Losing speed and transmission oil T-90

[VictorII]

During the weekend we had to motor about 9 hours a day and I noticed that a. the speed was lower than usual for the revs and b. I had to add transmission oil after every day.
Also, there was an audible vibration coming from the prop shaft under power which wasn't present before.

So I have these questions:
1. Can it be just a prop problem? Something around it or possibly electrolysis from some source (the boat has been in the water since August). In which case I will have to lift out.

2. Does anyone know which transmission it likely is? It's a Moody 36 of 1979 build. The previous owner told me to use SAE 20 oil but I read in the manual that transmission oil typa A is required for Hurth and Borg Warner. I looked the transmission over but didn't see a brand name. Does anyone know where to find it?

3. Finally, Can the vibration and loss of oil be related? (I would think they are) Any ideas on which's the cause and what the effect?

If it could be the transmission (a leak?) is there a manual available? What do I look out for for determining the problem?

Thanks
Paul Victor

 

[Gordonmc]

I suspect you may have a Borg Warner Velvet Drive G'box as I had a similar problem.
If you look on the top of the box, close to the shift linkage there should be a small brass plate which bears the Velvet Drive name with model index, drive ratio etc.
If there is none, and there are no signs there ever was one, you probably have a Hurth so don't bother reading any further.
The VD relies on oil pressure for drive. There are only two exit routes for the oil: through the box aperatures or through the cooling system. If the first, filler hole, drain hole or drive bearings, there will be a pool of fluid evident under the box.
Check the oil filler cap and dipstick first. It has a tapered cork gasket and if its just pushed back in place after checking fluid level, it will not seal and you will lose both pressure and fluid. Push the cap on, then screw down finger tight.
If there is no evidence of fluid under the unit its likely the cooler is the culprit.
After the fluid does its drive-thing it it piped to an external cylindrical cooler mounted (usually) on the top of the bell housing. Occasionally the stack pipes in the cooler leak fluid into the raw water circulation system.
If so, you will leave a slick behind you while under way. Check by catching some exhaust water with engine running and in gear. Let it settle and check for fluid on the surface. The cure is a replacement cooler, or if time is cheap, resoldering the stack pipes.
Fluid to use... I just use Automatic Transmission Fluid from Halfords. The manual says use Dexron Type F. SAE 30 if RPM doesn't exceed 3000, SAE 40 if faster.
SAE-API service class "CD"
I would sort the fluid loss before worrying unduly about the vibration...
Should you establish that you have a Velvet Drive, pm me an email address and I will send a pdf manual for the ASI-70C/ASI-71C models.

 

[alb40]

Possible answers:

1. Yes it could just be the prop. Check to make sure it isnt fouled or damaged at all.

2. A round shaped transmission is a borg warner, a square one, hurth. Both Use ATF anyway. A hurth box will say 'hurth' on the side. A prm gearbox would use engine oil, such as sae 20 or 30. These may have 'newage transmissions' stamped on top. if you can take a picture, that would help.

3. Vibration and loss of oil could be related if is bad, as the oil seal on the gearbox could leak. Check the oil cooler on the box if one is fitted too - around the hoses, and check to see if there is water in the oil. If the vibration is causing the leak, it will come from around the output flange, so check around that.

If you can identify numbers or manufacture, or get a picture, you could be lead in the right direction to getting a manual to fix it.

Hope this helps you

Alex

 

[rovjack]

Hi sorry to trouble you but I was just reading the topic on velvet drives is there any chance you could please send me the pdf manual for ASI 70C as I have this gearbox and am trying to find info on it Regards Jack