Timing Belt Skips

gary cheris · May 24, 2008

'84 SVO - had a reputable machine shop redo the head and installed it. Set up the cam, oil/dist, & crank gears just right with a new timing belt- timing was perfect. Engine started and ran great. Checked the timing and was right on. Went to move the car and at about 8 feet the engine quit and wouldn't start.

Re-checked timing and it was off. Re-set everything and started fine. Revved it up and down and worked fine. Went to move it and got to about 12 feet and it quit.

After lots of checking we've determined that the timing belt is skipping on the crankshaft gear - the cam and distributor stay in time with each other. The tensioner is strong and the mechanics at the dealership say the crankshaft gear is in good shape.

We're at odds to figure out what to do. One person suggested the cam shaft may be a bit warped but i don't think so because we had the engine running for about twenty minutes at times and you'd think something would have shown up.

Any viable suggestions would be really, really appreciated.

Thanks

cjones · May 24, 2008

may be a stupid question but, you are tightening down the bolt on the timing belt tensioner??

tensioner bolt (adjusting): 14-21 ft-lbs
tensioner bolt (Pivot) : 28-40 ft-lbs

gary cheris · May 24, 2008

Yes, but thanks for thinking about that.

RustBucket · May 25, 2008

Did they put the right belt on the car?

There were two different tooth patterns. round and square.

The teeth should be an exact match. I'm pretty sure you should have square-tooth sprockets.

gary cheris · May 25, 2008

You are quite right and yes we do. That was one of the things we really looked close at as well as making sure the tooth spacing was the same on al three sprockets. Thanks for the help!

RustBucket · May 26, 2008

I got an idea. Why don't you tell us what all has been done thus far and we can go from there?

gary cheris · May 28, 2008

Apology

Wow, that was kind of harsh! Sorry, I thought, probably mistakenly, that what I had originally written impied (guess I was wrong) that I followed correct and logical mechanical procedures. What I had hoped to receive was information on an oddity that is not commonly known to cause the problem we're having. Again, please accept my apologies.

65ShelbyClone · May 28, 2008

No need to apologize. The more information you can give us up front, the more precisely we can offer suggestions. Even if a procedure seems simple, we can't just assume that you did it right or even did it at all because many other people do not. I can't count how many threads I respond to with questions for the poster rather instead of answers.

You said the timing was off.....ignition timing or cam timing?

RustBucket · May 29, 2008

I owe YOU the apology.

I'm sorry. That was rude.

Anyway, Did they check the crank key? It's not common to see an issue with them unless they lost the original key and used another that "almost" fit or fit "close enough" There's not much of the key that holds the crank sprocket so if it or the crank sprocket is wiped out, the crank itself would be slipping in relation to the crank sprocket and could possibly present the scenario you described.

gary cheris · May 29, 2008

Timing Belt

As far as the timing is concerned, the cam and distributor are staying in sync but the crankshaft is skipping ahead. I can create the fault usually on starting the engine. Its like everything is at rest and then the starter spins the crank and the cam and distributor sprockets, having more surface contact with the timing belt, don't move momentarily - like there's some resistance, and the crankshaft sprocket skips ahead. One time I actually saw the timing belt buckle slightly toward the distributor sprocket.

I thinking about pulling and checking the camshaft for trueness.

Good idea on the key, i'll have to go look at that.

Thanks to all.....

Stinger · Jun 3, 2008

Sounds to me like you have a round tooth 2.3 belt on a square tooth 2.3 pulley arrangement, assuming there is proper tension on the belt before startup and the tensioner is tightened down. It's really the only thing that can cause it.

gary cheris · Jun 17, 2008

Thanks for the info. Just got back in town, so will check it out in a couple days.

Gary

gary cheris · Aug 3, 2008

Problem fixed!! New problem

Thanks to all of you for your patience and suggestions. You are all very kind. Problem fixed due to your input.

I had the young man (his car) who put the head back on the engine retrace his sreps by starting to remove the head. When he got to the pivot bolt on the tensioner pulley we found he had used a shorter one than required and basically locked the tensioner in one place preventing it from taking up the slack when necessary. He had had the bolts from two engines in one location and selected the wrong one initially. Works great with the right bolt!

Well, for about 150 miles. Then he started using water. Long story short, the original head w=had been cracked and so he took the second head off a spare engine that came with the car. It had rollers etc and was ported. Had the machine shop check it out and they said it was fine. But, whoever did the porting didn't leave much room and the water ate thru in two places ( about 1/4" across) so we're going to try to have a fiend TIG the holes.

Anybody have any comments on trying to do this? Anybody have a good head for a good price?

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