Ok let me start with 87 L98 auto 92K within last 3K miles new plugs, wires, cap, rotor, & injectors. Car ran perfect right up until I pulled away from a red light moderate heavy acceleration, backfire car dies no start. I have 40lb. pressure at fuel rail, it sounds like I jumped timing removed distributor cap & rotor there is play in the rotor mounting plate and I can move it about a quarter turn each way or 2 notches turn if I lift up on it. What do you think is this where I jumped timing from. I don’t believe I should be able to lift that plate and turn it. Is the dizzy bad? can this be rebuilt? bad gear? or better replacing. Car wants to start but sounds like timing is off and backfires out PVC hose. Any help be great. Let me add the dizzy base is tight and not moving. I will bring it up on TDC later see where rotor is pointing.
Upon further inspection I notice there appears to be a rubber gasket or seal around the harmonic balancer behind the crank pulley some of which is sticking out, some looks to be missing. Does a 87 L98 have the seal between the harmonic balancer & crank ,or does it have a keyway? should I be able to see it by looking down at the pulley, I know some motors have this just sure about a L98, I also know if this goes bad it causes the harmonic balancer to move and lose timing.
Thanks

 

Ok I turned over motor by hand with cap off a couple times it was ok a couple times it looked to get stuck & click about about the 11 oclock position loking from front of motor and now on TDC im about a 1/3 turn away from # 1 plug

 

Sounds like you might have ot reset your timing anyways so I would mark the dizzy where its at and get the eng to TDC. Then pull the dizzy and check out the gear.

 

Sort of what I'm thinking I will have some one turn it over in the morning and watch it and see what happens under a load. Can I just replace the gear or do I need the entire shaft ?

 

I'd check the car for codes first...the description I quoted sounds a lot like a exploding MAF sensor I had one time. Unplug the MAF and see if the thing will fire up.

There is a seal for the timing cover that rides close to balancer...this may be the seal you are seeing. The balancer is roughly comprised of 3 parts and small hub (slips onto the crankshaft), a rubber insert (which mounts around the inner hub) and an outer hub (which mounts around the rubber insert). The inner hub is keyed and bolted to the crank. If you think your balancer has spun draw line on the face of the unit from the inner hub to the outer hub...start the car if you can and see if the line changes. If your balancer has spun from the correct spot it would explain why you think your DTC markings are off on the dizzy's rotor position. If you find that you need a new distributor gear I know you can order them from Summit....you'll also want to install an new roll pin too to hold it in place.

 

I did try to start it with MAF disconnected same thing just turns over no start. Thanks for the Summit lead I/m going to TDC it in morning then pull dizzy see what the gear looks like.

 

Did you check for trouble codes yet? Take a look inside the MAF through the screens and check to see the filiment is still intact.

 

Your description of what the dist. is doind doesn't sound right. I agree with the others, you need to bring #1 to TDC, and pull the dist. to inspsect. Based on your description seems to be the likely culprit.

The balancer spinning on the hub will not effect the timing, just make it appear to be off.

Another thing to consider is that the timing chain jumped and the cam is no longer in proper phase with the crank.

You seem to be on track with your troubleshooting.

 

Well I had a neighbor come over to turn it over while I watched the dizzy and its not spinning all the way around. Sure enough removed it and some of the teeth on the gear are sheared off. I called my guy in Miami dizzy on the way. The only thing I can think of as to why it happened is some where on the shaft the bushings must be bad and caused play in the shaft.

 

WOW! you may want to take a look through the intake hole and inspect the cam gear for damage too.

 

One thing to think about - where did the shrapnel from the gear Go, anyhow? What is going to blow up Next?

And how bad is the matching gear on the Camshaft?

Throwing a new distributor (or distributor Gear, which is all you really Needed..) at it is just asking for trouble. Used car lot solution - patch it up and peddle it - let the buyer beware!

 

I will try see if the cam gear is bad but the shaft on the dizzy had some up & down play so I'll check when I get the newer one. No way will I patch it up and get rid of it its way to nice for that check my photo album. I will have the oil changed as soon as its back on road.

 

Just looks like a very high mileage gear...I just drop a new gear in there and take your chances. How many miles on the car?


Nice shot of the neighborhood......nice to not see a "for sale" sign on every house like here in Tampa.

 

Only 92K (87 L98 about 4k a year) however the dizzy spins much more then the crank dose and being 23 yrs old who knows if its even the same one that came with the car. Photos didnt come out good but not able to see down at cam gear. I would think Chevy made that harder then the the dizzy gear. They have been building these motors a long time I'm not the first with this trouble.

 

This has happened to me on a few occasions until I moved to GM's melonized gear. I attribute my excessive gear wear to running a HP oil pump, putting too much pressure on the gear mesh with the cam gear.

In every case, the cam gear was fine because, like what was said, I believe it's harder than the distributor gear.

If, after installing the new gear, there's still excessive up and down movement, grab a distributor shim pack and use shims (like washers) to take up the clearance.

Also, check side to side clearance of the distributor shaft in the distributor housing. If the shaft wobbles inside the housing, that'll cause excessive gear wear too.

Jake

 

Thanks for that information Im geting a different dizzy out of a 91 but I will check the clearences on it. I just thought $40.- $60. for the gear or buy a different dizzy with all the electroincs for $100. no brainer and I'll have back up if needed later.

 

Not sure that it is a no brainer if the new distributor does not have a melonized gear which it should.

 

I'll check to be sure

 

Well the new gear fixed the trouble although I came across a new issue. See post http://forums.corvetteforum.com/c4-t...ark-moved.html So till I can get a new harmonic balancer on it I'll just have to time it the old fashion way by ear unless some one has a better idea