Cummins Issue

xjmarc · Sep 7, 2015

I feel like every topic I put on here is about my truck but it's getting old and falling apart I guess. Anyway it's a 97 12 valve and is pretty much stock except for a #10 fuel plate. I was towing the jeep this weekend and now when it has a load on it and hits around 18-22 pounds of boost it shakes. Not before or after and without the trailer it doesn't do it. Also if I get on it a little and let out quick it sounds like the sound you make when you stick your tongue out, the spitting sound. Sorry that's the best way I know to describe it. It does this without the trailer or load too, just hit about 15 psi and let off and it does it. I'm no diesel expert, guess I need to be the way things seem to be going with the truck but all I can think is maybe waste gate. It's coming from the passenger side so near the turbo. The fuel plate came with a fitting that replaced the elbow off the turbo that attached to the hose that feeds the waste gate with a straight one that is restricted. I've towed with it since the plate though and it just started doing this about an hour into my trip Friday and the whole way home yesterday. So lets hear from those who know more than me which is most of you as to what it may be. Thanks

Sawzall · Sep 7, 2015

It is not good to get on the throttle hard and then let off. The charged air overcomes the exhaust gas and tries to forces the turbine to spin the other way making a fluttering sound. That can break the shaft on the turbo. Not sure about the shaking.

xjmarc · Sep 7, 2015

Sawzall said:
It is not good to get on the throttle hard and then let off. The charged air overcomes the exhaust gas and tries to forces the turbine to spin the other way making a fluttering sound. That can break the shaft on the turbo. Not sure about the shaking.

I was climbing mountains and this would happen when I would top a hill. I wasn't just getting on it for fun and letting off. I wasn't letting off completely just enough to slow down after topping the hills. It's a new sound but my driving style hasn't changed.

Craig_c · Sep 7, 2015

Pull the intake off and check the turbo for shaft play. The waste gates do rot out inside over time, but that's not at all likely to be your issue.

xjmarc · Sep 7, 2015

How tight should it be?

Craig_c · Sep 7, 2015

It can have a little play, but not a lot up an down. It should have NO in and out play. If you can move it enough that that compressor wheel will hit the housing its shot.

xjmarc · Sep 7, 2015

Thanks I'll check that tomorrow. It's just weird to me that it only seems to have a problem around 20 psi and even then only under a load. Guessing the load would make it more noticeable.

Craig_c · Sep 7, 2015

If the turbo is worn then when it's at just the right spot in load and boost it could be forcing the compressor wheel into the housing.

xjmarc · Sep 8, 2015

Turbo is tight, not movement front to rear and almost none side to side. Spins really easy too.

Craig_c · Sep 8, 2015

Auto or manual transmission?

xjmarc · Sep 9, 2015

Auto tranny.

Derek12v · Sep 9, 2015

Have you changed your fuel filter lately? It almost sounds like you start starving for fuel once your boost and engine load gets high. Are you over fueling at all on these hills? When it starts to do the fluttering/shaking, are you gaining RPM's or losing RPM's while pulling the hill?

xjmarc · Sep 9, 2015

It doesn't even have to be a hill just taking off. The RPMs continue to climb and once it's passed the 21-22psi point it's fine. I try not to go much higher than that but sometimes especially climbing hills it'll hit 28psi. It only has the shudder around the 20psi mark, smooth before and after, as smooth as a 12valve anyway.