Cat 3126e Power Loss

[RHMinetti]

Cat 3126e engine was operating fine cruising at 60mph. Got to the bottom of a long incline, started up, and all of a sudden the unit lost almost all power. Heard a low "pop" and heard what sounded like the turbo winding down. The transmission downshifted to 1st gear and the engine RPM went to 1500 max with the pedal floored. It was a 2 mile uphill climb at 5 MPH. I noticed some black exhaust smoke, but not much.

Engine temp, oil pressure, charge voltage were all normal. On flat ground I could go about 25MPH in 2nd gear. Checked turbo boost on the CAT Messenger and it was low to zero. What else besides a turbo failure would cause the Cat 3126e engine to limit power? Could a sensor have gone bad? The exhaust pipe got pretty hot and softened some of the adjacent plastic. I don't see any blown hoses.

PS The Cat Messenger did not show any error codes.

[desertdeals69]

It might be one of the cac hoses. I had one come off because the hose clamp broke. Reacted the same way as you discribe.

[wolfe10]

Yup, first thing to check is all connections between turbo and engine: Turbo to pipe, pipe to CAC, CAC to pipe(s) and pipes to intake manifold.

The other possibility is the the exhaust brake is frozen in the closed or partly closed position. Check that as well. If PacBrake, when is the last time you lubed it?

http://www.pacbrake.com/index.php?page=maintenance-4

Brett

[97VectraGT]

Experienced the same loss of power on my 1997 Vectra GT - Cat 3126 "a" vice "e", but could be the same type of problem.

Murphy was apparently alive an well on this "gotcha", since the loss of power was noticed pulling a CR-V toad eastbound on I-10 out of Mobile, enroute to Panama City. I do not recall hearing anything which I would attribute to the problem, but that's not say some "pop" did not occur. I couldn't find anyone in Panama City to look at it for the week I was there, ditto when I went to Destin. I even tried a couple of Freightliner repair shops on the way back to Colorado, but to no avail. One in Kansas had a flat policy to not even look at motorhomes, Freightliner chassis or not. It was a slow, dismal return.

The problem turned out to be a 1" - 1 1/4" split in a flexible connector joining the turbocharder output to the intercooler input - different vendors supplying different pieces, with a third party probably in there somewhere. Bottom line, the Cat-supplied turbocharger was pumping out full boost to the split seam right in the middle of a formed bend (of about 65 degrees) in the connector, resulting in the loss of enough of the boost to signficantly affect power to the engine. As with your description, the engine ran fine - no overtemp or other problem - except severe loss of power.

Functionally, the connecting piece in question also absorbs a certain degree of shock; given the turbo is engine-mounted, and the intercooler chassis-mounted. Point being, the split was probably as much due to eight years' normal wear and tear as any defect in the fabrication procss. The connector is quite flexible, appearing to be fabricated out of 3/4 -1" wide kevlar mesh impregnated with orange Permatex "Form-A-Gasket" material, all wrapped around (many, many turns) a form to produce the connective device. The turbo connection diameter was in the neighborhood of 1/2" smaller than the intercooler end. The entire piece would be charitably described, at best, as semi-rigid.

As I recall, the mechanic who correctly diagnosed the problem ordered the replacement part from Freightliner. He completed the entire R&R process by feel - the connector could not be visually sighted from either the top, bottom, or side! Maybe with the coach on a lift, but not flat on the ground.

Hope this helps.

[RHMinetti]

I found a blown inlet hose. Thanks.

[wolfe10]

EXCELLENT (and inexpensive to fix).

[RVerOnTheMove]

That's WAY better than the turbo being blown. Please don't ask me how I know!!!!!

[RHMinetti]

Brett,

Upon checking further there are no blown hoses ! I was feeling blind and it was part of the hose clamp I felt.

I'm thinking that there must be a faulty "Boost" sensor on the engine. Any further thoughts on where the sensor may be?

Thanks

Richard

[dickandlois]

Could the Wast Gate on the Turbo be stuck ??or damaged?

Rich.

[desertdeals69]

The gauge sender is probably located in the intake manifold. I think that if that was the problem the engine would still run ok. You might check the turbo. Take the intake hose off at the turbo and carefullly reach in and feel if the turbine/compressor shaft is free to turn. Should turn very free but have no side or end play. The waste gate has a very strong spring to keep it closed so I doubt if it is stuck open because it would have had to be opened under high boost at the moment of failure.

[wolfe10]

Actually, unless you are familiar with diesel engines, after verifying the "plumbing" and that the exhaust brake is not stuck partially closed, I would take it to a Caterpillar dealer for proper diagnosis.

That would be less expensive than replacing parts until the issue is found.

Brett