Using auto trans fluid cooler as oil cooler?
 

hi everyone.
i recently began to transplant a w115 240d engine and manual tranny into my 75' 280. when i got the engine it didnt have a radiator/oil cooler. im sitting in my garage looking at my radiator from my 280 and thinking hmm i need an oil cooler and a radiator and i dont have any money.. could i just hook up my oil cooler lines to the automatic transmission cooler on the bottom of my radiator? that would save me a buck or 200.

this would just be a temporary fix until i have the money to get a good used radiator/oil cooler, and the temperature wont be getting above 80 degrees Fahrenheit for a couple months. is this possible? has anyone done this in the past? thanks in advance

Can you use it as a short term fix? Probably. Without a turbo, the oil doesn't get as hot, and if you don't flog it continuously you'll probably be ok.

Generally the response I see for this is no, the transmission cooler will not allow the oil flow correctly. You can buy a universal oil cooler for fairly cheap on Amazon, that's the route I would go if you think you really need it and are on a budget.

This, from the FSM:

Therefore, it doesn't matter if the ATF cooler flow less than the stock cooler.

Really though, it shouldn't flow too horribly. It's designed to flow ATF and fully warmed engine oil won't be significantly more viscous.

If you can get an aftermarket cooler with the same threads then I would opt for this=>

But I think finding something that would fit onto the (also expensive) cooler lines would be difficult.

My gut feeling is that running the engine oil through that little transmission cooler is unlikely to work. It was designed for thinner ATF - I would expect engine oil to get blocked.

If I were you I'd do a WTB ad on the forum.

I thought 615/616 cars without A/C didn't have oil coolers. If you're not running A/C, you could probably just loop the cooler lines.

thanks for all the responses. i dont know for sure if it had an oil cooler, but it has the two lines coming off the oil filter housing that look very similar to the oil cooler lines on a w123. therefor i figured it did have one. after reading this and consulting a few manuals i think i will just loop the oil line and run it as usual. ill be sure not to drive for more than an hour or so without letting the engine cool down. im just planning as scooting around the neighborhood anyway since the cars got 700$ in back fees.

thanks again for all the comments

The early w115 engines (om615 220d) never had an oil cooler from the factory.

OP has a 240D drivetrain with oil cooler lines.

Yes, the OP made that very clear. What part of my post confused you? My point was simply that many similar vehicles have been on the road for ~50 years without oil coolers. So the OP need not worry about not using an oil cooler for a short or moderate amount of time (or 50 years). I will try to be more clear in the future.

I was wondering why you'd make a statement irrelevant to the OP's concern. He doesn't have a 220D. MB put an oil cooler on the 240D. They saw reasons why the 220 and 240 needed their specific arrangement.

Next time be more clear why your random statements relate to the question. :)