12 replies to this topic

[CRXRacer722]

Ok...the timing belt broke on my car in the shop while they were working on it, which i was sort of expecting it to, since it was old as hell anyway...

the question being....since the timing belt broke...whats the probability that the valves bent in the head? the guy cant tell me if they are or arent and wont give me a gaurantee that itll work if the timing belt is replaced

however i do know that theres an accord sitting next to my car for 75$ with the same problem...so does anyone think the valves are still straight? ive been out of work for 2 weeks since this happened and id like to actually get my car fixed

(damn, if ive known this was gonna happen i would have just spent 200$ in the first place, bought an engine hoist and done the work on it myself)

[1stGENcrxLOVER]

thar most likely bent i had a 86 civic si that bent them wen the same thing hapend in my back yard

[Ghost-One]

your valves are bent if a shop isnt telling you valve job they are just trying to rip you off

[bigk3000]

sounds liek the shop is rippign you off.. MAKE THEM PAY FOR IT since they are the ones who broke your belt.. it could just be a scam

a timing belt wouldnt just break at idle inside a shop whiel they are running your engine.. maybe it you were putting load on it, climing a hill, accelerating..

maybe im wrong.. but i know how shops liek to rip people off..

Edited by bigk3000, 09 December 2005 - 01:26 AM.

[kedwards]

SNIP
a timing belt wouldnt just break at idle inside a shop whiel they are running your engine..    maybe it you were putting load on it, climing a hill, accelerating..

maybe im wrong.. but i know how shops liek to rip people off..

<{POST_SNAPBACK}>

That has not been my experience. We had the timing belt break in our '85 Civic Wagon 4WD while it was idling in our driveway.

Keith, who has never heard of valves NOT bending with our '84-'87 engines...

[RARECRX]

SNIP
a timing belt wouldnt just break at idle inside a shop whiel they are running your engine..     maybe it you were putting load on it, climing a hill, accelerating..

maybe im wrong.. but i know how shops liek to rip people off..

<{POST_SNAPBACK}>

That has not been my experience. We had the timing belt break in our '85 Civic Wagon 4WD while it was idling in our driveway.

Keith, who has never heard of valves NOT bending with our '84-'87 engines...

<{POST_SNAPBACK}>

I second that!!! i cant count how many times i was making "valve fires"(hand lapping valve seats with that stupid suction cup lapping tool) due to bent valves..you may get lucky if they shut it down fast but i doubt it...Its "valve fire" time

[crxls]

if this shop really knew thier shit they would be able to tell you if there are any valves bent and if they are intake or exhaust valves and exactly what cylindar the bent ones are in. all it takes is a compression test on each cylindar with that particular cylindar at TDC (set cam and crank at TDC for that cylindar and then force compressed air into the sparkplug hole for that cylindar and see where exactly the air comes out, it's that simple).

[yodaboy]

if this shop really knew thier shit they would be able to tell you if there are any valves bent and if they are intake or exhaust valves and exactly what cylindar the bent ones are in. all it takes is a compression test on each cylindar with that particular cylindar at TDC (set cam and crank at TDC for that cylindar and then force compressed air into the sparkplug hole for that cylindar and see where exactly the air comes out, it's that simple).

<{POST_SNAPBACK}>

If the engine was running at the time the belt broke, the valves are bent. The ones that do not have the clearance are the four exhaust valves (as typicall noted when removing the cylinder head and looking at the dings in the tops of the pistons). The two smaller intake valves on each cylinder (on an Si at least) have a little clearance on the piston head itself, but not for the larger exhaust valves. I had this happen to me once and had to replace all four exhaust valves....bummer, but the car has been running since I've fixed it.

Also, not to be a bearer of bad news, unless your engine has fewer than 120k on it, you might be up for a bottom end freshening up as well since new valves tend to seal better than their original buddies. This in turn increases the compression (usually a good thing), which will cause oil blow by on the not-so-tight, high mileage rings (usually an undesirable thing). I experienced this first hand on my engine of only 150k on it.

All the bad stuff is a moot point if you don't mind checking your oil a little more often than usual....I'm lazy and I didn't like it since I have to travel frequently at high RPM on the freeways of California. Otherwise the top end (cylinder head related) repair shouldn't cost them a whole lot of money to repair....just some time....

