Weird oil leak

[t.mcginley.jr]

So I jacked my 90 NA up yesterday just to check things out, tighten the belts, etc. While I was crawling around, the first thing I noticed was an oil leak. On the passenger side of the engine, the whole side of the block from the motor mount back is covered with a film of oil. The head itself is dry, so I'm not thinking valve cover gaskets. Here's the area I'm talking about (not my pic, imagine everything installed):



So there's oil from the head down and from the motor mount back. The oil filter tree and oil filter are coated and there's even a bead of oil running down the header and one of the exhaust studs is wet. Everything else in that area is coated in oil too like the block/trans bracket, that part of the oil pan, the transmission harness, etc. The headgaskets/head bolts, valve cover gaskets, and everything else up top is brand new with less than 500 miles on it. I started it up and watched for a full 2 or 3 minutes but couldn't see anything actually oozing out, so I'm guessing it only happens under load.

Any ideas??

[BlackWidowZ]

try cleaning it really well. Then check for oil after its clean to try and pin point it.

[t.mcginley.jr]

Yeah I'll have to try that when I have more time later this week. It almost seems like the headgasket is leaking because the side of the head itself is dry, but from where the head meets the block is wet. But if it was headgasket, I'm pretty sure I'd have other issues like compression and mixing oil/water. Plus unless I had bad piston rings the oil should get on top of the piston..

[dszilke]

This happened to me. It was the oil pump. I had to let it run closer to 5 minutes before the leak actually started.

[t.mcginley.jr]

If it was the oil pump though, wouldn't the front half of the block be covered in oil? For mine the block is only wet with oil from the motor mount bracket back, and only on the passenger side. I'm kinda leaning toward the oil filter tree, but I don't know how it would coat everything around it including part of the header?

[IonZ32]

Yeah that sounds like the oil filter tree to me. A very similar thing happened to my friends '72 Challenger. Has a similar oil filter tree set-up, when that gasket starts leaking it gets everything pretty messy overtime. It got on the header, trans, everything. I'd check the bolts that hold it on first. If they're tight, maybe you can pull it off and reseal it down the road. Easier said than done, I know there is a lack of room down there.

[t.mcginley.jr]

Yeah I'll have to check the bolts because I put a new gasket on it when I had the engine out a few months ago. Maybe the tree was a little warped?

[t.mcginley.jr]

Now that I think about it, the old gasket was on there so good I had to use a scraper and wire wheel on the filter tree to get it all off. Maybe I messed it up doing that

[t.mcginley.jr]

Update time.

So the oil filter tree did end up being looser than it should have been. I pulled it off, cleaned both mating surfaces and put a new gasket + copper spray and tightened it up good. I also cleaned all the oil off the block/trans, etc. I came back about an hour or 2 later and everything had a film of oil on it again (I had started the car before doing any of this so there was some still up inside the top end). The sides of the heads are completely dry. I felt around the backside of the passenger side head and sure enough there was oil on most of it, and not old caked oil but fresh oil. I felt the driver's side and got the same thing.

The only thing is I'm not sure if its just the VTC solenoids leaking or the whole intake valve cover gaskets. When I did my rebuild 4-5 months ago I had put new intake gaskets, resealed the exhaust valve covers with RTV and also took off the VTC's, cleaned them up and resealed them with RTV. Either way it looks like I'll have to do a plenum pull. Is it possible I just didn't tighten the intake valve covers enough? With the coil packs and all in the way I can't tell if the whole gasket is leaking or just the back of it.

[itsa300zx]

Did you also replace the half moon plugs on the exhaust valve covers? Ive seen them leak before.

[t.mcginley.jr]

Yeah the half moons were replaced and sealed up with RTV, but thats on the exhaust valve covers which aren't leaking.

I pulled my plenum off today and found that both intake valve cover bolts (screws) weren't very tight. So the whole thing wasn't sealed very well, but the majority of oil was coming out the back. I used gray RTV on the VTC solenoid but I guess I didn't use enough or didn't tighten it up enough. I cleaned off the passenger side today and resealed both ends with a fair amount of copper RTV and tightened it up tight this time. Hopefully this fixes it