timing belt – bent valves?

[Amit Shakya]

hi everyone,

2000 accord 2.3L MT

in the process of doing the timing belt , i got to the part where i had the covers off and had NOT yet removed the tension or the belt.

so heres the situation:

1) crank was at tdc but 360 degrees off (i.e. i set it at tdc before removing upper cover as per instruction).
2) cam’s up mark was pointing to the floor (therefore indicating that turning the crank 360 would make everything TDC)

while i was getting reading to leave the rest of the job for another day, i was already irritated and i got dumb for some reason and decided the loosen the cam sprocket bolt (to change the seal) under these conditions:

1) car in 1st gear (forgot to put it in neutral)
2) crankshaft damper and pulley bolt removed but the crankshaft (the gear) itself still in place.
3) spark plugs still in, timing belt and tension still in place.
4) crank and cam positions as stated above.

i basically just used a breaker bar on the cam sprocket without holding it in place with a screwdriver (as suggested by others) and i heard “clunk” sound like either a metal to metal contact or a mental spring getting really tightly compressed (like a “twangggg” sound).

did i bend my valves? or was that just the bolt breaking loose (as i could remove the cam bolt after another push on my breaker bar after that)?

i wasnt mindful enough to see if the cam or crank skipped a tooth.

i dont know how these honda engines work and am curious logically what doing this would entail.

i am about to do a compression test to check but dont want that to damage anything further if this surely caused a bent valve.

also if i did bend a valve, i can just remove the head and take it to a shop and not have to worry about doing anything to the cylinder block right?

Topic

[Dan]

hmm i’m not to sure but one thing that might have happened is busting a hole in top of a piston if a valve did hit one and yes also it could have bent a valve . at this point i think i would just pull the head to be sure.

[Daniel]

Hard to say what it might be without hearing it myself.
I think you’re probably fine. After you get it back together, pull the plugs, and turn the engine by hand a few times and make sure nothing is binding.
Pistons are pretty tough. They have thousands of pounds of force beating against them thousands of times a second.

[Amit Shakya]

Hey guys,

Thanks for the input.

Can you guys help me understand what was going on when I was trying to remove the camshaft sprocket bolt?

I wasnt using anything to hold it in place so something must have held it in tension to allow me to unbolt to over 30 foot/lb of force. From what I am understanding, rotating the cam with the timing belt and tension on (but without the crank pulley bolt installed) would cause the pistons to the hit the valves?

[Daniel]

It’s more like the valve hit the piston or the cam sprocket just pinged off of something when it popped out in a way it was never designed to do.
Don’t do jobs like this without having a manual. Hopefully you didn’t fuck up the threads in the cam.

[Andrew Button]

Back off all the rockers completely and do a leakdown on it, then you will know, right away.

[Daniel]

So we are assuming he has a compressor and leakdown tester?

[Andrew Button]

Yes

[Amit Shakya]

i dont have access to do a leakdown test (no compressor).

i can rent a compression tool from o reily.

either way, what i am thinking is to put the damper and bolt back, tighten it a little bit, remove spark plugs, gear in neutral and try to manually spin crankshaft and see how it feels (i have had to do this before for valve adjustment) and whether both cam/crank line up at tdc.

is that safe?

also, i hear compression tests are supposed to be done with a warm engine and i dont want to start the car to risk further damage? or can a cold compression test say sth enough AND not do anymore damage?

didnt have time to do much expect check the rocker arms today. given the position of the cam (pointing down), cylinder 3 rocker arms were supposed to be loose enough to move a little by hand (like when doing valve adjustments) but the exhaust side was tight and i cudnt get it to move by hand at all. what does that mean?

also, what does backing off ALL rocker arms mean? i have removed rocker arms before…

if i had to replace the valves, i am willing to learn. i heard u can simply unbolt the 5 or so intake manifold bolts for the intake side to remove the cylinder head without dis-assembling fuel lines/etc. is that true?
thanks a lot guys.

