Oil leak after LIM/valve cover job

[FijiBill]

So my 1999 Ford 4.0 OHV has had a drivers side valve cover seep for a while (never made it to the ground). Plus it had a rattle at idle. And old plugs. I decided to pull the top of it off and replaced all the rocker arms, push rods, LIM, valve covers, thermostat, DIY injector clean, injector o-rings, spark plugs, wires, and ignition coil.

The good news. The exploder runs better than it ever has with more power, throttle response, better gas mileage, and the valve train is now silent, although I still have the famous 1999 wrist pin double rattle at times.

The bad news. I have an oil leak. Its only a few drips when I park (probably because a lot of it burns off on the cat) but it is slow. It can be easily seen on the outside of the M5OD bellhousing on the drivers side ONLY, as well as seeming to glisten down the exhaust pipe on the drivers side ONLY. It gathers/drips at the engine bellhousing joint but I doubt it is a rear main seal because the oil is on the outside of the bellhousing AND exhaust pipe and my clutch seems fine. The oil is of course brand new since I changed it twice (once after the job to get rid of junk/coolant and another time after running 20 minutes to get rid of the assembly lube on the rockers), so it is a very clean (and thin...) hard-to-see 5W30.

I used the Victor Reinz/Mahle gasket kit. Its a two piece and I used Ultra Grey in the LIM head/block corners and for the walls. I used Ultra Grey where the LIM/heads meet on the valve covers as well. Torqued everything with an inch pound wrench to spec. There are NO coolant leaks and NO coolant in the oil so the LIM is maybe OK. At least the four outlets are sealed.

My question. Should I take the entire upper intake off again and try to retorque all the LIM/VC bolts? Is an initial oil leak down the back of the engine common and this what folks normally need to do after some heat cycles? Or is this unusual and I should redo the valve covers and maybe even the LIM? Or should I just wait for the oil to get a bit older/thicker and hopefully it will gum the gap up? From what I understand none of these gaskets are under any pressure (I replaced the PCV valve just in case but it didn't make any difference).

FWIW the only weird thing I noticed while doing the job is that the Victor Reinz LIM gasket is thicker than the OEM, so the LIM is a bit higher at LIM/head junction instead of being a bit lower with the OEM one piece. But I would think there would be enough slop in the valve cover gasket to address this as the delta is the same just opposite--there is even some non-metal backed rubber in those areas of the valve cover gasket.

Hard to see anything back there. I did order a borescope to try to get some better looks. Oil level hasn't dropped any so I am driving it daily.

Sorry for the long post. Thanks!

 

[lobo411]

Retorque the valve cover bolts.

When I did the LIM using the "newer, better" 2 piece gasket design, it leaked 1/2 - 3/4 quart every 300 miles. I finally removed the LIM and found that the fast-curing RTV provided in the gasket kit had dried before I was able to get it all together, so no seal. I ended up replacing the gasket with the old style one-piece gasket, which is still available.

Check the rear valley area with your scope when you get it. You could try cleaning everything and then putting some UV dye in the oil. However, if it's just a few drops, I'd just live with it.

 

[FijiBill]

Thanks lobo, I'm going to try tightening everything first for sure. I'd really like the fix the leak, but I know that a small leak is better than a big one. Maybe I should just be happy

About 300 miles on it now, mainly hard driving up and down the mountain. Still no notable oil loss on the dipstick. Still no coolant loss. Still always a few oil drips when parking. After all this driving I can feel a bit of oil pooling around the base of the cam sensor that wasn't there before, so it is an oil leak from up high and likely back but that doesn't eliminate anything besides the rear main seal. Can't feel much oil around the valve covers but I guess it wouldn't stick around there very long. Borescope on its way.

 

[lobo411]

It sounds a lot like my leak, to be honest. I eventually stopped driving it so hard, relegating it to around down driving and the occasional hiking trip to the mountains. The leak slowed along with the driving, so I didn't mind topping it off ever few weeks. I decided to fix it for good after I parked on a steep incline in the mountains and went for a hike. I came back a couple of hours later and fired it up, and a massive cloud of smoke billowed out. Probably the oil had saturated the exhaust manifold, but I had my hand on the doorhandle in case the engine was on fire. Luckily the oil burned off, I went home, and fixed the damn leak...haha!

 

[FijiBill]

So I got one of those $12 pinhole LED USB borescopes. I put some shots of the rear driver LIM/block/head junction from the last three days below:

The green is the LIM gasket. The UltraGrey RTV leads off to the right from the LIM/block/head junction, and the head gasket slopes back to the left. Based on the first shot, it looks like the oil is coming from above the LIM/block RTV seal (it is collecting on the higher rib of the LIM as well as on the green LIM gasket). The RTV seems OK?

Based on that, I figured it must be the driver valve cover. Folks with Gen1s always talk about triangular valve cover bolt spreaders, but my 99 just had tiny washers to go under the bolts.

