Hi, I have a question. My 1991 lumina eurosport recently started leaking oil. Turned out to be the front most valve cover gasket. To remove that I had to disconnect the bypass line that goes to, the throddlebody or intake manifold, I’ve been told both, but it connects to the top of the water pump and has I believe a heater core line to the side of where it connects to the water pump. Anyway, I took the screws out of the water pump and from the heater core lline and water pump, came antifreeze, from the metal bypass line, came pure oil. I had somewhere to be so changed the valve cover gasket and ran it line that with no obvious leak or anything since then, no oil and antifreeze mixing or anything.
really it has barely lost any oil since then at all if any and never lost any coolent in this whole thing. I can tell, the level is where it was in September when I got the car.
Last weekend, when warm, the car developed a miss. First it was off and on but going through our day it got worse. This morning, same thing it was fine, then did it a little bit, it’s like every time we shut it off and restart it it’s good for a couple minutes then comes back worse than before. If the engine cools down it’s great for a while until it gets up to temperature for a little bit. Exhaust smells and looks normal but not smooth rhythm to it. Also, today it got bad on the way home about 10 minutes from home so we got it home, and smelled gas strong. I cracked a plug wire, must be original as well so am replacing them and the spark plugs tomorrow. Checking spark plugs, the 2 I looked at seem sooty and old.
First question, with oil in that bypass line, am I correct in assuming I have the dreaded intake manifold gasket problem? If so, is that as bad to replace as it looks or should I be OK doing it in my driveway? Second, am I looking at 2 different problems? The miss and that oil? I’ve only really taken the car out a couple times since doing the valve cover gasket because obviously I have work to do. It has low miles on it and the price was right, seems like if I can fix it dsI’ll be in good shape for a while. It’s the 3.1 V6. I just want to see if I’m on the right track before I get on a parts changing spree, if the intake manifold gasket is bad it can’t be too bad, oil and coolent look fine from what I can tell but I have a replacement anyway. I also have new plugs and wires, if I’m going to have to get in to this thing, I was going to do them anyway since the rear ones are a pain to get to, if I have to take it apart anyway I’ll change them, I was told they were done a few miles ago but I’d bet the rear ones weren’t done.
It looks like someone’s been inside this engine before, I hope I’m not all wet and that oil isn’t remaining from a long past problem, I’m seeing no sign of oil and antifreeze mixing or in the other’s territory at all since then. That bypass line also now gets hot to the touch with the engine running and I don’t remember it doing that before.
Thanks for any help or suggestions.