Broken timing belt questions.. | FerrariChat

Broken timing belt questions..

Discussion in 'Technical Q&A' started by JeffMN, Feb 14, 2004.

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  1. JeffMN

    JeffMN Rookie

    Jan 18, 2004
    I'm still searching for the right TR.

    I'm curious--exactly how bad is it if you break a timing belt? Does the whole motor generally go or is it time for a valve job? Is it just a matter of buying new valves/guides, and refacing the heads?

    I understand that the valve will contact the pistons and bend, but are the pistons actually trashed as well?

    The idea of having a $100 belt break and ruin my car worries me to no end.

    If this happens to a flat 12 in a TR, is the motor junk? rebuildable? Too expensive to rebuild?

  2. henryk

    henryk Formula Junior

    Dec 9, 2003
    Door County, WI
    The valves would be bent, for sure! I doubt that a head re-surfacing would be needed. If the RPMs are high enough, at the time the belt breaks, then I can see where a piston, or two, would also get cracked.

    If the rest of the car is asthetically pleasing, I can't see any reason not to re-build it. If not, then one can consider the TR as a parts car. I guess one can still sell the car, if the budget doesn't allow for a re-build.
  3. MS250

    MS250 Two Time F1 World Champ
    Lifetime Rossa

    Dec 10, 2003
    Full Name:
    I have an 86 TR, rule of thumb is 5/6 yrs for the belt change. No such thing as $100 for a ferrari, unless its time to put a full tank of gas. Belts on a TR when due is probably5-8K depending on what needs to be done. There are many topics on costs on this brd you can find aot in the archives. I have yet to hear of a broken belt but it does really depend on when and where. If your at 6,ooo rpm and she snaps...yes you now have a great parts car, by another TR and keep that one for parts. I have been following this car since 84 and love my car to death, I never worry about a belt because I change them every 6 yrs...and if it does break...well then I have the best looking flower pot in the region.

    Don't let that stop you from buying the TR...pretty built proof, just need to find a properly serviced car with matching history and keep up to date on the service.
  4. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    Under the assumption that the belt broke and you are looking at a TR with a non functional engine; my opinion is that a good deal more of the motor is trash than you anticipate. Certainly several valves will be bent, but the pistons that bent the valves will have suffered some internal (not necessarily visible) damage and are and will continue to be a grave reliability concern. I have known motors where the valves hit the pistons to harbor bent crankshafts and bent connecting rods (not Ferrari engines).

    Me, I would pass. The risk reward relationship is very far south.
  5. khayes

    khayes Formula Junior

    Nov 1, 2003
    Austin, TX
    Full Name:
    Kelly Hayes
    Mitch, I don't think he is looking to buy a TR with a blown engine but is simply asking what if the belt breaks after he buys it. Buyers remorse before the purchase.
  6. JeffMN

    JeffMN Rookie

    Jan 18, 2004
    Thanks for the replies.

    So far the only belt failure I've heard of is someone from this forum. They had 42,000 on theirs when the belt went.

    Paranoia! :)

  7. parkerfe

    parkerfe F1 World Champ

    Sep 4, 2001
    Cumming, Georgia
    Full Name:
    Franklin E. Parker
    I personally know someone whose had a cam belt in his TR break a little more than 5 years and 45k miles after his last cam belt service. He had a leaking cam seal and had been told by the dealer that it needed replacing for months prior to it breaking. The leaking oil had weakened the belts over time. It was on his roundtoit list that never got done. I beleive he said it cost him around $25k to have it repaired .
  8. Husker

    Husker F1 World Champ

    Dec 31, 2003
    western hemisphere
    Changing belts every 6 or 7 may give you some peace of mind, but it's probably not necessary. I know of two 308's (a 1980, and a 1981) that still have the ORIGINAL timing belts. Let's see...that's 24 years and counting...

    This topic has been beaten to death, but the simple truth is, out of the thousands and thousands of Ferraris out there, you will be hard-pressed to find ONE firsthand that the belt(s) has broken on, regardless of time and mileage. So the odds are pretty well stacked in YOUR FAVOR.

