Well, bad news gents. It's still leaking. I don't have access to a cherry picker so oil pan gasket and rear main are both out. I'm gonna try my front cover and if that's not it, I guess to the shop it goes.

Like a jackass, I messed up my steering gearbox by trying to reduce the play, so now my gearbox has a lot of resistance. I think that caused my p/s pump to leak already, so I'm gonna put some UV dye in the engine oil and see if I have any luck verifying where the leak is coming from. If I don't see any UV dye, I'll know its that p/s pump and the fan is just blowing it all over the place.

 

Well, it's been a semi-productive week. I got my steering issue fixed - it's back to being butter smooth again. I got my A/C fixed after a plug decided to back out, and I got my ABS lights off by replacing the ABS Control Module.

I still have been having a hard time finding the source of that oil leak, so I got some UV dye and ran that. I do have a very minor leak coming from that front engine cover, but it's very minimal. However, I have a TON of oil coming down the topside of my doghouse and onto my transmission. Have any of you seen rear main seals do that? My gut is pointing to the rear main, but I've never seen it come off the top of the dog house unless it was a topside engine leak. The top of my engine is clear, and the UV dye was showing pretty quick and that fast so it just keeps pointing back to that seal. I even took that UV light and checked back by the distributor. I don't have a transmission jack, but I may have to start asking around for one I guess.

 

The rear main should be leaking inside the transmission bellhousing. You should be able to look up into it and see if the torque converter and flex plate are wet. If inside the bellhousing is dry its not the rear main.

When you checked for the oil leak back by the distributor, were you able to see where the intake meets the engine block behind and under the distributor? You should see the oil pressure sending unit on the back drivers side of the block. The distributor is bolted on top of the intake so you need to look behind the distributor.
These trucks don't have a front and rear gasket for the lower intake. they just use a bead of silicone and over time are known to leak. But its where the intake and block come together

 

This can give you an idea of the seal that you are checking for.

 

Yessir, I did check both of those when I did the upper and lower intake gaskets and valve cover gaskets. I just replaced the oil pressure sensor and distributor o-ring earlier this year and they were still holding up fine from that job. I did go ahead and pull that inspection plate off the bell housing and no UV dye in there either. I'm thinking it's got to be the head gasket. I don't know what else there is and still can't see the point of origin for the oil leak.

 

I really dont think its a head gasket. I have never seen a head gasket cause an oil leak like you describe.
Is it possible that one of the valve cover gaskets is not sitting correctly and causing the leak even though they are new?

 

I've got the pass side of the engine down to the valve cover and alternator bracket removed right now. The more I get into it the more work keeps coming. I'm going to go ahead and just check that valve cover and see now that I have it down this far.

 

I think I found it! The valve cover gaskets were looking fine. I saw a ton of oil on top of the bell housing, and there was a little bit around the base of the distributor. It didn't look like much, so initially I accounted it to oil just getting spread around. So I pulled the distributor out and noticed a little bit of oil on the gasket. I remember replacing that gasket last time I pulled the distributor, but I didn't see any traces of an o-ring when I did that so I never put one back on. I went ahead and tossed an o-ring on it in the groove so now it has an o-ring along with the gasket. Then, I noticed the oil pressure sensor was loose. This was very well my fault. When I replaced it, I couldn't track down an oil pressure sensor socket (the one I got for the job didn't fit the oil pressure sensor), so I used a big wrench (27 mm, I believe) to tighten it down. Well, I was trying to be careful not to snap that small aluminum neck off in the hole so I didn't put as much torque on it as I probably should have. Sure enough, that thing was finger loose and there was a trail of oil on the bottom of the threads.

While I'm kind of kicking myself right now....I am SO glad I didn't have to do head gaskets!! I'm just kind of surprised though - no puddles of oil around the distributor area and the heaviest amount of oil was on top of the bell housing rather than at the base of the actual leak. Even when I checked with my UV light - no real traces in the immediate area. It didn't start showing until I got to the top of the bell housing.

 

Glad you got it figured out. I figured it was something simple because i have never seen head gaskets leak oil like you described.

 

97-98 Blazer 4.3 4wd. Big oil leak dripping off bell-housing on the passenger side. Thought it was a rear main seal, but popping off the inspection cover showed flywheel was dry and clean, no leak at seal. Followed the oil flow up the side of the bell-housing, and saw oil in the plastic conduit covering the wires from the oil pressure sender.
The sender is at the top of the engine, just to the right on the distributor, and the electrical connection points at the passenger side, so oil leaking out (under pressure!) was flowing down the wires and inside the conduit that runs down the passenger side of the transmission, leaking out on the way.

I feel so much better knowing it's not the main seal. I replaced the sender, added a new distributor cap/rotor, distributor gasket while I was in there.