1999 40hp elpto - Mystery Oil line behind oil pump?? - Can it be capped/removed?

Joined
Jun 26, 2017
Messages
24
I have a 1999 40hp elpto. I have been having oil slowly draining into my intake manifold when stored. It then drips out through the carbs if stored tilted or remains in the intake and eventually out of the center section of the motor and out one of the water holes above the lower unit if stored down.
I have come to the conclusion, that it is a result of a small oil line that comes from a fitting directly behind the oil pump (on the block), and into a T at the enricher hose that feeds the intake when primed. It is post enricher, so I am not sure of the purpose, since the mixture coming from the enricher is already mixed. I have not seen this set-up on other motors, so I was wondering if it could be capped at the block. The service manual shows the line, but there is no explanation. The local mercury "experts" are not aware of the purpose either.

One course of action would be to find out why the line continually pumps oil, as this was obviously not mercury's intention. I have removed & confirmed proper installation of the oil pump and seals. At the time one of the orings was a little messed up, but serviceable.

The other course of action would be to eliminate this oil circuit. I cant determine a purpose really. Unless to make sure there is oil in the prime shot of fuel, or as a oil pressure relief whereas the additional oil/pressure is just burnt off in the combustion cycle.
Obviously it was not the best ideas since I have yet to see this set-up on other motors. So the Mercury engineers scrapped it. So do anybody have experience with this or know if I can remove the line and just cap off the fitting at the block? My only concern is that if it is a pressure relief, is it necessary?
 
Joined
Jun 26, 2017
Messages
24
No Title

This is a pic of the hose that is behind the oil pump.
 

Attachments

  • photo274614.jpg
    photo274614.jpg
    199.2 KB · Views: 0

wn6ngp

Petty Officer 1st Class
Joined
Aug 12, 2012
Messages
209
Is that a photo of the port side of the motor? The square thing in the middle is fuel pump right? I've got a 90 ELPTO and I somehow didn't see that line.

Maybe yours is more different than I would expect. I'd be reluctant to simply cap off that line. It must have a good purpose. That wouldn't be the vaccum line that runs the fuel pump would it?
 
Joined
Jun 26, 2017
Messages
24
No Title

It is the starboard side of the motor. yes the square thing is the fuel pump. I have not seen this hose on any other motors in that series. Which is why I wonder if it can be blocked. The oil pump is in the bottom of the image. The oil fitting in question is directly behind the oil pump on the block. I had the oil pump off recently to try and figure out where the oil was coming from. The fitting on the block taps directly into the round opening that the bearing and bushing for the oil pump shaft is located. When I removed this hose it has pure un-mixed oil in it.
It runs from the block directly from behind the oil pump to a T in the en richer circuit. I added some pics, including one from the service manual.
 

Attachments

  • photo275082.jpg
    photo275082.jpg
    235.3 KB · Views: 0
  • photo275083.jpg
    photo275083.jpg
    366.6 KB · Views: 0
  • photo275084.jpg
    photo275084.jpg
    316.6 KB · Views: 0
Joined
Jun 26, 2017
Messages
24
No Title

OK, It has been solved. I will share what happened, since I know I have seen this issue go unresolved in many posts.

The hose/line in question is only used on some motors. There is no specific reason why some do or do not have it, but it is a drain line from the enricher circuit. It releases fuel from the circuit - probably more for storage.

In any case, the final problem ended up being the oil pump was leaking from the drive shaft of the pump. So as it was stored, it would leak pure oil back into the case. When tilted it would leak out the carbs and upright it would fill the case until it ran out the tailshaft above the lower unit.

How I determined this finally is that I removed the pump, cleaned it with brake fluid so it would be clean & dry. Then I pressurized the oil tank and shortly after the shaft became wet with oil and then to a drip.

The pics also show the hose in question a little bit better for those who would swear there inst a hose there. Hope this helps someone.
 

Attachments

  • photo275245.jpg
    photo275245.jpg
    131.1 KB · Views: 0
  • photo275246.jpg
    photo275246.jpg
    130.2 KB · Views: 0
  • photo275247.jpg
    photo275247.jpg
    126.8 KB · Views: 0
  • photo275248.jpg
    photo275248.jpg
    193.9 KB · Views: 0
Top