Force 50 hp Lower Unit Leaking Oil & Water from Bolts

[N2Motors]

I have an 1990 outboard I recently purchased and unfortunately don't know the history.

I took off the lower unit and looked at the impeller and all looks fine. I also flushed the lower unit oil and added new.

I ran the engine on muffs 2 weeks ago and all looked and sounded well. When I was adjusting the trim today on the engine stand, a bunch (maybe 1 - 1.5 cups) of oil and water came running out of one of the 4 bolts that holds the lower unit to the main part of the engine (the bolt closed to the transom on the side with the vent and drain plugs)

Should I be concerned? The water and oil was not milky nor did appear mixed (but it had been some time since I briefly ran the engine on muffs). Again, it has never been in the water since I put new gear oil in and I did replace the gaskets to the vent, drain and gear pin on the lower unit.

 

[foodfisher]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Murky description. How were you adjusting the trim to cause the 1-1 1/2 cups of oil water mix to leak out of a bolt hole with the bolt still in it? I'd be concerned if I did some unexplainable something. Leave the slotted screw in the photo alone.

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Foodfisher,

Thanks for your initial thoughts. When I meant adjusted the trim (I simply trimmed the motor down and turned it on its stand. As a result, the water/oil mix leaked out of the bolt that is closest to the vent slotted screw you see in the above photo.

Could there be a seal that is blown that allowed gear oil and water to mix when running on the muffs? I'm new to outboards so thinking about pulling off the lower unit again to take a closer look.

Thanks

 

[cbercaw]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

There is a built in drain next to one of the bolts that holds the lower unit to the motor leg...look closely and you should see one pinhole. This is normal and is designed that way. No need for alarm. Chris

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

cbercaw,

Thanks for your feedback. I was just looking at a parts diagram to figure out what seals I may need.

For my own edification, how does this built in drain work? My thought is that if gear oil can get out, water can get in Did I possibly fill the gear case too full of oil? Also, my fear was if water got in here just on muffs (and oil got out), I was worried how much water would get in there once I submerged the lower unit in water...

Thanks for reassuring me this is normal!

 

[foodfisher]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

"Gear" oil=big concern. Unburned fuel/oil=normal. edit, smell the stuff to tell the diff.

 

[cbercaw]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Food fisher is right... It is possible to fill the LU too full but not if you opened the vent first, then filled the LU with oil until the fresh oil pours out the vent, then you replace the oil fill screw. The vent prevents you from overfilling and establishes the correct oil level. Unburnt fuel mix is usually kind of bubbly (normal) and when water gets in the LU oil it will appear milky (abnormal/bad seals). Can you perform a vacuum/ leak down test?

 

[cbercaw]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Hard to say without seeing EXACTLY whats coming out of your drain hole

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Guys, thanks again for all your initial feedback.

I did fill the LU with oil with the vent cap unscrewed, but it was the middle of winter and oil was very thick. I stopped filling once oil came out of the vent plug, but perhaps that caused an issue.

I'm nearly positive this was gear oil and water mix than came out of the drain hole referenced above. I'll take off the LU and try and get some photos. I'm really too new to boating to conduct a vacuum / leak down test, but hopefully I can at least get you a better look at what is going on.

Thanks

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

All, I've attached some photos of what I found when I dropped the LU form the motor leg. In two of the photos you can see the gear oil that somehow made it's way out of where it is suppose to be. In the other photo you can see where the oil leaked out (of the drain hole).

I suspect I have a broken seal. Based on the amount of oil you see, should I jump to seals or perform a seal test first? I suspect the oil is all towards one side due to the tilt of the motor vs. an indication that the oil is necessarily leaking form that general area.

Thanks

 

[jerryjerry05]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Very first thing is to pressure test the unit.
Drain it and check the color see if it has water in it?
Since you didn't use it I doubt you overfilled it and it was overfilled when cold.
There is a drain hole or 2 that was probably clogged and the gunk was oil and unburned gas and water that didn't leak out.
Sometimes the mating surfaces are real tight and won't leak?
Most motors get tilted at sometime and the gunk drains out.