    Follow the manual (which is probably way overkill as well) AND DRIVE IT.
  9. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    The Cold North
    Full Name:
    Glad it's you're wallet and not mine :)
  10. gabriel

    gabriel Formula 3

    Absolutely. The best way to keep everything running well is to drive it!
    I'm sure there have been belt snafus, but they aren't at all common - I really don't know of any first hand, and you do intend to maintain it, don't you?

    The TR is an awesome machine...
  11. Mark 328

    Mark 328 Formula Junior

    Nov 6, 2003
    Orange, Ca
    Full Name:
    Mark Foley
    I have heard that most belts break at idle not at high RPMs and it would make sense because at idle there is less rotating inertia.
    Additionally, the belt breaking at idle has been my experience on another car.
    Breaking at idle would tend to minimize the valve/piston damage.
    PS one of my neighbors had 50K+ on a 308 with original belts!
  12. pdavis

    pdavis Rookie

    Oct 31, 2003
    Morristown New Jersey
    Full Name:
    It's extremely rare to hear of a TR belt failure. Kindly like the US Gov. still looking for weapons of mass destruction? Buy the TR and enjoy it! pd
  13. Slim

    Slim Formula 3

    Oct 11, 2001
    Pacifica, CA, USA
    Full Name:
    If the belt brakes, I suspect there won't be much damage to pistons. You'll know right away and the car won't run. If a valve snaps for some other reason and the head is still in there bouncing around while the engine is running, well, in that case it will indeed damage the piston.
  14. tbakowsky

    tbakowsky F1 World Champ
    Consultant Professional Ferrari Technician

    Sep 18, 2002
    The Cold North
    Full Name:
    You can have damage to a piston that is not visable unless you remove it from the engine, and have it magnafluxed or sonic checked for cracks.
    Many times a ring land can be crushed and you would never beable to tell with the piston still installed in the engine. If you can see were the valve hit the piston(and you most defenatly will) then depending at what rpm the engine was could have more damage the you know. A conn rod could bend..the con rod bearing could get wiped out, etc,etc.

    Mind you like others have said the belts snapping are few and far between,but if your are going to purchase a TR be sure to get the belts changed if the service history is not complete aleast for the last 5 years.

    Worst case is the belt snapps at high rpm valves break and bend and get smashed into the cylinder head..then the piston gets smashed into chucks which falls into the sump and the resulting matel bits find there way in between the crank and the main bearings and the wipes out the crank. Even before this happends..with in a matter of seconds,you will need the following

    2 new or used cylinder heads
    new set of pistons
    new set on con rods
    new crankshaft(or recondition your old one if possiable)
    new oil pump (because of the metal from the piston)
    new rings
    more then likely atleast 3 cylinder liners
    piston pins and bushings
    main bearings
    con rod bearings
    all gaskets
    possiable valve springs and retainers
    valve guides and seals
    timing belts
    have the cams checked for damage from the valve being rams up against it when the piston made contact with it

    I have seen a timing chain break on a Lambo Diablo due to a faulty tensioner. The list above is what we had to do inorder to put the engine right again. Cost over 40,000 to do this job.

    Please don't skimp on this service..just get it done and you'll save in the long run. Trust me.

  15. ShanB

    ShanB Formula Junior

    Jul 9, 2003
    Full Name:
    Tom - good points and appreciate your insight as a mechanic. At what point does it just become cheaper to replace the engine rather than rebuild? Just a thought.

  16. Ken

    Ken F1 World Champ

    Oct 19, 2001
    Arlington Heights IL
    Full Name:
    Anecdotal evidence suggests most belt failures come from oil leaks on them. I've read a zillion threads here on belt failures and I can say that they seem to be rare, and oil leaks are almost always mentioned in the same breath. (Standard disclaimer: my car has a chain)

  17. Ksullender

    Ksullender Formula Junior

    Sep 3, 2003
    Most cam belts aren't in danger of a breaking point at the service interval, but the cam belt tensioners are worn which in turn can result in a slipped belt or other belt failure. The belts themselves are typically very durable, way beyond the service interval. Make sure if you check service records the tensioners are replaced.
  18. JeffMN

    JeffMN Rookie

    Jan 18, 2004
    Thanks for all the info.

    I PROMISE I won't start another belt thread.


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