Had sludge in engine,and it was drain.Now oil pressure is dropping


Asked by Feb 27, 2017 at 10:26 PM about the 2002 GMC Envoy 4 Dr SLT 4WD SUV

Question type: Maintenance & Repair

I had a valve cover replace on my 2002 gmc envoy
slt.the guy working on it found sludge built up.she
drain it for 3 days and refill with new oil,now low oil
pressure is coming on.Is it safe to drive it like that

1 Answer


I just wonder if this sludge has drained down to and on/in pump pick up tube. I think it will come out but may need a intervention to do so, I think pulling the pan to check and if sludged up then clean pan and pick up tube and if its really bad pull the pump out look at it and if need be replace it. I have seen some bad sludge in engines, one way to deal with this is to drain all oil pour in diesel fuel until whole engine is full and let sit overnight and then use crank wrench and spin engine over a few times, drain it and repeat until it comes clean, Now you say why would I do this it can break down the sludge and can pour it in over the head with valve covers removed to get the sludge out of the oil circulating ports, if it gets rock hard (it will) then its too late as there is noway to push rods threw it completely to get it all out while engine is assembled.

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