Trying to figure out oil leak
 

I have an 88 3vze engine It does not smoke, all spark plugs look good make that great. The engine needs a quart of oil about every 1500 miles. I drive the truck very mildly and don't notice an oil smell, but on the interstate after a few miles of 2400 rpm it has a hot oil smell from the engine. I do not have an oil stain under the truck where I park it my driveway. I am thinking it is the valve covers and the oil is pooling in the valley but I see no sign of oil on the top the engine. It does not have a head gasket issue the coolant is like new and always full, again there is no exhaust smoke.

Does anyone know where this oil could be going? Other than the valve cover is there any other gasket that can cause this problem?

valve cover leak on to the exhaust manifold maybe?

try tightening up the valve covers

Sounds like a great first step thanks for the advice.

The best way to find an oil leak that is not obvious is to use a UV light and leak detection dye. Add the Dye to the oil, drive the vehicle for 20 minutes, and break out the UV light. The oil may burn off, but you can at least see the dye stain in the location of the leak. Available at most auto parts stores.

I didn't know about that I will try that next

Mine uses that much oil in 1500 miles; always has.

Like others said, check valve cover gasket. My 87 pickup sometimes get's that smell, and its leaking out of the driver side valve cover gasket straight onto the exhaust manifold (22r). However, mine also burns oil so I add a quart about every 750 miles. Was about every 450 miles before I put Lucas in it.

I took a look at the engine from underneath. I can see where oil has built up on the back passenger side of the engine and getting on the crossover exhaust. I am hoping it's just the valve cover.

If it's the head gasket wouldn't it be getting into the cylinder? I tried tightening the valve cover it was not loose so I just added more torque. I think the heat from the crossover has damaged the gasket.

Be careful adding too much torque, you can over-torque valve cover bolts and actually make the problem worse. It can compress and crush the gasket. Valve covers are quite sensitive to their torque numbers imo

Yup - they don't need to be very tight at all. If that continues, replace the gasket.
Clean it up (Simple Green and flush it off, rags, etc)...and keep an eye back there. I thought I had something REALLY wrong on mine, with all the oil as you described it. Changed the gasket and 1/2 moon camshaft covers, and it has been fine since.

Not to hijack the thread, but speaking of oil leaks, anyone know how hard it is to replace a rear main seal on one of these? 22r specifically? Trans have to drop out completely of just be unbolted? Thanks

Depends on your know-how, TJ. Download and check out the FSM, and Haynes manual, for that. I'd want a friend with experience to help with the details, but the idea isn't so bad. It's the stupid stuff, like those 2 bolts on top of the tranny>engine that can ruin the day!!

I haven't done it, but I ALMOST did (thought that oil leak was rear main seal). Make SURE it's not the valve cover gasket first!!!! Or you'll have a lot more work than is necessary.

Way I see it: you must disconnect the clutch slave cylinder, remove crossmember, detach rear drive shaft and maybe some of the front shaft stuff, drop the transmission and at least part of the oil pan (tranny can be pulled back, I have heard). Then the 'housing' for the rear main seal should be accessible. It is at the rear of the crankshaft. I'd drop the oil pan all the way and do the gasket just to say it is now oil-tight. I would also do my clutch at the same time, since how often do you get to remove the tranny? So now, read the procedure for THOSE things! Awesome mechanic = 1 weekend. The rest of us....several, probably.

Symptoms: clutch slipping, oil pouring out of your bellhousing (rather than AROUND it, as valve cover gasket causes), unexplained oil loss. Check above bellhousing - if it has oil up there, not likely main seal. Everyone I've asked says "Yup, your clutch WILL slip when it is a problem".
My 2 cents.....

Alright, thanks. I'll replace the valve cover first, because it isn't really coming out of the bellhousing I don't think, just think it's coming over it. And then hanging up on it. I also don't think my clutch is slipping, but what are the symptoms of clutch slip? As far as I know, it just hard shifts when cold in the morning because I should change the fluid, but first I have to figure out what tools I need to do it, because I don't think I have a wrench big enough.