Loud bang - smoke...timing chain?? Need help

[atl95gt]

i was getting in my '97 eddie bauer 5.0L (99,300k miles) this morning and tried to start it up - heard a loud bang and smoke started eminating out from under the right front of the hood. popped the hood - no busted belts and nothing visible.

i then started the motor but it ran uneven with a rough idle (ranging from about 700 to 1500 rpms). i have done some research on this site (which has proved incredibly helpful for some other minor issues), however, didnt see anyone with the same issues as this.

could the timing chain busted a link and/or skipped a tooth on the sprocket? do i need a new chain kit? if so, what is involved and what parts do i need?

i have seen some discussion of the 00M12 recall and some other acronyms that i dont know about.

thanks in advance guys.

 

[atl95gt]

update

quick update - just spent some time looking/listening under the hood - no residual smoke and no leaks that i can see. i started the motor which now runs around 1000 rpm at ilde (slightly higher than normal) but the motor has a high pitch whirring sound inside the manifold (or at least thats where it sounds like it is from).

every 10 seconds or so, the motor drops idle a little bit and shakes and then the rpm's pick up, but the 'whirring' sound is apparent the whole time.

i am stumped. anyone have any ideas/similar experiences?

 

[Doug]

Hrm, I doubt it's the timing chain. If the timing chain broke your motor would not run. Your truck does not have the timing chain issues like some others, those issues where limited to the 4.0 sohc motor. Check the motor real good again, Check the PCV valve and all the vaccuum lines you can find. I once had a vaccuum line pop of for no reason and the truck ran like crap and you could hear the vaccuum leak.

 

[atl95gt]

it actually does sound like a vacuum leak - a really loud one inside the motor - but i couldnt find one - i did find a rubber end cap inside the engine bay that was obviously misplaced but couldnt find its home. the thing thats confusing is the loud bang and smoke this morning.

 

[atl95gt]

just to close this thread - i found the problem. under the fuel rails on the driver side running along the manifold is an open tube that must be capped off by an rubber end cap. the bang and smoke this morning was the end cap blowing off and the residual smoke in the exhaust manifold. thanks to J. Danna in another thread for providing enough guidance for me to find the problem.

 

[section525]

Rock on!

 

[gijoecam]

just to close this thread - i found the problem. under the fuel rails on the driver side running along the manifold is an open tube that must be capped off by an rubber end cap. the bang and smoke this morning was the end cap blowing off and the residual smoke in the exhaust manifold. thanks to J. Danna in another thread for providing enough guidance for me to find the problem.

Glad you found it! It may have been either a back-fire, or something may have ignited the un-burnt exhaust fumes in the crank-case, blowing the cap off the vacuum line. The high idle gave it away.... the thing that most commonly causes a vacuum leak is a missing cap or split hose. That can easily happen if the crankcase gets pressurized, which can happen from a back-fire or excessive blow-by when cold.

Glad you got it fixed!

-Joe