# 1993 2-stroke Yamaha - gear oil through weep holes?



## ccolton (Jun 22, 2012)

Dear All,

It's been a long time since I worked on 2-strokes and it's showing!

This 1993 Yamaha 9.9 is new to me. When I examined the lower unit, I noticed that the housing just before the propeller was cracked. I replaced it, the bearings and all seals.

I then replaced the lower unit gear oil - when I did, not only did the oil come out of the top screw, but also out of two small holes, one on either side, just ahead of the top fill screw. So, after several attempts, I was able to get both top and bottom fill screws in and tight.

When I started the engine, gear oil was weeping from these holes. It has subsequently slowed, but it seems odd to me that any would come out. 

So, is this a bad sign or is it normal? I am thinking that I may have to remove the entire lower unit and replace seals.

is there a .pdf manual available for this engine?

Thanks,

Chris


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## dabnis (Jul 29, 2007)

ccolton said:


> Dear All,
> 
> It's been a long time since I worked on 2-strokes and it's showing!
> 
> ...


Not famalier with your particular motor but the two small holes are probably water drain holes from the exhaust passages. The gear case should not be open to the water passages or the oil will become contaminated. When you replaced the housing perhaps a gasket is not properly placed or it masy be the wrong gasket. Maybe the lower unit was cracked from freezing and there is damage inside. Perhaps a Google search on Yamaha mlotors might turn up the manual you are looking for. Let us know what you find.

Paul T


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## ccolton (Jun 22, 2012)

Hi Paul,

What you suggest is what I suspect!

The weep holes are well above the area where I worked and what I did was very easy - I doubt they are related. I think I will need to remove the lower uint and see what's up...unless someone else here gives me a better prgnosis on the problem!

Thanks,

Chris


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## dabnis (Jul 29, 2007)

ccolton said:


> Hi Paul,
> 
> What you suggest is what I suspect!
> 
> ...


Forgot this, I had a 35HP Evinrude 2 stroke. After trolling for a long time and sitting on the trailer at home the weep holes used to have a black thick oil discharge come out of them. Probably a result of unburnt 2 stroke oil accumulating in the exhaust passages. If I ran it for a few minutes at full throttle before pulling out there was no discharge. If the oil you see is clean and looks just like the gear oil then you may have a cracked lower unit. Some pictures would help.

Paul T


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## ccolton (Jun 22, 2012)

Hi Paul,

Thanks for your reply!

Here are the pics: not pretty! The first shows the engine lower unit in the water and the milky green lube that has seeped out. The second, I was alone, shows the engine lower unit with the engine partially raised. You can see the weep hole toward the front of the engine with milky green fluid seeping out.

Chris


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## tommays (Sep 9, 2008)

NORMALLY if you service a lower unit you would do a pressure and vacuum test with a small hand pump similar to a brake bleeding tool


The seal rubber gets hard as it ages and the shafts will also grove in the seal contact area at some amount of hours


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## dabnis (Jul 29, 2007)

ccolton said:


> Hi Paul,
> 
> Thanks for your reply!
> 
> ...


Definitely looks like gear oil that has mixed with water. Kind of hard to tell from the pictures but the upper part with oil seeming to come out of the steering post is a puzzle, it would have to travel upwards from the gearcase, not sure how. Maybe there is an exhaust leak, with cooling water in it, that is pressurizing the gear case and forcing the gear oil/ cooling water mix back into the inside and out at the steering post connection? As Tommays suggested if you can pressurize the gear case a little and watch for the pressure to drop that will indicate a leak into or out of the gearcase. Finding the leak may be another matter? All in all, it appears that either gear oil is escaping out of the gear case or being blown out?

Paul T


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## dabnis (Jul 29, 2007)

dabnis said:


> Definitely looks like gear oil that has mixed with water. Kind of hard to tell from the pictures but the upper part with oil seeming to come out of the steering post is a puzzle, it would have to travel upwards from the gearcase, not sure how. Maybe there is an exhaust leak, with cooling water in it, that is pressurizing the gear case and forcing the gear oil/ cooling water mix back into the inside and out at the steering post connection? As Tommays suggested if you can pressurize the gear case a little and watch for the pressure to drop that will indicate a leak into or out of the gearcase. Finding the leak may be another matter? All in all, it appears that either gear oil is escaping out of the gear case or being blown out?
> 
> Paul T


This may be a stretch but maybe the gearcase is vented through a tube or passage up into the upper part of the lower unit or power head? If the seal between the water pump and the prop shaft is bad water may be forced into the gearcase resulting in the oil to be forced up and out the breather if there is one. In the motors I have worked on I was never aware of a gearcase vent but that is not to say there wasn't one. If you pressurize the gearcase and the oil flows out the steering post or weep holes it is either from a vent or a crack somewhere.

Paul T


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## ccolton (Jun 22, 2012)

Maybe this helps,

When I squeezed the gear lube containier to fill the resevoir, the expected happened; i.e., the lube came out the upper screw hole. The the unexpected; it also came out of the weep holes! Further, after screwing in the upper screw, which I thought would create a little vacuum, the lube came streaming out. It took me many trys to fill the resevoir.

The engine has not been run in 2-3 years - could it just be the oil seals in the lower uint - there are two more that I did not replace.

Thanks for all help.

Maybe time to take the lower unit off.

That won't happen until I finish with the diesel! Beginning to hate engines. I bought a sailboat, right?

