FE Intake Oil Leak -- End Gaskets or Not?

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....

Quote:

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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....

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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!!!!!:LOL::LOL::LOL:

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?

Quote:

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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?

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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.

Thanks John. I'll definitely get another set of hands to help me.

By the way, I called Edelbrock today. After being on hold for 30 minutes I spoke with a technician. He said the reason they recommend not using the gasket is that the cork gasket tends to slide out from under the manifold over time. He said installation is tricky but even if you get it right, the cork gasket slides out from under the manifold over many duty cycles. I told him that a 1/4" bead risks air pockets like mine experienced that failed very quickly. He acknowledged that was a risk and said it is my choice. I asked him if there was a measurement for the gap where a gasket is more or less desirable. (The compressed RTV from my previous install measured at 3/32). He said there was no range where they would change their recommendation but the larger the gap, the less desirable RTV is for the install. (Somewhat contradicting himself). He did say the Right Stuff is a great substitute for the RTV.

Hopefully this helps others avoid a re-do. Thanks again!

Quote:

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Originally Posted by jawarner

He said installation is tricky but even if you get it right, the cork gasket slides out from under the manifold over many duty cycles.

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"Factory Original Equipment", on "Millions of Ford motors", over decades! I rest my case!

I agree with you John, even on the aluminum manifold. I am not sure what about an aluminum manifold would make the cork gasket slide out any faster than the heavy cast manifold from the factory. (Maybe the way it expands and contracts?).

Even if the gasket slides out after 20-30,000 miles, that is 20-30,000 more than I was able to get out of RTV alone.

I'll be do it the original way.

Thanks again.

I've haven't used the end gaskets in years. The deck height or milled heads have
a lotto do with that. Take a punch and knurl the ends of the surfaces on the
top of the block. Maybe a little on the manifold too. I just did the block surfaces
and it work fine.Use gaskets if there's room and knurl the surfaces. If not silicone.

so i just got done installing a new engine in my truck its a fe 390 with the performer intake. my intake is warp just enough that it doesnt sit on the heads evenly... i used the gaskets that the machine shop gave me and i think it was engine pro.. they are thicker gaskets than the fel-pro... i put that copper rtv in the corners where the haynes manual says to and let the rtv set up like the tube said to. i had a slight problem with one side on the front and back gasket trying to slide into the valley area while setting my intake. by the time i was able to get the gaskets to settle where they needed to be while i set my intake on there they were staying.. i had to use my seal picks very carefully as to not rip them though.. in the past i have used the blue rtv in place of the cork gaskets and it did a good job of sealing the are but i was graceful applying more than enough to make sure it sealed. yes it looks a lil tacky for a "show car" but it gets the job done... ive done the rtv and cork set up and never had luck with it sealing completley either. although im proud to say without using fel-pro gaskets i have no leaks.. they seemed to always not be thick enough. if you would like i could get the companies name that the machine shop used for gaskets.... btw anyone know the rated horsepwer and torque at the flywheel for the 70 models of 390's with a 4 barrel?

Hello guys,

I put the engine back together using the end gaskets and the finger full method. I've put about 3 hours on the engine since and I thought I was home free. This afternoon I looked under the car and there was a puddle of oil. Before it was leaking from the driver's front. Now it is leaking from the passenger's front. What is odd is that it didn't leak at all and then once it started, it began running out of the engine fast.

Now I am lost. I've taken this apart twice now and put it back together, once with the gasket, once without. Both times I had a leak in after about 3-4 hours of use.

Does anyone think there may be another root cause of this? The leaks have both come from the front of the motor and both went from no leak to fast leak in almost no time. I am wondering if there is something about the oil galleys at the front of the heads that might cause this? Or possibly excessive crankcase pressure?

If anyone has any ideas on what to try next, I would be very appreciative. I have already spent two weekends and a couple hundred bucks for gaskets and supplies and still have a leaking motor.

(BTW, recall these are Edelbrock Performer RPM Aluminum heads and Edelbrock Performer RPM Aluminum manifold).

Thanks

Jeff

Just a shot in the dark here, so I have no idea if this is a fix for you or not.

