water in my MS4A gearbox

PhilfromOhio

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Feb 7, 2010
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I have an MS4A gearbox on my port engine (TAMD41A) Volvo Diesel. The gearbox is water cooled from the heat exchanger and when I went to service the oil this month I noticed a lof of milky oil and water. I am hoping its a simple o-ring. Does anyone have any ideas?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Follow the manual for trouble shooting
 

alldodge

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I have an MS4A gearbox on my port engine (TAMD41A) Volvo Diesel. The gearbox is water cooled from the heat exchanger and when I went to service the oil this month I noticed a lof of milky oil and water. I am hoping its a simple o-ring. Does anyone have any ideas?
Looks like the MS4A has a internal oil cooler. Many have had trouble with it and are replacing with ZF. Here is what another said about differences

The MS4 transmission can be replaced by the ZF 45a but it's not an exact replacement. Both transmissions have an 8 degree down angle, but the ZF has slightly more drop center, about 3/4 ", and it is also about 3/4" shorter than the MS4. Unfortunately I am not at home right now and thus can't give you the exact dimensions. In any event, this means that the engines will have to be raised and moved rearward these amounts inorder to match the gearbox output flange to the existing prop shaft flange position. Alternatively, you might raise the engine and slide the shaft forward if you have the extra length, or fit a drive saver if there isn't one there already.

The MS4 transmission was a mechanical gear with a cone clutch, and the forward and reverse reduction ratios were identical to each other, but the ZF is a hydraulic actuated gear, and as I recall there is a slight difference between the forward and reverse ratio. This shouldn't give you any problem and I doubt you will have to do anything with the props.

Another thing that is different is that the ZF gear uses an external oil cooler, as opposed to the internal cooler on the MS4, so you will have to make some changes to the raw water plumbing lines. (Don't forget to buy a cooler and hoses along with the transmission)

Lastly, this would be a good time to check and probably replace the torsional spring plates on the flywheels, especially if they are the originals units. These things don't last forever.

DougR

https://www.cruisersforum.com/forums/f54/volvo-penta-gearbox-ms4a-123025.html
 

QBhoy

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Mar 10, 2016
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8,319
Hi. On occasion, these tamd’s have a reverse gear oil cooler. I’d have a look at the seals on this for certain, if it applies to you. Likely has a shaft gland cooling fitting and hose around there too. Be unlikely perhaps, but make sure it’s not weeping and entering via the dip stick further aft.
 
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