Low oil pressure help. 88 GMC 1500
Question:
First check the idle speed. If you’re turning 500rpm or less, you will probably have 10lb of oil pressure. You better check for oil consumption or leaking and get that problem fixed. Odds are that you’re burning the oil. If the rpms are up where they should be then you either have a tired oil pump or the engine is just about worn out. 135K miles shouldn’t have too much wrong but if the oil has been run down then it’s probably fried. Good Luck. BTW, you can put straight 30W in or even 40W and get more life out of the engine. — Bob May I don’t read attachments to posts as they may give me a virus If I expect an attachment from you I will open it.. You may have a brilliant thought but if you put it into an attachment I won’t read it and thus both you and I lose. I don’t like to say it but unfortunatly, there are those who insist upon being nasty to the rest of us. Bob May
Response:
How is the oil pressure when you first start it up? If your oil pressure is fine when it’s cold, but starts to drop once it warms up, that’s normal, especially on high-mileage vehicles, where there’s normal wear.. When your engine heats up, the oil becomes thinner, so the pressure will drop. A possible solution would be simply to go to a higher weight oil, 10W40 for example, if you’re presently using 10W30. The pressure was dropping when you were going around corners because the oil would slosh over to the side of the pan, away from the oil pump pickup, which indicates a very low oil level. Pressure also drops at the stoplight because your engine is turning fewer revs, so the pump isn’t pumping as fast….sounds fairly normal for an engine with the miles you say yours has. I’d venture to say that it’s a combination of normal wear in the engine and a worn pump. Replacing an oil pump is not a simple two-hour job, since you normally have to disconnect the engine at the motormounts and jack the motor up enough so you can drop the oil pan down. But it’s not hard…if you a decent set of handtools and a hydraulic jack, you could probably get it done on a Saturday afternoon. – Hide quoted text — Show quoted text – > I just bought a 1988 GMC 1500 Sierra SLE stepside. Sharp truck. Drives > great. 350 AT with 136k miles. At first I noticed a couple days after > I bought it that the oil pressure dropped to zero going around corners. > It took 2 quarts to get the dip stick wet. Yes I checked it during the > test drive. Filled it up with Quaker State 10W30. Good oil pressure > (35 PSI). > Then today, after driving it for an hour on the highway I noticed low > oil pressure at stoplights (10-15 PSI). So far the oil level checks > fine. I fear it’s the oil pump. There are no leaks or puddles of oil. > The exhaust doesn’t smell like oil. If it is the oil pump, where is it > located so I can change it. Also, how difficult a job is this ? I’m > fairly mechanical but I’ve never done this one before. Any advice ? > — > Thanks in advance, > The Elfster > Share what you know. Learn what you don’t.
Response:
- Hide quoted text — Show quoted text – > I just bought a 1988 GMC 1500 Sierra SLE stepside. Sharp truck. Drives > great. 350 AT with 136k miles. At first I noticed a couple days after > I bought it that the oil pressure dropped to zero going around corners. > It took 2 quarts to get the dip stick wet. Yes I checked it during the > test drive. Filled it up with Quaker State 10W30. Good oil pressure > (35 PSI). > Then today, after driving it for an hour on the highway I noticed low > oil pressure at stoplights (10-15 PSI). So far the oil level checks > fine. I fear it’s the oil pump. There are no leaks or puddles of oil. > The exhaust doesn’t smell like oil. If it is the oil pump, where is it > located so I can change it. Also, how difficult a job is this ? I’m > fairly mechanical but I’ve never done this one before. Any advice ? > — > Thanks in advance, > The Elfster > Share what you know. Learn what you don’t.
Some of these trucks had problems with the oil pressure sending unit. I would replace that before I tore into the engine. You might want to get a mechanical gauge, a direct read gauge and hook it up. I have seen a few of these trucks where the gauge would max out and then return to normal. Check the oil pressure sending unit.
Response:
I just bought a 1988 GMC 1500 Sierra SLE stepside. Sharp truck. Drives great. 350 AT with 136k miles. At first I noticed a couple days after I bought it that the oil pressure dropped to zero going around corners. It took 2 quarts to get the dip stick wet. Yes I checked it during the test drive. Filled it up with Quaker State 10W30. Good oil pressure (35 PSI). Then today, after driving it for an hour on the highway I noticed low oil pressure at stoplights (10-15 PSI). So far the oil level checks fine. I fear it’s the oil pump. There are no leaks or puddles of oil. The exhaust doesn’t smell like oil. If it is the oil pump, where is it located so I can change it. Also, how difficult a job is this ? I’m fairly mechanical but I’ve never done this one before. Any advice ? — Thanks in advance, The Elfster Share what you know. Learn what you don’t.