My first pickup was a 69 F-100 with a 360 and had the eternal intake end gasket leak which drove me crazy. No matter what I did it always seeped oil out from one side or the other, and the cast iron intake was a bear to take off and put back on by myself. Went to a friend of my dad that had a garage and paid him to make it stop leaking. I got him to tell me what he did to make it seal the first time.

He had removed the intake and used a center punch to hammer in raised dimples along the flat mounting surface to "bite in to" the strips of gasket you lay in to place. His claim was the gasket design was very prone to being pushed out in the middle because of crankcase pressure, causing the ends of the gasket to pull in away from the point where the intake, heads, and block all come together. He told me in the worst cases he actually drilled small holes along the flat surface every inch or so and would stick coathanger wire in the holes and clip it off with a pair of sidecutters to leave a small barb sticking up to lock the end gasket in to place.

Thanks for the description and thoughts. Like I said, I am getting desperate and am willing to consider any and all ideas. I most certainly will try the center punch idea as I don't think it can hurt and it might really help. Before using this method when you were fighting it, could you see the end of the front and/or back gaskets pulling away? How long did it take?

The odd thing here is I can't see any visible change in the gasket's position. And the time I used only RTV, I couldn't see it move either. It is as though those front oiling holes in the heads are putting out so much pressure that the gasket or rtv just fails quickly and then there is a breach like a dam and once it starts leaking it goes from a seep to a full out stream within seconds. I've heard it is a poor design. And the intake is a real bear because you have to pull the rockers and I have adjustable valves so I have to readjust them every time. But I would think it would just seep not breach and then pour out.

I wonder if the heads have too much oil pushing through this hole and no matter what I do it will eventually fail. The no gasket (as Edelbrock and Permatex recommend) lasted 4 hours and the gasket lasted about 3 hours.

Thanks again for your input.

How well did you clean the surfaces? I clean everything with brake parts cleaner on a rag to insure proper adhesion.

I was very thorough in cleaning the surfaces. I used Permatex's Gasket Remover following by a parts cleaner and a scotch-brite pad. On the manifold, I also hosed it off and blew it out just to make sure I got all the dust and loose gasket material. (obviously I couldn't hose out the engine).

The odd thing is when pulling it apart I can't see where it failed. I'd sure like to avoid another redo on this.

thanks,

Jeff

Quote:

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Originally Posted by jawarner

I was very thorough in cleaning the surfaces. I used Permatex's Gasket Remover following by a parts cleaner and a scotch-brite pad. On the manifold, I also hosed it off and blew it out just to make sure I got all the dust and loose gasket material. (obviously I couldn't hose out the engine).

The odd thing is when pulling it apart I can't see where it failed. I'd sure like to avoid another redo on this.

thanks,

Jeff

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I feel your pain, Jeff. I spent all day Saturday putting an Edelbrock Performer intake/carb on the 352 FE in my 66 F100. I used Edelbrock gaskets & Permatex per the instructions. When I cranked it up, the oil started running out the back and I waterjackets didn't seal well either cause there was coolant in the oil. :CRY: I pulled everything off again and learned that apparently I didn't put the Permatex on thick enough to amply fill the gap.:( I re-cleaned all the surfaces and used Fel-pro gaskets this time with the cork ends. I glued the ends in place with Gasgacinch and used the Permatex in the corners and on the water jackets. I'll finish it up in the morning and hopefully, it will work this time! Will let you know.

Randy

Sorry to hear that Randy. That is the tough thing about the FE motor. That gap where the cork gasket goes is huge. As I wrote earlier in the thread, I spoke with both Edelbrock and Permatex, both swore that I should not use the cork. Their theory was that with a cork gasket, you have 4 surfaces that might fail. With "the Right Stuff" and no gasket you only have 2. (Intake, Cork Top, Cork Bottom, Block). When you say Permatex, which product? I used the Right Stuff.

I will say the "Right Stuff" was unbelievable sticky and I think is a good choice but I still think when I go back, I'll use the cork. I'll probably go overboard putting too much instead of too little myself. It sure is painful having to clean all those surfaces up without getting it into your motor right?

Good luck with your FE! Hope you're leak free by this time tomorrow.

