How do I fix a leak at the case seam?

[Rick Lee]

I fixed all the leaks I could when I had my engine out in June. And the fixes worked well. There was a lot of caked stuff underneath. Sunday, I started spraying brake cleaner and using a wire brush on my case underside. Would you believe, that within seconds, I saw the leak at the seam return? I torqued those case bolts to spec back in Feb, as they were loose. But that obviously did not fix the problem. I doubt I'll ever get the case totally dry on the inside, so smearing some sealant there on the outside probably would not hold. What do I do about this? Thanks.

[john walker's workshop]

not much you can do about it. options are a complete teardown, or the smear tactic. you might try sikaflex 292. it's a marine sealant that's both tough and flexible. most engines leak there after awhile.

[88911coupe]

Just read this and am looking to find solutions on what MIGHT be a case seam leak on my '88 near the RMS. I looked up Sikalex 292 and it appears to be an adhesive but I see Sikaflex 291 listed as a sealant. Since this thread's over 20 years old maybe the products changed? Would 291 be ok to try? TIA

[Dpmulvan]

Check out the devcon titanium 10770 or plastic steel 10210. It’s a long shot you’re going to stop a case seam oil leak but what do you have to lose other than a couple hundred bucks.

[MrBonus]

Amazon boxes, smooshed flat, and rotated every 3-4 months.

[rokemester]

Priceless

[mike sampsel]

Originally Posted by MrBonus

Amazon boxes, smooshed flat, and rotated every 3-4 months.

Right it's a great solution, unfortunately, it does not fix the smell of the oil on the crossover exhaust though.

[mike sampsel]

Henery Schmidt mentioned a "wicking" loctite is made. He said it might work but he had not tried it. I cannot find the thread where it's mentioned.

Loctite 290 a thread locker wicker?

Not used by me

[MrBonus]

Originally Posted by mike sampsel

Right it's a great solution, unfortunately, it does not fix the smell of the oil on the crossover exhaust though.

The scent of character.

[proporsche]

Originally Posted by 88911coupe

Just read this and am looking to find solutions on what MIGHT be a case seam leak on my '88 near the RMS. I looked up Sikalex 292 and it appears to be an adhesive but I see Sikaflex 291 listed as a sealant. Since this thread's over 20 years old maybe the products changed? Would 291 be ok to try? TIA

can we see the leak ?
Ivan

[88911coupe]

Yes. I will add a pic as soon as I can get to other computer.

[PeteKz]

Originally Posted by MrBonus

Amazon boxes, smooshed flat, and rotated every 3-4 months.

DOesn't everyone do this???

More seriously, I was getting a weep near the drain plate, and at the last oil change I carefully swabbed out the inside of the case seam as far as I could get one finger into it with carb cleaner, then brake cleaner. Then I put some black RTV along the seam and let it dry for a day. So far, it's working.

[88911coupe]

Here is a pic, note that the inside of the transmission was totally covered with oil.

[proporsche]

Originally Posted by 88911coupe

Here is a pic, note that the inside of the transmission was totally covered with oil.

are you saying that this flywheel seal is leaking?There is not a spot of oil on the exhaust cross pipe?
Are you sure it is an engine oil not transmission from the mainshaft seal ..plus there is a o ring on the guide tube which could be leaking

Ivan

[88911coupe]

There is oil at the bottom of the area behind the flywheel and on the case seam below the seal or at least that's what it looks like to mel. It does not smell like transmission oil but I had never thought of the tranny leaking...May have to take a look at that. I will say I HAVE noticed transmission oil at the FRONT of the case but I was thinking that was a leak in the shift rod seal which I plan to replace.

[David Inc.]

Sure it's not coming from above? The seam above looks wet and there's oil pooled on top of the seal.

[88911coupe]

Yes I agree and noticed the same thing. I plan to find some sort of sealant to at least try in addition to a new seal. I measured it and it’s 1.3mm proud of the case…maybe that is too far? Saw another thread going back and forth on which seal sucks and which doesn’t with a lot of conflicting opinions.

[David Inc.]

Pretty sure it's supposed to be flush but there's a lot of good information here on the forum about which seal to use and how to install it.

[proporsche]

Originally Posted by 88911coupe

Here is a pic, note that the inside of the transmission was totally covered with oil.

since you have the engine out look inside the tube with a flash light and bell housing of the trans..picture if possible to see

Ivan

[88911coupe]

I looked into the tube and can't see any indication of anything leaking. Maybe I should remove the guide tube?