Cummins blue smoke under acceleration with shudder.

6BangBronk

6BangBronk

Well-Known Member
Joined
Jul 15, 2005
Location
Durham
I'm getting so many different answers from searching the general internet that I really don't know where to start? Thought I'd ask here to see if there was a general consensus...

So I was towing with 94 dodge 12v cummins this weekend and had a follower that told me I was puffing blue smoke. And I was noticing a shudder when I was climbing hills. So I started watching the tailpipe and put the shudder and blue smoke together. Truck is an automatic and I was using cruise. I was able to bump the "coast" during hill climbs and it eliminated the blue smoke / shudder but also put a damper on my speed. But after I dropped off the load it never happened again.

I checked oil, tranny fluid and air filter and all was good.

So far for answers...
Fuel Filter needs changed
Turbo bearings going bad
Air leak into turbo
Valves need adjusted
and oil leaking into intake manifold

I'm sure I can find more if I keep reading. All I know is there seems to not be a sure answer? Just seems so isolated that it should be diagnosable.

Haven't bought the gage set so only have stock gages and dummy lights to go from. It ran fine besides the hills and trying to give it more than it could take. All gages were showing good.

Any help would be appreciated.
 
How much is it turned up?
 
Sounds like pump to me..... Mine did the same things but it was a rotary pump
 
6BangBronk said:
Air leak into turbo
Click to expand...

typically that can be diagnosed from a whistling sound that gets louder under load.


my .02
blue smoke - possibly valve stem seals leaking
shudder - a rough shudder can be the torque converter


also, if you're getting oil into the intake manifold of a cummins, you're doing something!
 
snappy said:
Sounds like pump to me..... Mine did the same things but it was a rotary pump
Click to expand...

Consensus here at work with my 2 gear buddies is to check exhaust side of turbo for oil and wiggle turbo for play. AND BUY GAGES FOR NEXT TIME! Although it would do me no good now to not have a comparison.

Truck just turned 192k. I do oil/filter every 6k for I tow heavy only occasionally. Bought it with 160k and have absolutely no idea the history besides the seller telling me "it was driven by lady with only her horses" Could have been a fleet of 20 Clydesdales with a custom 40' trailer as far as I know...
 
I say sell it to a flatbiller for $30k and tell them anyone can roll black coal, this truck rolls blue! :D

Other than that I have nothing productive to add, hope you get it worked out.
 
We see lots of fuel pressure issues cause similar concerns, timing slips, bad injectors. I'd start with a quick timing check and lift pump pressure verification!
 
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