Jeff

Quote:

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Originally Posted by jawarner

Sorry to hear that Randy. That is the tough thing about the FE motor. That gap where the cork gasket goes is huge. As I wrote earlier in the thread, I spoke with both Edelbrock and Permatex, both swore that I should not use the cork. Their theory was that with a cork gasket, you have 4 surfaces that might fail. With "the Right Stuff" and no gasket you only have 2. (Intake, Cork Top, Cork Bottom, Block). When you say Permatex, which product? I used the Right Stuff.

I will say the "Right Stuff" was unbelievable sticky and I think is a good choice but I still think when I go back, I'll use the cork. I'll probably go overboard putting too much instead of too little myself. It sure is painful having to clean all those surfaces up without getting it into your motor right?

Good luck with your FE! Hope you're leak free by this time tomorrow.

Jeff

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Hey Jeff,
It worked!! Yay! This time I used a Felpro gasket set with the cork ends like I said in the previous post, I think. The side gaskets hook into the head gasket tab to hold them in place. I glued the cork ends in place with Gasgacinch and used the black Permatex Ultra to put a big glob on the corners where the cork meets the sides and around the water jackets on the intake. I torqued it down to spec and it seems to be working fine. No leaks yet and I've been driving it around a lot today. I still have a little fine tuning to do to the carb but so far, I'm pleased with the change.
Good luck on yours. Sounds like a nice car. Have you posted any pics of it?

Later,
Randy

I install a lot of FE intakes with pretty good success. But I do a lot of up front legwork first. I measure the angles on the heads/intake to be certain they are even, test fitting the intake with flat gaskets and no end seals and checking front & back, top and bottom with a feeler guage - the distributor is used as a center locator. Once I am satisfied that all surfaces are parallel and square I will use a really small amount of Motorcraft TA-31 diesel silicone - so thin its like a coat of paint - you can see through it - on the intake gaskets to glue them in place.

I use a finger to make a thin layer on the front and rear seal surfaces both block and intake - smearing it in to assure adhesion before putting a nice thick bead of the same silicone down on top of the block - no end seals - but carry a thin layer up the filled corners toward the drainback holes in the gasket. Put the intake on using the distributor to locate it and start all the bolts - don't tighten any until they're all in.

Tighten it down and remove the distributor. There will often be some squeezed out silicone in the distributor hole - clean it ou with a finger. Use a moistened finger to smooth the front and rear seal surfaces for both cosmetics and to verify a solid seal.

The TA-31 silicone is gray, looks nice, and is really oil resistant. Dries in a couple hours.

we use that TA-31 on Detroit diesels.... On the Caterpillars we use contact cement on the gaskets. Solvent removes it when the time comes to change.
These hold 90+ lbs of oil pressure sometimes with bolt gaps as far as 8inches apart.... I'd think it'd work on the intake manifold.


Another question, if crankcase pressure is the problem, could we just vent the crankcase better?

Drew

Hello Everyone,

I appreciate all the knowledge and insight into this topic. On my 4th attempt, I think I have it sealed. (Knock on wood because it has only been 2 weeks of leak free service). I admit, I am a hobbyist, not a professional mechanic. And the method I use below would not be advisable if I had to do the job at flat rate. I'll describe what I did below and anyone can feel free to criticize as I know there are probably better ways. But any FE builders out there who might benefit from trying this method are certainly welcome to it, especially if you kept fighting leaks shortly after reassembly. Given I failed the first 3 times, maybe someone can benefit from my blunders. Keep in mind, each blunder means about a full day if not more of work plus the expense of gaskets.

Using cork end seals or not?
I tried to follow Edelbrock and Permatex's intructions to not use the cork twice and had a leak after 3-4 hours on both tries. I called Edelbrock twice and they finally said, it might be better to use the cork if I've tried RTV twice and it leaked. The compressed thickness of the front and rear gap on my manifold was 3/16". The instructions say to lay a bead of 1/4" RTV down. I did this and used the "Right Stuff" which many swear by. My experience is that 1/4" is just a lot of RTV to apply having 2 disadvantages. First, I was really nervous about it covering up an oil whole in the corner or have silicone break off and it end up fouling my oil pump. Maybe I am paranoid. Second, with that much silicone, you are bound to have a thin spot or a void. When I pulled the engine apart on both failed attempts with RTV only, both had a little pinhole in them. To each his own, but my experience taught me, RTV only doesn't work consistently. I know others have and will swear by this and I can't dispute them except to say, it didn't work for me.