Rather than try to hammer down the bolts and tiny washers, I ordered Tom Morana's valve cover spreader, which is a thick piece of steel that completely encircles the valve cover. I didn't really want to remove the covers, so I just replaced the bolts with the new studs one by one and then slid the spreader over the installed cover and studs. I know the driver side valve cover leaked on the manifold at this point, but I'm not sure how important it is to install a steel carrier VC gasket dry since it can't slip. Maybe I will pay for that . I torqued the new nuts down to 62 inch pounds and because of the beefy spreader I'm pretty sure it must be flat.

After two days, it's still dripping a bit. Maybe all the residual oil which dumped when I loosed the covers? From the pic, it looks like the leak is subsiding topside, but I'm not sure. Anyway, I'm hopeful.

 

[FijiBill]

Well, it still seems like it is dripping. I cleaned up the drivers LIM/head/block area but after a drive there is still persistent oil in the drivers LIM/block crevice (base of green intake gasket at left):

You can faintly see RTV behind all that oil but its hard to say if the RTV makes it all the way up to the LIM from the block.

Just next to this as the joint curves back, there is oil but the RTV looks good bottom to top, its even oozing at the LIM roof (ignore my stylish RTV flare at the back from laying the bead):

I've been studying how I put down the RTV. The bead seems thick enough based on the above--I'm not sure more would have helped. One thing I did notice is how low the gaskets are at the head/LIM valve cover area. They came up when I tightened down the LIM. I wonder if they scooted up and dragged the RTV away from the base? Maybe I should have fine tuned and pinched the metal tabs on the intake ports to get the gaskets exactly upright.

Sigh... looks like I am probably doing this again once the weather warms up. Any advice appreciated.

 

[lobo411]

Here are the directions for Permatex Ultra Grey. Frankly, I don't see how you can do a proper job of torquing if you follow them as written. You're supposed to assemble when wet, but only finger tighten until you get some squeeze-out. Then you let it cure for an hour, and tighten 1/4-1/2 turn.

When are you supposed to torque the bolts? After it cures for an hour? Before? Kinda sounds like a recipe for leaks.

DIRECTIONS:

1. For best results, clean and dry all surfaces with a residue-free solvent such as Permatex® Brake & Parts Cleaner.
2. Cut nozzle to desired bead size. Gaskets are best formed using a 1/16" to 1/4" (2 to 6 mm) bead.
3. Apply a continuous, even bead of silicone to one surface, surrounding all bolt holes. Assemble parts immediately while silicone is still wet. Finger tighten until material begins to squeeze out around flange. Allow to dry for one hour then retighten 1/4 to 1/2 turn.
4. Silicone will skin over in one hour and fully cure in 24 hours under normal conditions. Allow more time for cold or very dry conditions. Clean uncured silicone from hands, tools and clothing with Permatex® Fast Orange® Wipes or Fast Orange® Hand Cleaner.

 

[FijiBill]

Ya I am with you on the vagueness for the instructions.

I did the finger tight/wait for an hour/torque when I used RTV for my rear differential cover and no issues.

But with the LIM, I was most concerned about the gasket at the coolant ports getting proper torque, so I didn't want to wait an hour and risk the RTV lifting the gasket up, especially with only 12 pounds on the bolts. Plus the crush washers on the LIM gasket should keep the wet RTV from spewing out.

I didn't wait long to drop the LIM, probably 10 minutes at most. As far as torquing I took my time but I didn't wait an hour or anything. I'm sure the RTV was still wet.

Not that that is the correct way to do things, I am the one with the oil leak...

Here are the directions for Permatex Ultra Grey. Frankly, I don't see how you can do a proper job of torquing if you follow them as written. You're supposed to assemble when wet, but only finger tighten until you get some squeeze-out. Then you let it cure for an hour, and tighten 1/4-1/2 turn.

When are you supposed to torque the bolts? After it cures for an hour? Before? Kinda sounds like a recipe for leaks.

 

[lobo411]

That sounds like what I did, and it didn't work out for me either. I ended up using the old type one-piece gasket, Fel Pro MS95739. They went to a two-piece gasket for a reason (durability issues, I think), but I figure the one piece should last 100k and at the rate I drive the truck will rust before the gasket dies.

 

[FijiBill]

Ya, I strongly considered switching to the one piece, but I was able to get another set of these same two piece Victor gaskets on closeout. That and I thought I might have better luck a second time with the exact same stuff plus some hard earned experience.

The gaskets are doing the job on the coolant ports and the air intakes. I just need to figure out this oil and RTV thing:

1) I'm going to crimp the gasket tabs this time to fine tune the gasket repose before the LIM drop.
2) Wait for warm weather. I heated the garage overnight to 60s last time but you never know.
3) Use a bit more RTV--This Steve guy uses a ton:

How To Install An Intake Manifold - MustangSteve.com

I didn't want to risk RTV getting loose in the engine, so I was cautious before, but I'd like to see it squeezing out externally. I'm definitely not gluing the gasket down, as I think our aluminum LIM is designed to float some on the iron block/heads. Steve also says it is good to put a thin wet layer of RTV on the underside of the LIM ends to promote adhesion to the bead which makes a lot of sense to me.

