I need to replace the automatic transmission cooler hoses on my ’99 ML 430. Questions:

1.) With the engine off, are the hoses pressurized?
2.) Will I loose more ATF fluid than what is in the hoses?
3.) What is the easiest way to loosen the fan shroud so I can access the cooler hose connections by the radiator?
4.) What is the correct way to check the fluid level once the hoses are installed?
5.) Any other tricks in doing the hose replacement correctly?

-Thank you very much-

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Jim Herold--Current: 1987 190E 16V, 1999 ML 430--Past: 1971 280 SL, 1972 250

initially yes, then once it settles, no
You will need about a quart to get back to the correct level
remove the fan first, remove the two 10mm bolts at the lower left and right sides and pop off the clips that the bolts screw into. then wiggle the shroud and play with it a bit to get it out around the assorted fittings attached to the radiator, it will come out without removing any of them.
with the dipstick when fully warmed up
you'll need 6 crush washers as well, good luck. dont overtighten the lower fitting into the radiator other wise you can pop the collar off inside the radiator and then you'll be in need of a new one.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

I was able to get information from a number of people on and off this site, which I very much appreciate. To return the favors and maybe help someone else, here is my report on a completed job:

Johnhef was right on with his responses above. Hoses were not pressurized and the ATF fluid loss measured very close to 5 ½ oz.

My first step was to get the fan shroud out of the way to provide clearance to the cooler line fittings on the passenger side of the radiator (banjo on top and flare on the bottom). Once I removed the metal section running lengthwise under the radiator, I could access the two 10mm bolts, one on each side of the bottom of the fan shroud. With these bolts and their clips removed, I could pull/loosen the fan shroud from its upper attachments and shift it to the driver’s side enough to get working room.

The banjo fitting near the top of the radiator is fully accessible as are the two at the transmission. However, Murphy’s Law dictates that there will always be at least one trouble spot. The lower cooler line connection at the radiator is a little tricky to access. It is also the most difficult to seal and caution is advised to not over tighten. I had my ML on axle stands with the right front wheel removed. I removed 5 of the plastic nuts and pulled back the front portion of the plastic fender lining. This provided wrenching access to the lower cooler line flare fitting at the radiator.

Much to my surprise, all the connectors I worked with were SAE and not Metric. I found the best fit was a 1 ¼” open end wrench (not 32 mm)to keep counter pressure on both radiator connections while loosening and tightening the two AT cooler line couplings themselves. My best fit for all three banjo fittings, one at the radiator and two at the transmission, was a ¾” socket. A 5/8” open end wrench perfectly fit the lower flare fitting at the radiator. Again, I used a 1 ¼” wrench to provide counter pressure while I removed and tightened both fittings at the radiator. I know my ML was made in America, but I didn’t expect SAE fittings.

My local dealer quoted over $450 labor for this job and much more for the ATF cooler line assembly than I paid. In the scale of projects, this was not difficult.

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Jim Herold--Current: 1987 190E 16V, 1999 ML 430--Past: 1971 280 SL, 1972 250