Loud clunk after dizzy install...

[jleblanc06]

So i replaced my water pump and intake manifold gasket (had to remove dizzy of course). After putting it all together I was cranking it and it didn't fire, felt like the timing was way off. Then all of a sudden while cranking I heard a real loud metal clunk. Sounded like I left a wrench and a belt snagged it and slammed it on something. I obviously stopped immediately but can't find anything that would have caused that noise...(getting super worried)

Could the distributor not have been seated properly and caused a loud clunk like that? Is that even possible? I checked the dist and it was snug and appeared flush but not 100% positive.

Any ideas on what I screwed up?

 

[1987 GMC Jimmy]

Accessory bolts and fan shroud clear of the fan? Lifter valley was clear upon reassembly and the rocker arm area was clear when you put the valve covers back on? It very well could have been a bolt or a nut getting slung away.

 

[74 Shortbed]

Could be a lot of things, crank it over again and see if it does it again, just tap the key a few times.. Speaking of the distributor, did you put it in without a gasket first and check the clearance to the intake???, don't want to clamp it down and have it bottom out you'll wipe out the pump in very short order..

 

[Honky Kong jr]

Or snap the distributor base where the clamp sits.

 

[74 Shortbed]

Or snap the distributor base where the clamp sits.

Yep, that could happen too I guess..

 

[jleblanc06]

Well I triple checked and found nothing obstructing the belts, fan, or any moving part. I tried cranking the engine and another loud clunk. So something is definitely amiss....

What do you mean by check the clearance of the intake? The intake is the original, I didn't replace the intake, just the gasket. So shouldn't it fit the same?

the one mistake I can think is I don't know if I aligned the distributor base with the oil pump shaft. I dropped the dist in and it turned down easily. If I didn't get it aligned could it try to pop out but jamb up since the dist is bolted in?

EDIT: SOLVED. the clunk was 100% "starter kickback" from timing too advanced. Got the timing set the proper way and she fired right up and no clunk or scary noises.

 

[shiftpro]

Automatic?
Flex plate loose from converter.

 

[shiftpro]

Does the rotor turn when the engine is cranked over?
You might want to consider getting someone to watch the dizzy, cover off, while you get underneath and turn the crank pulley with a socket.

 

[HotRodPC]

Are you building oil pressure? Shiftpro may be onto something. Is the rotor turning? Need to make sure the bottom of the dizzy has engaged the oil pump rod properly and dropped down low enough that the dizzy gear is meshing with the gear on the end of the camshaft.

Do you have anyone to watch the dizzy while cranking? If the dizzy is jumping up and down as you crank, it's not engaged in the cam gear and oil pump shaft correctly.

 

[RustyPile]

Busted starter snout....

 

[Rusty Nail]

Did you check the oil!?

 

[74 Shortbed]

Well I triple checked and found nothing obstructing the belts, fan, or any moving part. I tried cranking the engine and another loud clunk. So something is definitely amiss....

What do you mean by check the clearance of the intake? The intake is the original, I didn't replace the intake, just the gasket. So shouldn't it fit the same?

the one mistake I can think is I don't know if I aligned the distributor base with the oil pump shaft. I dropped the dist in and it turned down easily. If I didn't get it aligned could it try to pop out but jamb up since the dist is bolted in?

If the distributor don't line up with the drive it won't drop all the way down, you'll know it, and you rotate the motor until it drops down, then keep rotating to TDC and see if the rotor is facing where you wanted it. Clearance from the intake to the distributor base, was that "ever" checked??, distributor base should sit on the intake without a gasket, if it does you're good to go, but if it don't you need to check how much gap there is, it has to be less than the thickness of the gasket, if not it needs to be shimmed so it don't bottom out on the drive(They come in a kit). You said you changed the gasket, is it the same thickness as the old one??, those vary quite a bit, don't have to change the intake for things to change, just a different intake gasket will change the height of the intake, also the distributor base can be off from one unit to another by a few thousands, anytime "anything" is changed that clearance needs to be checked.

 

[jleblanc06]

I didn't watch the oil pressure while cranking unfortunately. I'll have the wife watch the rotor while I hand turn the engine over and see what is happening. I'll let you know..

(I checked the starter snout, it looks good still. Didn't see any cracks or signs of damage.)

 

[jleblanc06]

If the distributor don't line up with the drive it won't drop all the way down, you'll know it, and you rotate the motor until it drops down, then keep rotating to TDC and see if the rotor is facing where you wanted it. Clearance from the intake to the distributor base, was that "ever" checked??, distributor base should sit on the intake without a gasket, if it does you're good to go, but if it don't you need to check how much gap there is, it has to be less than the thickness of the gasket, if not it needs to be shimmed so it don't bottom out on the drive(They come in a kit). You said you changed the gasket, is it the same thickness as the old one??, those vary quite a bit, don't have to change the intake for things to change, just a different intake gasket will change the height of the intake, also the distributor base can be off from one unit to another by a few thousands, anytime "anything" is changed that clearance needs to be checked.

I did compare the gaskets before swapping them, they seemed to be the same. But I still have the old one I'll make sure its the same.

 

[crazy4offroad]

My first thought was the oil pump drive wasn't engaged, and if you had the distributor hold-down tight it likely popped into place. If the hold-down was tight and is loose now, that's likely what happened. If it was a louder noise, make sure the rotor is turning when you crank it, it's possible the roll pin on the gear sheared.