I have an 86 F-250 with a 302. The engine was rebuilt about 10,000 miles ago, and has been consuming oil ever since. I followed the break in specs to a tee. It burns about a quart every 200 miles. I broke it in with 10W-30 oil and have continued to use it ever since. One person recently told me to try a thinner oil, but I think if anything, that made it worse. I may try a 10W-40 next.

The question is, what's causing the oil consumption? The engine has plenty of power, and does not smoke excessively on start-up. I checked the plugs, and they acutally look OK. Some were a little white and one had a little carbon build-up. I just replaced the radiator because it was heating up on the highway. That probably caused the white on the plugs.

The truck does have a high volume oil pump, and the oil pressure always runs high. Also, when the truck first was started up, it lost oil pressure immediately. One of the freeze plugs had popped out of the core.

Is it possible that the high oil pressure is blowing by the valve seals or oil rings? Also, are there any freeze plugs that located against the exhaust manifold?? If there is, and one let go, oil could be blowing directly into the exhaust.

One more thing, the exhaust doesn't smoke constantly. Sometimes on idle I see no smoke. At other times, usually when it's warmed up, it will smoke constantly at idle, and the RPMs will bump up to about 1500. Any thoughts???

 

The first thing you should do is a dry and wet compression test.

The dry test will tell you how well the rings are sealing with the cylinders, and the wet test will tell you how well the valves are sealing the combustion chamber. This will rule out or indicate any internal problems.

There are 6 freeze plugs in the block, 3 on each side, right in a row. These freeze plugs seal coolant, not oil.

The high volume pump is just that, volume. It shouldn't cause excessive pressure. The HV pumps are ment to help keep adequate oil at high RPMs. Your pressure still shouldn't be over 60ish.