Problems after timing belt replacement

[deadchevy]

I am having trouble getting my 92 Z34 back on the road. Vehicle stopped one night, had it towed to mechanic for diagnosis, a broken pulley was revealed, new pulleys, tensioner, and belt installed. Vehicle ran horribly. Took vehicle to dealer. Had leak down test(no problems), reset belt timing/adjustements. Car starts hard, very slow turn over. At approximately 50 MPH it feels like it is going over railroad tracks. Exhaust tone is totally different, sounds like a miss or leak, not the clean tone it used to have. Idle is not smooth, much vibration. Have replaced plug wires, plugs were replace 500 miles ago before pulley problem. Power is close to previous but not the total kick in the a** it had before pulley problem. Any help out here? Fuel injectors and trottle plate/bore have been cleaned at time of new plugs.

[SappySE107]

Have it timed properly as I bet both banks have the cam flats facing up at the same time.

[deadchevy]

It is at the chevy dealer now, they have re-timed it twice.

[SappySE107]

Yeah, not all dealerships know how to time this motor. Ask them how they have the flats on the cams setup.

[bve32k]

Ben may be right. I timed my car and both flats were facing up. It was so loud and sounded like there was an exhuast leak. So much vibration in the engine bay.

Then I did it the right way and it started right up normally.

[napatiger]

with all the money you spent at the dealer, you probably could have gotten another car.....

I will never have the dealer work on my car again.

You should at least know how to do some stuff on this engine if you plan on keeping the car. and this site is a great way to learn!

Pull plenum, pull cam carrier covers, check to see that flats are up on one side and down on the other, also check that each pair is level.

Plenum can be a bitch to pull, but after 15 times or so should only take about 30 minutes.

Good luck.

[dohcfiend]

with all the money you spent at the dealer, you probably could have gotten another car.....

I will never have the dealer work on my car again.

You should at least know how to do some stuff on this engine if you plan on keeping the car. and this site is a great way to learn!

Pull plenum, pull cam carrier covers, check to see that flats are up on one side and down on the other, also check that each pair is level.

Plenum can be a bitch to pull, but after 15 times or so should only take about 30 minutes.

Good luck.

ha!!

[deadchevy]

TY for the info. I realize what a great error I made trying to throw money at this problem. It's my daughters car since I stopped driving it 3 years ago. It has only 97,000 miles and figured it still has many more to go, so a couple of bucks would be a good investment. I really didn't want to spend any time at all on it and having someone else do the work was at the time the logical thing to do. Oh well I guess I needed another hobby and didn't know it. My 64 El Camino is dream to work on compared to this vehicle.

Was the "ha!!" to me for my stupidity or to getting the plenum off in 30 minutes?

[SappySE107]

It takes about 10 minutes to pull the plenum but you gotta know what all is needed. 7 bolts that are obvious, 2 in the back, the MAP sensor lines (3), EGR, brake booster (i just take the line off the booster and deal with routing it vs trying to pull it off the plenum first), 2 vacuum lines behind the TB, TPS and IAC sensor plugs, and finally, the coolant line that is right under the TB. If this has the squeeze to remove hose clamps, just cut the rubber line and get a new section from the store. Then use real hose clamps. Use a screw driver on reinstall to hold the pipe that the hose connects to in place while you reseat the plenum. I don't mind pulling it, but I don't like lining up the EGR with the gaskets and the plate it bolts to, nor the coolant line.

[GTP_MuNkY]

Say he pulls the cam covers and both sets of flats are facing up, whats the easiest was to re-align them?

I think that "HA!" was for pulling the plenum....
*mutters* stupid TB coolant hose (last person to pull mine used hose too small and a squeeze clamp... I had to cut it off)

Jamie

[deadchevy]

The first mechanic that did the replacement of pulleys and belt mentioned to me that when he turned the crank it took a while for the top shaft to move. I am guessing he turned it counterclockwise and the tensioner was moving. Is it possible the timing chain jumped a tooth when he did this?

[RollinonZ34]

Just a thought, but have you considered a Coil going out or Spark Plug wires crossed and not in the right place on Coil.....p

[deadchevy]

Been out of town. Going to give it a once over as soon as I can. Plug wire order will be checked. All wires were changed and no difference was noted.

[SappySE107]

If it is spun backwards, your cam timing will probably be screwed. It says in the manual to not do that and given how the tensioner works id say the cam timing would be messed up. It won't affect the timing chain though.

Im a little confused on the "top shaft" part though so its possible that your timing chain is screwed but not from spinning it backwards.

[deadchevy]

My problem is solved. It was a cam timing issue. Had already spent the money at the dealer so I just kept on them till they solved it. The lastest reason for the problem was a bad tensioner. They replaced it, supposedly, and retimed it and it runs perfectly. They stated that it kept jumping timing due to the bad tensioner. I can't say for sure that was it but it took persistence to get them to do it right. If this car is kept around here long enough to need any more major repairs I will definetly be trying it myself.

THANK YOU TO ALL WHO POSTED.

This board is a tremendous help. I would not have been able to present to them the knowledge of what was really wrong with it if not for all the infomation here.