oil leak off intake manifold on 390

[65BLUBIRD]

I replaced the valve cover gaskets and these are not leaking. Took some rags and cleaned up all around the engine as best as I could. Ran the engine for about 10 minutes and then started feeling around. The engine is wet at the back just under the intake manifold. This seems like a fairly common failure. Mine is not leaking too bad but enough to bother me. From what I have read this is a fairly common failure. I've checked the manual, some other posts and some videos on it and seems pretty straight forward. What I have seen suggested is to use silicone over the cork gasket. Agree, disagree? Any other tips on this job? Looks like about a whole day, maybe more? If I decide to go forward, any thing else to fix or change out? When I pulled the valve covers the rocker arms and such were remarkably clean.

[Jerryjimenez36]

Did you get this fixed mine is doing this too? I am from Pomona so not to far have a 64 TBird.

[65BLUBIRD]

I haven't gotten around to doing it, not leaking bad enough I guess. What I have gathered is the cork gasket works best if manifold is stock, silicone if otherwise. There are some online videos on youtube. Local garage gave me a reasonable price on it and he has done other work on the car with good results. Unless you have a cherry picker or hoist it looks like a 2 person job to get the manifold off and on. Stock one is a beast.

[WC145]

My '66 was leaking badly from the front and rear of the intake manifold. A month or so ago I replaced the factory cast iron behemoth with an Edelbrock Performer RPM, I used Edelbrock intake gaskets on the heads and no gaskets front and rear per the Edelbrock directions. I used "Right Stuff" silicone goo instead and it worked great, no more leaks. From what I understand it's hard to keep the front and rear gaskets in place when setting the manifold back down on the engine, no surprise since it weighs like 80lbs. I was able to put the Edelbrock on by myself, it only weighs 23lbs.

[65BLUBIRD]

Thanks for the info. I am still holding out awhile as the leak is not so bad, yet. Waiting for something else to go haywire before I tackle this one. Good to hear yours is working well. Keep me posted if everything stays tight down the road.

[Jerryjimenez36]

Hello,
I have a 1964 Thunderbird and mine was leaking super bad from the rear of the intake manifold. I have very little experiance with american muscle cars. I have worked on import cars. I did the job my self and it was not that hard just time consuming. Make sure you have a engine hoist or some serious strong muscle to remove that 100lbs+ manifold. I will post this a link to this video that I found helpful its a great tip so that your intake seals correctly. Also I used "Rightstuff" Silicone and worked great I am now leak freeeeeee! :) Let me know if you have any questions.
Mustang Shop: Intake gaskets (easy stuff) - OperationMustang.com - YouTube

[asarkisi]

My 1965 engine had a small leak in the front "china wall" area of the intake manifold. Being spoiled by today's new engines with no oil leaks whatsoever, I went after it and decided to replace the stamped valve cover with a cast cover while I was at it (have to remove the valve covers anyway to remove the intake manifold. Removal of the intake manifold on an FE engine involves removal of the push rods. Be careful when replacing the intake gaskets as they look symetrical left ot right, but are not. Similarly, be careful about the carburetor gaskets as the gaskets on either side of the spacer/riser are unique. And be careful to mark the temp sensor wire and the distributor advance wire as they look identical.

I did use the blue urethane instead of the cork for the china wall. It works. But I think I messed up when switching to the Cobra cast valve cover as I am now blowing oil. I believe the cast cover may not have a baffle under the PCV orafice. Does anyone else have a similar issue when changing valve covers?