I've got an 86 2.3L carb'd trooper that is going through oil at a rate of about a quart every 100-200 miles. Compression is fairly good, I get almost ZERO blowby coming out the oil filler plug with the motor running, and not much blue smoke coming out the pipe. Compression checks out at 140ish, no more than 10psi difference across all 4 holes. Wet test gives less than 10PSI gain. With the oil filler plug out and the motor running there is no air coming out the crankcase, nor sucking in. It will sometimes smoke a wee bit on startup, and might blow a little blue/black smoke if I really wind it out. There is NO external leakage, not even a single drop in the driveway, and only a very little bit of wet below the front main seal when I crawl under it.
So, I'm wondering where I should look for my oil loss. It has to be coming out the tailpipe. Compression test could be better so a bit is probably getting past the rings, but does not seem like I could be losing a quart every 100 miles there. That leaves me just a couple ideas. It could be going past the valves. Replacing stem seals without pulling the head is no picnic though and that is the only way I know to tell if that is it. I did put a fuel pump on it, and I got to wondering if I could have a defective pump pulling oil out. There is nothing coming out of breather tube on the pump though, so it would have to be pushing oil into the gas. Supposedly that isn't supposed to be able to happen, but maybe the new pump was put together wrong. Swapping out the pump is a major project though, and again it may not be the problem.
So, ANYONE have any ideas that I can use to narrow this sucker down? I have thought about bypassing the fuel pump and running an electric, but even that is a challenge given where the pump is tucked under the intake.
There is a lot more to this story, but I'm trying to keep from writing a book. I just can't imagine where that much oil could get through. Cracked block? but no leaks outside and the water is clear, no milky oil. That was what got me thinking fuel pump, it is new and running oil with gas through the carb it might not tend to smoke as much. I've had rigs that blew giant blue clouds but did not use this much oil.
