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

[Amit Shakya]

also what is the 4 stroke rule?

I also got lost in this sentence due to the lack of full stops and commas. “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.”

did you mean that with crank at tdc and rockers backed off, you can rotate the cam without any damage? why the “with not cam sprocket on”? how can u rotate the cam without the sprocket on?

[Daniel]

You can’t combine what we both told you, because we are telling you two different things. Just do all the things in your list except backing off the rockers.
We want to make sure nothing is binding. We can’t do that if the valves aren’t opening (rockers are backed off).
Put it back together (in other words ready to start and drive). Instead of turning the engine with the starter; pull the plugs (to make it easier on you) and turn the engine by hand. This will prevent any damage (if it is binding).
Before you do anything else on that car GET A SERVICE MANUAL!!! Stop taking advice from the internet. There is a lot of misinformation on the net. You need to learn the proper procedure for doing jobs like this. The internet misinformation is why you’re here in the first place.
Not to be rude, but you don’t have the knowledge or experience to figure out what is bad advice. Get a manual.

GET A MANUAL

GET A FLIPPING MANUAL

[Daniel]

If adjusted correctly, you shouldn’t be able to move the rocker arms freely.
I know the manual doesn’t cover this. That’s because you did it wrong. The manual tells you how to do it correctly. It does not tell you how to fix something that you messed up because you got impatient and tried to take a short cut.
I’m telling you to consult the manual to figure out how to do the job correctly. That way you can try to fix the situation you are in. Take everything apart like the manual tells you to do (in the timing belt replacement section). Take the timing belt off. Put the sprocket back on Put the marks on the sprockets where they are supposed to be. Then install a BRAND NEW timing belt following the book step by step. The old belt is probably messed up because of your shenanigans.
Honestly, if you can’t figure out how to get this thing back together using the manual than there is no way I am going to be able to help you. I’m not even sure why you are taking advise from the internet when you have those manuals.
Short cuts can be taken by people who are experienced and know how to take short cuts correctly. You should not be taking short cuts.

[Amit Shakya]

thanks again.

i understood everything u are trying to say. big f(#@ up. i know. and will do as you instructed so when i get off work tmrw.

BUT my crank is at tdc but my cam is 180 degrees off. so u are saying with the timing belt off, rocker arm still in place, i can simply the rotate the cam to TDC without damaging anything more? the instructions say to put both cam/crank at tdc before removing the timing belt.

i dont understand engines and shouldnt be doing the job but doesnt it make more sense to remove the rocker arms and camshaft and put the cam to tdc, then go on with the normal timing belt replacement procedure?

sorry buddy for all the trouble. i appreciate your help in not only doing the job but understanding why. thanks.

[Andrew Phillips]

[quote=”karmapacox” post=131155]thanks again.

i understood everything u are trying to say. big f(#@ up. i know. and will do as you instructed so when i get off work tmrw.

BUT my crank is at tdc but my cam is 180 degrees off. so u are saying with the timing belt off, rocker arm still in place, i can simply the rotate the cam to TDC without damaging anything more? the instructions say to put both cam/crank at tdc before removing the timing belt.

i dont understand engines and shouldnt be doing the job but doesnt it make more sense to remove the rocker arms and camshaft and put the cam to tdc, then go on with the normal timing belt replacement procedure?

sorry buddy for all the trouble. i appreciate your help in not only doing the job but understanding why. thanks.[/quote]

Your crank fully rotates TWICE for every full rotation of your cam. That is because the piston is at TDC once at the end of compression stroke and again at the end of exhaust stroke. It is perfectly NORMAL for the crank to be at TDC and your cam be 180 degrees off. That means #1 is on exhaust stroke instead of compression stroke. For timing the engine, it needs to be at TDC on compression stroke, because the plug fires at the end of compression stroke initiating the power stroke.

EDIT: Hopefully that noise you heard wasn’t damage to the engine caused with #1 cylinder being on exhaust stroke and the exhaust valve opened when it would normally be closed during this procedure. Before you attempt to start the engine, make sure it rotates 360 degrees freely without binding or noise, and run a cold compression test to make sure all the cylinders are sealing up.

[Amit Shakya]

“Your crank fully rotates TWICE for every full rotation of your cam. That is because the piston is at TDC once at the end of compression stroke and again at the end of exhaust stroke. It is perfectly NORMAL for the crank to be at TDC and your cam be 180 degrees off. That means #1 is on exhaust stroke instead of compression stroke. For timing the engine, it needs to be at TDC on compression stroke, because the plug fires at the end of compression stroke initiating the power stroke.”

i know that.

what i am asking is how i can get both to tdc before i continue with the TB job. here are the options:

1) WRONG:::leave TB on and tension on and rotate to make crank and cam at TDC. (this could make the current wrong alignment create further damage [not sure about this as i dont see TB damage and at max a tooth or two off at cam]).

2) WRONG::: remove TB and rotate cam to TDC (wrong for obvious reasons)

3) RIGHT??? make sure crank is tdc. remove TB, rocker arm, camshaft. re position cam to TDC. contiue with normal TB job.

thanks again guys.

