1987 88SPL oil residue

[Rodney Quam]

My 88SPL has oily residue all over the lower unit after running on the water for the day. The residue starts oozing out from somewhere under or around the powerhead and down. It is much worse if I troll for hours with it. The only time it isn't too bad is if I only run it at WOT for the day (to get to the hotspot and back-and use my electric motor for fishing) Plugs look OK. I have never adjusted the carbs because the engine runs great...will idle all day long and plenty of power and holeshot performance. I mix at 50:1. Can the crank seal go bad to cause this? If it is unburned oil from the combustion process, isn't that oil supposed to go out the exhaust and thru the prop? No residue there. Where can all this oil possibly come from?

 

[HybridMX6]

Re: 1987 88SPL oil residue

Sounds like an exhaust plate gasket that's bad. I have a 2000 55hp that does the same thing. It's worse when you idle a lot because you don't burn all the oil in the combustion process, so what's left becomes sludge and oozes out like that. I just did my water pump and tilted the LU against a workbench when I was done. When I came back out there was a LARGE puddle of this crap that had oozed out of the exhaust, I'm guessing it was in there from me having it tilted on the boat until I got it all removed. I store it/trailer it that way also.

 

[Rodney Quam]

Re: 1987 88SPL oil residue

Exhaust plate gasket? I have the Evinrude manual for the motor. Where is this gasket/seal you speak of? Last year I replaced the head gaskets and what I think you may be referring to as the exhaust plate gasket on the powerhead. If this is what you refer to, maybe my gasket replacement didn't take? I trailer with the motor up but store down. Down is when all the stuff oozes out. Thinking about it, if that much oil is supposed to be going out the exhaust, I understand regulation to go 4-stroke or build cleaner 2-strokes.

 

[tashasdaddy]

Re: 1987 88SPL oil residue

before tearing into anything, does this happen after you tilt the motor all the way up. if so the carbs are running over, because they are out of level. thus spilling into the lower pan, then leaking out. leaving the fuel line connected when tilting causes this.

 

[HybridMX6]

Re: 1987 88SPL oil residue

Well, the gasket I was referring to is between the powerhead and the lower cowl/midsection.
I don't tilt my motor all the way up, as it's a manual tilt, so it's only maybe half way up that it's trailered in. I don't see any fuel below my carbs (not sure if the OP does or not), and mine comes out the lower cowling, and runs down the midsection. Doesn't look like 2 cycle oil anymore either, it looks black, like burnt. I'm assuming his is the same stuff as mine.

 

[bagnallt]

Re: 1987 88SPL oil residue

I am with Tashassdaddy...
I had a 2006 Mercury 150hp and it did the same thing when tilted up. It was brand new at the time I took it back to the place i got it from and they explained what it was. Showed me what was happening and suggested that I turn off the gas before tilting the motor. ( it had a fuel cut off in the fuel lines). I did this and it reduced it to a small amount. Apparently suction continues from the fuel tank for a while due pressure from the fuel pump. I was told to wipe the motor housing when i got home from any trip. I did this and no problems again...
BTW the fuel bowls on the motors dont look like they hold a lot of gas but it only needs a little. Also the gas is very good at cleaning as it goes and loosening any dirt hence the sludge. ALso it looses grease from the pivots for the motor brackets... and so you get yucck sludge. Also when trailering its amazing how much dirt sticks to the motor. making this look worse...

 

[Rodney Quam]

Re: 1987 88SPL oil residue

I always disconnect the fuel lines when not in use and store with the motor down. I clean the gunk off before and after every trip. (some runs down over time in storage especially if its hot out) It oozes out bad when in operation on the water. It doesn't appear that the carbs leak. I'll take another look. Chief, (how ya doing brother) to replace the gasket you speak of, would I have to pull the powerhead?

 

[tashasdaddy]

Re: 1987 88SPL oil residue

HybridMX6, your thoughts are very good, but let's look at the simple, and common, first.

bagnallt. also with the fuel line connected and heat expansion, floats not sealed, the fuel keeps flowing.

 

[emdsapmgr]

Re: 1987 88SPL oil residue

Likely the powerhead base gasket has failed. 321727. It's a common failure on these crossflow engines. While not a critical failure, it is messy and there is usually a lot of exhaust smoke under the cowling which gets sucked back into the airbox as fresh air and can cause running issues. You need to replace it.

 

[Rodney Quam]

Re: 1987 88SPL oil residue

Thanks for your help...all. Closer inspection looks like the LCDR is right. The powerhead to exhaust gasket/seal is bad. I'll have to pull the powerhead and replace it. Have a Great Navy Day!!!