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Honda Accord Timing Belt broke while on highway

Hi experts,

My wife was driving our Honda Accord 2002 with 117K miles on the highway at 65 mph when the car quit, she immediately pulled to the shoulder. We had it to towed to a nearby mechanic shop. The mechanic, after diagnosis, said the timing belt broke(more like shreded) along with broken crankshaft sensor. He thinks it could have damaged the engine with bent valves etc. He wants $700-$1000(no firm estimate is possible as per him) first to fix the timing belt and then try to figure out if there is a damage to engine(which he estimated could another $2000).

I had more than $1000 worth of work done on the car in Febraury 2010 with another shop, part of which they had replaced the timing belt, water pump, other belts, crankshaft sensor, tensior etc. They said the labor warranty is only 90 days and so wants to pay for any labor(screaming arguments over the phone). Now I do not feel comfortable going to the old shop now and have to figure out my legal options on dealing with these guys. Now here are my questions:

1. What is the likelihood of bent valves in this case? Very high, high, medium, low etc.

2. Is there a way to find out upfront if there are any bent valves so that I can better negotiate the entire job upfront. I read about this tool. Would this be helpful? Or there alternate ways to find out.


3. What are the chances of more damage to engine other than bent valves like piston damage etc. Again would I be better of with replacing the engine. Otherwise, the car is in excellent shape.

I have pictures of the damage, how do I upload here

Get a mechanic to first remove a valve cover and check valve lash.
This is a 30 minute job to determine if there’s valve damage.
No need to replace the belt or any other parts to check for valve damage.

There is a way to check to see if the pistons and/or valves are leaking. Lock the crankshaft in a neutral position where a piston cannot fly up and strike another open valve; turn the camshaft of the cylinder to be tested until both the intake and exhaust valves are closed; pressurize the cylinder using a leak down gauge with shop air; and listen at the intake, exhaust, and crankcase for escaping air. Once you have determined how many cylinders have a bent valve you can negotiate the likely cost of repair.

It is likely that when the heads come off there will be additional damage found.

BTW do you have the I4 or the V6 in this Accord? Did the diagnosing mechanic opine the cause of the belt shreading/breaking? Are any of the replaced or nonreplaced items jammed? Are the camshafts free turning? Just curious.

4 or 6 cylinder? A new timing belt, and associated hardware should not have failed in only 6 mos. if done right. Something is fishy here.

1 Like
  1. Bent valves high
  2. Assume they are bent, you cannot get a price for this work ahead as damage varies
  3. Usually very little other damage to engine. You need to evaluate new engine cost

Timing belt cars are the pits. My wife’s Subaru Legacy will be my last timing belt equipped car as I will never buy one of these again. My Subaru I plan on trading off/selling when it comes due.

I am sorry, here are some more details as requested.
The car is 6 cylinder. The diagnosing mechanic could not say for sure what is the cause, just guessing that some nut or something small was left behind. I am not a car guy, so I will ask the current mechanic on Researcher’s questions. Yes, I am suspecting a shady job by the old shop but not sure how to prove it.
I am attaching the pictures and hope someone can explain the catastrophic failure especially the crankshaft sensor where in the pictures you can see it is clearly broken.

Likelihood of bent valves? 99.99%

The belt does not have to be replaced to determine damage. Checking valve lash, cam rotation until the valves are closed and applying compressed air to see if air hisses out intake manifold, etc. are a couple of methods.

If the original shop replaced the tensioners, belt, water pump, etc. then the odds are near dead certain they screwed up. The current shop should be able to tell you why.

I can understand the 90 days labor warranty but in a case like this where I feel that someone screwed up the shop should make an exception and eat the cost of this one. However, it sounds like they’re not going to.

Normally the only damage that occurs is to the intake valves, all of which must be replaced along with performing a complete valve job.
A couple of tips if you have this done. The tops of the pistons will be nicked up and any and all sharp edges on those nicks must be rounded off. Failure to do so can create hot spots due to glowing metal. This leads to detonation, possible serious engine problems, and back to square one.
It would be a good idea to go back in and recheck the head bolt torque and valve lash approximately 1000 miles after the repair is done.

Normally the rest of the engine will not be damaged but there is a posibility of microscopic piston cracks or damaged rods/rod bearings. This is no way of determining this without a near complete engine teardown.
Hope some of that helps and do NOT spend a chunk of money determing whether damage exists or not. It’s not necessary.

It is possible that a new belt will get your car running again but it is unlikely. The leak down test is the most dependable. Damage to pistons is possible but rare. The damage is often barely noticeable on a visual inspection as the dings on pistons and valves is usually very slight. Just enough to keep the valves from seating. The real nightmare is when a valve head breaks off and bounces around for a while.

Why did the crank position sensor break? Most likely a strand of the timing belt wandered onto the pulse ring for the sensor and jammed itself between the ring and the sensor’s pole piece.

Based on the picture, the belt did not come completely off. What may have shut the engine off was the crank sensor being broken by the shredding of the belt.

Its possible the broken crank sensor shut the engine off if the belt only shredded and did not come completely off, saving the engine from damage. If this is the case they should be able to check if the old belt is still aligned or close. Maybe it only skipped a couple teeth and not enough to cause valve damage.

Hi all,

Thank you very much for your responses. americar, your comments are little bit encouraging. You were right, the belt did not completely come off. The belt is seriously shredded and I am uploading the rest of pictures.
ok4450, I will print this entire thread and discuss with mechanic to make sure they address the issues you have raised if the engine repair is performed.

