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8V-71 - Eng Oil in Tranny

Current Sea

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Can engine oil leak through the main seal (or from any where else) into the tranny reservior?
The tranny fluid is going dark and the level has increased slightly.
Tranny is a Torqmatic Marine Gear.
 
Well, my short answer is that I don't know but I'll speculate with you if you like. Not likely in my opinion. Engine rear main seal has no pump pressure against it to enable any transfer. Additionally you would also need a coincedental path to open in the converter to allow fluid ingress and that is pressurized so you would think that any fluid exchange would go the other way.

If you are running a red transmission hydraulic fluid and it goes dark like oil, it could be from slippage and heat. That doesn't explain though why you are getting a slight fluid level increase. Does the increase in trans fluid level coincide with a decrease in engine oil level? Are you running a trans cooler and, if so, is it engine mounted in a housing with the engine oil cooler?
 
The engine and transmission both take the same oil (30 weight). The tranmission oil was quite clean prior to a trip one month ago. I added 2-3 quarts to the engine during our trip. Engine oil level is currently pretty close to the correct level. These old Jimmy's do use a litttle oil. My recent findings were noted after approximately 40 cruising hours.*
I will investigate the oil cooler question this weekend. I think they both have seperate coolers.
I*plan to*change the oil, filter and clean the strainer. Maybe I had some clutch slippage.
Thanks for the assistance.*
 
Yes the rear seal will leak into the transmission. The flywheel is part of the transmission and shares the transmission fluid. When the rear crank seal starts to fail it puts engine oil into the transmission. This is why the oil is getting dark. The engine oil will eventually harden the seals in the transmisson and you will see slower shifts and lower pressures. You should plan on correcting this over the winter or change the transmission oil every 100 hrs as you do the engine service.
 
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