chasing leaks...TBI 305 / 700R4

[LEEVON]

I HATE OIL LEAKS!!! I've replaced the oil pan gasket, one-piece rear main seal, oil pressure sending unit, and oil plug. All of the above helped tremendously but... There is a leak coming from up high I don't think it's the rear main again because there's no oil on the flywheel and it's coming down both sides of the bellhousing. I am thinking distributor gasket or backside manifold, any thoughts???

Also I replaced the transmission and it doesn't leak a drop...except for the freaking huge spot it leaked from the brand new tailshaft seal when I parked uphill in my drive the other night. Could there be a burr in the tailshaft or a bad seal, or bad yoke, any thoughts???

[PhilaTruck]

Originally Posted by LEEVON

I HATE OIL LEAKS!!! I've replaced the oil pan gasket, one-piece rear main seal, oil pressure sending unit, and oil plug. All of the above helped tremendously but... There is a leak coming from up high I don't think it's the rear main again because there's no oil on the flywheel and it's coming down both sides of the bellhousing. I am thinking distributor gasket or backside manifold, any thoughts???

Putting my money on the intake, especially cuz you said it's coming down both sides. You didn't notice anything when you were in replacing the oil pressure sender?

[LEEVON]

well it was nasty back there because the sending unit itself was broken and the brass fitting was leaking, but now it's clean as a whistle. I'm thinking manifold too...just wondering if there are any other fittings. Oh well, just gonna have to bit the bullet and start taking crap apart.

Ahhh, to be leak free is all I wish for!

[Prong]

On your tranny, I recall someone mentioning an o-ring or o-ring kit for those T700's that goes in the tailshaft for that purpose. I'm sure someone else more versed on the subject can specify what you need.

[PhilaTruck]

Originally Posted by LEEVON

Ahhh, to be leak free is all I wish for!

I can see, especially with that nice garage floor. Try getting back there and cleaning everything off, drive it for a coupla weeks or days, depending how often you drive it, then get your fingers back there to search.

You also might appreciate one of those little telescoping mirrors.

[rfmaster]

Back China wall is notorious for leaks. Factory gasket tend to leak right at the bands. Whenever I swap intake manifolds I use Black RTV gasket maker and no gasket for a leak proof installation.
There are couple more places for leaks - behind the flex plate there are 3 oil gallery plugs plus a camshaft end seal. Chances are they are OK, and if they weren't you would have a gusher!
On the left side of the block there another oil gallery that goes from left side head plane and intersect main oil passage. This one also never leaks unless during rebuild someone did a lousy plug install.

//RF

[chevymotocross]

That tail shaft seal is mentioned here: http://73-87.com/7387garage/drivetrain/yokeleak.htm

I currently have that nasty leak when I park my 87 truck uphill. I haven't gotten around to replacing it yet, since I am currently tackling a new radiator and condenser replacement. Everytime I get close to actually buying a lowering kit for my truck, something else breaks.

[LEEVON]

I decided to remove the intake tonight on the '87 and replace the gaskets. Boy what a mess. The EGR ports were completely blocked and the there were definitely vacuum leaks under the TBI and in the front of the manifold. Funny because the truck seemed to run pretty well. I hope I am surprised at how well it runs when I'm done.

The back screw on the distributor wouldn't come out and I had to bust the cap off making it impossible to mark the rotor. Dangit .

Since I'm this far might as well replace cap, rotor, plugs, wires, rebuild TBI, maybe oxygen sensor and fuel filter.




These photos make the truck look like a pos! The engine bay looked pretty good before this.

[rfmaster]

Better get that antifreeze cleanup ASAP from lifter valley! Use high quality SS scraper to remove the last of intake manifold gasket material. DO NOT USE ABRASIVE pads of any kind. The residue dust is will get into engine oil and will destroy your bearings.

Nice progress all around

//RF

[LEEVON]

Well, I got that oily mess all cleaned up and replaced a few parts while I was in there; cap, rotor, plugs, wires, tbi rebuild, temp sensor, cleaned egr. I was able to get the block and manifold surfaces very clean. I applied a nice 3/16 bead of black rtv up about 1/2 onto the fel-pro gaskets. I even crawled up into the engine bay (I'm 6'-3"/245lbs) to drop the manifold down perfectly straight. After putting it all back together, I couldn't get the truck timed and discovered the timing mark had slipped about 20deg. After finding TDC with a piston stop and setting base timing she ran like a champ. Timing advanced correctly with the ESC connected so I took her for a spin. Came home and it didn't take long for the leak to start again. PISSED! One broken shop light and a few choice words later she was parked 100 yards from the house while I cooled off. To top it off I had to drop some nova parts off at the blaster today and had no choice but to take the truck, it ran fine but died while idling at his house and won't start.

There it sits, is this what a divorce feels like?

End of rant.

[rfmaster]

Leevon

Hey - been there done that (divorce that it is) - leak can be fixed, but once she is out that door, it is kinda all over. The question where is the leak? And now it will not start - hmmm - fuel, spark timing?

Post what you see - we'll slog through this one...

//RF