2003 Johnson 90hp 4 stroke leaking oil

[Jennermike]

Hello I need help ASAP! My 2003 Johnson 90hp 4 stroke is leaking a lot of motor oil into the water through the prop I’ve replaced the base gasket and it is still leaking any ideas of what else it could be would be great! The model number is J90PL4ST

 

[boobie]

Could it be lower unit oil??

 

[Jennermike]

No it is definitely motor oil

 

[jakedaawg]

Is the oil over full? A bad fuel pump will make them leak but it would be hard to get it to come out the prop.

 

[Jennermike]

Oil level goes down well running will loose a half a quart out the prop in a hour and a half of running non stop I don’t smell any fuel in the oil

 

[jakedaawg]

Get a manual and check valve adjustment.

 

[Jennermike]

okay would it have bad compression if the valves where out of adjustment? and if they where out of adjustment that would cause engine oil to get down there?

 

[jakedaawg]

I think a lot of things would have to be wrong to get unburned oil out the prop...one path is through the exhaust.

 

[jakedaawg]

I thought you already did compression...sorry too many threads.

Yes, perform compression test with throttle open while testing. Preform leak down test as well. Listen for where the air is leaking out, exhaust, intake, crankcase etc.

 

[jakedaawg]

My guess would have to be a cracked oil pan or block somehow allowing oil out into cooling water but not water in to oil as you did not state milky oil...

 

[jakedaawg]

I wonder if the spacer-exgaust adapter-casting could be cracked or bad gasket. Just dont know.

 

[Jennermike]

Yes I checked compression on it yesterday all cylinders have 210 psi seemed high to me but might be Normal I’m using my works leak down tester tonight and there is not water in the oil that’s why I found it hard to believe that the block is cracked I also noticed that when I remove the dipstick well it’s running I am getting quite a bit of air that is coming out of it is this normal? I always throught that it should have vaccume there not air coming out

 

[jakedaawg]

Crankcase are pressurized to some extent, probably Normal, Depends how much pressure your talking about.

 

[jakedaawg]

Does it leak if it's just parked and trimmed down in the driveway?

 

[Jennermike]

yeah i noticed some dripping out of the prop when i had it shut off but it could of just been excess oil from when it was running

 

[jakedaawg]

My thinking is thus:

1. If it's not leaking while sitting you must be looking for a place where pressurized oil is getting into the cooling water.

2. If it always leaks you can look for a bad casting/crack where oil could get into exhaust or unpressurized cooling water.

I have a feeling your going to have to disassemble quite a bit and check for cracks or take the oil pan and exhaust adaptor to a machine shop and have it checked.