4) Still not sure on the torque timing. Waiting the hour still doesn't sit well with me.

Maybe the LIM removal autopsy will tell me what else I am doing wrong. Also, having the borescope now should help verify the surface cleaning better and will let me check the post drop install.

 

[koda2000]

Ya, I strongly considered switching to the one piece, but I was able to get another set of these same two piece Victor gaskets on closeout. That and I thought I might have better luck a second time with the exact same stuff plus some hard earned experience.

The gaskets are doing the job on the coolant ports and the air intakes. I just need to figure out this oil and RTV thing:

1) I'm going to crimp the gasket tabs this time to fine tune the gasket repose before the LIM drop.
2) Wait for warm weather. I heated the garage overnight to 60s last time but you never know.
3) Use a bit more RTV--This Steve guy uses a ton:

How To Install An Intake Manifold - MustangSteve.com

I didn't want to risk RTV getting loose in the engine, so I was cautious before, but I'd like to see it squeezing out externally. I'm definitely not gluing the gasket down, as I think our aluminum LIM is designed to float some on the iron block/heads. Steve also says it is good to put a thin wet layer of RTV on the underside of the LIM ends to promote adhesion to the bead which makes a lot of sense to me.

4) Still not sure on the torque timing. Waiting the hour still doesn't sit well with me.

Maybe the LIM removal autopsy will tell me what else I am doing wrong. Also, having the borescope now should help verify the surface cleaning better and will let me check the post drop install.

Best to follow the directions on the RTV tube. I used Ultra Black RTV on my rear diff cover (no gasket) and I followed the directions to the letter. It gave me a perfect seal.

 

[FijiBill]

I guess the RTV could separate from the LIM/block. I thought it would be stickier than that, but as I assembled things, my RTV certainly would not be under any compression at all.

OK next time will drop/finger tighten the LIM immediately, then torque to 12 after an hour. I'll cross my fingers as I watch the coolant level .

On another topic, I'm thinking of cutting down the stud that holds the dipstick to a more reasonable length. Any downside to this? I'm tired of bending the dipstick bracket up and over it each time I mess with the EGR to remove the upper intake.

Best to follow the directions on the RTV tube. I used Ultra Black RTV on my rear diff cover (no gasket) and I followed the directions to the letter. It gave me a perfect seal.

 

[lobo411]

You shouldn't need to bend or cut anything to assemble or disassemble. I used to have trouble with the dipstick tube too, but I took my upper intake off yesterday to retorque the LIM bolts and had no problems. I've learned to put on a leather glove and then pull the dipstick tube up while moving the tube in a circular motion. As soon as I have the tube clear of the stud, I turn it so that the tube mounting bracket is out of the way. This frees the space for removing the stud, but the tube stays in the hole in the block so I don't have to get it back in again when I reassemble.

 

[FijiBill]

Unfortunately, mine is seriously stuck in there--it's never budged a bit. So I've just been bending the bracket rather than risk breaking the tube.

You shouldn't need to bend or cut anything to assemble or disassemble. I used to have trouble with the dipstick tube too, but I took my upper intake off yesterday to retorque the LIM bolts and had no problems. I've learned to put on a leather glove and then pull the dipstick tube up while moving the tube in a circular motion. As soon as I have the tube clear of the stud, I turn it so that the tube mounting bracket is out of the way. This frees the space for removing the stud, but the tube stays in the hole in the block so I don't have to get it back in again when I reassemble.

 

[FijiBill]

Autopsy! After 3000 miles of driving and about a third of a quart of oil leakage, I tore the LIM off and this is what I saw:

Front block with small oil leak to the drivers side

Rear block with large leak to the drivers side

Front LIM with some of the RTV bead attached

Rear LIM with no RTV bead

So the leak was definitely from the back of the LIM and there was even a leak from the front which I hadn't noticed.

The LIM drop seemed OK as the RTV bead was intact (some left on LIM, some left on block), but there obviously just wasn't enough RTV for the gap that the Victor gasket set creates. Remember the Victor LIM gaskets are a bit thicker than the OEM one, so the gap is bigger too.

To fix:

I took the advice of Mustang Steve and put down a huge bead of RTV that was the size of the width of the china wall.

I also applied a flat bead of RTV to the bottom of the LIM walls as Mustang Steve suggests to encourage adhesion. As quick as possible I dropped the LIM to avoid the RTV from skinning over (so that the RTV halves would join). I put in the LIM bolts finger tight. Then waited an hour as per the RTV instructions, then torqued down to spec. Using the borescope, I validated a nice squeezout at both the front and back but nothing too crazy.

I waited 10 days to make sure the RTV was fully cured, since there was so much of it.

I've been driving a week now and no leaks. The driveway is dry. I guess third time is the charm--even my dipstick tube finally released.

 

[lobo411]

Thanks for the follow-up. Sounds like exactly the same thing that happened to me, except I switched from the two piece Victor Reinz to the old one-piece Fel Pro design when I replaced the gasket.