Crank case leaking on 1990 evinrude 88 spl

[Zack19919853]

So I have a leak on my 88 spl on the crank case. I will have to disassemble and reseal it. Would it be beneficial to hone and put new rings on the pistons or no? If doing so would I need new pistons? Just a curious thought

 

[racerone]

Stop !!-----There are no pistons in the gearcase.-----So step #1 here is to post the actual compression values here.----Pressure test the gearcase to see if it is leaking.----Any water in the gear oil ?-----Gearcase is completely separate from the engine and piston rings have nothing to do with the oil you see leaking.

 

[Zack19919853]

Stop !!-----There are no pistons in the gearcase.-----So step #1 here is to post the actual compression values here.----Pressure test the gearcase to see if it is leaking.----Any water in the gear oil ?-----Gearcase is completely separate from the engine and piston rings have nothing to do with the oil you see leaking.

Sorry, I totally meant crank case. The two halves. It’s leaking and it needs to be resealed.

 

[havoc_squad]

Sorry, I totally meant crank case. The two halves. It’s leaking and it needs to be resealed.

Do a leak down test on each cylinder first.

Then pull exhaust and intake along with engine heads for inspection. This will be a major headache if a salt water outboard, easy if fresh water.

If no visible damage found from pulling heads, then check for sticking or broken rings through intake and exhaust ports.

If piston, rings, and cylinder are in good condition with no more than 15% leakage test, I see no reason to pull pistons. Service water diverters and head covers with new exhaust gaskets and new head gaskets.

Resurface heads before installing with mirror glass using 600 grit sandpaper and an accurate straight edge using feeler gauge to verify they are within tolerance for flatness per factory service manual specs.

 

[Zack19919853]

Do a leak down test on each cylinder first.

Then pull exhaust and intake along with engine heads for inspection. This will be a major headache if a salt water outboard, easy if fresh water.

If no visible damage found from pulling heads, then check for sticking or broken rings through intake and exhaust ports.

If piston, rings, and cylinder are in good condition with no more than 15% leakage test, I see no reason to pull pistons. Service water diverters and head covers with new exhaust gaskets and new head gaskets.

Resurface heads before installing with mirror glass using 600 grit sandpaper and an accurate straight edge using feeler gauge to verify they are within tolerance for flatness per factory service manual specs.

Thank you, that is exactly what I wanted to know!! A leak down test consists of pressuring the cylinders with air correct? How much psi is too much or not enough?

 

[racerone]

Rare for the crankcases to leak.-----Unless the motor was molested by a wannabe mechanic.-----But maybe the bypass cover gaskets are leaking.----That would be an easy fix.----Post the actual compression test values here.----That will give the information you need.-----And it is a mistake to put new piston rings on old pistons on these motors !!

 

[havoc_squad]

Thank you, that is exactly what I wanted to know!! A leak down test consists of pressuring the cylinders with air correct? How much psi is too much or not enough?

Compression test numbers in this situation might be sufficient enough as Racer says.

I've ran into situation personally however where compression numbers were even on all cylinders but one cylinder failed leak down test which found one damaged cylinder wall which I was glad to find before spending any money on this latest acquisition.

Usually cylinder inspection with head off and checking through intake and exhaust ports piston and rings condition will reveal what a failed leak down test would indicate.

I just find leak down tests a far better use of time in checking health of cylinders.

This is what I am referring to as a leak down test: "

"

They do this on a four stroke but same principles apply on two stroke. If you get significant leakage into the intake portion or exhaust, its likely the piston & rings, or cylinder issue. If you can hear the air in the cooling system, it's likely a head gasket leak or an issue with the head.

 

[saltchuckmatt]

If you end up needing to open up everything then the only answer is to do a complete rebuild. Why would you not when your already there.

Now if your time is worth nothing and you don't mind having a dead motor on the lake/river/ocean then.......

Otherwise I'd do what race says first, post those numbers and wait for his response. Leakdown is more involved and you can do that after.

Hopefully this helps.