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When the timing belt breaks while driving,how many valves can I expect to be bent?

I know the best way to find out is to pull the head,but...the car is in a different town and I want to order the parts and show up to fix it.(Its my daughters car)

 
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all of 'em.

Happened to me. CKP sensor bolt came loose, did a number on my timing belt. Shredded it down to 1/4" wide. Did so at maybe 2500 rpm, probably 200 feet from a stop. All 16 valves bent.

 
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Watch This.


enjoy

 
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if thats the case i would just buy a used/refurbished head and replace it,

also you should be looking into WHY it snapped in the first place, was there a parts failure?....or was it just old and neglected to change it?

 
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I will say I've had a hard time finding a rebuilt or even used head at a decent price.

 
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Don't know what your budget is, but it's almost easier to buy a complete used engine from a JDM importer. I've noticed that head costs are just about the price of a used JDM engine. In Houston the D17 complete is going between $450-$500. Yes, it has 40,000 to 60,000 miles on it but.....

BTW it's a good idea to change out the timing belt and water pump every 70k-80k miles.

 
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some might have survived, but do you want to go to the job of removing head, replacing the valves, then installing, just to find out you need to redo the job?

 
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How much would a set of valves cost if you were to reuse this head?

 
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I was quoted 446 CAD for all the valves.I had someone else tell me that most times only 4 valves get bent.

I was just hoping to hear from others who had this same thing happen and find out how many valves they bent.

I'm travelling from out of town to do the repair and need to do it all at once and not rip it apart and wait for parts.

 
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Is that from a dealership, a machine shop, or a parts store?
446 CAD is not expensive enough to include any labor, of course.

If it stripped the belt during cranking, it might only bend 4.

If yours let go while driving at 2000-2500 RPM, it's very likely all 16 are bent.

Ah, this puts it in perspective now.

 
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That quote was just for the valves and was from a dealership.The other side of this is I'm trying to keep the repair cost down.

 
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Any clue why the timing belt let go yet?
Get a tensioner and spring kit from a Honda dealer. NO aftermarket. Far too many horror stories of incredibly premature failures that wipe out all the valves...before the first oil change.

Valves may be quite a bit cheaper if you look around....but can you DIY valves?

I don't have a source for rebuilt heads in Canada....but
If you pick up a used head, it's gonna need checked for flatness and valve sealing.

 
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The belt broke due to age,I believe.It was the original belt and the car has 190k kms. I will be replacing the tensioner and waterpump when I do this.

 
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So I bought all the parts from a Honda dealer except the valves.I located a used head and sent it to a machine shop and had it checked and milled.When I get the car torn down I realize the two heads are different.

When I roll the cam over with a ratchet,on the junkyard head, only one intake valve opens fully and the other one opens just a small amount.Is this from a VTec? What is this new head from?

 
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Ya, one head is VTEC and the other is not.
Not a match. You got the wrong head.


What year and trim level is your car?

 
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I have a 2001 LX w/1.7 base engine.This is what the head was listed as coming off.I had never worked on one before and didn't know the difference when I picked it up.I'm bummed because I now have the car torn apart and need a different head.

I'll take my original head to a machine shop and have it gone through.

 
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On the plus side, the valves are the same part numbers between the two head versions, so if they need to swap a pile of valves they should work ok.

Intake valve #s match, exhaust valve #s match

 
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i got aftermarket valve for 67 dollars a set.. they run fine... my cam bolt came loose at idle.. i bent 12 valves... bolt came loose after 2 years after i replaced my timing belt.. and i did torqued.. fiy to everyone use loctite.. comes from factory with some loctite ..

i just replaced the valve.. the problem after the valves is i got slow oil burn, somehow from that impact i had a high millage engine, it must have knocked the carbon or broke the oil rings somehow or jammed them.. i have perfect compression at 210 psi , and i did cylinder leakege test with no loos of pressure...... so after all, i might still be tearing it down this spring summer to change now my rings.. pissses me off... to be more exact oil rings..

 
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Ouch, too late here.

You can use the head, although the vtec will not work and you will have less power. Torque should be better. But you would need a controller for the vtec. So, for quick change, the correct head is easier.

The oil rings collapsing are normal. I believe mine are too...

 
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You will have to change all of them valves, pistons and head also could be damaged, depends of the RPMs during the breakage of TB.

 
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not really,

it only takes one revolution to smack the valves and do the damage, engine revolutions after that will not do any more harm, all the damage is done instantly,

 
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I was talking about the damage to the pistons and head. I have seen cracked pistons before, IMO it has a lot to do with the force of impact (RPMs) during belt breakage. Sometimes things get even worse - valve gets disconnected and falls down the cylinder, you can imagine what happens next )

 
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it still doesn't matter,

if the valve was going to fall like that it would do it the first time it was hit,

the piston can only hit the valve ONE TIME, after the valve is bent out of the way the piston does not contact it again, it only takes one revolution and one smack....1000 rpms or 6000 rpms would make no difference in the damage caused,

 
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If RPMs didnt matter, then the damage would always be the same - a few bent valves and scratched pistons, right?
But somehow, sometimes we get cracked pistons, heads, torn up valves, holes in the pistons, etc.. I wonder how that happens if RPMs make no difference? )

 
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the difference is in the condition of those items at the time of impact....pistons and valves will crumble a lot easier after 500,000 miles as opposed to after 10,000 miles

 
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Its great to see that my initial inquiry has created so much discussion.

I want to add that once I pulled the head and sent it to a machine shop,I was surprised to find out that there were no bent valves.I wish I would have done a leakdown test before tearing the head off.It would have saved me a bunch of time and money.

I've got the car together and running and on the bright side I have a resurfaced head with a valve job and new seals.

 
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That's almost unheard of. Amazing, IMO.

Some people have reported bending valves trying to replace a timing belt by spinning the crank with a wrench.

 
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You did not watch the video I posted here? Eric O described all this perfectly. Many times he has had broken timing belts and the video posted here is the first time he has ever seen bent valves on the civic 1.7. So it is not so uncommon in his experience to see no bent valves. Life is a lesson in learning. Glad the car is running nicely! Enjoy.