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Having a bear of a time locating a transaxle fluid leak. 94 Sedan Deville 9.4. 148,000. So far I have found 2 not really tight hoses to the Hayden cooler by the grill and 4 transaxle pan bolts loose enough to be turned by hand. Why I think I havent found the leak, is because the oil pan had fresh fluid on it. The radiator is only a few years old. I didn't replace it, Dad had an indy mechanic do it. I really don't see any leak points even though my brother who has been a mechanic (not caddy specific) for the last 40 years says there should be a huge puddle somewhere. In the begining I was adding 1 quart (yes quart) every other day. No puddle in the garage, at work, or at the diner. Not so much as a drop. I have also found what looks like a wet lower radiator hose. The tranny fluid line above that is dry as is the point that it enters the radiator.

If anyone can sugest any places that may be common leakers please let me know.

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What does the coolant look like in the radiator? If transmission fluid is getting into the radiator, then coolant could be getting into the transmission which is a very bad thing - it will ruin the clutches in the transmission.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The extra cooler in front of the A/C condenser is the power steering cooler.

My understanding is that you are loosing transmission fluid, as verified by you adding a quart a day of transmission fluid when you drive the car every day.

Generally, if you are losing fluid (transmission fluid, oil, power steering fluid, brake fluid, coolant) when you drive the car but not when you let it sit (except possibly for a drip right after you park the car), the leak is in a section where the fluid is under pressure. The most likely place for transmission fluid leaking under pressure is the transmission cooler, which is a heat exchanger in the left radiator tank. If the radiator was replaced recently, it's possible that one of the fittings is loose or even cross-threaded.

If it's not the transmission cooler lines where they attach to the radiator, check the fittings at the transmission end, and also the hoses themselves. If the cooler lines and fittings are OK, then clean off the car as well as you can, drive it, and then put it up on a lift and identify where fresh fluid seems to be coming from. It may be possible to let the car idle in Park on a lift and watch for a drip.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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The extra cooler in front of the A/C condenser is the power steering cooler.

It sounds like there is an external auxiliary oil cooler for the transmission fluid on this car.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Someone also pointed out what should be an obvious idea, but that wasn't to me: Wrap your various connection points with a bit of paper toweling and put a bit of masking tape around it to hold it in place. If you've got leaking under pressure going on you're sure to have the toweling at (or near to) the leak in question become saturated with whatever's leaking.

Brian

Brian

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Bri the Tech Guy   http://britechguy.com
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The extra cooler in front of the A/C condenser is the power steering cooler.

It sounds like there is an external auxiliary oil cooler for the transmission fluid on this car.

This is a 1994 Sedan DeVille, that apparently has the 4.9 liter engine, not the Northstar. The 1993-1999 Northstar cars use a power steering cooler, at least the VIN "9" drivetrains; the VIN "Y" drivetrains (which will include the DeVille) may not. He calls it a Hayden cooler, which is an aftermarket item, and says that the clamps were not tight, which would be unheard of in an OEM system unless the hoses have been replaced - unlikely even in a 1994 model.

So, since it's a 1994 DeVille and the hose clamps were loose, I suppose that yes, it's a transmission cooler.

Which opens the question, why did someone add an air cooler to the transmission? There are only two really good reasons that I can think of, a leaking transmission cooler in the radiator tank, and to tow with the car. And, the owner, Frankman, recently replaced the radiator.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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What does the coolant look like in the radiator? If transmission fluid is getting into the radiator, then coolant could be getting into the transmission which is a very bad thing - it will ruin the clutches in the transmission.

Engine coolant is nice and green.

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The extra cooler in front of the A/C condenser is the power steering cooler.

My understanding is that you are loosing transmission fluid, as verified by you adding a quart a day of transmission fluid when you drive the car every day.

Generally, if you are losing fluid (transmission fluid, oil, power steering fluid, brake fluid, coolant) when you drive the car but not when you let it sit (except possibly for a drip right after you park the car), the leak is in a section where the fluid is under pressure. The most likely place for transmission fluid leaking under pressure is the transmission cooler, which is a heat exchanger in the left radiator tank. If the radiator was replaced recently, it's possible that one of the fittings is loose or even cross-threaded.

If it's not the transmission cooler lines where they attach to the radiator, check the fittings at the transmission end, and also the hoses themselves. If the cooler lines and fittings are OK, then clean off the car as well as you can, drive it, and then put it up on a lift and identify where fresh fluid seems to be coming from. It may be possible to let the car idle in Park on a lift and watch for a drip.

