1988 Silveradio 4x4 problem, and oil in exhaust

My boss just got a 88 silverado, and the 4 wheel drive doesn't want to engage. It tries, and the light blinks on and off, and will sometimes stay engaged for a few mins, then back off it goes. I'm sure this couldn't be good for the transmission, so we were wondering what we could look at to possibly fix this. I'm thinking maybe a short somewhere, but i don't know where to look.

Also, when you rev the engine up, LOTS of oil shoots out the exhaust, I'm thinking bad rings, but it doesn't smoke at all, so am I wrong? Thanks.

I'm not positive, but I think the '88 may have had a Dana transfer case. I'm not very well versed on those or their control schemes, but I'd be more concerned about the transfer case suffering damage than the ransmisison.

As for the oil on start-up, if there is liquid oil from the exhaust there is a serious problem. However, if there is bluish oil smoke in the exhauist on start-up, that is very likely due to hardeed and dried valve stem seals, and actually causes very little trouble with anything. If it really bothers you, you can pull the valve springs and change out the seals. If it doesn't consume any noticable amount of oil between changes, however, you can simply disregard it and let your engine enjoy the extra upper cylinder lubrication on start-ups.

I'm just guessing that the problem with the 4wd may be the thermal actuator on the front axle. Is the 4wd system a floor shift or push button? Are you in a cold enviroment? Has the front actuator previously been upgraded to the motor driven actuator? When you put it in 4wd and the front wheels are not pulling, try turning the front driveshaft by hand.

James

The thermal actuators aren't worth crap on these models and usually will have failed before 19 years, mine did ('88 Silverado.) They will behave exactly as you describe. It's easy to install a new one. As for the oil, I'd drop the head pipes and see if the oil is coming from just one side. If it is, I'd replace the valve seals on that head. If it's both sides, replacing the seals wouldn't hurt seeing as you'd do that anyway if it turned out to be the rings and you rebuilt it.