Picture 002 looked pretty encouraging, Picture 001 however not so much. You still could have gotten lucky though.

A couple Questions 

Did the check engine light come on prier to the engine shutting off?

When the engine quit running was there a clunk sounds that could be associated with valve parts crashing together?

Lots of lights flashed on the dashboard including the check engine light and they were all on after the car was stopped on the shoulder.
There were some sounds but my wife is not sure about the type of sounds(whether due to breaking of belt shredding and broken belt strings coming and being piled up as shown in the picture or the clunk sounds with pistons hitting the valves).

Sometimes if a belt breaks at idle speeds one may hear a brief rattling sound. At higher speeds when this occurs the noise may be a split second whirring sound. It can be difficult to hear this due to other engine noises, road noise, accessories being on, etc. and with the momentary alarmed feeling and the fact that it happens so quickly being a factor.

It would be easiest to pop a valve cover and inspect for loose rockers on the cam lobes (intakes). The valve bends, this prevents it from seating fully on the valve seat, and this is what causes the excess lash.
The intake valves have larger heads than the exhaust valves and so they’re generally the ones that hit.
Got to love an interference fit engine, huh?

HI all,
I am original poster, I thought I will provide an update and seek further advice on the next best steps to fix the problem. After much haggling back and forth, I went to the original shop to have the timing belt fixed. He replaced the timing belt as it was covered under warranty. The bracket on cranksensor was broke and was not a part that was replaced previously(thus not covered under warranty) and thus bracket was aluminium welded and the mechanic assured me that it is ok to do so. Also the pulley attached to the tensioner had a hairline crack from one side to another side, this was covered under warranty as well. He did give a some break on labor($200) but he checked the engine and said cylinder 1 has misfire(due to bent valves). I asked him to do the tests that were recommneded here and he went into this speel about what is point of doing when we know for sure there are bent valves etc. He says I could drive the car for sometime but performance will eventually degrade and engine would need repair. He would charge me $400 for whatever he has already done so far if I take the vehicle out right now. There is still no clear establishment of cause of the problem, labor or part failure for obvious reasons, I guess.
Now, he would give a further break on whatever he has done so far($200-50% discount) if I have the rest of the job done with him, which he quoted $1500 + $200. I am still little bit worried about him fixing the job due to first time not doing it right and so I asked him I want 12 months parts and labor warranty which he says he cannot do it as it is too risky for him. He said others would charge double for the same work if they provide 12 month warranty.
Meanwhile I did talk to couple of other mechanics who supposedly work in Honda dealership who said they would do the job on the side for total of $1000-$1200 and would provide 12 month labor warranty. Of course, I have never worked with them before and got contacts through Craigslist. Ok, finally my questions:

  1. Should I still work with the original mechanic? Downside is 3 month labor warranty and I am not 100% convinced that he has done a similar engine work with Honda before though he claims he has 35 years of experience, used to work for GM.
  2. Should I go with one of the experienced Honda mechanics who have experience in fixing such problems regularly. Downside is, how do I do ensure they would honor 12 month warranty if something goes bad as these folks are doing this on the side and not as an established business. With established business, at least you can report to BBB, State etc.
  3. Of course, there is another option, which is replacing the engine and the quotes for which have ranged from $2000(independent mechanics) to $3500 with dealer. Not sure if this is better long term option if the used engine would have much lesser miles than the current 120K miles engine and of course, engine replacement I believe is much more complex?

Thanks for your time and effort in responding to my questions.

I’ve seen very dishonest mechanics take the $600 from someone for a timing belt replacement, but NEVER do the job…Someone who’s NOT very knowledgeable won’t know if they did or didn’t…It’s a gamble the mechanic makes…If after a year the belt doesn’t break…he’s home clear…

Tough call but at this point I’ll say that I’m not too impressed with the guy who did this.
It would be interesting to know exactly how this damage all came to be because there is simply no way that it should have happened if the job was performed properly.

This guy stating there is no clear reason why this happened would be suspicious to me. Maybe he knows and wants to keep it murky to you.

Personally, I think he’s a fool for even considering putting a belt back on it much less actually doing it.
And then he tells you to drive it around? This will finish off the cylinder head to the point of being unrepairable, kill the converters, kill the power and fuel mileage, leave you with a chronic CEL, and if you live in an emissions testing state will also kill that.

Honda has managed to pull the old trick Ford was famous for, specialized tools. If your GM mechanic doesn’t have the specialized tool required to remove and reinstall the crank pulley bolt, then the bolt will come loose and shred the timing belt, like yours did. Chances are he just used an impact wrench.

I think you would have been better off at the dealer for this job in the first place. Check with the so called Honda mechanics and if they have the specialized tools, then they probably are genuine and you should pick one of them. Check Angie’s list and/or the mechanics files on this web site for more information about them.

A specialized tool is available but not required to do this job right. In this instance it looked to me more like the tensioner seized up which usually shreds the belt and the belt shredding took the crankshaft sensor with it.

I have never needed a special tool to replace a Honda timing belt, water pump, tensioner and cam/crank seals. More than likely the tensioner either wasn’t replaced, or was replaced with either a low quality or defective one that seized.

Do you have the partially shredded timing belt? I wonder if somebody could tell if it’s the original Honda belt that’s 8 years old or if it’s a belt only used for 5 months.

To know the cause of this disaster, you would have had to bring it to an independent mechanic that you could trust. Maybe he would’ve discovered something like the loose crankshaft bolt, seized pulley, or some other obvious cause.