My 6.7L cummins just turned 100k and I have noticed that sometime my boost is really low. I will be at 15k fuel pressure and 2 - 3lbs of boost (under acceleration). This doesnt seem right at all. Other times it is around 8 - 10lbs like normal.

I recently flushed the coolant, replaced the water pump, thermostat, upper and lower radiator hoses. To get to the lower radiator hose I took the clamp off the turbo/cool side outlet that runs into the inter-cooler in order to get to the hose clamp. All the clamps seem tight.

I did notice that when I took the oil filter out that there was a very thick sticky black stuff on the inlet of the turbo. Is this normal? Is there maintenance that needs to be done on this turbo?

My mileage is also down by 3 mpg

Thanks in advance

 

Do you mean air filter? Nothing should be in the intake area or the turbo. Check your crankcase vent system which ties in there. Have you replaced that filter?


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Filter has been recharged, prefilter cleaned, ccv filter changed, map sensor cleaned, no change in boost.

There is defiantly something going on here im just not sure what.

 

Oil at the turbo inlet may be from the CCV or even over charging of the air filter? Boost issues may be coming from the drive side of the turbo as well. no CELs?

 

Are you saying there is oil on the compressor side of the turbo, going to the hot side boost tube, leading to the intercooler? If so, I would seem to think that your turbo is spitting oil into the intercooler. Not a good thing, that happened to me and my intercooler ended up getting full of oil and it was time to replace the turbo.

I'd check your oil level and make sure you're not low. Check the CCV filter and see if its clean, it should've been changed at 67,500. If your filter is bad and you're getting too much blow by then there could be a build up of oil if you're CCV tube is still connected to your air intake.

If you are saying the oil was thick at the oil filter, then I would think that sounds like mixing your oils (synthetic vs. regular). I don't know if it is necessarily true when you mix the two if it will "gunk up" but I have heard it before.