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

All,

I took the LU off the motor today and just undid the drain plug. A fair amount of water gushed out prior to any oil so I definitely have a problem with seals. Before I get into which seals, is it possible I had the water pressure up too high when running on muffs and blew a seal? Not sure if that is possible (or perhaps only possible with seals that are disrepair). Also, jerryjerry05's comments about "Since you didn't use it I doubt you overfilled it and it was overfilled when cold" intrigues me. Does this imply I should be filling up my LU when it's cold or hot or I am reading in to this too much.

This leads me to my next series of questions.

As I only ran this on muffs, presumably there are only thee seals that would be the culprit in this scenario (obviously water may leak in from a different part when the LU is submerged vs. just on muffs). In looking at this diagram (see link) would the parts below be the only areas of concern on muffs?

http://www.**********/parts/search/Merc2/Force/50%20H.P.%20%281990%29/507F90D/GEAR%20HOUSING/parts.html

#43 - Seal, shift rod lower
#46 - Seal, driveshaft upper
#50 - Driveshaft Seal - Water Pump

I also see that #57 is a Gear Housing Seal Kit, but I have yet to figure out if this will include items referenced above or if that only includes other seals. Anyone have any luck with ********** parts or can recommend another place.

Many thanks!

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

Struggling with the URL / Link:

"http://www.**********/parts/search/Merc2/Force/50%20H.P.%20%281990%29/507F90D/GEAR%20HOUSING/parts.html"

The part with asterisks should simply be boats"dot"net and everything else is the same.

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

ALL,

I was able to jury rig a pressure test. Looks like the only area where I have leaking is around the shift rod seal as there were no bubbles around the propeller shaft and the drive shaft. NOTE - I also tested the fill and vent plugs, but I had purchased new seals for these so they appear to be good.

Is there a way to pull out the lower gear shift rod so I can more easily take out the seal without completely disassembling the LU? I'm also a afraid to pull it out (possibly after taking out the "Gear Shift Pivot Arm) and then having everything within the LU get out of whack or not be able to get the shift rod back in. Am I worry about tnothign here?

I've attached the photos of the bubbles for reference. Thanks much!!

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

All, a little help? Please!

I've pinpointed my leaky seal. Now, the only question is whether I have to take apart the lower unit in order to replace the seal for the shift rod. I'd like to take out the shift rod and I've read some screw in/out. I also have a little pit in the bottom of my LU and wondering if that pin connects the rod with the gears. Perhaps it is as simple as taking that off?

Again, I'm fearful of taking something out and not being able to get it back together without completely disassembling the LU.

Thank you!

 

[jerryjerry05]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts




No the seal can be pulled from the outside.
The oil can be filled at anytime,cold/hot.
The unit will heat up and expand the oil and when it cools it will suck in water.
If your gonna buy a kit cahnge all the seals.
The iboats site won't let you put in another sites info.

You will ahve to take the drive apart a bit.
The section with th eseal will need to be seperated from the bottom.
The shaft needs to be out of the seal to use the puller.
Put the drive in a vise,then a slide hammer with the single lip puller.See pic.It's the small single piece that attaches to the slide.
A couple of yanks and it should pop right out.
Make sure that you seal it and grease it.

 

[N2Motors]

Re: Force 50 hp Lower Unit Leaking Oil & Water from Bolts

jerryjerry05

Thanks for the feedback. I get your explanation on the hold/cold fill up of the LU. Thanks.

Makes sense on the website link...guess i wasn't thinking there.

I was also reading that the lower unit shift rod can be unscrewed out and then slid out with out taking apart the LU. May give that a shot too so the only seal I have to replace is the leaking one. I'll keep you posted on how this goes.

Hopefully my part will arrive in < 3 weeks!

Thanks
Brian