What damage does not changing a timing belt do?

Hey guys, this question is for the Jap specialists out there.

As we all know, in an interference type engine, the timing belt breaking , basically causes a lot of damage to the engine.

What damage is caused, if the timing belt has not broken, but has been used for a longer time than required?

Is the fuel efficiency/power out of whack? Are any components damaged because of additional strain to the vehicle?

Previous threads that discuss this are here:



Thanks a lot.

For a 98 Honda civic, the belt is supposed to be replaced at 90 K. One particular car that interests me has 135K without the change…
What should I expect, apart from the normal timing belt replacement expenses?

Here’s what can happen when a timing belt/chain fails.


If the timing belt has not broken or stretched and jumped a cog (or jumped bacuse the tensioner was just plain tired), no damage will exist…but if it’s overdue, damage is inevitable eventually. The longer you postpone it, the higher the odds of posting back here saying “my timing belt broke and my engine is trash…what should I do?”.

A timing belt stretched enough to cause bad valve timing (which is what you’re suggesting) will have jumped a cog or broken.

As ok4450, one of the most skilled mechanics on this site likes to say, “Your car will run very normally right up until the milisecond after the timing belt snaps”.

While it is possible that an old timing belt might stretch a bit and “jump” a cog or two, it is more likely that nothing unusual will happen until that fateful moment when the belt snaps–without any prior auditory or visual clues that it is about to fail.

Ouch! Whappa whappa bang!

Thus: the answer is:

  1. Nothing really bad happens to the engine if the timing belt has been stretched and is overdue.
  2. When the timing belt is so stretched that it breaks, then a LOT happens , in approximately 0.5 milliseconds.

If the timing belt DOESN’T fail…then NOTHING will happen…UNTIL IT DOES FAIL. There is no strain on the vehicle…nothing bad will happen WHILE THE BELT IS STILL IN TACT…The problem is…that the longer you wait…the higher the risk of the belt breaking.

Perfect. Question answered, case closed!
I have said this before and I’ll say this again. You guys are awesome, with a capital A, the size of the Hollywood sign.
Three cheers for cartalk!

One of the mechanics I worked with dropped a retaining nut when he was removing the valve cover,thinking it fell safely to the floor he just replaced it with a spare,all it took was a second of starter engagment and the engine was junk (the nut fell where it could interfer with the belt and cam gear. Dealer bought that car and sold customer new one (BMW M20 engine) Lots of those M20’s broke their belts,easy to diagnois (just look through the oil fill cap and give the engine a spin,the cam doesn’t turn)

I was in a car that lost it’s timing belt at highway speed. The car was recently purchased, nearly 15 years old at the time, and unknown maintenance. The car was running fine right up until the belt snapped. Behaved just like someone had turned off the engine. We managed to cruise at an off-ramp and parking lot. The belt shredded, and was painfully obvious that it was the timing belt with strands of belt sticking out from under the plastic covers.

Fortunately, it was a non-interference engine. We got the belt replaced and the engine re-timed and we were on our way a few hours later.

This was a timing chain engine. Here’s what’s left of one of the timing chain guides. This is one of the reasons I’ve never believed a timing chain lasts the life of the engine. Unless you believe the life of the engine is when the timing chain fails?

And that’s what happened! The plastic timing chain guide material failed and fell between the timing chain and the gears. Just like the nut.


Houston Rice, You May Have Misunderstood Our Earlier Conversation.

I said, "It makes me wonder what else was neglected. I don’t know Hondas. Maybe somebody else will jump on here and tell whether any damage was done to the car by not doing the 100,000 mile service."

I was referring to maintenance other than the timing belt. Neither the 100,000 mile service was done, nor the timing belt. Then the car was run up to 130,000 miles and therefore has 30 to 60 thousand miles possibly without recommended service.

I don’t know what was missed, valve adjustment?, transmission service?, brake service?, etcetera, and what damage or wear could result. I just donn’t know the care and feeding of a 98 Honda.

If anybody missed the discussion, it’s down the page on this Toyota question.


The owner tells me:

he took it for regular maintenance about 2 months ago and the recommendation was that the tune up should be done soon which is why the price was adjusted from the blue book value.(people always want kbb value. Dealers offer a pittance!)
The timing belt wasn’t mentioned at all by the person who did the regular maintenance. He read the thread that you sent. Unfortunately he cannot adjust the price by another $500.00.

Exactly what you mentioned on the other thread…the Hondas dont go too low on prices.
Question is, is it worth the 2000$ , with 700 added for the timing belt? Should I learn how to change the belt myself and do it?

CSA, if you feel comfortable, I’d like to mention a few things which a public forum might not allow me to do without compromising a lot of peoples feelings and privacy.
my email address is : my city my university @ gmail dot com; in other words;
my login id at gmail.com

FWIW, two Toyota V6 pickups have been serviced here with noisy idle. The timing belts were past due and the belt slack had hammered the timing cogs’ key ways, destroying the crankshafts.

It is possible it might not stretch before it breaks, but if it does, the timing could be off, and the engine would run rough or not at all. If it stretches a lot, and it skips several teeth, you could end up with the same consequences as a broken timing belt.

I notice your jpg picture designation as BMW, which one was this? I just had to call my BMW friend and he says yep it happens but it usually proceded by thousands of miles of chain noise,espically on cold start up. Most likely e-36 318? or maybe even a older e-30? I snapped the guide on one of those taking the head off, not a good move.

agreed—I had a timing chain failure that trashed the interference type engine.

I have since learned that the chain guides and tensioners need to be replaced every 100K miles to prevent the chain from slippage/ disengagement. Even at that though the chain could still break…

could be stranded with a trashed engine or stranded with an engine that needs a new timing belt.
I think it depends on if this is an interference type engine…

Thanks for the reply.

How does one get to know whether the timing belt has been changed or not, just by looking at the timing belt and water pump, in the absence of receipts??