I have a 91 5.0 TPI with about 150k miles...
I need to verify, but looks like I'm gonna need to get new Injectors...
Going with SouthBay Bosch III...
There is oil on the back of my engine... I need to clean it, then try and see where it is coming from... Do these engines normally leak from the manifold base, valve cover gasket, head gasket...??

I'm gonna have the timing chain & water pump replaced while they're that far into it...

Thanks,

Rafael

 

You basically have 3 points, well technically 4.

1 - It's leaking out of the distributor hold down gasket.
2 - It's leaking off the valve cover.
3 - It's leaking off the rear china wall.
4 - It's barely wicking and leaking out of the partial seal between the rear china wall and the intake gasket on one of the rear corners.

No oil should be flowing through the heads. It's only coolant passages and the oil stays on the topside inside the valve cover.

Clean it up really good and get a small mirror from Auto Parts store. They carry telescoping type for a few dollars.

I had a similar leak on mine after my intake gasket replacement it was wicking past the corner seal. I cleaned it really good with some rubbing alchol on a papertowel and put some black RTV on it. It has sealed up fine so far. I was to lazy to go get another set of Fel Pro 1206s else I would have just put another intake gasket on it.

 

Thanks for the advice... please clarify, "rear china wall" ?

Rafael

 

Rear wall of the lifter valley.

 

Exactly what Apeiron said. It's the rear gasket that runs the back of the intake manifold between the intake runner gaskets. They can be cork, rubber, or RTV.

 

If it is the rear china wall gasket and needs to be replaced, don't. By that I mean, if you have to pull the intake manifold, just squirt about a half a tube of RTV, each, literally, on the front and rear walls, Then, install the manifold, torque it down and leave it sit 24 hours. You should be golden. I don't understand why somebody doesn't come up with a 1 pc. intake gasket like they have the 1 pc. oil pan gaskets now. For years, the SBC faithful had to pray for good results with the 4 piece ones. Now, they're a snap. And, don't forget about 1 pc. RMS as opposed to the old 2pc./rope seals.

 

Question is that your leaking oil, not coolant? The oils like the member said its most likly the valve cover gasket area of 50% from the dis seal, if your car is running slower then the norm, your getting oil in the voltage area and will also cause this issue,

Take to a shop or just do this yourself for a much better result because no one love me these cars like we do and they will just put on and forget about all the other bolts needed in most cases, that's just my personal theory because I went threw this countless if times, u need a 3rd gen lover which is us.

Get your timing gun ready, buy a distributor O ring from napa store 8 dollars which is a lot but that seal is spot on compacting to others I got before,

Valve cover gaskets, just don't do 1 and leave the fallen behind, have your tools ready and your space and time available because to do the rear valve cover gasket on the passangers side it's a pain in the AZZ. And blanket to place on the fenders because your belt or zipper will just s scratch your paint to oblivion, and u will just call it quits right there on the spot!

It's a 91 model, so u have the density sys, which is a lot more wires to discount, which is more involved like removing the water hoses on the box area side to do it right....

If u don't have 1 already, also pick up a burp hose from **** to have it done while your right there anyways, this is a must for all 3rd gen's alike with v6 models to, so your car will have to burb out any air in the coolant sys,

I am as we speak am doing the same thing u are or already have done, but this is for other readers to view, and take note to....

Simply cut the small hose about 3.5 inches on both sides the smaller Hose that's located on the top passangers side that black cover box top one, and add your coolant burp air out screw type, for got the real name of it, but preston is the best one to buy, follow the instructions on how to burp your sys,

This is just a quick reminder and a helpful thning to do when doing the rear back passangers side area,

Also a quick note: several costumers told me that they always don't bother doing this to there 3rd gen's with maintains because of the A.I.R sys in the back because it's just to much work to do, and with the smog hoses and ect..... Like tons of readers here always say do it right the first time so u can actually forget about doing this again in the future and when u sell your car (if) people will see that they won't low ball u money because of this.....


Helpful hints for you guys;
Hope this helps
John

Iroc z parts and supplies
Houston tx.

 

Also could be as simple as the oil pressure gauge sending unit.