Chris


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## dabnis (Jul 29, 2007)

ccolton said:


> Maybe this helps,
> 
> When I squeezed the gear lube containier to fill the resevoir, the expected happened; i.e., the lube came out the upper screw hole. The the unexpected; it also came out of the weep holes! Further, after screwing in the upper screw, which I thought would create a little vacuum, the lube came streaming out. It took me many trys to fill the resevoir.
> 
> ...


I sure seems that the gearcase is open to the atmosphere, somewhere. You mentioned a crack in the housing forward of the prop, any thoughts as to why it cracked, frozen from cold weather, impact, or other reasons? A good parts schematic may help before you open it up? Let us know what you find.

Paul T


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## ccolton (Jun 22, 2012)

I will definitely post pics and reply with results...but it may take a week or so. I was just at the boat and removed the tubes from the heat exchanger. After cleaning the entire unit, I need to install a new exhaust system from the exhaust flange back. And then maybe a little sailing!

I will be back with information shortly.

Chris


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## ccolton (Jun 22, 2012)

I have pitcures and videos - what I do not have is know-how! Please forgive me. I will post by tomorrow. Apparently, there is some issue with Iphones/google sites...and me!

So, yesterday, I removed the lower unit and found several seals that were in need of replacement - these parts have all been ordered. The gear lube was coming from two holes just ahead of the top fill screw - there is a plastic fitting inside that seems to want to cover these holes - I have a new one coming. 

Pictures will do a better job of describing this - I promise to work on it!.

Chris


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## ccolton (Jun 22, 2012)

I was not able to upload the videos - I think they are too big. So, here is a link to the site I am creating to track my boat restoration project and to share the changes I make with any interested parties.

There are videos and pics under the engine room section related to this thread.

Thanks,

Chris

https://sites.google.com/site/mabelscassetete/home


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## ccolton (Jun 22, 2012)

Update: After receiving all of the ordered parts, my son and i began to remove all of the old parts...and realized that I had missed one! So, since I need to place another order, I think I will remove and clean the carburator and see what needs to be ordered there. I will be back.

Thanks again.

Chris


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## therapy23 (Jul 28, 2007)

Nice you can still get parts.

If mine had not been stolen it would have been nice for me too.


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## ccolton (Jun 22, 2012)

Dear Therapy23,

I feel for you. In 2003, after having rebuilt a differen 9.9, it, along with the new dinghy, was stolen! I also had a dinghy with a 6 hp stolen in St. Marten.

Maybe I should learn from this? Oars?

Chris


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## ccolton (Jun 22, 2012)

Dear Group,
First, thank you for all your support and help! 
On Friday, I received the remaining seals and gaskets necessary to rebuild the lower drive uint. Although I was somewhat trepedatious when I set the engine on a saw horse and lowered it into a garbage can of water, I was pretty confident that the gear lube leak was fixed. When I finally took the entire unit apart - yes, every piece and seal - several seals had been dessicated over time and others were actually ripped! The worst offenders, no surprise here, were related to sealing water from oil.

So, When running the engine, no problems with the leaking gear lube! I was very happy. But...

The engine stalled easily and ran rough. So, I removed the carburator and took it apart. Clean as a whistle! Not what I had hoped for. But, I also took off the gas filter and found water mixed with gas plus a few bugs. Cleaned and replaced everything and then set the gap on the spark plugs - again to be sure.

The engine is now running like a charm!

Thanks again.

Chris


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## dabnis (Jul 29, 2007)

Good to hear, persistence pays off. If monofiliment fishing line gets caught in the prop it can wind up inside the prop and work its way around the shaft and into the seal, eventually destroying it. If the seals on the verticle part of the drive shaft failed that is a mystery to me. Of the eight outboards I have had over the last 65 or so years, I have never had those seals fail? Thanks for the feedback.

Paul T


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## ccolton (Jun 22, 2012)

Hi Paul,

It sounds like you are an expert - I am definitely not! My method was to keep taking things apart until I had replaced everything and hoped that during the way I found something wrong!

Additional information that may help. This engine came with my boat. I know for sure that it had not been run for 2 plus years and like had not been run for 3 plus years. Sitting in the sun and having no maintenance at all probably contributed to the dryness. I agree, the ripped seal is a bit of a mystery. BTW, this was not an oil seal, which are very strong, but a rubber bboot type seal.

Chris


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## dabnis (Jul 29, 2007)

ccolton said:


> Hi Paul,
> 
> It sounds like you are an expert - I am definitely not! My method was to keep taking things apart until I had replaced everything and hoped that during the way I found something wrong!
> 
> ...


Not even close to being an expert on anything, just "been there and done that" 
over the years, but thank you anyway. A "boot type of seal?" Of all the many Japanese products I have had they all had the great feature of not leaking oil, in addition to running perfectly. I would suspect that possibly some time back someone had it appart for some reason and damaged the boot when re-assembling it? Unless the boot had direct sunlight on it, or really excessive heat on it i doubt it would just dry out and crack?, but who knows?

Paul T


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## ccolton (Jun 22, 2012)

If this engine is anything like the boat, at one point someone probably did rip it. A good mechanic is worth 20x what he gets paid but the bads one out number the good ones.


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## therapy23 (Jul 28, 2007)

Good to hear you got it right.

It is a really great motor.


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## ccolton (Jun 22, 2012)

Thanks. Now for the Perkins 4.108 exhaust system - install that this week and maybe some sailing.


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