I'm (603 motor) thinking of running the trans oil cooling task over to a dedicated trans oil cooler (& bypassing the radiator) to help with the very popular & hellish southwest desert highway travel temps this summer.

Basically taking the trans heat load off the radiator and allowing the radiator to focus on the motor and hopefully reducing transmission heat transfer to the motor as well...may even help the AC indirectly?

Anybody else have any experience with this kind of set up?

Thanks...rob

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1986 300SDL 440,xxx

But with several Volvo's, an F350, and a 3500 series Chevrolet pickup, I have. And I think about doing it with our '79 300. My only concern would be the placement of the tranny radiator so that it wouldn't still be transferring the heat load to the engine radiator too much, other than that, it sounds like a good idea. Especially in the desert.

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1985 300D-189k The 'UD', Ivory and Pinkamino
1979 300D-211k Dark Gray, Parchment
A 1980 Harley-~166k and
A 1994 Ford diesel pickup-349k and
A 1990 gasser Volvo wagon-145k

I'm interested in this as well. But don't ask me to design it for you

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Never be ashamed to ask for help.

1985 300D
1987 300SDL
1970 Jaguar E-Type OTS
2002 Dodge Intrepid (Traded In)
2011 Ford Crown Victoria

Con’t….fit nicely under the right fender / vented bumper area. Similar to the oil cooler located on the driver's side.

Main objective is to improve motor cooling system performance by lowering transmission heat load transfer to the radiator. Secondarily reducing transmission temps by improving its cooling system which may actually reduce conductive transmission / motor heat transfer as well.

When the car was new it never under any driving condition operated as warm as these days so I conclude that with a 348,000 motor & drive train (trans rebuilt) components are getting old and just create more heat particularly under load or higher speeds which the stock cooling set up has a little trouble keeping up with.

The cooling system is in top shape R & R wise (new components & citrus flush). Exhaust restriction corrected, timing good, etc. The cooling system is reportedly performing within normal temps, just I feel they are on the high side during high ambient temps & long grades.

A stacked plate cooler of approximately 7.5" x 11" by 1" will surpass the radiator based trans cooler line performance. Any additional cooling capacity will be gravy. Some info suggests the new cooler to be 200% more effective than the radiator based trans cooling set up.

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1986 300SDL 440,xxx

"R+R transmission Air/Oil Cooler."
Fits into the Passenger side space opposite the Engine Oil Cooler on the Driver's side.

'Has a thermostatically controlled "Puller Fan" behind the "Lil - ATF Radiator".

'CRAZY that MB didn't put these on ALL the W124s and W140s.

'Might have to plunder around the Re-Cycler's yards to find all the parts.

The only drawback in the (Stuttgart) Engineer's mind was that the "Tranny" didn' t
enjoy the rapid "Warmup" from the heat transfer of the Radiator.


BUT in the less than SubArtic conditions of CONUS,Who cares?

(Yeah,well Maybe a little angst over the OM603's cooling capabilities on that model chassis?)

Attached Thumbnails

 

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'84 300SD sold
124.128

so my question is this-

The average transmission is 'supposedly' running at between 175 and 200 degrees F when operating normally. By 225 you are supposed to be lessening the life of the component, and then on a curve upwards with less mileage and higher trans fluid breakdown the hotter it gets.

The majority of these engines when in tune would be operating between 175 and 210 F, maybe around 190F.

So in that circumstance, if everything is operating at the correct temp, the transmission cooler lines would be on average slightly lower temp than the radiator, so wouldn't the reverse be true? Instead of removing a hot load on the radiator, aren't you removing an additional source of cooling for the radiator?

Personally, im in favor of an aftermarket trans cooler, since the stock cooler inside the radiator is nothing more than a copper tube from one end to the other (at least in the 123s), but having said that, I think its not really any kind of load on the radiator, and may actually add some slight benefit by providing access to another heat exchanger.

If I were to do this, id rig it like heavy trucks with multiple oil coolers, id leave the stock exchanger in line, and add an aftermarket cooler in addition, not in replacement, on the trans cooler supply line to the radiator. Then you would get the benefit of both coolers, and maintain that positive heat exchanger for the radiator as well by cooling the trans fluid a bit before running through the radiator. That would benefit both systems

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This post brought to you by Carl's Jr.

Mr. Compress Ignite’s comments are spot on. Mr. Dropnosky has a good point that an "intune" cooling system might benifit from cooled trans fluid running through it.

With my "refreshed" trans and cooling system driven in ambient temps below 95 F the motor does run in low to mid normal range temp wise. It just loves winter here in S. Cal. But when the ambient temp rises to 95 or above it seems that for almost every degree rise in ambient temp the motor runs a degree warmer telling me the existing set up is maxed out.

I have come to conclude that an "experienced" motor just creates more heat than a new motor (<100,000 miles) no mater how fresh stock cooling parts are. Same holds true to for the trans. Even rebuilt I think the trans runs hotter 'cause builders generally re use older components that still meet spec but are worn.

So when pushed a bit out of optimum operating environments with the A/C on and ambient temps up over 95 F I think the system needs either a bigger radiator which I don't know of or an extra cooler i.e. trans cooler.

