Thread: FE Intake Oil Leak -- End Gaskets or Not?

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Hello. I am new to the forum and need some help.

I have a 69 Mustang with an FE Motor I've rebuilt. It has Performer RPM Heads and matching Performer RPM Intake Manifold. The installation instructions with the manifold say NOT to use the end gaskets for the intake manifold. I followed the instructions and used RTV. I put a 1/4" bead across the rail and if anything was too generous with it. I've put about 3-4 hours on the motor and today when I brought it to operating temperature it started leaking from what appears to be the front driver's side corner of the intake. It is coming out fast enough you can watch it flow.

Now I am second guessing whether I should have used the end seals. The problem with using a 1/4" bead is there could be a void somewhere in it because it is being applied so thick.

I have a relative who says to use the seals but apply them and let them set up before coming back and installing the manifold.

I am interested in the forums' opinion. I've searched and can't find anything specific on the FE motor. I've read some say to use Right Stuff.

I don't think this leak is something I can fix without pulling the intake again. So I really only want to do this one more time.

Any advice?

Thanks.

I was a FORD tech for seven years in a very large dealership. It was during the FE engine's primetime (64-71).

We contacted cemented the intake gaskets to the heads. And contact cemented the end corks to the ends of the block. We then used "a finger" worth of sealer just in the four corners where the intake gaskets meet the end corks. The manifold went on dry. Make sure the contact cement is dry on both surfaces before you stick it together, "too soon" and it will not hold.
The end corks are thick, more than I would want to use silicone to seal. Silicone works great, but not to fill a quarter of an inch IMO.

We also "always" used a new bypass hose and mounted the manifold without the hose clamps to make the hose easy to flex up while mounting the manifold on a engine that already had the water pump mounted. We put the hose clamps on after the mainfold. It's also a much easier job to use two people to install the manifold, one on each side. A large vise grip clipped in the middle on each side makes a good hand hold.

Thanks John,

This is very similar to what my relative told me. On the "finger" full of sealer, would you use that "right stuff"?

A quick question for you. I can't explain why this suddenly starting leaking. The one other clue is that up until now, I did not have a PCV installed. I recently bought a new one and installed it. Do you think this could cause an oil leak suddenly? I would think a new valve would help the situation but maybe the crankcase is building a lot of pressure and instead of have it open it is restricted (with a new valve).

Am I grasping at straws?

For me the key for RTV to work on the ends is to put a healthy, 1/4" bead on, heavy in the corners and then to let it set up long enough that it has a surface skin before setting the manifold without any front/back shifting. The corks lose their "sponginess" over time with repeated thermal cycles and leak, in my experience.

Thanks for the reply. Would you feel the same about the rubber gaskets on the ends?

Also, before I pull it apart, is there any way I can absolutely be sure it is the intake that is leaking? I used the 1/4" bead method putting it together and ran it for 3 hours on a test stand. (Several heat cycles). Then I installed the motor and worked on electrical and body. (This took me 4-5 months). This is the first time I've brought it to temperature since being installed. And it leaks.

I followed the leak and can see that it seems to be coming from the front right corner nearest the distributor. I've looked to see if maybe it could be a valve cover and can't see any signs of leak. But I'd hate to blow a weekend pulling it apart again only to find it was something more simple to fix. Is there anything I can do to test to verify this is the source of the leak?

I like the Fel-Pro "lifetime" blue gasket sets, but Edelbrock says that the Permatorque Blue's are for stock type cast iron manifolds only, and that they are not to be used for their aluminum manifolds. They also say to use only Locktite 598 OEM HT Silicone as others may damage O2 sensors - never heard of that before, and hard for me to see how silicone on the oil/water side affects O2 sensors? I'll probably spring for a tube, just to be safe, and it's not an issue for you on a '69.
If I had a leak that I could watch flow I would look first to the valve cover, and being sure that I did not have a gasket slipped, loose bolts on cast or too much torque on tin covers? Maybe Dave will come in with some Ford FE mantra for intakes & oil leaks

I've always used the end gaskets on the FE's....installed in the same manner John uses... Toughest part of the whole job is setting the cast iron monster in place!!!! I uses a small amount of old Permatex Gasket Cinch to hold the gaskets in place. Once it tacks up it holds them quite well....

Originally Posted by Dave Severson

I've always used the end gaskets on the FE's....installed in the same manner John uses... Toughest part of the whole job is setting the cast iron monster in place!!!! I uses a small amount of old Permatex Gasket Cinch to hold the gaskets in place. Once it tacks up it holds them quite well....

