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SM 1990 drive unit seals


Helen and Kostas Yuvanidi
 

Thanks to everyone who gave us information!

I thought I would update on what we did to solve the problem of the seal.
In the end we managed to solve the problem of the leaking oil, but it looks as if we must have damaged the upper part of the transmission, when we lost the oil. We no longer loose oil but at close to 2 hrs on 1800 rpm the transmission was really hot. We can motor for about 1/2 easily without the transmission getting hot, so can get in and out of harbour easily. Therefore we decided to leave the rest of the repair till we haul out at the end of the season.
I’ll attach the photos of how we made the seal.
The problem was that the seal between the fibreglass funnel and the aluminum transmission was in parts only 5mm. So we added 30mm stainless corners on all 4 sides so they we now had 35mm to make the seal. It worked!!

Thanks again!
Best regards,
Helen and Kosta on Meditation SM 29 , 1990

The fibreglass funnel.

The aluminum transmission with 2 corners attached and showing where the mechanic filed the transmission body so that the corners would make a seal.

Attaching the corners.

All 4 corners attached.

Back in place and seal made.
We took the transmission to a machine shop to have the corners made and to modify the transmission and corners so that the corners fitted tight and could make a seal with the transmission.

On 22 Jul 2020, at 3:03 PM, Helen and Kostas Yuvanidi via groups.io <helenmi57@...> wrote:

Hi Mitchell,

Thanks!!
We never had the oil seal...we have taken it apart many times in the 20 years we have her...that is unless it was removed before we bought her....:/
It would be a great help though if you could point it out for us on the plans.
We always managed to make the seal with just the gasket maker.... the fibreglass trumpet is not in a good condition anymore, perhaps that’s the problem!
Did you make any repairs to that?

Best regards,
Helen and Kostas SM 29 of 1990

Sent from my 
On 22 Jul 2020, at 9:13 AM, Mitchell Petersen <Mitchell.j.petersen@...> wrote:


Hi Helen,

I miss read what you were doing. I thought you were referring to the lower unit.

As far as your oil leak goes. There is a 85x110x12mm oil seal with stainless steel spring at the top of the lower unit where the trumpet looking fibreglass thing marries with the lower unit. I believe this oil seal is designed to retain the oil, should this leak as a backup you have the silicone gasket you are using where the upper unit is bolted to the fibreglass trumpet looking thing. I would guess this oil seal has been dislodged or damaged when the upper unit was repaired/ reinstalled.

The lower unit needs to be removed to replace this seal. This is not a difficult task once you have the upper unit off but the boat obviously has to be out of the water.

For economy I just replaced the oil with engine oil as originally recommend by Amel. When examined all gears top and bottom had very little where so I believe engine oil is sufficient to use in this light application. It is my opinion damage caused to these units is most likely often from miss aligned engines rather then anything to do with oil grade.


Let me know if it is unclear where the oil seal is located and I will mark it up on the plan.

Mitchell


On Mon., 20 Jul. 2020, 5:17 pm Helen and Kostas Yuvanidi, <helenmi57@...> wrote:
Hi Mitchell,

Thanks!!
Our fibreglass did not have the aluminium part, at least not since we have the boat, we have taken it apart many times in the 20 years we have her, probably Amel made the change after our hull.
We changed all the bearings and gears in the upper part, but didn’t touch the lower.
Have you changed the viscosity of the oil you use or do you still use the 15W 40?
All the best,
Helen and Kostas on Meditation SM 29 of 1990


On 20 Jul 2020, at 12:03 AM, Mitchell Petersen <Mitchell.j.petersen@...> wrote:


I have the aluminium one which I recently fully rebuilt with all new bearings on both the upper and lower unit which requires cutting through the fibreglass and glassing back to original shape.

There is meant to be a small (approx. 2-3 inches) section of aluminium tubing glassed into the lower unit where the propelled shaft exits the until / where the fibreglass tapers which sounds like is no longer there since your service.

Mitchell 
SN33 1993

On Sat., 18 Jul. 2020, 1:11 am Helen and Kostas Yuvanidi, <helenmi57@...> wrote:
I’m sending the plans Maud sent me. It’s not exactly like any of them.
We’ve measured the difference between the aluminum and the fibreglass and it’s 3mm, but again there is nothing to hold an O-ring in place.

Many thanks,
Helen and Kostas Meditation SM 29 in 1990


On 17 Jul 2020, at 6:04 PM, Helen and Kostas Yuvanidi via groups.io <helenmi57=gmail.com@groups.io> wrote:

Hi Bill,

Thanks for the prompt reply!
Unfortunately ours is different and doesn’t have the O rings , or any likely place to put one. I’m sending you photos to see what ours is like. On looking at the plans Amel sent us our set up is not exactly those either. We have bolts to fix it in place which are inserted from under the fibreglass part, shown in one of the photos. 
It might be possible to put an O-Ring around the aluminum part which inserts slightly into the fibreglass, only there is nothing there to hold it in place, any ideas will be very much appreciated!!
Thanks again 
Helen and Kostas on Meditation SM 29 of 1990

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On 17 Jul 2020, at 4:54 PM, CW Bill Rouse <brouse@...> wrote:


The drawing shows 2 each "Joint Toriques" which is an O-Ring. Follow this link.


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Fri, Jul 17, 2020 at 8:31 AM Helen and Kostas Yuvanidi <helenmi57@...> wrote:

We are having trouble with the seal between the transmission and the rest of the drive unit after having it serviced. The oil leaked out between the transmission box and the fibreglass part of the drive unit. The machine shop had used a paper gasket and some sort of red sealant. We are on anchor so are trying to do it ourselves.
We took it apart and resealed it , it leaked again after about 4 hrs motoring. We had used a high Temperature RTV gasket maker but no paper gasket because we thought that that was the way it was originally.
We have the plans from Amel, but it is not clear if there should be a paper gasket.
Should we try to find card to cut a gasket or try again with the RTV gasket maker? The fibreglass part is not in a very good condition.

Helen and Kostas on Meditation SM 29 of 1990