Any other votes out there before I go for the “upgrade”?

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1986 300SDL 440,xxx

In order for the above to work out it the ATF would have to pass through the Radiator Cooler and then through the add on Transmission Cooler.
But, that would mean the Radiator is still having to get rid of some of
Transmission Heat.
So, if relieving the Radiator of that Extra Heat was a goal it would not work.

Adding a Cooler to the out going ATF from the Radiator might mean you could get by with a smaller cooler.

It might be possible to set it up with some valves so that in the Winter you could bypass the add on Transmission Cooler.

I think it is if more advantage to have the whole Trans Cooler system external to the Radiator so there is no chance Coolant getting into and ruining the Transmission.
I think a Cooler with a Thermostat would be helpful during the Winter.

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84 300D, 82 Volvo 244Gl Diesel

I had asked the same question here as I read on the FSM that there was an additional transmission cooler that fit in the RHS fender with its duct and fan, its relay fits in the fuse/relay box and also utilises a 100 degree centigrade switch to switch on the ATF cooler fan.

so far I have not seen the transmission lines get any more hot than the radiator itself which is 95 degrees centigrade. I have got myself a general purpose ATF cooler and now seeing how to mount it in the car with a duct too. The FSM also tells to install an extension of the water splash shield to prevent mud and water from hitting the cooler and fan.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Last year when we had my 1985 300D's radiator out I back flushed (back to front) the fins of the radiator with a hose end sprayer on full sharp spray. The resulting crud that I removed allowed the temp gauge to read 5 degrees cooler on average. I was amazed at all the fluff, seeds and just stuff there was. Doing the same to the condenser would also help as all that fluff acts like insulation and doesn't dissipate any heat.

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Pete Williams, President emeritus - MBCA-International Stars (Eastern Mich.) Now Wi. & Az.
1985 300D Manual 4 speed Green Hen's tooth
1979 MGB triple black Az car nice
1969 back 1/2 of MGB (Az home built trailer)
1991 Volvo 245 Wagon Nice AZ Restored Gold Brick
1983 Jeep CJ7 37,600 Miles Summer use only

I like it I wanna do it..It's hot here in summertime

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-SpecialDelivery
1985 300CD Silver/Blue H&R Suspension (Sold, still cryin over that)
1982 300SD Silver/Blue '85 OM617 (Sold)
1982 300D - Blue/Blue (Sold)

TBH I'm more worried about the in-radiator cooler failing and pumping the transmission full of coolant than the trans running too hot. I should put a temp gauge on there and see what it gets up to in traffic.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

every study I've read about it says the in radiator coolers are a compromise, and air coolers are the ultimate best for transmissions.

figure transmission temps to be 70F higher temps than engine temp... so, if you are hitting 100C (212F) the transmission is hitting 282F... 80F higher than desired operating temp and component / oil breakdown is occuring.

now, this is not the case under normal driving conditions, as the lower portion of the radiator is often ambient, or close to it of around 100F, and 170F is just peachey for a transmission temp. but when the engine temps climbs, SO does the radiator and consequently the transmission.

several magazines have installed temp monitoring systems in the radiator, transmission, etc, and rigged up valves to monitor temps under various conditions, and nothing beat the straight air cooler for the transmission.
having a thermostat to open or bypass the cooler for transmission warmup would be ICING!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I once saw a transmission cooler on a toyota cressida that was made for the ME market - it was an air cooler that had a thermostat built into it, uptil the time the ATF was cold it just short circuited back to the transmision, when it was hot enough, the thermostat closed off and the ATF went through the cooler channels

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

We should all drop what we are doing and bypass the radiator entirely as an ATF pathway and move to a separate air cooler.

I have only had three transmission failures in 722.3 or 722.4 vehicles counting about a dozen vehicles and millions of miles from first original owners, family members, and myself. All times were due to the radiator. The first time it was moderately weeping, the second time it was barely weeping. Replaced the radiator with a Nissens brand one, and flushed the lines when installing the replacement transmission the first time.

Three years later I’m putting in a transmission again and disappointed that it didn’t get 25 years of life like the first one did. This time I only saw the telltale strawberry milkshake in hidden crevices when I tore down the second transmission after the third one was in there. Unfortunately driving the car around doing all these tests and adjustments with the newly installed third transmission, in the interim, was enough to toast that one too. Now I realize why so many are winding up in the junkyards that aren’t wrecked. Let’s add copper radiator cooling ATF circuit to the list with biodegradable wiring. Many of these cars are built so well they stay on the road until wrecked, but his could be a time bomb appearing. The wasted time testing values for every input and adjustment on springs, valves, pressures, ect was incredible. Not to mention the loss of the car’s original transmission and two replacement transmissions. I was all prepared to blame worn clutches or mis-adjustment as the assigned transmission killer.

Please be warned people this could happen with your radiator, and by the time you notice anything it will be too late. I think my cars will all get their transmission cooling pipe in the radiator bypassed.

Maybe Peach/Pelican should start selling retrofit kits assembled for each chassis.

On a second note, I’m disappointed that the Nissens unit only gave 3 years of service before contamination of the ATF from the cooling circuit happened with Zerex G05 being used exclusively. The original MB radiator provided 25 years of service.