Oil coming from exhaust, Mariner 40

[djay22]

Hi. I dropped the lower unit on my Mariner 40hp ML engine, serial number 6E9 L 359629 to change the water pump impeller.
Whilst waiting for the parts to turn up I changed the gear housing oil. The lower unit has been sitting for a couple of days upright, separated from the rest of the engine and I have noticed the clean gear oil is leaking around the prop.
I removed the prop and the prop shaft seals are dry, the oil is coming out through the exhaust not the seal carrier.
Any suggestions where the oil is leaking from?
The only thing I can think of is the gear shifter linkage seals, but according to the diagrams there is no seal only a sleeve.
Darryl

 

[djay22]

Re: Oil coming from exhaust, Mariner 40

Just checked the gear linkage rubber boot and sleeve and this is above the oil level so cannt be this.
Does the seal carrier body have a seal?

Darryl

 

[Texasmark]

Re: Oil coming from exhaust, Mariner 40

Should be like most engines:

Under the water pump housing is the upper drive shaft seal, actually 2 seals back to back.

The prop shaft, immediately preceding the prop thrust washer also has 2 back to back.

The shift shaft has one also.

The vent and drain screws have seals.

Mark

 

[djay22]

Re: Oil coming from exhaust, Mariner 40

Thanks for the reply Mark.
The lower unit is removed with the water pump housing not fitted at the moment.
It is leaking oil, not, allowing water in to mix with the oil.

Drive shaft seals under water pump housing are above the oil level, so not this.
Prop shaft seals as mentioned in the first post are good as it is not leaking from them.
Shift shaft has a rubber boot that stops the water going into the oil, this is above the oil level and in good condition.
Vent and drain screws have new seals and are not leaking.

The oil is leaking out off the exhaust, and I suspect there is an O ring or seal around the seal carrier that may be leaking.
Darryl