OIl Leaking from front of carbs on 40hp elpto (99).

[dacostadesigns]

I have been trying to track down an oil leak. I have had mystery oil leak that after sitting for a week or so after running clean new oil was coming out of the top weep hole of the lower unit (This I found is an exhaust tube drain). Also was loosing quite a bit of new oil and a heavy smoke at start-up. SO what I found was oil was leaking out into the lower cowl and working its way down the exhaust tube to leak. It would then burn off when started. It was not actually combustion burnt oil. Perhaps some was leaking back into the intake through the carbs. So after a good cleaning, I removed the oil tank for another repair, and the next day there was still oil - coming from the carbs and into the breather box, then into the lower cowl. SO now I have no clue why there is clean new oil coming from the front of the carbs. I recently changed the check valve of the oil going into the fuel pump. It also has an "enhancer" which I am not sure of its function exactly. Any help or suggestions would be appreciated.

 

[ondarvr]

My guess is it's not oil, it's fuel, but as the gas evaporates it leaves the oil behind. Oil can leak from the carbs when the motor is tilted, but may also leak if the float and/or needle isn't working correctly, (dirty, not adjusted correctly, float sinking).

​Smoking on start up is normal for a couple of reasons.

It's running richer when you push the key in to start it, it also won't atomize the fuel as well when cold, so less of it burned.

​Also the fuel left in the carb after the last time it was used will start to evaporate over time, but will leave the oil behind, so on start up there will more oil than normal in the float bowl.

 

[dacostadesigns]

Well, I would agree, however my oil level in my reservoir is depleted. So it would seem the injection system is pressurized. When I use the boat for multiple days consecutively I don't get the oil loss.

I have tried running fuel out of carbs when storing and also tried leaving fuel in carbs - as I have read both could effect this. Still no change.

I have tried storing the motor both tilted and not tilted and the results are the same.

The carbs are not "Full" of oil, at least not that I know of. It starts and idles very easily. I had the carbs off a couple of months ago and they were very clean. I had some accumulation in the jets and was having full throttle power issues. I cleaned them out and it runs perfect. I dont know about the bowl level, as I didnt check it. I would imagine it would run poorly if they were off too much.

The symptoms seemed to happen at once, not a gradual increase of oil loss or smoke. I use the boat a few times a month, so it is weird.

It starts easily, which makes me think the carbs and combustion chamber is not flooded. Again once it is started for a minute or two it goes back to expected 2 stroke smoke (minor). It also stops loosing the oil.

 

[ondarvr]

If your Merc is the same as mine, the oil is injected into the fuel line right after the fuel pump, so the only way to have oil dripping out of the carb is to totally remove all the fuel from the line and all the way through the carbs. If this happens you wouldn't be able to start it easily because the float bowls would full of oil.

​If the float needle isn't sealing well fuel can drip out over time, but it may still start and run well.

 

[dacostadesigns]

Back with the same issue. So I have sorta corrected the problem of oil leaking from the carbs and it was from storing the motor in the tilted up position. And yes it was clean - non fuel mixed oil, not evaporated mixture. So what has not been fixed is the oil leak issue. So now after storing upright, the oil continues to leak and it seems right into the intake manifold. What was happening before was the oil would leak into the manifold and then out the carbs from being tilted. SO My guess is that there is a small oil line that comes from a small nipple on the block right behind the oil pump and into a t-fitting on the "enricher" hose that feeds the manifold. This hose is very thin - perhaps 1/8 ID This is original hose routing. It is shown in the service manual, but not explained. It looks like it was intended to add a little bit more oil to the enrichment shot of fuel. It doesnt really make sense, because the fuel that enters the manifold is already mixed.

So it would allow oil to flow directly into the manifold if the oil tank was pressurized (perhaps by Florida heat). I have not seen this small oil line on any other motors in this family. I was wondering of anybody had experience with this and could it possibly be capped off a the block and the t fitting removed. I just lost a quart of new oil, after sitting for only about 10 days.

 

[dacostadesigns]

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.

The final pic is just some of the oil that poured out of the block.

 

[wn6ngp]

Thanks for following up with your final solution. Your motor design is totally different from my 90 hp ELPTO. you just cannot make any assumptions about these motors.

 

[swing]

DA - masterful! Ive been looking all over the web for this answer for 2 weeks, talking to people, etc. Most said "bad check valve" - but that made no sense. My issue was that over the hot Florida summer, it was tilted & oil reservoir (mostly) full. When i got back to FL in Nov, I had a oil puddle on the floor, and an empty oil tank!%. I cleaned it up, shrugged & added more oil. A few weeks later went to start it - white smoke everywhere - and much higher compression reading on bottom cylinder! ...and oil came out the bottom carb drain screw....and out the pump-port you show. So, Bingo. Seems it thinned out and "capillaried" past the driveshaft on the Mikumi pump....and right into the block. Blasted everything clean with WD40, and ordered new O-rings for the pump shaft, etc. I will also try to connect it "loose" to the tank & pressurize, and see if it starts to leak as well - No more tilting over the summer, and maybe even disconnect or empty the oil reservoir (and leave a big note on the motor/steering wheel reminder to re-connect!%) My wife would LOVE to keep the oil injection working....rather than f around pre-mixing. Thanks for your >throrughness to come back to post the solution!! - Jon in Sarasota