Leaking case halves/Crankcase

[healey8390]

86' 110. Motor has been back together since May after doing a hone job and rings. It recently started sneezing and doing a stumble/pause when it sneezes. I found smoke coming out from what I thought was the top bypass cover on the starboard side. Unfortunately it is the case halve. I confirmed by swapping the bypass covers. There isn't a visible gap in between the crankcase but when it's dark I can see combustion. Kind of fascinating to be honest, though I'm disappointed and irritated. I took a screenshot of the combustion from my video.

When I applied the gel seal I used a lot, I thought I actually used too much. I got great bleed out though. However if you look at the pic, the top left side looks a little skinny exactly where the leak is. But with all the bleed out I'm still a little dumbfounded. I assembled using a torque wrench and I don't recall but if there was a sequence I would have followed that too.

I think my mistakes were not using primer and I "dabbed" the gel seal with the tip of the tube to build it up. Looking at the pics it kind of looks like there are low spots instead of a continuous "smooth" bead.

I know there are some threads floating around on this but I wanted to share my story and frustration. Please let me know if the "dabbing" is what caused this or whatever I may be missing. Thanks as always!!

 

[flyingscott]

Sounds like it was not torqued correctly. If you used loc tite 518 it needs 24 hrs to set up without primer.

 

[racerone]

Never had a problem and I use about half of what is shown in these pictures.

 

[healey8390]

Sounds like it was not torqued correctly. If you used loc tite 518 it needs 24 hrs to set up without primer.

Anything is possible. I will use primer this time, do I spray both halves or just the side that I put the gel seal on ?

 

[racerone]

If you can see " combustion " at the joint you have some problems that need to be looked at.

 

[F_R]

That lean sneezing you reported is when the fuel/air mixture explodes in the crankcase. I must say I'm impressed that you managed to be there at the right instant to get a picture of the "combustion/explosion/fire which goes out about as soon as it happens..

 

[racerone]

He states it was " picked " off a video.----I am not sure how you could get a gap that big on a V-4 crankcase.-----Unless it was molested when taken apart.----Since the high and low speed mixtures are fixed you need to fix / address the combustion in the crankcase I say.

 

[ahicks]

First, I apply case sealant more like a paint than a bead. A very thin, pretty much transparent coat of paint

Second, if the case half bolts were installed and torqued properly, and you have a gap like that on a seam, I'm not sure I would bother taking it apart. Time spent looking for another short block might leave you further ahead. The one you have now is very likely warped beyond repair.

 

[racerone]

I always use about a 1/8th bead of sealer.----Factory gel seal or loctite 518.----Never a problem.

 

[healey8390]

First, I apply case sealant more like a paint than a bead. A very thin, pretty much transparent coat of paint

Second, if the case half bolts were installed and torqued properly, and you have a gap like that on a seam, I'm not sure I would bother taking it apart. Time spent looking for another short block might leave you further ahead. The one you have now is very likely warped beyond repair.

Definitely a concern I have. If it warped I'm wondering how?? been using the boat practically every weekend for 4-5 months. It hasn't overheated or anything. At least a handful of trips have been 30ish miles with long runs up to 15 miles.

 

[racerone]

These engines and the crankcase joint are precision stuff !!----It is in fact a metal to metal joint.----Has to be , to properly clamp up the bearings.----The sealer has to be " low filler content " and most if not all should squeeze out.-----I dare say on a new assembly you do not need sealer.----There is no way that any air of concern could leak across the joint.-----The sealer ( less than 0.001" ) is only there in case of any minor imperfections !----I have measured a film of sealer 0.008 " on some parts motors which is sad workmanship.

 

[healey8390]

These engines and the crankcase joint are precision stuff !!----It is in fact a metal to metal joint.----Has to be , to properly clamp up the bearings.----The sealer has to be " low filler content " and most if not all should squeeze out.-----I dare say on a new assembly you do not need sealer.----There is no way that any air of concern could leak across the joint.-----The sealer ( less than 0.001" ) is only there in case of any minor imperfections !----I have measured a film of sealer 0.008 " on some parts motors which is sad workmanship.

Absolutely precision. Which is why I'm wondering why this leak showed up later rather than sooner. I don't see a gap with the naked eye so hopefully it's not warped. I have other financial priorities right now so it's worth trying it again in my book.

 

[tblshur]

i would check the center sealing ring when u put the crankshaft in it has a small dowl pin in the case that mates up with a hole in the ring on the crankshaft sorry i dont know the correct terminology for those parts

 

[racerone]

That would be the center MAIN bearing.----It is not a sealing ring.

 

[healey8390]

i would check the center sealing ring when u put the crankshaft in it has a small dowl pin in the case that mates up with a hole in the ring on the crankshaft sorry i dont know the correct terminology for those parts

I appreciate it trust me!!

 

[healey8390]

Got it apart, there's hardly any gasket material there. I'm surprised it lasted that long and that it's only leaking in one area. I'm hoping it was because I didn't use primer. I thought that it was to clean the metal which I did so I didn't use it.

From what I've read now, the primer helps the sealer stick to inactive metals like aluminum and other types of metals that don't rust. Has anyone reassembled with primer and had no issues? If this wasn't the problem I don't know what else to think?

 

[racerone]

As stated the sealer is supposed to squeeze out !!-----I assemble these with no primer.----Meticulous preparation.----Cleaning with laquer thinner.----Never use primer.----No problems either.

 

[healey8390]

As stated the sealer is supposed to squeeze out !!-----I assemble these with no primer.----Meticulous preparation.----Cleaning with laquer thinner.----Never use primer.----No problems either.

I had PLENTY of squeeze out. Maybe I didn't clean it good enough.

 

[tblshur]

you could bolt the 2 halves [with no crank shaft] and check the area with a feeler gage good luck