The radiator was replaced about 4 years ago, which to me seems recent in the life of radiators. I haven't yet checked the transmission end fittings, but thanks for reminding me. Trudging forward

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The extra cooler in front of the A/C condenser is the power steering cooler.

It sounds like there is an external auxiliary oil cooler for the transmission fluid on this car.

This is a 1994 Sedan DeVille, that apparently has the 4.9 liter engine, not the Northstar. The 1993-1999 Northstar cars use a power steering cooler, at least the VIN "9" drivetrains; the VIN "Y" drivetrains (which will include the DeVille) may not. He calls it a Hayden cooler, which is an aftermarket item, and says that the clamps were not tight, which would be unheard of in an OEM system unless the hoses have been replaced - unlikely even in a 1994 model.

So, since it's a 1994 DeVille and the hose clamps were loose, I suppose that yes, it's a transmission cooler.

Which opens the question, why did someone add an air cooler to the transmission? There are only two really good reasons that I can think of, a leaking transmission cooler in the radiator tank, and to tow with the car. And, the owner, Frankman, recently replaced the radiator.

There are two small external coolers in front of the radiator. I googled transmission coolers and the Hayden cooler is the one in the car. Aftermarket, maybe since there were 2 owners before me.

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In my 1997 ETC, there was one cooler in front of the A/C condenser, the power steering cooler. The second one is aftermarket, and can be a transmission cooler or an oil cooler. The car already has an oil cooler, in the right radiator tank, and a transmission cooler, in the left radiator tank.

I think the production arrangement, with the oil and transmission fluid coolers as heat exchangers in the radiator tanks, is a good one because there is only so much air through the grille and unless you are going to present a hotter radiator surface to it you aren't gaining rate of heat shedding by putting another radiator grille either in front of or behind the A/C condenser or coolant radiator. I think that the power steering cooler is there because the radiator only has two tanks and they are needed for the higher heat transfer needs of the oil and transmission fluid cooler, and, possibly, while dealing with curves and traffic on the Autobahn at 195 kph all afternoon you might get some higher-than-coolant temperatures at the power steering cooler.

The radiator heat exchangers have the benefit of warming the radiator and oil on startup in cold weather, which can reduce wear in the engine and transmission. And, a liquid-to-liquid heat exchanger can pass a lot of heat in a small size, relative to the liquid-to-air radiator and condenser, so if you really need to pass a lot of heat out of the engine or transmission, the capacity is there.

But aftermarket transmission and oil coolers are out there for special purposes. Only by examining the particular car and seeing where the fluid lines go can you tell for sure which it is cooling.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I believe I have a factory extra cooler on my '96 deville. I recall it was the towing or livery package, and it included the extra cooler, and the car is factory pre-wired for a trailer. The connector is still wrapped in plastic wrap in the trunk and never used. Not sure why I got this option.

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Some people get the towing package so that they have a heavy duty transmission, radiator, and brakes. But, the Northstar already has all these things because it's designed to run with the big dogs on the Autobahn. Winterset, please look and see which cooler on your radiator isn't used. If the left tank has plugged cooler lines, you have an extra transmission cooler. If the right one has plugged cooler lines, you have an outside oil cooler. Frankman, checking for which set of cooler lines is plugged or isn't there in your radiator might be easier than trying to follow hoses under the car.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Some people get the towing package so that they have a heavy duty transmission, radiator, and brakes. But, the Northstar already has all these things because it's designed to run with the big dogs on the Autobahn. Winterset, please look and see which cooler on your radiator isn't used. If the left tank has plugged cooler lines, you have an extra transmission cooler. If the right one has plugged cooler lines, you have an outside oil cooler. Frankman, checking for which set of cooler lines is plugged or isn't there in your radiator might be easier than trying to follow hoses under the car.

I have auxilary transmission oil coolers on my cars - even the ones that do not do any towing. The trans. fluid is pre-cooled in the radiator side tank and then passes through the auxilary cooler prior to returning to the transmission.

The factory cooler setups are just like I described above - it is not a case where the radiator tank heat exchanger is deleted if there is an auxiliary fluid cooler.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Double cooling! Interesting. At least one of the hoses will be short, to a radiator tank, if Frankman has a double cooler. So, check the radiator tank fittings and see which one has a hose going forward, not backward, or has plugs instead of fittings and hoses. Right side, the Hayden cooler is an oil cooler, but left side, it's a transmission fluid cooler.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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