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Oil Pressure 88' Suburban

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willdickinson

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I have an 88 suburban with 150,000 miles on the engine. When I start the engine cold the oil pressure is normal between 20 -30, however after driving for 30 min the oil oressure then slowly reduces to almost 0. Can someone help with an explanation and a recomendation. Thanks
 
Most likely you have an oil leak or a motor about to take a ****.

If the motor still runs strong then you probably have a bad oil pressure sending unit. I had to replace mine soon as i got it off the flatbed. Looks like a big metal spinning top with a 3/8 thread and a flat plug in... hard to explain. If you have a manual then you know what im trying to say.

Make sure the fitting is screwed in all the way on your sending unit. Might want to try a thick oil too. valvoline max life 20W-50 is about the best you can get for older motors. Mobil one is good too.
 
yeh when my 350 was making its slow death, could start it and it had 40lbs of pressure. Course that was 20w-50 and 2 bottles of lucas oil stabilizer, so my oil was the consistency of gear lube......but i digress. After the motor warmed up, it would have 0 at idle and 15-20 runnin down the road. Also had a 6.2 sounding knock at idle. Hopefully yours is just a bad sending unit.
 
88 suburban oil pressure problems

ok, I guess I need to do a little more investigating. the oil in the engine is 10w-30 and the engine has not made any knocks that I have heard. everyone tells me that I will know it if it knocks. It does not leak oil but It smokes when you start it. So I guess the seals are getting old. Am I correct in thinking that I need to change the oil to a thicker one and check the sending unit. Does anyone know if the sending unit can be bought at any auto parts store or if it is a dealer only item. .

What will happen if I do not do anything about the oil pressure as long and the engine is not knocking. that I think is my real question.
Any help is greatly appreciated
 
I had this problem on my 88 k5. the oil from the sending unit was leakin on my y pipe and dripped across the whole pipe. the previous owner drove it like this for a while so it was baked on and smoke like crazy every time it got up to temp. If your sending unit is bad or loose the oil will leak and cause the pipes to smoke. I'd bet money its loose and it's not getting the right reading. or it's bad.
 
Don't worry about the big things until your rule out the little things, brother.

First of all, swap out the oil pressure sender for a new one. They are dirt cheap and a breeze to swap out. If that doesn't change anything, before you panic you should install a gauge somewhere under the hood and compare those readings with the readings on the dash gauge. The factory gauges are well known for giving inaccurate readings over time.

I would avoid runnning a thicker oil until you are sure that's where the problem lies. Of course, if the engine is worn enough to need a thicker oil then you should be seeing smoke more often that just during a cold start.........

Keep us posted!!:waytogo:
 
I have a question to ask. I have an 89 Jimmy and the gauge in the truck is reading pegged out at 60 and then later it drops down to the 30 to 40 range and then flucuates with the rev of the engine.

I changed the oil pump and the sending unit but it is still the same so I'm thinking the gauge is pooped.

Where can I hook up another gauge at for oil pressure sending unit. Or how do I get the factory one out and get another kind in there. It is a angled fitting on the OEM version on mine. I would like to put an Accel performance gauge in the truck instead.

Any suggestions?
 
there might be another spot..

Some small blocks have a 1/8 pipe thread plug in the block just above the water pump on the passenger side of the block,under the front of the intake manifold--( behind the altenator,off to the right )--you can plumb a gauge into that hole just as you would in the original sending unit hole--not sure if the pressure will read the same,since its farther from the oil pump than the stock sending unit hole,but its a lot easier to get at than the one in back of the distributor...if your block doesnt have that plug,the sending unit hole is where you will have to plumb it in--later blocks might have plugs above the oil filter you could remove and adapt to your gauge with pipe thread bushings,but most trucks have switches there for the computer too,or the oil sending unit is down there for the gauge or electric fuel pump cutoff switch...:crazy:
 
My 88 had the stock hole on the drivers side near the pan. My 77 block has it to the right of the distributor on top of the motor... neither had the front plug.
 
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