79corvette

I had my car running for about 40min, and the oil pressure fell below 40lb at about 700rpm, it had been right at 45lb when I started the car. Also when I revved the engine during that time ,near the end of the 40min, there would be a lot of smoke coming out the back. It had been sitting in my garage for 10years. The oil was changed about 1 year ago and never since. The oil is a 20W50 not SE. I know, I know, you should change oil every 3000 miles. The car had only ran 1 time till about June, when I got the car. So to get to my questions: Does oil go bad over time? Also, is it the wrong type oil inside the engine, so that's why I am buring oil and running a little low on pressure when it heats up? I replaced the vavle seals, so is it time to replace the piston rings(59,000miles on odometer, it doesn't work anymore, car looks more like 159,000)?

WESCH

Hi
40 PSI is very good. Of course, the pressure will drop once the oil heats up.
I would change the oil to a lower viscosity, change the filter and drive the car carefully a few hundred miles.
When sitting for so long time, all might be a bit sticky and needs to be washed off.
Give it a chance, whatch the oil pressure and check the oil level frequently.
You can only determine oil consumption when driving.
Just my 2 C. Don't hesitate to give any different oppinions, pls.
Gunther

Jvette73

Oil pressure sounds good. Are you sure its burning oil? Other things can cause smoke. Oil would be a bluish color smoke. Are you having to add oil to keep it to the full mark?

79corvette

The smoke is definetly a bluish color. I haven't been able to drive it enough to the point of adding more oil, but I did add some one time. I just thought blue smoke, bad, must be oil. Just every time I rev the engine I get the blue smoke, and sometimes when I start it up I think.

Jvette73

You say you replaced the valve seals. What kind of seals did you use? The factory type O-ring seals are lousey. Especially if the valve guides have any wear. Even the standard umbrella type seals dont always work well. My heads were assembled by the guy who did the valve job. He used umbrella seals. When I installed the heads there was a sudden oil controll problem. I was burning a qt. every 3 or 400 miles and fouling plugs. I noticed the fresh oil deposits aroung the plug threads which indicated to me the seals were leaking. I then got a set of Crane Cams positive street performance seals PN: 99819. They lock down over the guide and stay put, unlike the umbrella seals that ride up and down with the guide. These positive seals totally cured my oil consumption and plug fouling problem. There are a number of different positive seals available out there that will work on stock guides without machining. Its a matter of finding out what diameter your current guides are to get the correct seals. 99819 fit the heads on the vette. I then went to put them on my 350 in my truck but found that someone had replaced the exhaust valve guides on those heads sometime previously. So I used the 99819's on the intake valves but had to get a different set fot the exhaust guides. Dont remember that # off the top of my head. The point is, good seals are out there. Its a matter of determining exactly what you need, then installing them.

79corvette

Unforntuanetly, I replaced my seals with the stock O-ring design. I realized that there were none of the original valve seals left or they formed a brittle hard substance. It seemed to me that after I replaced them I noticed less smoke coming out the back. Should I go take a look at my plugs to see if there is oil on them, indicating bab vavle seals?

Jvette73

If valve seals are bad enough, usually there will be freah oil deposits around the plug threads. :yesnod: