Indicated low oil pressure at idle when hot.

Tiny
OLDHOTRODDER
  • MEMBER
  • 2005 CHEVROLET SUBURBAN
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 164,000 MILES
Oil pressure gauge drops to 5# or less at idle and chime starts when hot. Using scanner for readings. NO internal engine noise ( bearings or lifters ) at idle. Engine is quiet. Replaced oil pressure switch w/ o.E. Service switch. Replaced oil pick up tube "O" ring. Pick up screen clean. Replaced oil pump w/ o.E. Service pump. New oil filter and 10/30 oil. Have pressure at cold start ( no engine noise on cold crank). Oil warms up, pressure drops, chime sounds at idle. No prob. Off idle. Gauge seems slow to respond. Is this oil press. And chime possibly an electrical issue with the cluster or ECU? I'm a retired ASE Master. Specialty in foreign vehicles, GM was not my expertize.
Wednesday, July 23rd, 2014 AT 11:47 AM

6 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check the pressure with a manual gauge first to see if it's electrical, then put a decent oil filter on it like Purolator, wix, napa, or bosch. A/c is ok too. If it's a cheap filter like a fram will cause issues like this.
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Wednesday, July 23rd, 2014 AT 12:24 PM
Tiny
OLDHOTRODDER
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  • 4 POSTS
Sorry for the delay. Mechanical pressure is 5# at idle, hot. Mobil1 filter. Still 10/30 Castrol hi mileage oil. Sense we've gone this far, we're going to roll a set of mains & rods on the crank. Bottom end will be secured and apparently it's not electrical. At 164,000 mi. I'm considering straight weight oil. Will find out after bearings in.
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Monday, July 28th, 2014 AT 11:10 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If you are going that far, take the pump off and check thereleif valve for sticking it may have some junk in it causing it to stick when hot.
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Monday, July 28th, 2014 AT 11:59 AM
Tiny
OLDHOTRODDER
  • MEMBER
  • 4 POSTS
New Pump. Normal crud in pan. No crud in bottom of pan. Nothing loose to address and we cleaned inside of pan. Internals looked clean. We'll find out after bearings. We'll find out after bearings. Still thinking straight weight oil. Only happens when oil gets warm. Crud should have given us normal pressure for a while.(?)
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Monday, July 28th, 2014 AT 1:56 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Re won't be any benefit at all with straight weight oil I fyou put new bearings in you can still use the 5 or 10w 30. You shold not use the high mileage oil in your vehicle though If your pressure is ok then use synthetic if you like much better oil but expect some usage at first
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Monday, July 28th, 2014 AT 3:33 PM
Tiny
OLDHOTRODDER
  • MEMBER
  • 4 POSTS
New bearings worked. Pressure up to about 10# at hot idle. No chime. Dumped high mileage oil and put in our house oil, Castrol 10/30. Drove it about 150 mi. And every thing seems normal. THANKS! For the help.
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Tuesday, August 5th, 2014 AT 12:11 PM

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