The third attempt I did use the cork. I glued it down with brush tack. I was nervous about doing it this way because I wasn't sure how good of a sealant brush tack really is for oil. I put a finger full of RTV down on the corners and sat the manifold down. I gradually torqued it watching the cork to make sure it didn't squirt out. This is nerve wracking. I thought I had it done well. I then let it set up over night (26 hours) and installed my pushrods, rockers arms and set my valves (adjustable Harland Sharp). I finished the top end and fired it off and once to operating temperature, the passenger rear corner was leaking. You can imagine how PO'd I was. I immediately pulled it apart to find the cork hadn't squirted out, it squirted in leaving a gaping hole there. The RTV helped seal the corner, but about 1 inch in (just past my finger full) the gasket squirted in and left a nice slot for oil to leak.

So I developed a new plan.
The problem with using RTV only is there can be voids and that is just a lot to use.
The problem with using the cork only is that when torquing, the cork wants to squirt in or out.

One of the forum members suggested using contact cement. I contemplated that but was concerned it may not help seal imperfections in the cast surface.

So what I did was use a hybrid approach. I temporarily installed the manifold with RTV on the bottom side of cork. Removed and then reseated. Sound odd? Here is how I did it:
1) Clean all surfaces super good. I scraped, cleaned with a brillo pad, used brake cleaner etc.
2) I used Gasgacinch to place the intake port gaskets in place with a thin film of RTV around the water ports. I chose to put this gasket down so I could make sure the tabs line up perfectly from the cork.
3) Put down a thin film of "The Right Stuff" across the full length of the ends with a little extra in the corners. Main goal here is to fill in any imperfections in the block and get something the cork will adhere to.
4) I placed the cork seals down on the thin film and worked them into the precise position with extra attention again to the corners. Note, I was careful not to get RTV on the top side of the gasket.
5) I then placed cellophane (sandwich wrap) on top of the cork. The reason I did this is because I wanted to put pressure by temporarily placing the manifold on the cork gaskets to get them to tightly seat without having the manifold stick. I was so paranoid that the cork would flex in or out that I wanted to let the bottom side of the RTV set up overnight and then be able to pull the manifold off to verify the cork stayed where I wanted it. Worse case, if it moved, I wasn't starting all over - only restarting from the tear down point.
6) I set the manifold on carefully trying to get it as close to perfect as possible. I did not torque it nor even put the bolts in the holes. I chose not to do this as I didn't want to risk moving the cork gaskets around and I also didn't want to torque and then untorque the manifold gasket. I did not connect the hose to the water pump bypass as this would be useless since it was temporary and the sliding around may cause the gasket to move. I didn't install the distributor either. The theme is to set it straight down and try not to slide it. It doesn't have to be perfect since it is coming back off. It does need to put pressure in the right places on the cork. I did put about 135 pounds from my weight set gently on the top of my manifold to help put downward pressure on the cork and rtv.
7) In the morning, I came out and gently removed the weights and then the manifold The cellophane kept it from sticking in case any RTV happened to move torward the manifold. At this point, the cork is stuck very well, imperfections are filled in with RTV on the block and I can visually inspect all mating surfaces before permanently setting the manifold down.
8) Next I took more Right Stuff and put a finger full in all 4 corners being careful to get the tabs and inner seams sealed. I put a thin film on top of the cork all the way across.
9) I then placed the manifold down with little fear that as I aligned it and slid it around the cork would move. I used the distributor to center it and all the normal advice for starting and torquing the bolts down.
10) I then let it set up for 24 hours even though the Right Stuff says 20 minutes is enough.
11)I finished reassembly (I installed pushrods and rockers, adjusted valves and rest of assembly after it set up) I then fired it off. So far, no leaks. I hope I have it right.

As I said earlier, I know this is an extreme method and most mechanics probably scoff at this because there is no way you could make money doing it this way. But it was worth it to me to be a sure as possible to keep it from leaking.

I have pictures and more details if anyone wants to try something similar.

Thanks again for all the advice.