Getting rid of oil sludge

Messages
21
Location
TX
i think oil sludge has made the oil pressure relief valve stick open. What's the best way to get rid of sludge?
 
Messages
7,430
Location
beaver land EH?
hard to speculate what's going on with your pressure relief valve if you do not provide the specifics (e.g. vehicle type, engine, maintenance, OCI, service history, etc.) I would certainly refrain from casually throwing in a "quickie fix" .... Q.
 
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23,591
 Originally Posted By: harbison
i think oil sludge has made the oil pressure relief valve stick open. What's the best way to get rid of sludge?
For starters, how about changing the oil and the filter?
 
Messages
7,550
Location
North Alabama
 Originally Posted By: moribundman
 Originally Posted By: harbison
i think oil sludge has made the oil pressure relief valve stick open. What's the best way to get rid of sludge?
For starters, how about changing the oil and the filter?
Simpleton! ;\)
 
Messages
39,806
Location
Pottstown, PA
 Originally Posted By: harbison
i think oil sludge has made the oil pressure relief valve stick open. What's the best way to get rid of sludge?
Let's get the details (like Quest asked) ..and what makes you believe that the relief valve is stuck? Have you blown off a few filters ..or do you have low oil pressure?
 
Messages
16,150
Location
Silicon Valley
Why is there sludge in the first place? 1) too long of an OCI? Change more frequently 2) Head Gasket leak? Fix it 3) engine design problem? Change more frequently 4) contamination? Find the source and fix it. Find the root cause and then fix it. Otherwise it will come back even if you clean it off.
 

harbison

Thread starter
Messages
21
Location
TX
DETAILS: 1999 Chevrolet Suburban 5.7L 200,000 miles Not driven much. Between 3,000 to 5,000 miles a year. Changed oil. Oil change interval had been year and half and about 5,000 miles. As soon as I had the oil changed began to have low oil pressure (5 psi) at idle after oil was warm. At 2000 rpms maintains 40 psi driving down the highway. Also pressure on the high side when cold (above 60). In the past it has always fluctuated between 50 when cold and 40 when warm. Suggestions received: change oil pressure switch beneath distributor. Done-no change. Change oil. Done-no change. Use heavier weight oil, went from 5w30 to 10w40 but no change. My theory is that pressure valve is stuck open which would make the pressure go high at start and drop when oil thins out and rpms go down to 500 at idle. The oil pressure is not being maintained. Hope these details help.
 
Messages
4,837
Location
Kansas
 Originally Posted By: harbison
DETAILS: As soon as I had the oil changed began to have low oil pressure (5 psi) at idle after oil was warm. At 2000 rpms maintains 40 psi driving down the highway. Also pressure on the high side when cold (above 60). In the past it has always fluctuated between 50 when cold and 40 when warm.
My bet is that you have internal problems that an oil or a de-sludging won't fix.
 

PT1

Messages
5,746
Location
near the mistake
I would put a quart of MMO in the crankcase and see if it does anything. Have you put a mechanical oil pressure guage on the oil pump and done a cold start test? I would do that as well. Could be a bad pump or clogged pickup. You may end up pulling the pan to get a look at it. Don't forget unless you put a mechanical guage on the oil pump you are not sure your pressure readings are accurate. Are you getting top end valvetrain noise at 5psi?
 
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harbison

Thread starter
Messages
21
Location
TX
PT1, No noticable differences in engine at low psi. No noise. Engine runs great. Has never used oil. I'm considering pulling the oil pan, but if it could be avoided that would be great. I appreciate everyone's input. This is a great forum.
 
Messages
34,988
Location
NY
If you've checked with an accurate mechanical gauge, (not the dash gauge) and the readings are accurate it could be a few things. The bearings could be bad, or going, or the pump could be starting to go, or clogged screen, and not be able to handle the hot thin oil. Now since you said thicker oil didn't matter when it gets hot, (low pressure), my guess is the oil pump could be bad. Checking bearings is not an easy job, if I were pulling the oil pan I would probably change the oil pump and screen and see what happens. The good news is there is no knocking noise when the engine is hot or cold, no oil use, and it runs good. Before I drop the pan I would check pressure with a good mechanical gauge.
 
Messages
782
Location
Alberta
 Quote:
Before I drop the pan I would check pressure with a good mechanical gauge.
+1 Your oil pressure gauge in the vehicle could be on the fritz.
 
Messages
2,081
Location
Los Angeles, California
 Originally Posted By: harbison
i think oil sludge has made the oil pressure relief valve stick open. What's the best way to get rid of sludge?
harbison, Consider changing your oil to a synthetic type this time and include a filter. Then take it for a nice long drive. That might clear-up the issue. Durango
 
Messages
1,606
Location
Watertown, New York
If the relief valve was stuck open you wouldn't get 40 psi of oil pressure. You would likely have zero, maybe a few pounds. If the valve is stuck open, then I doubt any chemical will fix it. I agree with the posters above, your oil pump is probably worn or your bearings are getting excessive clearances. You can try changing the pump, I would recommend a high volume unit. I would check the pressure with a mechanical gauge before I did anything, the stock electric gauges are notorious for being inaccurate.
 
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