[Andrew Phillips]

[quote=”karmapacox” post=131161]Your crank fully rotates TWICE for every full rotation of your cam…

i know that. [/quote]

Umm, then you should know that if you just rotate your crank 360 degrees, the cam won’t be 180 degrees off any more… Rotate it 360 deg OPPOSITE the direction of normal rotation. Leave the TB and cam sprocket in place and with tension to avoid skipping a tooth.

[Amit Shakya]

I know rotating the crank 360 will get the cam to tdc at this point but if there is something wrong, wouldnt that just make it worse?

also, i thought rotating 360 the opposite direction would cause damage?

there is an interesting discussion here: http://honda-tech.com/acura-integra-6/my-timing-belt-broke-how-do-i-find-tdc-2746384/ (towards the end of the page) about valvesprings tighetening feeling like pistons hitting valves. From the sound i heard, it was more of the thick springs geting really taut (possibly valvesprings?). how do i remedy the situation if it was simply the valvesprings tightening?

[Andrew Phillips]

[quote=”karmapacox” post=131164]I know rotating the crank 360 will get the cam to tdc at this point but if there is something wrong, wouldnt that just make it worse?

also, i thought rotating 360 the opposite direction would cause damage?

there is an interesting discussion here: http://honda-tech.com/acura-integra-6/my-timing-belt-broke-how-do-i-find-tdc-2746384/ (towards the end of the page) about valvesprings tighetening feeling like pistons hitting valves. From the sound i heard, it was more of the thick springs geting really taut (possibly valvesprings?). how do i remedy the situation if it was simply the valvesprings tightening?[/quote]

Rotating it in the opposite direction by hand will not hurt an engine, if you haven’t already done it in. OF COURSE you should STOP turning it if you feel it binding up in any way! If you have already caused some damage, turning it backwards certainly won’t hurt it any worse, and will be the easiest way to align the cam/crank. You need to get it back together so you can run a compression test and see if it is still basically functional.

Valve springs compress and release during the travel of the camshaft. They float on both ends, are not captive or anchored in any way, except by the retainer and keeper. They just sit there between the head and retainer. There is no situation to remedy, unless one has broken, which you should easily be able to see.

[Daniel]

Make sure everything is TDC compression stroke on cylinder 1 (unless the book says exhaust stroke on 1). If you pull all the plugs it will be relatively easy. It will not hurt anything to rotate the cams the opposite way. Just get them lined up. If you are turning the cams and feel a binding, back them off a bit and turn the crank. Don’t worry, cause this doesn’t indicate a problem. Because the valves and crank are now out of sinc you may have to move one to make room for another.
When the belt is off, think of the crank and valves as completely different entities. They might bump into each other, but as long as they end up in the right position you’ll be fine.
Once you get it all together correctly (with the new belt on) then you turn the engine to see if there is binding.

Here is an animation that might help you understand what’s going on inside. Just remember; without the timing belt the valves rotate independent of the crank. (This is a Toyota engine, but has the same basic construction of the Honda engine.)

[Andrew Button]

To much information being thrown out there. If your valves are backed off, so they don’t open you can rotate anything and all things any way you want. The Crank just needs to have its no 1 piston at TDC first, without timing belt connected. Then you put you cam/sprocket with the mark on the sprocket pointing up ( position where all the no 1 valves are closed.). whatever you want to call it, then connect the belt back up. The piston goes up twice for every rotation of your cam, as said. On engines in general, this is why when your timing marking on your balancer or whatever can be either correct or 180 off. This, however is never the case when the cam is not connected.

[Amit Shakya]

thats kind of what i was thinking as the safest method.

by valves backed off, do you simply mean loosening the valve adjusting nuts and tappet/screws OR removing the rocker arms altogether? im guessing with valves backed off,i dont need to remove the cam and realign but rather just move the sprocket to align it?

im learning a lot through the forums guys. thanks.

[Andrew Button]

Can you loosen the adjusters enough so the valves don’t open ? Try to take as little apart as possible. Whatever the method, make it so you can rotate the cam or cams with or without sprocket on or off, it so it doesn’t open the valves, any of them. You will of course have to readadjust them once the cam is back in the correct position. Whatever the case, however you do it, if your valves are ALL closed on number 1, and your piston number 1 it at top dead center, then you know you have it. As the other poster stated, once your belt is off, your valves and cam and pistons are different entities entirely. Normally when changing the timing belt the phasing of the cams is never off enough to need to go back do all the extra work, but since we are not there to see it, thats why all this extra work is involved so you can you know where you are at. Easy method, just make sure your number 1 piston is at TDC and your valves are closed for that cylinder, nothing complicated about that. Eric has a video on finding TDC with a vacuum gauge, if you watch that, it may give you a better understanding because his gauge shows what happens with open vs closed valve in relation to piston travel.. Bottom line is this. If you cam phasing is correct, your vacuum gauge will do what his does…. if something else happens, keep looking working.

[Andrew Phillips]

If you back the valves off, no matter which way you do it, whether loosening the tappets (not recommended) or removing the rocker shafts (recommended), you will have to adjust the valve lash when putting it back together.

[Amit Shakya]

hi everyone,

had some time yesterday to touch the car again.

i just removed the plugs and rotated the engine and everything lines up perfectly with no binding (as far as i can tell).

is there anyway i could have messed sth up and it still lines up like it does?

any way to check via looking at rocker arm movement while rotating the engine?

i have some tmrw to do a compression test. safe?

thanks guys.

[Author]

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