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Old 20-08-2016, 13:29   #16
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Re: Perkins 4-108 Dual Oil Cooler/Heat Exchanger

My cooler uses fresh water (re: antifreeze)

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Old 20-08-2016, 15:49   #17
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Re: Perkins 4-108 Dual Oil Cooler/Heat Exchanger

Fuel oil in the crankcase would not cause I smoke in the exhaust. But it would cause low oil pressure.
I had both a bad lift pump & seals in the injector pump leaking fuel into the engine oil.

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Old 20-08-2016, 19:04   #18
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Re: Perkins 4-108 Dual Oil Cooler/Heat Exchanger

I had fuel in the oil in a Perkins 4-236. A injector was stuck squirting raw oil into the cylinder, the push rod on the exhaust valve came off the rocker, was just sitting alongside the rocker arm. Surprisingly the engine seemed to run fine, I never would have known it if it wasnt for the oil getting fuller and fuller. About 1.25 quarts too much at one point. Raw fuel was staining the water from the exhaust also. No smoke to think of.
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard

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Old 22-08-2016, 10:32   #19
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Re: Perkins 4-108 Dual Oil Cooler/Heat Exchanger

I'm surprised that your heat exchangers are freshwater cooled, as on my 4-108, (Westerbeke 40-108), all accessories are raw-water cooled, with only the block being freshwater cooled; (but there are many possibilities in this area).

For $20 you can get a lube-oil sample kit from an auto parts store. Get a sample of the oil in the engine sump. You will then find out what it really has in it, as opposed to speculating. Fuel oil, (diesel), dilution is a common problem with marine diesels, and this is what you will probably see. Diesel oil dilution of the sump will not cause smoke, it will decrease the viscosity of the lube oil. A slight dilution is not much of a problem, and will clean the inside of the engine. I've done this intentionally before an oil change. A larger dilution can be serious, raising the acidity of the oil and decreasing the viscosity. In the Merchant Marine the rule of thumb is to make sure to change-out the lube oil at no greater than a 10% dilution.

Another possibility is that the sump can go up and down if the lube oil has drained out of the oil filter. I always run my engine for a few minutes, (to fill the filter and the oil gallery), then wait a few minutes, (for the cold oil on various surfaces to drip back to the sump), before checking the oil. This way I get consistent results.

I am used to fuel oil dilution of the lube oil coming from dribbling injectors, but, it sounds like it could come from the lift pump or injection pump too, (as mentioned above).

If the dual cooler pictured above is similar to the one on your engine, there is no way that the oil could have migrated from the transmission to the engine sump, through the coolers. Though it could get into the cooling medium. If that is freshwater it would show in your antifreeze, if raw-water, it would go overboard, (assuming the oil-pressure is higher than the water pressure, otherwise you might get water in your oil).

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heat exchanger, oil, perkins

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