Perkins 4108 oil vs transmission cooler

[Paul M]

Hi all,
I have a 1973 Morgan out island 41 foot with the original Perkins4108 and velvet drive transmission. We recently were told that we could takeoff the transmission cooler because this transmission does not need it and we thought it may be the source of the leak. We made a couple of other changes at that time with other systems but since then we’re having some overheating issues that we didn’t have prior to removing the cooler and changing the prop. When I read the out island owners manual it has no references for transmission cooler but it does reference “oil cooler“. The discussion about the old cooler is related to checking transmission fluid, and the part we removed is connected to the transmission.

I’m just trying to figure out if this engine and transmission has both an oil cooler and a transmission cooler. If it does have an old cooler I have no idea where it is. We regularly take apart the heat exchanger, the strainer, replace thermostat etc and I Think I would’ve seen an oil cooler if it were on there.

Cheers,
Paul

[DougR]

When I owned a 4-108 , (1979 version) the engine was equipped with a twin cooler which cooled both the transmission oil and the engine oil. There were two coolers in the same housing and it was easy to follow the oil hoses and see where they went. This twin cooler was mounted on the starboard side of the engine and connected in the freshwater system between the rear mounted heat exchanger and the coolant return to the block.

Something else to consider might be that you changed the propeller, and the overheat began after that. Are you certain that the replacement prop is the same size as the earlier prop? If the prop is larger or has more pitch it could be overloading the engine and contributing to the overheat condition.

[Bill Seal]

There may just be a bypass hose. If you just plug the outlets/inlets, you'll blow the clutch packs.