Dave, do you use the end gaskets on aluminum intakes, too? I'm getting ready to put an Edelbrock Performer intake on my 352 FE engine in my 66 F100. I've researched this on various FE sites & Ford truck sites and get varied opinions. Even Edelbrock says not to use the end gaskets but to use RTV instead. Some have said it depends on how much gap you have at the ends when you dry-fit the intake before putting it on for good. Personally, I'm open to use it or not, I just don't want it to leak when I'm finished! LOL!

As mentioned on the Edelbrock site, depends on the gap on the intake ends...but yes, I still prefer to use the end gaskets, have even gone so far as to make my own from thin cork gasket material on some small gap intakes...the old Offenhausers come to mind as fitting tight... But yup, still the old Gasket Cinch, drop of RTV in the corners.... Other methods probably work too, just never saw a reason to quit doing what works for me... One thing I have to admit, being the geezer that I am, I used the cherry picker to help with the last install I did with an FE cast iron intake!!!!!

Thanks for all the input guys. I've taken the suggestion and tried to rule out all the other stuff (valve covers etc). I just don't see any sign the leak is coming from anywhere but the intake. However, I did tighten the valve covers down and it did seem to slow it down but it might be in my head.

Assuming it is a slow leak at the intake, do I have any other choice but to R&R the intake? Is it possible to force some RTV or other sealer into the corner to stop it? I know this is probably futile but if it would save me a weekend of work, I'd try anything at this point.

Thanks for the posts. I have tried to rule out all the simple things. Tightening the valve covers seemed to slow it a little but I still don't think that is it. (Just wishful thinking).

Assume it is the intake with a slow leak in the front driver's corner. Is there any alternative to R&R'ing the intake? As you know with an FE, that means rocker arms, resetting valves etc. Is there any hope of pushing some RTV into front corner or anything I can do to save a weekend of work?

Originally Posted by jawarner

Thanks for the posts. I have tried to rule out all the simple things. Tightening the valve covers seemed to slow it a little but I still don't think that is it. (Just wishful thinking).

Assume it is the intake with a slow leak in the front driver's corner. Is there any alternative to R&R'ing the intake? As you know with an FE, that means rocker arms, resetting valves etc. Is there any hope of pushing some RTV into front corner or anything I can do to save a weekend of work?

Very slim chance, but probably worth a try before disassembling again.....

I agree with Dave in both cases I've always done mine the same way.
I also did my big block 440 dodges like that as well even with the
Valley oil pan, But I also used a tack spray with that on the dodge.
But if you were not real careful that dodge would leak in the corners too.
No slidding around, drop the intake straite down or you had problems with it.
Kurt

Guys, thanks for all the input on this.

I decided I might as well bite the bullet and tear it down. Upon removing the manifold, I saw a pin hole sized void in the RTV close to the front right corner where the leak was coming from. I don't know if this was an air pocket in the RTV when I applied it or it was caused by oil pressure at the spot. I tend to think it was an air pocket because the engine only had about 4 hours on it since installing. I measured the compressed thickness of the RTV and it was less than 1/8 inch. A 1/4 inch bead of that stuff leaves a lot of room for air pockets and other inconsistencies.

I think I'll go with a combination of the input provided here. I am going to use the cork gaskets applied with contact cement. While they may break down over time, I am hoping it is longer than 4 hours. I am leaning toward using the "Right Stuff" in the corners and maybe a thin film on top of the cork. I've also been told to use a thin film of sealant around the coolant ports on the heads/manifold.

Any other reassembly advice on the top end of an FE motor is greatly appreciated. Thanks again for all the input!

Here's my take on the "no end gasket" suggestion from Edelbrock. From their point of view they may very well be correct because I'd bet that most of their aluminum manifolds get put on "milled head" engines that have poor fitting manifolds due to the heads.

As Kurt stated, you only get one chance to set it on straight without knocking a gasket or sealer off. The "trick" is to use two people and have some "hand holds". The vise grips in the center of the top lip by the valve cover rail make for a good handle balance point. Leave the hose clamps off the bypass hose to give yourself a little more wiggle room.

In my youth (note, many years ago, LOL) I would crawl into a Ford truck engine compartment, feet on the frame rails, and grab the cast iron manifold sitting on the inner fender and stab it on the engine. Everyone was busting their butt to earn a living on flat rate in the 1960's. I also did one head R&R's without pulling the intake manifold. Aww, the days of warranty flat rate.