1993 Chevy S-10 engine oil pressure

MLINTON

MEMBER
1993 CHEVROLET S-10

Engine Mechanical problem
1993 Chevy S-10 6 cyl Four Wheel Drive Automatic

I just put a rebuilt 4.3 V6 W series engine with multi-point fuel injection in my 1993 Chevy S-10 blazer. I drove it about 30 miles so far breaking it in. When the oils cold I have 70lbs. Of pressure at an idle, but when it warms up it drops to about 10lbs. At idle. I think I'm getting fuel in the oil pan. And possibly thinning the oil too much to hold pressure. I know when we first tried starting the engine fuel flooded the cylinders and fouled out the plugs so it wouldn't start. And the fuel pump wouldn't stop running when we shut the key off and we would have to unhook the battery cable. The fuel pump does quit running when the key is shut off now. I changed the oil before taking it out on the road, to get the fuel out of the oil. But I think it's putting fuel in the oil still, because the oil level seems to be going up and my wife says she can smell gas on the dipstick, my nose doesn't work as good as hers.
What would be causing the fuel to go into the oil pan?
There's no water in the oil, so it must be gas.
If you think the oil pressure may be caused by something else, your advise will be much appreciated.
Thank you

1 Reply

ROB2008

MECHANIC
258 POSTS

Actually, trace amounts of fuel get into the oil under normal circumstances. The reason is that, even though the piston rings seal against the cylinder walls nearly completely, the seal is not perfect, and trace amounts of fuel will escape past the pistons and get into the oil that is below the piston, thus mixing with the oil. Under normal circumstances, this is a minute amount that, if you change your oil regularly, will never cause a problem.

There can also be extreme situations where large amounts of fuel can get into the oil. This is caused when there is a problem, such as a stuck fuel injector, an inoperative ignition system, or a fuel flooded engine, where the cylinders are overwhelmed by fuel, and the piston rings become unseated from the cylinder walls, and there is a breech that allows larger amounts of fuel past, into the oil below. If this happens, once the problem is repaired, the oil needs to be changed.