W23G, BB1-0111.

    I weighed the two SKF tensioner bearings and found the left-side bearing weighing 388 g and the right-side bearing weighing 385 g. The scale had 1 g accuracy, and the bearings were measured about 20 times to get some statistics. Not sure if this 3 g weight difference equals the amount of grease that had leaked out. I proceeded to remove the sealings for the bearings and took the picture shown below. The bearing on the right with the red X is the failed bearing. Notice that the balls are shiny and almost completely dry, whereas the balls for the other bearing are coated in a thick layer of grease. I feel that I have dodged a bullet on this one.

    Needless to say, I replaced the tensioner bearings with Hill Engineering PT355 bearings and I also replaced the 25 year-old original hydraulic tensioners (BTW: I measured the clamping force for these and they were exactly the same as the new ones (Ferrari 157356)). The engine now runs fine with no squealing noise whatsoever.

    Conclusion: I’m very disappointed with the apparent lack of quality control for the SKF cambelt tensioner bearing. The seal on the rear side of the bearing failed very early and grease started to leak out. I could not find any obvious cause for the seal failure. There was no rupture or visual degradation of the seal. Image Unavailable, Please Login
     
  2. johnk...

    johnk... F1 World Champ
    Owner

    Jun 11, 2004
    11,192
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    John Kreskovsky
    Too me that you continues to drive the car for 5 years says it all. :rolleyes:
     
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  3. steved033

    steved033 F1 Veteran
    Owner Silver Subscribed

    Apr 12, 2017
    9,884
    Atlanta, GA
    Full Name:
    Steve D.
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  4. Jackie and bill

    Jackie and bill Formula Junior

    Nov 29, 2014
    795
    GB
    Full Name:
    William
    What? What does it say to you?
     
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  5. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
    11,192
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    John Kreskovsky
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  6. Ferrarium

    Ferrarium F1 Veteran
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    Jul 28, 2018
    5,728
    Central NJ
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    Eric
    the general rule is don't use the OEM ones use the Hill ones, as you did.

    You hear a noise you stop and figure it out you don't keep driving with the noise. In your case 6 years. I suspect they were not replaces you were just charged for it. Your lucky you did not have an engine failure.
     
  7. Jackie and bill

    Jackie and bill Formula Junior

    Nov 29, 2014
    795
    GB
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    William
  8. Kokose7en

    Kokose7en Karting

    Dec 5, 2019
    209
    SF Bay Area
    Using this date code chart. Your bearings was manufactured 23rd day of 2010 if based on (W23G) engraved on your bearing. SKF bearing date codes suck, so this may still be an unreliable chart. The (W) in the front isn’t mentioned, can only assume it’s a filler for low numbered days. It would make better sense if it was “023G”.
     

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  9. johnk...

    johnk... F1 World Champ
    Owner

    Jun 11, 2004
    11,192
    CT
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    John Kreskovsky
    Are You serious? Didn't Eric already answer it? If you hear a noise from the engine you shut it off and find out what it is. Doesn't matter if it's a Ferrari or a lawn mower. Anything else is asking for trouble. That the op got way with driving 5 years, 5000km doesn't justify doing it. It shows extremely poor judgement.
     
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  10. Jackie and bill

    Jackie and bill Formula Junior

    Nov 29, 2014
    795
    GB
    Full Name:
    William
    Thank you ;)
     
  11. ewn355

    ewn355 Rookie

    Jan 19, 2014
    16
    Wow. Tough crowd. Immediately attacked by the woke morality police. Am I cancelled now?

    To make my post politically correct without offending anyone:

    - Car: Ferrari F355 M2.7

    - Symptom: Squealing noise from front of engine

    - Problem: SKF tensioner bearing, marked SKF, ITALY M, W23G, BB1-0111, started leaking grease shortly after installation (< 2000 km)

    - Solution: Replace tensioner bearing with Hill Engineering PT355 bearing

    - Conclusion: Disappointed with quality control at SKF

    But it is actually an interesting discussion to have: What do you actually do when your F129B starts making a noise? You know, when you don’t sit behind the keyboard and already know the outcome

    - Do you immediately fork out over 5 k$ to have the engine taken out for inspection? I didn’t

    - Do you start running some diagnostics and gather more information? I did, but in hindsight I admit I could potentially have made a bigger effort

    - Do you keep a close eye on the situation and see if it develops? I did, knowing the potential risk. I admit it has been bothering me for 5 years.

    - Do you deal with it on the next occasion? I did. Thankful and relieved that the risk I took turned out beneficial for me in this particular case.

    I may have made a bad call. That’s why I’m sharing the whole story, so that other owners in the same situation may find some relevant information. I find that these kind of “owner’s experience” posts are often the most valuable in these forums.
     
  12. Ferrarium

    Ferrarium F1 Veteran
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    Jul 28, 2018
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    Eric
    Just a thought you've been a member since 2019 at some point you could have had a post and said I've got this strange noise at the front of my engine and the ideas what it could be? Pretty sure you would have got that answer. It's not actually that hard to pull the motor yourself by the way I know some people don't want to do it and that's fine. Fortunately you didn't have an engine failure so all is well that ends well there.

    And I don't believe for a second that shop replaced them.

    Any event glad to hear it's resolved. And yes those bearings large number of them including on 348s were really crappy quality. Now go enjoy it!

    Sent using FerrariChat.com mobile app
     
  13. salbrech

    salbrech Karting

    Dec 20, 2013
    105
    Hi all,
    correct me if I am wrong about the "hydraulic tensioner" (not about the bearing):

    - correct technical designation us: tensioner with mechanical spring and hydraulic damping
    - measuring the force is useless (as long you want to judge the damping)

    Regarding Serviceability or the necessity of it:
    - how severe would be the effect when loosing all the damping? (assuming the mecanical spring is intact)
    (this is not a religious or economical question)
     
  14. Andy 355

    Andy 355 Formula Junior

    Jun 2, 2013
    434
    Sydney
    The internet keyboard warriors would destroy anyone who dares answer that. The only acceptable answer is to replace both the bearings and tensioner units when the belt change is performed, especially when our cars are as old as they are. Well advised to tack the pulley fences also. See you in 5 years.
     
  15. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
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    John Kreskovsky
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  16. 26street

    26street Formula Junior

    Jan 30, 2021
    453
    Westchester New York
    Full Name:
    Mark k
    Wow driving with that noise for 5 years would have made me “nuts” glad to hear you got it straightened out and as far as the bearing I have to say yes the seal letting the grease out is poor quality but the fact that the bearing lasted all that time with out grease has to say something— I would not want to run my car this way but knowing the bearing can handle working under those conditions may have saved your engine



    Sent from my iPhone using FerrariChat.com mobile app
     
  17. MAD828

    MAD828 F1 Rookie

    Oct 8, 2011
    2,620
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    Elliott Caras
    Tacking the pulley fences doesn’t seem to be all it’s cracked up to be Andy based on a recent thread by @Ferrarium
     
  18. Andy 355

    Andy 355 Formula Junior

    Jun 2, 2013
    434
    Sydney
    Typically, the belt should not ride on the fence. As noted, many tensioner bearings can indeed fail, thus pushing a belt onto the fence. How can you be sure your fence is ok at this age? I know from years of supercharger belt experience alignment is absolute priority. Any bearing that has failed, or indeed close to fail has the potential to push the belt fence off.
     
  19. Andy 355

    Andy 355 Formula Junior

    Jun 2, 2013
    434
    Sydney
    Additionally, the it would seem the Ferrari factory welded these in engines built after 97' can anyone confirm this is the case?
     
  20. jjtjr

    jjtjr Formula Junior

    Aug 29, 2016
    755
    Vermont
    Full Name:
    john truskowski
    Everyone has different risk tolerance, and yours could be considered high based on the potential costs involved if failure had occurred. But do know that a lot of people who own these cars are very picky and want every issue resolved immediately, and myself included would not want to take a chance on having an engine failure due to a tensioner bearing. Also, you should know that the experience that you had could be considered rare (having a "new" bearing fail) and lasting for 5 years. Count your lucky stars. :)
     
  21. A348W

    A348W Formula 3

    Jun 28, 2017
    1,846
    North Wiltshire, UK
    Good you caught it.

    I had a 3 year old, 9k miles Hill Engineering bearing out of tolerance so it happens to all of them!
     
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  22. ewn355

    ewn355 Rookie

    Jan 19, 2014
    16
    The car had major services with the cambelts swapped in 2007 and 2015. The cambelts were dated 2014 and the bearings were dated 2010, according to the table that Kokose7en provided. I know the mechanic that carried out those services. Reputable shop.
     
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  23. KevZep

    KevZep Formula Junior

    Feb 17, 2020
    568
    New Zealand
    Full Name:
    Kevin Bennett
    Thats right, they should never be "welded" "tacked", they will fail.
    Use the right pulley.
     
  24. ewn355

    ewn355 Rookie

    Jan 19, 2014
    16
    A good explanation of how a hydraulic tensioner works can be found here: http://www.rockauto.com/genImages/64/HydTens.html
    I did not analyze the damping properties. I inspected the old hydraulic tensioners and found no indication of oil leaks. I also carried out a control measurement of the "clamping" force for the 4 units (old and new), which I assume is a factor that plays in when the belt tension is set. I added that information to partially rule out that there was a correlation between the failure of the tensioner bearing and a hydraulic tensioner being faulty.
     
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  25. johnk...

    johnk... F1 World Champ
    Owner

    Jun 11, 2004
    11,192
    CT
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    John Kreskovsky
    Funny thing is that if you look at the part pictured on Ricambi it looks nicely TIG welded at several points. If you look at the same part on Maranello Classics it looks like a tack weld at two points, but at least it looks like the welding was done before plating. Lastly, if you look at the new parts the Eric actually got recently (from Ricambi?), there doesn't appear to be any welding of the fence.

    Anyway, from a engineering point of view, the fence will have circumferential vibrational modes. When tacked at two or more points the two things happen. The modal structure will change and stress will be contracted at the weld. And if the weld is not heat treated to mitigate changes int he grain structure of the metal at the weld point this can all lead to failure at the weld point as seen in Eric's case.

    [​IMG]
     
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