Buying and Installing a Transmission Cooler W123 - Page 2 - PeachParts Mercedes-Benz Forum

R Leo · #16 02-23-2006, 09:50 AM

Quote:

Originally Posted by Al Magaloff

Tranny cooler should be placed first thing out in front of the radiator. I would never be satisfied with a cooler that uses neopreme hoses, hose clamps and barbed fittings. I would use something like the B&M Super cooler, with pipe thread inlets. Then stainless braided line to the tranny, or hard line with inverted flare fittings, to pipe thread into the cooler.

Maybe so. However, my son's old ride ('85 300TD) had a bad in-radiator cooler that leaked coolant into the tranny fluid and killed the transmission (when we got the car, the tranny fluid looked like Pepto-Bismol™). After replacing the transmission, we plugged the cooler's outlets at the radiator and plumbed in a small neoprene hose unit to the tranny lines. That car made 2 1/2 trips across the continental U.S. plus a trip to Skagway, AK and back without a hint of trouble from the tranny cooler.

The biggest challenge was finding a cooler that would fit in front of the radiator below the bumper. Not much extra room in a W123.

SD Blue · #17 02-23-2006, 11:31 AM

Quote:

Originally Posted by Al Magaloff

Biopete, the aux tranny cooler won't need the fan.....

You will note that I prefaced my comment "with any kind of heat".

If you live in my area of the country and do much towing it would be a great investment for overall cooling, not just the tranny cooler. Heat is your biggest enemy when towing. For a 1000# trailer, in winter temps, I agree with Brandon for a one time towing job.

angst · #18 02-23-2006, 12:12 PM

What do you guys think of the idea of cooling fins on the transmission pan? JCWhitney sells these pans in their catalog for large trucks. They claim a measurable temp drop.
I was thinking about the idea of welding on some fins to the pan the next time it came off for a fluid change. Good idea or bad? Welding heat warping is a risk but fins could either be TIG'd on or even braized on. If they fell off, so be it.

#19 02-23-2006, 12:35 PM

Quote:

Originally Posted by angst

What do you guys think of the idea of cooling fins on the transmission pan? JCWhitney sells these pans in their catalog for large trucks. They claim a measurable temp drop.
I was thinking about the idea of welding on some fins to the pan the next time it came off for a fluid change. Good idea or bad? Welding heat warping is a risk but fins could either be TIG'd on or even braized on. If they fell off, so be it.

It gets so hot under the car from the heat of the engine dropping out around the tranny that you probably wouldn't pick up much cooling. I could see cooling at ultra high speeds but once the thermostat is open and the car running down the road, the tranny is sitting in a blanket of hot air heh.

Al Magaloff · #20 02-23-2006, 12:41 PM

The torque converter makes the most heat when moving slow speed forward or backward, not the tranny. Brandon, gimmick, without much merit. That area under most cars is fairly low pressure air. If there were really enough cooling air in the tranny pan area, a rear main seal oil leak, or tranny leak, would manifest itself with oil on the back bumper.

angst · #21 02-23-2006, 12:50 PM

Well, I was just thinking of easy fun mods. Also working on the assumption that you would have the pan off already for another purpose (ie changing fluid) and a 1hr. diversion to do the mods could get you maybe 10deg. less trans temps on the hwy.

Al Magaloff · #22 02-23-2006, 01:00 PM

RLeo, mechanical forensic pathology

is what I do. When it really needs to stay together, we don't use hose clamps. The probability of failure of both of our methods, occupy different ends of the curve. Hose clamps, been there, done that, got the T-shirt. As always, YMMV.

R Leo · #23 02-23-2006, 02:03 PM

Quote:

Originally Posted by Al Magaloff

When it really needs to stay together, we don't use hose clamps.

Agreed...just offering forumites a real-world, alternate 'been there, done that (for 30,000+ miles) and got the t-shirts to wipe the fog off the inside of the windshield' solution.

biopete · #24 02-23-2006, 05:24 PM

Thank you , thank you. I will just do the trip with changing fluid and filter and hopefully get a trans temp gauge installed in pan before i go for kicks. Fluid is still nice red but I just got the car in Sept. and should change anyway.

I'll watch the temp gauge and maybe in summer put in cooler. I'm still confused about where to mount it when i get one. In front of fan i dont know if it would fit. The hood grille would hit it i would think. Why not between the Main engine cooling fan and radiator? Is the air too hot there by the time it passes throug AC condensor and Radiator?

Hopefully someone can post a pic of an install. That would be nice.

cheers

Al Magaloff · #25 02-23-2006, 06:28 PM

RLeo, got ya!

t walgamuth · #26 02-23-2006, 09:20 PM

you want to install between radiator and main fan. not enough room. the idea of using the ac condensor seems ok, but you lose the ac option.

i dont know how much cooling you would get from the fins on the bottom of the tranny, but it would help. the sdl has fins on the bottom of the diff unit. also if you have a tranny or seal leak it does appear on the back of the car.

i am not sure you can weld them on without warping too much to seal. if you want to do that i suggest getting a spare pan in case.

tom w

Al Magaloff · #27 02-24-2006, 05:10 AM

Quote:

Originally Posted by t walgamuth

you want to install between radiator and main fan.

Tom, I don't think you'll find that to be the recommendation of any of the aftermarket cooler manufacturers.

rwthomas1 · #28 02-24-2006, 10:42 AM

Torque converters generate the most heat when the difference in input and output speeds, internally on the torque converter, are greatest. This happens at low speeds, both forward and reverse AND also while accelerating and pulling a load or climbing a grade. The torque converter generates almost all the heat in an automatic transmission.

Modern vehicles all have locking torque converters that have a clutch to "lockup" the torque converter once the vehicle is moving. This effectively makes the transmission directly connected to the engine much like a manual transmission with the clutch engaged. The advantage, especially for pickups that are intended to tow, is much lower temperatures.

Since MB transimissions of this vintage do not have a lockup torque converter they will generate lots of heat when used to tow, etc.

There is an upper limit on how hot transmission fluid should be, right about 260*F. Synthetic ATF will help survive high temps but thats only half the problem. The seals in an automatic transmission are rubber and will harden and crack over time if subjected to high temps. Once this happens the transmission looses its ability to hold pressure on the clutch packs, the clutches start to slip, the ATF has that nice BBQ smell to it and the transmission fails.

The safest thing to do is install a transmission oil temperature gauge to monitor the temps. The sensor should be installed in the oil line going to the oil cooler! Installing it in the transmission pan will be misleading as the cooled ATF is returned to the pan post cooler. The line leading to the cooler will have the oil at the highest temperature it will achieve in use.

Installation is not that difficult. The temp sensor can be installed in a brass "T" fitting of the appropriate size/thread and then installed inline. If the temps prove to be too high then a cooler can be added later.

Adding a cooler with a fan has the advantage that placement is not at critical for operation. A cooler equiped with a fan can even be mounted underneath the vehicle if there is no room up front. There is a long thin transmission cooler made for street rods that might fit low and behind the bumper on a 123.

RT