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Old 09-01-2003, 11:58 PM
Phalcon51 Phalcon51 is offline
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Join Date: Jun 2002
Location: Monrovia, CA
Posts: 490
Just finished the job of replacing the expansion valve, receiver-drier and the entire A/C Manifold/Hose Assembly - what a chore!

Once I took off the vacuum line holder behind the brake booster it made it just barely possible to get both sets of fingers back to the exp. valve to remove the bolt and then the two 3mm allen screws. The new valve uses a stud and nut instead of a bolt and, sure enough, I lost the first nut down under the brake booster, never to be seen again. It's a little tricky getting the nut started, but once you do it goes together easily. The receiver-drier is a no-brainer and easy to get at.

For anyone who replaces the A/C hose assembly with the fuel cooler on an early 300E, plan to spend the better part of the day at it. And here's a tip - before you start, take off your gas cap, and make sure you have a 27mm open end wrench. One of the first things I did was to get under the car and disconnect the fuel lines from the fuel cooler on the old A/C hose. I routed the inlet hose upward so it was at the highest level it could be, well above the level of fuel in the tank. As the morning progressed, I realized that I needed to go buy a 27mm wrench, so off to Sears I went. When I got back about 45 min. later, there was a very strong smell of raw fuel in the driveway. I looked under the car and there was about a 3 ft diameter puddle of gas and more dripping all the time. Seems that as fuel heats up in a closed container, it expands - gee, who woulda thought? As soon as I popped off the gas cap, the gas stopped leaking, but the damage had already been done to my asphalt driveway. It just ate away about 1/2 to 3/4 inch from the surface of the asphalt, and now it's real crumbly, so be warned.

It was a bit of a job to get the new hose in place as the bends were slightly different from the original as well as having a small chamber near the cooler that the original one didn't have. It's already crowded under there and this just made it a little more difficult. The hardest part was routing the pipe to the condensor. The bend was a little different, the bracket that bolts it to the inner fender didn't quite line up and the pipe interfered with my trans cooler lines that I installed last summer. I also had to reshape the plastic shield that mounts just to the left of the radiator as the new pipe fouled it and wouldn't let me remount it in it's original position without grinding some additional clearance in it

But all in all, I'm glad I did it. I saved probably four to five hundred dollars easily in parts and labor over dealer prices and at least I know the job is done right. BTW, someone in a reply to an earlier post I made suggested a product called Nylog for sealing all the o-rings and threaded couplings. I went out to my local friendly refrigeration supply house and bought a 30ml bottle of Nylog Red Label (for R12) for a whopping $4.85. This is probably a lifetime supply for me. You use just a little bit at each junction and it looks like it will probably seal better than anything else I've seen. It's basically a mineral oil base with something added that makes it thin but very stringy. You apply it to threads by touching it one spot then wrapping it around. Neat stuff. Has a shelf life of about forever. There's more information about it here:

That's it for now. Next weekend I'm replacing the parking brakes and rear discs. Should be a cinch after this.

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