[Andrew Button]

No, you wouldn’t want to do a compression test. Wrong answer. If you back off all the rockers so the valves are closed, and run a leak down test, it will tell you if you have internal damage. With closed valves you don’t need to turn the motor at all, thats the point. If there are bent valves then then head comes off and has to repaired by a machine shop, not you. Head is bolted to engine block with a bunch of fasteners, and yes you have to take a bunch of things off and apart to remove it. Avoid that if you can. If you are unsure about cam position, but have full confidence your number 1 piston is at TDC, with the rockers backed off you can rotate the cam and make sure you have the correct positioning following 4 stroke rules when there is no cam sprocket on and no valve spring pressure it spins freely. racing guys do this when degreeing cams with a really light spring just to check positioning.

[Andrew Button]

here is something for you that may be of use

Attachments:

• stroke.jpg

[Daniel]

Just put it back together.
Leak down test is “supposed” to be done with the engine warm so the pistons have the correct fitment in the cylinder. If you do it cold you’d still be able to tell if the valve is sealing, but this is pointless right now.
The noise you heard was probably the cam sprocket. Don’t ever take it off like that again. You shouldn’t have to take the sprocket off at all to do a timing belt.
Just put it back together, turn the engine like I suggested, and get yourself a service manual before you do any other repairs on the car.

[Amit Shakya]

oh man. this etcg forum is alive and kicking. awesome.

some clarification: by back off rockers, you are suggesting loosing the adjusting nut as you do for valve adjustments?

thisisbuod, what do you mean by put it back together. i didnt remove the timing belt or tension so all i need to do to get it back as it was (except the cam position if that got messed up) is to put in and tighen the crank pulley bolt.

if the cam position did get messed up, dont i need to align it back before i try rotating the engine? and how do i align the cam back without moving the crank?

thanks guys. i have work today but tmrw i should have time off to check things out. when i do, if the cam/crank seemed perfectly aligned as it is, does that mean i didnt do any damage?

and the sprocket removal was because the main reason for this job was to change the cam seal which has been leaking for 5 years. i saw that etcg in his vmanual just had the tension on and used an impact. i lost my head and got dumb towards the end of the day and thought why wouldnt just using the breaker bar do the same (STUPID!). oh well. i just thought “ok. if the cam moves while trying to remove the bolt, the crank would do the same due to the TB being in tension just like how the PS belt can be used to turn the engine” maybe not.

when i get back to my carport tmrw, i will also post a pic of what a “slightly” wobbling crank can do to a lower cover and what a 5 year oil leak into the TB area does.

[Mason]

A friend of mine just had the same situation with his e30 where his timing belt snapped while he was driving and immediately the shut down due to most of the valves bending out. Instead of getting it repaired he just went to Pick-N-Pull and picked up another set of heads off an e30 there, and it was as easy as unbolting the old heads and swapping in the new ones. I have a 99 2.3L Accord myself and I can tell you from experience that a set of heads from Pick-N-Pull should run you no more than $80-$100 and a few hours of your time.

Obviously this is only helpful IF it is in fact bent valves that you’re dealing with, so hopefully that’s all it is.

[Daniel]

By “put it back together” I mean take the tension off the timing belt, replace the timing belt (because it probably got fucked up when you pulled the cam sprocket off INCORRECTLY), set the timing, put the new belt on…..then pull the plugs and turn the engine.
What you did was dangerous and could have messed up something VERY expensive. When working on a car (especially the engine) you need to follow the proper procedure.
Get a service manual before you touch that car again.
Tou NEED a new timing belt and you NEED to put it on correctly (using the service manual). If you try to fix this with out consulting a manual first, than I have no sympathy for you.

[Amit Shakya]

sooooooooooo….

just to make sure i got this (combined understanding what all of you are saying):

1) back off rocker arms (i am guessing that means either remove the rocker arm assembly, which is easy, or loosen the tappet adjusting screws)
2) remove timing belt tension
3) align the cam back (if the rocker arms are off, i am guessing the cam can be rotated without moving the valves or causing any damage?)
4) put everything else back
5) remove spark plugs
6) rotate engine via crankshaft to see if there is any binding?

thanks guys. i am positive crank is at tdc and that the cam is close or at cylinder 3 (i.e. point to the floor). i am still not clear on how to move cam back to position without damaging anything (unless what i said above is accurate).

also, can i loosen all tappet adjusting nuts (to make reinstallation of rocker arms easier) without moving the cam/crank to the respective cylinders?

[Author]

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