I am having a pretty severe issue with a timing belt change that I hope you guys can help me with:

I swapped everything over including new pulleys and belts and turned the engine over by hand multiple times with all marks remaining at TDC with no problems. I then started and idled the car for a minute again with no problems. I put the accessory belt back on and buttoned the car up. I tested it one more time and revved the motor to about 2000 rpms when I heard the belt jumping teeth. I shut the car down immediately.
I think the tensioner pulley slipped and let all the tension out of the belt but now I am very fearful that I broke something. Also, I don't know how to line the crank and cams back up while keeping everything in phase...since now they've slipped.

I know that some of you have a lot of experience so I'd like to ask for some input from you.

I greatly appreciate your time.

Best,
Dave

Some questions:

1. Do the crank and cam gears rotate in phase? that is, are the cams always at TDC when the crank is? Or does one spin faster than the other?
2. I know the oil pump spins a lot faster than the crank, how can I be sure that it's in phase when I reset everything.
3. How would you go about setting everything to TDC if you were installing everything from scratch?

Thanks again

 

good chance you bent all your valves bro. Did you not replace your tensioner with everything?

 

I replaced everything. I still don't undesrtand what went wrong. I guess the tensioner pulley slipped...even though i torqued it properly.

I'd say the motor was on for less than 5 seconds after i heard the slippage. I hope that I didn't cause that much damage.

 

The cam gears are much bigger in diameter than the crankshaft gear (I forgot by how much). The cams rotate at a much slower speed (for every 1 crank rotation, the cams rotate only partially). First thing I would do is undo the tensioner and take the belt off. Try to move the crankshaft to the TDC mark by hand. If you feel any resistance, stop, the crank should move fairly easily. Now use a wrench to try to get the camshafts into their respective TDC positions. You shouldn't run into much resistance, since the belt is OFF and if a valve hits a piston top it should just rotate the crankshaft and no damage will result. Did you check the tensioner gap properly? If you don't measure the gap, you are playing with fire. Do a search on this forum to see how to get the phase of the oil pump correctly. There is a trick to it (when pointing the arrow straight up, it should fall and rotate a certain way).

If you manage to get the engine running again, DO a compression check. Chances are you crushed a valve and need a full engine rebuild.

 

Thanks for your reply.

I checked the gap multiple times....i had the motor idling without a problem, as well. When I applied throttle, though, it slipped. It looks like the tensioner pully rotated on the arm and the hydraulic tensioner is all the way out now. I had checked and double checked and torqued everything....

I understand the checking of the oil pump phase, that's no problem.

If I just place the cams and crank at TDC, will I be guaranteed that their phases will be correct? That, with cams and crank at TDC, i'll have a TDC of Piston 1 condition?

Thanks again

 

The cam sprockets rotate at exactly 1/2 the speed of the crank.

The oil pump sprocket is the only place where just lining up the timing marks won't do.

 

yes, good luck

 

cams spin half as fast as the crank does , when putting it back on make sure u have cylinder #1 on TDC compression stroke before pulling anything apart , makes it a hell of alot easier. But there is a good chance your valves lost the war against your pistons , but hopefully not.

 

If the exh skipped you have more valve to piston clearance, if the int skipped you have less clearance.

For the questions you asked you should have done some reading firsthand before proceeding with the job

 

Actually i dont think this issue had anything to do with preparation as i know for a fact dave read the FSM and did his research before doing this. He is more than able to perform this job.

 

this looks like a helpful thread...

https://www.evolutionm.net/forums/sh...d.php?t=191385

 

Thanks for the replies. I had been read up and felt prepared.

The FSM and How-To all rely on the fact that you've pulled off a working and properly timed belt and that your replacements will be with all of the valvetrain in phase.

Setting the balance shafts in phase are no problem, I understand that. What I didn't understand is how you can be assured that everthing's lined up when the cams spin slower than the crank...I've got it now, though.

I shelved it last night while I did some more research, I'll be putting it back together tonite and doing a compression check.

The tensioner pulley slowly let go and was allowing the crank to jump back and forth with respect to the rest of the timing system. The tensioner only slipped once I revved the motor slightly...the tension settings check that the FSM and these forums provide was OK and would have showed no indication that it would fail.

The car was running at idle for minutes with no problem and I had turned the car over by hand a dozen times, with the marks always lining up.

I'm going to have a tough time keeping faith in that tensioner...I'm really not too happy with that mechanism. But, I'll assemble it tonite and see whether or not I need new valves. Keep your fingers crossed that I don't!

 

Best of luck man! My fingers are crossed for you!

 

how did you set the tension?
You are suppose to set it with the tensioner pulley, with the hydrolic tensioner reset and pin installed.
If you did this properly you should be able to rotate the engine 2 full rotation and be able to pull the pin and push it back in.

 

That's exactly what I did. Counter clockwise 1/4 turn and then clockwise a few revs...Per the manual.


It ran OK, even with the car on. It only slipped once I gave it gas. I thought everything was going to be OK