I have a pretty bad oil leak...

[Rogue_Alphonse]

SOMEWHERE at the top of the back of the block, and it's a nice steady drip... it has the trans, starter, and everything else under the truck covered in oil, even has a baked on black spot on the long tube header, just on the passenger side. I replaced the intake gaskets twice, once with and once without the rubber inserts for the middle. Distributor is clean. It's our basic TBI 5.7 from 1990, .202 heads if that makes any difference. HALP!

[76stepsidechevy]

oil pressure sending unit or line for a gauge?

[Rogue_Alphonse]

Originally Posted by 76stepsidechevy

oil pressure sending unit or line for a gauge?

The sending unit is down on the driver's side of the block, and where the other style unit would go on top is totally dry

[76stepsidechevy]

Im trying to think of where else it could come from back there. Is the oil pooling around the intake bolts?

[INSIDIOUS '86]

You have to have the middle seals. The plug at the back may be leaking as well as the distributor seal. Otherwise your valve cover gaskets are shot
Posted via Mobile Device

[Rogue_Alphonse]

Originally Posted by INSIDIOUS '86

You have to have the middle seals. The plug at the back may be leaking as well as the distributor seal. Otherwise your valve cover gaskets are shot
Posted via Mobile Device

I had a guy at a race shop tell me if the rubber seal is blown, don't use it. Also when I got the new intake gasket kit yesterday and put it on, all it came with was the ones for between the intake and head, and a little tube of black silicone for the front and back. Distributor got a new gasket as well, because it was also in the kit. from what I can feel, it's the intake AGAIN but then again the oil could just be running along the seem where the intake meets the block. Oh yeah and the valve cover gaskets are the best I've ever seen for being re-used once!

Is it possible that the intake could be cracked where the distributor goes through? Only thing is, like I said, intake is dry, block is wet.

[Rogue_Alphonse]

Originally Posted by 76stepsidechevy

Im trying to think of where else it could come from back there. Is the oil pooling around the intake bolts?

No, it's basically running down the bell housing and starter wires and thanks to driving it's all over everything else behind the bell housing. FLywheel is dry [havent put the clutch dust cover back on yet]

[92GMCDriver]

I had the same problem with my tbi it leaked all over the trans and down onto the starter it turned out to be the distributor seal. i know it might not look like it at first because mine sure didnt until i took it out to get a closer look.

[jhngardner367]

I agree.It's either the distributor gasket,or the neoprene seal between manifold/block has slipped.I don't use them,anymore.I just use Hi-temp silicone,and clean/dry the surfaces.

[bilfman]

Valve covers are usually the culprit here. Make sure you bang your covers straight, another good upgrade is get some extended tabs for the covers it spreads the bolt tension farther out on the cover. These are a little wing shaped steel tab that you put your existing bolt through. Seeing as you have done the intake I would make sure your valve covers are straight and tab them up.

[Rogue_Alphonse]

Originally Posted by bilfman

Valve covers are usually the culprit here. Make sure you bang your covers straight, another good upgrade is get some extended tabs for the covers it spreads the bolt tension farther out on the cover. These are a little wing shaped steel tab that you put your existing bolt through. Seeing as you have done the intake I would make sure your valve covers are straight and tab them up.

TBI, bolts are in the center and I have thick as hell rubber gaskets. No evidence of leakage at all from either one.

[Rogue_Alphonse]

Originally Posted by jhngardner367

I agree.It's either the distributor gasket,or the neoprene seal between manifold/block has slipped.I don't use them,anymore.I just use Hi-temp silicone,and clean/dry the surfaces.

Yeah I went your route the second time and still, same issue.

[grs]

My 87 with a 305, and TBI leaked like yours is leaking. It was the intake. I paid a shop to replace it, because I did not feel like doing it. You said you replaced yours. Maybe you did it wrong. Clean it real good then drive it, and put it on a host and shine a light up the back of the engine, and maybe you will see where it is leaking from. Let us know what you find out.