TIMING IS OUT HELP PLEASE

[DRAGN1]

I WAS REPLACING MY TIMING BELT AND THE RIGHT SIDE CILINDERS MUST OF HAD BACK PRESSURE AND THE RIGHT SIDE SPUNN ON ME ABOUT 100 DEGREES OUT I THEN ROTATED IT BACK AND LINED UP THE TIMING MARKES BUT IT JUST WONT RUN RITE  HEL[P PLEASE

[Chrisj CMA]

I hate to tell you this Dragn1 but if one cam spun 100 degrees with no belt on it, then you have valve damage.  THis has happened to people before, I know of at least one other

[John U.]

For the benefit of those of us who would like to change belts or install a trigger wheel, could someone explain how a cam can spin on its own, and how to avoid this problem?
Don't get me wrong, I'm not doubting anyone's word, just trying to find out before I get myself in trouble.
Thanks in advance

[Ricky-D]

When you release the crankshaft resistance from the camshaft (like removing the belt) there is some remaining force (from the valve springs) trying to turn the camshaft. Most of the time if you are careful with what you are doing when removing the belt, like being dead on TDC, the cam will not rotate. mess with the cam belt wheel a little and bam, the cam will rotate.

The crankshaft could turn also due to the forces from the other bank of valves working back through the remaining cam belt.

The best advice I can offer is to get the manual and read the manual until you fully understand the ramifications of cam belt replacement and related pitfalls.

[mikehallbackhoe]

when changing belts, never turn the engine over without both belts on. when replacing the belts, put them on by placing the belt on opposite the tensioner. for example,the right side belt should be put on from the bottom of the gear, since the adjuster is on the top side of the gear.removing the adjuster belt completely makes it easier to put the belt on. always check to see if the marks on the gears line up with the pointers. when finished, turn the engine over using a wrench on the crankshaft. removing the spark plugs makes this easier, but is not nessecary. remember, the valves have very small diameter stems, for light weight and good flow, and bend very easily. the key is to work slowly, and always double check your work

[Chrisj CMA]

I always remove all the sparklers.  Compression (I think) worsens any tendancy to try and rotate on its own.   Hope its not that bad bro!

[Robert]

Dont know if you got to the bottom of the running issue but it could be a bent valve like Chris said. But when the cam rotates on its own most of the time you will not bend the valve from that. Most of the time its a retiming issue. They make a camshaft holder for this problem but in reality you can let the cam turn after you have the marks set up and as you take the belt off, hold the cam with your hand or wrench and let it turn easily, don't let it bounce if you can. When the new belt goes on take the belt put it on the crank then turn the cam with your hand or a wrench in the direction that it moved from. But turn it easy there should be only the resistance from the spring and if you feel solid resistance then theres a problem. Remember mark the old belt and all the marks with a mark you did, this will let you confirm your assembly so that you can recheck what you've done. It also helps to mark the belt to the cam and the crank with finger nail polish so that you again can recheck your alignment when you have the new belt on. If you hold it up in the position that it supposed to go and the marks line up with the new belt on then you should be good to go. Also do take the plugs out because you can turn the engine easier and if there is a slip up it allows you to turn the engine by hand first and verify that it turns smoothly without binding BEFORE using the starter.

[Robert]

Just reread your post and realized I really didn't offer any help so here goes. First see if you can isolate the offending cylinder by pulling the plug wires one by one.Then recheck your timing marks and see if all lines up. The second is a compression test, if that is OK then you may not have to pull the heads. The other thing about maybe bending a valve this way is that it may not be bent enough to really lower compression but may be blowing back into the intake causing problems. The way to diagnose this is to put air into the cylinder and see if it leaks out and where. This is a test of comparison meaning that use the rest of the cylinders to compare the results of the cylinder you are testing. If one is leaking more air then that may be your problem cylinder. The leakdown test has to be done with the valves closed and the piston either at tdc or bdc. The way I have describe to do it is not the regular way but it does work.

[Shepard]

I did something similar last summer. I was coming up on 100k and thought it would be a good idea to replace the belts on my '97 Standard. Rather than match the cams "up" with the timing mark on T1.2, I figured since I ain't doing the valves that I could replace the belts in the position they were currently in. I pulled the right belt and watched the cam flip with horror in my heart. I thought I was doomed and I should have been for being so careless with my baby. Luckily I was able to rotate the cam back to the up position and did the same with the other side, checked the timing mark alignments a couple of hundred times to be sure and then put the cover back on and that has been 20k miles ago or so. It was a lesson I will not forget.

I hope it is just out of time and not bent valves.


Shepard

[f6john]

OK, so what's the status on this? Any progress?

[Chrisj CMA]

ya, hows this going...inquiring minds want to know