1990 Johnson 90 hp leaking from crankcase

[GlastronEvinrude]

Hi everyone, first time on boards, I thank you all in advance for any help with this issue. I own a 1990 90hp Johnson, model VJ90TLESB, she just got carburetors rebuilt, compression on all 4 cylinders 115psi, starts and planes fine. Carburetors needed rebuilding due to the bowls being warped and leaking fuel. I thought this was the problem with a constant drip line of fuel coming down the midsection of the motor (see pic). Even running engine out of fuel still causes this drip line of fuel. Upon further investigating, I noticed one of the crankcase bolts loose (starboard side, see pic), trying to tighten it, just spun in place. I backed it out and someone before me helicoiled the bolt in but it was now loose. I retaped hole with 1/4" 20 tap and recoiled hole, added red loctite and new 1/4"-20 bolt which was a bit longer to grab more thread. All worked fine, started engine right up and runs fine, but clearly did not fix leak. The hole that I retaped has a lock pin right below it.

1) Could this be the cause of the leak?
2) What would cause this bolt to loosen?
3) Could the gasket be compromised causing this drip?
4) Any ideas of what to do? (obviously pull power head and tear engine apart up to this gasket is already in the back of my mind)

Thanks for any help in trying to save my family from a summer of no water fun.

 

[Faztbullet]

Well someone did a poor job of repairing if they stripped bolt. Now the halves are leaking do to gelseal fitment has failed. Also if fuel mix can leak out air can leak in and can cause a lean fuel mix and damage piston.Pull powerhead and split halves and repair properly.

 

[GlastronEvinrude]

Thank you Faztbullet, before I pull engine and split halves, is there a way I can check to see if indeed the gelseal is compromised? Reason I say this is that after pulling the bypass cover of the port side, the lower bypass cover gasket was broken and I believe this may be the leaking issue. If I replace the bypass cover and put the engine back together, is there a way I can spray some soapy water in that area to see if air is escaping that seal?

 

[healey8390]

In my opinion if it is compromised you’d be getting smoke out of the case halves seam and it wouldn’t run right. Also, there are six large bolts that hold the halves over the crank and they do most of the work. I’m not saying the outer bolts aren’t important but I don’t think one loose bolt, especially where yours is by a taper pin getting a little extra support, will cause a crankcase leak.

 

[havoc_squad]

In my opinion if it is compromised you’d be getting smoke out of the case halves seam and it wouldn’t run right. Also, there are six large bolts that hold the halves over the crank and they do most of the work. I’m not saying the outer bolts aren’t important but I don’t think one loose bolt, especially where yours is by a taper pin getting a little extra support, will cause a crankcase leak.

Where does that smoke come from? Do you mean fuel/air mix leaking out?

It's an intake chamber, not exhaust.

The only two locations where significant exhaust is present is the cylinder in the exhaust down stroke and the exhaust housing of the block.

I have that exact type of block sitting in my house for assembly waiting on an extra part that was missing. There's no way that crankcase chamber with it properly sealed at the piston rings is going to spew out significant exhaust fumes back inside the crankcase chamber and out that crankcase seal.

As a suggestion, you could do a crankcase leak test using propane gas around the suspect area to see if the engine sound changes any to detect any crankcase seal leaks.

Bear in mind this is potentially very dangerous, so one would need to be very careful and take necessary fire safety precautions to avoid being hurt.

Example at 7:40 of the video:

https://www.youtube.com/watch?v=f3O_dqvCDIU&t=460s

 

[racerone]

I think this issue was resolved by the OP but never closed out on this website !!

 

[GlastronEvinrude]

Hi Everyone, I am back, no, not closed yet. I pulled the PH. There was still fuel spewing somewhere from under the engine even with the carbs disconnected. I am trying to split the crank case. Can I split the crankcase without removing flywheel and reed housing. It seems there are four 3/8" bolts and two taper pins on each side. Can I just remove these to split the crankcase?

 

[racerone]

??---There are no short cuts !!----You have to remove the flywheel.----And you have to remove the reed valve housing.---Taper pins only come out one way , driven towards were the carburetors are.------Do not use a hammer to split this block !

 

[GlastronEvinrude]

Sorry for the delay in writing you, for some reason I am not getting notices of your comments.
I've been busy, Pulled the powerhead, stripped it down.
Ok, so now what? I split the halves, that area where I thought was the leak, also area of the loose bolt, and also the area of a broken mount is a little warped, See pics.
Will Loctite 518 seal a warpage of .013"?
or
Should I buy a crankcase halve on ebay or somewhere?
Can I sand this down?
Thanks again for all your comments.

 

[flyingscott]

You cannot just replace a half. They are machined as a set. How well do you trust that ruler it.looks pretty rough. I would fix the stripped bolt gel seal it and put it back together and see what happens. I don't think you can machine those halves either, maybe you can. Racer or bullet will know.

 

[ct1762@gmail.com]

they are technically speaking, machined as a whole unit, yes. However you can use another good crankcase half from another motor if it's arrow-strait and test fitted and found to have no warpage. I've done it a few times with no issues, but if you want to do it by the book then yes, get a new block!

 

[Faztbullet]

You can use a different front halve just leave out the taper pins on reassembly

 

[GlastronEvinrude]

Faztbullet, why leave out the taper pins?
Found a front half on ebay, being shipped to me early next week. I was not happy with the mount being cracked and knowing this was my possible leak.