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98 Hatchback
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Discussion Starter #1
I'm working on a buddy's car - Apparently his timing belt jumped and the car wouldn't run. Before I started dealing with it, he said when he would try to fire it up it would run for a few seconds, very poorly, and shut down.

I took it apart and sure enough, the timing was off by a few teeth. The slack was on the wrong side, where it winds through the tensioner pulley, and tension was on the left where it comes straight down from the cam to crank pulley. It looks as though it was bouncing around in the cover a bit.

So I've got a couple of questions:

How far does the timing need to go out before valves start bending?

Is there a way to tell without tearing everything apart if valves have been damaged?

Last, what may have caused the jump?

Basically what I planned to do was to reset the timing, temporarily button it back up so that I could fire it up, and if all runs well then we'll go ahead and replace belt, tensioner, water pump, etc.

Thanks guys!
 

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ej1
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If that works you'll be able to rev it up a few times and bend them back. But don't get you're hopes up too much. I helped a guy try it this year and it wouldn't start so we tried to toe strap it:3dtard: and ended up just jumping timing again. You may get desperate and pull the head to bang the bent valves closed with a hammer after pulling the cam back out of it. Don't count on them being totally straight though.
 

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re set the timing correctly and do a leakdown that should give u a good hint on if u bent anything
 

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nothing
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well if he has bent valves i wonder if he has any cracked guides?
 

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ive broke timing belts before and never had an issue with bent valves.
 

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In circles.LOL
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just reset the timing.And turn over the engine with the ecu fuse out and listen with a mechanics stethoscope to the cylinders at the top were the head makes contact with the block.If you don't hear a tap then check your compression.That will reveal quite a bit.If CR is low then you have a bent valve.If it is around 165-185 for a stock engine all 4 cyls then take it for a cruise.Your good.
 

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98 Hatchback
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Discussion Starter #9
Tron, yes, the slack should be on the left. In this case, it was on the right. Thanks for the tips guys.

Luckily this belt isn't broken, just off by a few teeth. Hopefully it wasn't enough to damage anything.

I guess we'll see what happens when I work on it again tomorrow. Night all
 

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94 civic, 90 talon
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Tron, yes, the slack should be on the left. In this case, it was on the right. Thanks for the tips guys.

Luckily this belt isn't broken, just off by a few teeth. Hopefully it wasn't enough to damage anything.

I guess we'll see what happens when I work on it again tomorrow. Night all
Always firewall side for slack. Engine spins counter clockwise.
I'm pretty positive on this one!

Edit: I just took this off turbo D16
"How to Adjust D16 Valve Clearance
CAUTION:Always rotate engine in direction of normal rotation(counterclockwise as viewed from front of engine)" So why would the slack be on the core support side?
 

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you are right wall.Thats why you turn the crank pully counter clockwise when tightning the belt the three teeth the book says to when replacing belt.(lefty loosy to tighten.)
 

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:3dtard:
If that works you'll be able to rev it up a few times and bend them back. But don't get you're hopes up too much. I helped a guy try it this year and it wouldn't start so we tried to toe strap it:3dtard: and ended up just jumping timing again. You may get desperate and pull the head to bang the bent valves closed with a hammer after pulling the cam back out of it. Don't count on them being totally straight though.
:3dtard:

What? rev it up and bend them back? that is about the worst thing you could do. Valves need to seal perfectly to get compression. No compression, no combustion. And when a valve bends, it is best to remove everything and replace the bent valves.


Anyway,... to the OP. Do a compression check and/or a leak down test. Reset the timing belt and check the valve lash,... don't adjust, just check all your valve lash to see if any are way off(a bent valve will have a grossly open valve lash. These are a few good ways to see if any valves are bent.
 

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90 CRX
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Bent valves don't bend back. Think of it like breaking your leg off. Never gonna work right again after re attached. Do a compression check. It's not gonna make it any worse if you try and start it. It really might be ok, but still do a leak down test along with a compression test.
 

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94 Honda Civic Vx
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If that works you'll be able to rev it up a few times and bend them back. But don't get you're hopes up too much. I helped a guy try it this year and it wouldn't start so we tried to toe strap it:3dtard: and ended up just jumping timing again. You may get desperate and pull the head to bang the bent valves closed with a hammer after pulling the cam back out of it. Don't count on them being totally straight though.
wow dude you are a idiot. Do not post unless you know what your talking about... Your giving this guy bad information...........:gayfight2: People like this needs to read and learn more... Retarded people really get on my nerves...
 

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See above...
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The slack on our T-belts are measured on exhaust side of the belt's rotation. A max of 3/4ths of an inch deflection is allowable...and yes, you need some slack in your belt.
 

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98 Hatchback
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Discussion Starter #18
The slack on our T-belts are measured on exhaust side of the belt's rotation. A max of 3/4ths of an inch deflection is allowable...and yes, you need some slack in your belt.
That's more like what I meant last night. Just too tired to put it into words lol.

Thank you very much for the info guys, well... most of it lol -

I know plenty not to try to bend the valves back lol - dass just crazy talk.

I'll do some checks if I can find my diagnostic tools - pretty sure they're packed away somewhere from my last move, haven't used them in a while.

For now I'll reset the timing and check the valve lash. Depending on the results there, I'll either fire it up, or deliver bad news.

I'm curious if anyone has a basic idea of how many teeth the timing belt would need to jump, or how far the timing would need to be out to be likely to have caused damage? Basically if you're looking at the crank and cam pulleys from the side, when the cam pulley is lined up, the timing mark on the crank pulley is off to the right a bit from where it should be lined up with the mark on the block.

Thanks again for all the input everyone, much appreciated
 

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My timing belt jumped 1 tooth once and still ran, but with really bad bad performance(no valves bent).

Another time the belt broke while I was driving in the freeway, and I tried restarting it many times while it was still moving(not knowing it was the timing belt). I was sure I bent the valves to hell. I tore it appart without even checking it and no valves where bent. This was on my Y8, maybe it was because vtec wasn't engaged and the valves weren't open to the max??? Don't know. When i took them all out and checked them, I was pissed at myself for not checking them first.
 
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