Oil injected overflow tube for 1999 mercury?

barrett60

Cadet
Joined
Mar 27, 2008
Messages
7
I have a 1999 mercury 115hp ELPTO that's oil injected. The last time I filled the oil I noticed some leaking out from the motor floor and traced it to a rubber tube that was sitting just above a pool of oil in the bottom of the cowl. My first thought was that this was the injection tube, but I did not see a place nearby that it may have come off from. Do these motors have some sort of overflow tube that drains extra oil into the area described? Seems like if so it's not a very practical area. The tube originates from the top of the oil container and if I add more to the container it will again drain from this tube until a certain level is reached. I just don't want to run the motor and risk burning it up if it's the injection tube that's off. Any advice would be greatly appreciated.
 

gss036

Commander
Joined
Jan 18, 2003
Messages
2,914
Re: Oil injected overflow tube for 1999 mercury?

That tube should be coming from a 2 psi check valve. It is designed to allow air to suck into it, but not out. Check the main tank on the boat to see if it is still holding pressure after the motor has been shut down for 10 minutes or so. If it is still hold pressure, the check valve on the lower side of the block is defective. If not then go back to the on the motor oil tank. I have never had any luck cleaning one and getting it to work. They are only about $13 or so and takes about 15 minutes to change.
 

barrett60

Cadet
Joined
Mar 27, 2008
Messages
7
Re: Oil injected overflow tube for 1999 mercury?

Thanks for the help. How would I check the pressure? Is it just a matter of whether or not oil drips after it's shut off for a while or do I have to get another tool? Does this affect the injection to the motor? I appreciate any advice.
 

gss036

Commander
Joined
Jan 18, 2003
Messages
2,914
Re: Oil injected overflow tube for 1999 mercury?

Look at the tank to see if is bulging, then remove the fill cap, there should not be a "poof" of air escaping. You could also loosen the cap on the motor tank (when the engine has sat in the off position a few minutes), if oil continues to flow, one could assume there is pressure in the boat tank since that is how the system is designed to work. This is not rocket science, just common sense.
 
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