Turbo Problems

[cliff winn]

Guys i need help, have a 2001 LB7 6.6 changed engines had myn turbo rebuilt, rebuilt injectors replacede fuel pressure regulator turbo boost sensor the problem is the turbo seems to be whinning even at low speeds, truck seems to run good but when i accelerate the whinning gets worse can someone tell me what to do PLEASE

[DmaxMaverick]

Welcome aboard!

It may be normal, depending on what you mean by "whine". Any aftermarket (or modified OEM) intake or exhaust can exaggerate the turbo whistle/whine. Any time the engine is running, the turbo is spinning, so the sound is always there. It gets louder as load builds, then should quite some as the load (boost pressure vs. airflow volume) increases past the harmonic stage. If it sounds "normal", but just louder, check your intake and exhaust system for integrity.

A loose plumbing connection, on the other hand, can be quite different. Check all your hard and soft connections, paying close attention to the position and tension of the spring clamps, and the V-clamp at the down pipe.

[rapidoxidationman]

I don't know if the plumbing is similar on the LB7, but on my LLY I had a screeching noise that was in tune with the turbo after replacing the passenger side head gasket. Had the sinking feeling to go along with it, believing it to be a turbo bearing gone bad from a bit of overheating.

It turned out to be just a bad gasket seal at the rear of the EGR cooler. It's a pressurized section of the exhaust IIRC and it sounded just like an inflated balloon does when you pinch the hole shut; the gasket became the reed in a poorly tuned saxophone.

Hopefully yours is a similar problem.

[DmaxMaverick]

No smog on any 2001 LB7, in any state (started on 2002 CA, then 2004.5 Fed models). Simple in-out plumbing on the 2001. A leak somewhere is certainly suspect, but the noise will be very different than turbo whistle/whine. They often sound like a REALLY BIG whoopy cushion under load, if it's a hose clamp leak. If it's noisy at idle, it's not likely a charge air leak (no charged air at idle, and very little at no-load higher RPM).

If a turbo bearing is gone, they usually don't run long enough to really find out what it is, until you see the carnage. They self-destruct pretty fast. That, or it just freezes up (what normally happens). If the rebuilder installs the wrong compressor and/or turbine wheel, they can be VERY noisy (and VERY inefficient), with a jacked up A/R.

[Kennedy]

There were some noise issues with the early Allisons I believe. I thought it was mostly the 8.1's though. Been a while...

[cliff winn]

Guys nim new todiesel workings , so my question is should the actuator on the Turbo move when engine is revved, i think it is op0ening an exhaust gate, mine does not move when engine is revved up. Help woul be greatly appreciated

[More Power]

Guys nim new todiesel workings , so my question is should the actuator on the Turbo move when engine is revved, i think it is op0ening an exhaust gate, mine does not move when engine is revved up. Help woul be greatly appreciated

No, the actuator on the LB7 turbocharger won't move till boost pressure reaches/exceeds 18-20 psi. That won't happen unless the engine is being worked hard, which can't happen in a driveway. Jim

[cliff winn]

Thanks

[cliff winn]

Thanks for all the help guys i got my turbo problem solved, but now i think i am having a problem with my fuel pump had to prime it to start. do you know if on a 2001 LB7 does it have a lift pump or just the fuel pump in the tank, i would appreceiate any help. Thanks

[bmoeller]

Neither. Mr Kennedy has a pump kit to remedy that omission by GM.

[cliff winn]

im confused, you mean it does not have a lift pump or in tank pump, then how does the fuel get to the filter

[DmaxMaverick]

No lift pump in the tank or otherwise, unless someone installed one. The only fuel pump installed from the factory is the high pressure pump located on the engine, which draws fuel from the tank. The fuel supply system is suction from the tank to the high pressure pump. It is not self-priming. Having to prime for a start is normal, if the system has been open, such as during a filter change. If you have to prime it repeatedly to start, the fuel system has a leak, either in the plumbing or the filter. If you only have to prime to start, but it runs relatively normal, the leak is small. Typically, a poorly sealed filter is the cause, and reseating the O-ring(s) will usually cure it. If the water drain is loose, it can allow air intrusion, although it may not leak fuel externally.

[cliff winn]

Thanks, just where is the pump is it on the filter housing

[jbplock]

Thanks, just where is the pump is it on the filter housing
Injection pump is on the top front/center of the engine.