Hope this helps and doesn't bum you out too much.

[DarkHand]

I bent an exhaust valve when my Civic's belt broke:



No idea why the other one on the same stroke didn't bend, but it seems just fine.

[crxls]

I bent an exhaust valve when my Civic's belt broke:



No idea why the other one on the same stroke didn't bend, but it seems just fine. 

<{POST_SNAPBACK}>

they both look bent to me, just the one on the left looks more severe.

[trevor72]

I bent an exhaust valve when my Civic's belt broke:



No idea why the other one on the same stroke didn't bend, but it seems just fine. 

<{POST_SNAPBACK}>

they both look bent to me, just the one on the left looks more severe.

<{POST_SNAPBACK}>

YA they both look bent to me too, If it were me, It just replace them all!, try rolling it on a flat surface, you sould be able to tell. Remember the naked eye can only see to .2mm accuracy, and that's way too much bend for a valve, remember that the valves have to be able to turn and, this obviously would affect it's ability to seal.. Trust me, if even if they're $26/valve or something outragious, you'll be gladd you did them all.

Just re-read the original post, and man you need to have a serious talk with your shop! Did you drive your car to the shop? what was it going there for originaly? It sounds like some young/unknowledgeable twit was WINGing your motor to the moon. Yes timing belts just go, but this sounds fishy. I think that before a timing belt would break at idle you'd have a higher propability of having it skip a tooth and start running shitty, before it would break a belt at idle. Just think about how much power your motor makes, now torque... ok that's top torque numbers and that's definately not at idle, the force on a t-belt at idle is a fraction of that. If the t-belt broke it was fatigued and it was most likely ratted on just prior. it should have, at 1000rpm just started running like a bag of hammers and then the idle would have gone down 700, 600, 500, whatever, then just died, or if it did brake the belt the motor should have been slowing down enough from runnng like crap and having the belt sliping. and at that, it is possible that only one cylnder would have bent valves.

Good luck man.

Edited by trevor72, 12 December 2005 - 02:40 PM.

[yodaboy]

I bent an exhaust valve when my Civic's belt broke:



No idea why the other one on the same stroke didn't bend, but it seems just fine. 

<{POST_SNAPBACK}>

they both look bent to me, just the one on the left looks more severe.

<{POST_SNAPBACK}>

YA they both look bent to me too, If it were me, It just replace them all!, try rolling it on a flat surface, you sould be able to tell. Remember the naked eye can only see to .2mm accuracy, and that's way too much bend for a valve, remember that the valves have to be able to turn and, this obviously would affect it's ability to seal.. Trust me, if even if they're $26/valve or something outragious, you'll be gladd you did them all.

Just re-read the original post, and man you need to have a serious talk with your shop! Did you drive your car to the shop? what was it going there for originaly? It sounds like some young/unknowledgeable twit was WINGing your motor to the moon. Yes timing belts just go, but this sounds fishy. I think that before a timing belt would break at idle you'd have a higher propability of having it skip a tooth and start running shitty, before it would break a belt at idle. Just think about how much power your motor makes, now torque... ok that's top torque numbers and that's definately not at idle, the force on a t-belt at idle is a fraction of that. If the t-belt broke it was fatigued and it was most likely ratted on just prior. it should have, at 1000rpm just started running like a bag of hammers and then the idle would have gone down 700, 600, 500, whatever, then just died, or if it did brake the belt the motor should have been slowing down enough from runnng like crap and having the belt sliping. and at that, it is possible that only one cylnder would have bent valves.

Good luck man.

<{POST_SNAPBACK}>

That didn't occur to me until just now....my original reply was assuming the car was running prior to bringing it in (hence the belt was correctly installed before)....if the belt was being replaced as a maintenance scheduled change and the folks at your shop put it on a few teeth off, then that'll cause valve problems as well......

[DarkHand]

Good point, they may just be trying to cover their butts.

As for those valves, the pictures were taken on an uneven surface... The other one seemed pretty darn straight to me, but they were all thrown out anyway, intake and exhaust.