engine kickback at startup

Occasionally at startup just after I release the key I will get one or two loud clacks. It sounds like metal parts contacting but it has done it occasionally for a while now and I dont have any known internal issues or at least it doesnt have a lot of blowby and it fires up fine 99% of the time.

Any ideas what this might be. It sounds like it is coming from the flywheel area but I really can't tell for sure. it occurs so rarely that I am never really listening to where it is coming from.

You might pull the inspection cover and have someone bar the motor over for you. Inspect the starter ring and flywheel/flexplate for cracks.

I will check that tomorrow. Gotta look for a boost/dp leak too. May as well add it to the list.

Anyone else think of anything else to check?

I would be looking at the drive gear on the starter as well. I would probably pull it off to check it out.

Before you pull the starter check to see if all the bolts are there and how tight they are. I've had mine back off before. If they are loose put some loctite on them and you should be fine.
Might want to look at your exhaust if it's aftermarket to see if it may be hitting something.

I checked the ring gear and flywheel and all looks good as far as cracks go but I can see a little damage on the leading edge of the teeth on the flywheel. It looks like the starter tried to engage after releasing. What would cause it to do that?

neverkickn said:

I checked the ring gear and flywheel and all looks good as far as cracks go but I can see a little damage on the leading edge of the teeth on the flywheel. It looks like the starter tried to engage after releasing. What would cause it to do that?

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no, that's either where the starter biffed it one time, or walked into the ring gear instead of ratcheting in..

Ok it did it again yesterday and I got a closer listen. It is actually trying to stall and right before it quits it starts firing again. My guess is that the loud clack is the sound of the engine beginning to fire again after a sudden drop in rpm. It is alot like a cylinder or bank dropping out for a split seccond and only randomly at startup. I mean to say that if it persisted longer than just a millisecond then It would sound like I was running on one bank.

I have checked and rechecked the uvch connections inside and out. New ipr, new cps, termy hpop, reman 160 injectors. It does it with fresh oil too. I am thinking something mechanical because I have no codes.

Any ideas on what to check.

If your truck runs good othewise I would still be thinking the starter if this happens while the starter is still engaged.

Tom S said:

If your truck runs good othewise I would still be thinking the starter if this happens while the starter is still engaged.

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Well it does it with a new starter. Not a reman but a new delco. It did it just the same as with the old starter. I guess that doesn't mean that it isn't the starter staying engaged, just that if that is the case it has to be another component causing it to stay engaged.

What other relay, sensor, switch could cause that?

There is that fender solenoide on the pass fender that is for the starter that might be going bad.