Berserker78

My 78 just started doing something wierd. I had it in storage over last winter, got it out, drove it around town for a while. Had no problems for a couple months. I replaced the spark plugs, rebuilt the distributor, and cleaned the carb. I didn't have any trouble the first time I took it on a long trip, but the other day, I went about 5 hours up the highway and on the way back, I noticed that my oil pressure goes up and down with my RPM.

From idle up to 3000, the oil pressure goes from about 8 lbs to 18 lbs. Is this somewhat normal? Or is there something seriously the matter? I had never seen such a thing before.

Thanks in advance,
Tumithak

LT1driver

I'd say that is not nornal, and your pressure is rather low. Ideas, partially clogged line, sender problem, oil pump getting ready to go, clogged oil filter, bad ground if electrical sending unit. I would definately find the problem before driving it anymore. My 2 cents. :cheers:

Berserker78

Where would you start? As in, what is the easiest/most likely thing? Whatever it was happened during that 8-9 hours of driving. I am not an expert mechanic, but I know my way around a toolbox.

Thanks

Nomad78SA

It sounds like the oil pressure bypass valve is stuck open. If some trash got into the system it could hold the ball back. All it is , is a metal ball held in place by a spring and when a certain pressure is met the spring gives allowing some pressure to bleed off. If some trash keeps the ball from seating your oil pressure will have a tach effect. You can buy the pressure valve kits for a few dollars or just change the oil pump out.
If you have a service manual for your car, pull it out and read the troubleshooting section on the engine. It will cover it. I can post the pages for a 78 if you don't have one.
Neil in Tenn


[Modified by Nomad78SA, 9:09 PM 12/30/2001]

Bob Jenkins

What does your oil level look like? If it is low, you may be sucking air in turns or during acceleration cuasing the low pressure readings. I would try adding some oil and see if your symptoms change... :chevy

Berserker78

It has plenty of oil. I will try swapping out the oil pump. I do have a chiltons for it. Thank you for the offer. No big hurry now, we got a couple feet of snow now. It is in the garage for the winter. Bummer