2004 LB7, RMS Replaced, Still leaks

[lb7dmax]

About 4 years ago my mechanic moved the crankcase ventilation hose to facilitate the install of fuel lines for a second fuel filter. He forgot to put the hose back, leaving it kinked and closed off.

 

I picked up the truck and once it warmed up, 6 miles down the road, I had a big cloud of oil smoke behind and with me. Mechanic said pressure had built up and blew out the RMS. He replaced the seal but thereafter the engine always had a seep, not a drip at the rear of the engine where the RMS would be the usual suspect.

 

Prior to this incident the engine had never leaked any oil or other fluid. I've put up with the seep as it wasn't dripping and I chalked it up to a careless job of installing the RMS under duress.

Now its a drip. Drip started after a 1500 mile trip pulling a 5^th wheel. Truck has previously pulled this trailer 10000 miles since the rms replacement without dripping.

Took it to three shops for diagnosis-all pointed to the RMS as the culprit.

I had the RMS replaced with the GM part. When I picked up the truck, the mechanic was a little sheepish, saying the old RMS was in perfect shape, 'like new' and so was the crankshaft. They could see no other source of a leak when the rear of the engine was exposed.

I still have the drip, exactly as it was before. It drops about a quarter sized spot when the engine is hot and shut off. Doesn't seem to leak when running or when cold.

Went back to the mechanic.....has no answers. Put dye in the oil and ran for 10 days. Mechanic can still see no source of the oil leak. There's no leaks on the outside of the engine besides the original place.

Since it always seeped after the RMS blowout incident, I suspect some other seal/gasket was also damaged and was 'ok' for 4years but finally gave it up into a leak situation.

Anyone have any idea what else could be leaking? Thanks for your help in advance.

[gmtech4]

What is an RMS ?

[Jsdirt]

I think he means Rear Main Seal. I've never heard of that acronym either, so don't feel left out.

 

 

Oh just realized this was a Dmax .....

 

There's some oil lines back there too - can't remember if they were oil or coolant .... but there's plenty of places for oil to leak on a D-max ... and all require yanking the engine to fix if they're coming from the rear ...

[gmtech4]

I think he means Rear Main Seal. I've never heard of that acronym either, so don't feel left out.

 

 

Oh just realized this was a Dmax .....

 

There's some oil lines back there too - can't remember if they were oil or coolant .... but there's plenty of places for oil to leak on a D-max ... and all require yanking the engine to fix if they're coming from the rear ...

 

Ya no one uses that lmao !!!

 

Dmax's are pretty tight , from when I was at the dealer .....

 

Op, rear leaks are a gigantic PITFA, the tech needs a good light and a brain to find it , not much anyone else can say here , good luck

 

might have to loose the tranny to check with black light