just trying to get it broken in and running good after all the money in the head and tonight something went wrong. i have the wastgate set back at 40psi, and was doing about 70-75 on my way home tonight when a car came off a ramp pretty quick. i get on the loud pedal a bit to move up and get him some room to merge. i was at full throttle (my stupidity) when the exhaust goes POP POP POP POP POP like a really bad back fire. so as im cruising home i notice there is still some blub blub blub blub noise in the exhaust, no engine sounds, nothing up front, its only coming from the stacks. whatever it is that is broken (valve, gasket again, bad piston) can not be heard over the normal engine rattle. the pop or blub sound at the stacks can be heard easily from idle and when i popped the hood with it idling you can hear that same BLUB BLUB BLUB at the AFE intake, but no excessive valve noise etc.

the truck has lost ZERO power, i gave it a 3/4 throttle blurlp on the way home and the power is still there like normal, boost like normal, EGT's normal. i will post some really crappy videos i took with my digi-cam in a minute but you can still hear the noise.

so what do ya think, exhaust gasket leak, valve/pushrod bent, turbo, head gakset leaking and losing compression? i mean there are no codes to tell me anything and the only way i know something wrong is by this new (and kinda cool sounding) burping in my exhaust.

 

sorry for poor quality, its a cheap digi-cam

video 1- idle next to intake then move to the stack
http://s97.photobucket.com/albums/l2...t=IM000022.flv

video 2- cruising, getting on the loud pedal slightly to hear the noise change with rpms
http://s97.photobucket.com/albums/l2...t=IM000021.flv

 

Flat cam lobe.

 

what would cause that, and why would there not be any power loss etc?

 

Just guessing about the flat cam lobe. You said you did head work I thought.

A flat bad cam lope will cause popping out the exhaust, valve not opening all the way. Wouldnt notice much power loss. Could be a loose rocker too.

Friend of mine built a new BB chevy for his drag boat started poping out the header, I took a ride in it. Pulled the brand new cam and it had a flat lobe and others were bad. He didnt lube it or break it in right.

Could be a burnt valve too . Could be something else too

Just a guess!

Rick

 

thanks, i guess after work tomorrow ill check it out...

weird question, can you idle a cummins with the valve cover off without oil going everywhere (ie: does it trickle out the top, or does it shoot everywhere inside the cover) i was thinking maybe if i could let it idle and see if there is any particular valve not opening or something.

 

Hopefully nothing major is wrong . I dont know if the oil will skirt out, havent tried starting with the Valve cover off.

Again I was just making a wild guess

 

you can idle them with the valve cover off with no problems

 

Check your valve lash.

 

Yes, you can idle it, but if you bring the RPM's up alittle bit you'll have oil running down the back of the engine.

 

im going to do that tonight...another forum suggested same thing.

but why would it just happen when im at full throttle (i was prolly near 3k rpms) when it sounded like an automatic rifle popping off rounds so i let off the throttle. this noise didnt just come up, it was due to whatever happened at full throttle that made it backfire.

 

any more suggestions?

 

Check all your exhaust connections. I had a similar noise when the wide band clamp came loose on the connection from the downpipe to the rest of the exhaust. Just a thought

 

ill check but this noise is something with a single cylinder (gonna check valves tonight) it only started after the bad backfiring that happened at WOT. i just hope its something minor and not expensive

 

I hope so too man. That sux- its been one thing after another for ya this year