W124 Climate Control Vacuum Valve Repair DIY - Page 3 - PeachParts Mercedes-Benz Forum

Jeremy5848 · #31 06-27-2013, 11:46 AM

Quote:

Originally Posted by Zulfiqar

If your valve is faulty - locate any other valve and do a gut swap, similar with the pump, MB made this certain assembly on a modular design (i honestly think an intern was appointed and yelled at constantly while making it)

the elbow piece that leaks looks like it was tacked on later, its not part of the original mold - mine actually broke off and I did a very careful and neat repair on it - The only plastic bond is between a very thin collar on the inside. I use the radiator tank repair kit on it (its very very hot when mixed)

I think they used a separate subcontractor for the elbow piece -- the plastic looks different. Definitely not the quality we're used to.

I picked up a radiator repair kit yesterday at the local NAPA store . . . thanks for the "hot" warning . . . and have the cracked elbow piece removed for cleaning and sanding. Will reassemble before applying the epoxy and Fiberglas® so I don't get glue on the sealing surfaces. I might use a cable tie to keep the wrap tight around the elbow piece while the epoxy sets up. Will post pictures when it's done.

Jeremy

Jeremy5848 · #32 06-27-2013, 11:29 PM

Here are some pictures of the valve repair process using the "radiator repair kit" from the auto parts store. The kit I bought was NAPA part number 765-1544, which sells for about $20. That's a lot for a piece of Fiberglas® fabric and an epoxy glue package but a lot less expensive than a new valve/aux pump.

The glue will stick a lot better if you use the sandpaper in the kit to rough up the plastic surface of the cracked part of the valve. To make it easier to handle I took the valve apart and cut a strip of sandpaper.

Once the plastic surface was roughed up, I blew off the dust, rinsed off the plastic with alcohol, and put the valve back together.

With the assembly lightly clamped in a vice, I mixed some of the epoxy (I used only part of the package) and wrapped an epoxy-soaked strip of Fiberglas® around the valve. The epoxy has a very short working life (only a few minutes) so you have to work fast. When the epoxy starts to cure it gets very warm and that's your signal that your time is up.

By the time I had the Fiberglas® wrapped around the valve the epoxy was starting to harden and I had to mix a second batch to smear on top. I was glad I hadn't mixed all the epoxy at once.

I'm going to give the epoxy 24 hours to completely cure (the kit says 20 minutes) before installing the valve in the car. I'll post results.

Jeremy

freesoul · #33 07-01-2013, 01:17 PM

I stopped by our local indy shop on Saturday- the guy who runs the place said to take the valve off by the 4 screws and if the diaphragm is torn there is a rebuild kit that is 1/3 the price. When I did that it was not torn, so I think I need a new one. I cleaned up all the electrical contacts and hoped it would work but it still pushes hot air into the cabin with the AC on...

Zulfiqar · #34 07-01-2013, 01:21 PM

try smacking the valve lightly with a hammer, when I bought my car it was stuck - aka no heat, one tap and it worked thereafter.

Also this is one of a reason to use the correct BASF Glysantin (ZerexG05) coolants in our cars, its quite slick and keeps moving parts moving.

gsxr · #35 07-01-2013, 01:36 PM

Quote:

Originally Posted by freesoul

I stopped by our local indy shop on Saturday- the guy who runs the place said to take the valve off by the 4 screws and if the diaphragm is torn there is a rebuild kit that is 1/3 the price. When I did that it was not torn, so I think I need a new one. I cleaned up all the electrical contacts and hoped it would work but it still pushes hot air into the cabin with the AC on...

I'm not aware of a rebuild kit for W124 valves, only the old W123 valves...

freesoul · #36 07-01-2013, 01:58 PM

Quote:

Originally Posted by Zulfiqar

try smacking the valve lightly with a hammer, when I bought my car it was stuck - aka no heat, one tap and it worked thereafter.

Also this is one of a reason to use the correct BASF Glysantin (ZerexG05) coolants in our cars, its quite slick and keeps moving parts moving.

I'll try that but like I said mine has been leaking since I bought it 4 years ago. I also used the green stuff last year, going to flush it now and put the recommended fluid in.

Jeremy5848 · #37 07-01-2013, 02:07 PM

Quote:

Originally Posted by freesoul

I stopped by our local indy shop on Saturday- the guy who runs the place said to take the valve off by the 4 screws and if the diaphragm is torn there is a rebuild kit that is 1/3 the price. When I did that it was not torn, so I think I need a new one. I cleaned up all the electrical contacts and hoped it would work but it still pushes hot air into the cabin with the AC on...

The monovalve used in W123 cars had a rebuild kit but that is no longer available (sold out ~2007). There was never a rebuild kit offered for the monovalve in the W124 model.

You can test the solenoid with the monovalve taken apart or even with it still in the car; momentarily touch 12 volts to the terminals (polarity does not matter -- I just tested mine) and you should get a firm and obvious "thunk" as the solenoid pulls the metal cylinder up into the coil. The connection you make with your jumper wires should spark a little.

If you do not get a "thunk" and do not see a little sparking then the solenoid may be burned out. You can test it with an Ohmmeter; the DC resistance of a good solenoid is about 12 Ohms. AFAIK all W124 monovalves use the same solenoid; you should be able to get a monovalve (whether the kind combined with the aux pump like ours or the ones with the separate valve and pump) from a junkyard 124 or from a forum member who sells such stuff and rob the solenoid from it.

If the solenoid seems to be working but you still get heat when you don't want it, try clamping off the hose that comes out of the aux pump and goes to the thermostat housing. This hose is on the other side of the inner firewall near the coolant expansion tank. Use padded vice-grips to clamp that hose and the flow of coolant will be shut off. If that stops the heat then the valve is definitely leaking.

Unfortunately the valve in the '95 E300 is unique to that one model because it is a two-way valve (a very few late 1993 model year 300D-2.5 cars used that valve too). Here's a picture of the monovalve taken apart:

Some of the rubber parts may be common with other 124 monovalves but I'm afraid that if yours indeed has a leak rather than a stuck solenoid you may have no choice but to replace the entire assembly.

Jeremy

freesoul · #38 07-01-2013, 02:19 PM

Quote:

Originally Posted by Jeremy5848

The monovalve used in W123 cars had a rebuild kit but that is no longer available (sold out ~2007). There was never a rebuild kit offered for the monovalve in the W124 model.

You can test the solenoid with the monovalve taken apart or even with it still in the car; momentarily touch 12 volts to the terminals (polarity does not matter -- I just tested mine) and you should get a firm and obvious "thunk" as the solenoid pulls the metal cylinder up into the coil. The connection you make with your jumper wires should spark a little.

If you do not get a "thunk" and do not see a little sparking then the solenoid may be burned out. You can test it with an Ohmmeter; the DC resistance of a good solenoid is about 12 Ohms. AFAIK all W124 monovalves use the same solenoid; you should be able to get a monovalve (whether the kind combined with the aux pump like ours or the ones with the separate valve and pump) from a junkyard 124 or from a forum member who sells such stuff and rob the solenoid from it.

If the solenoid seems to be working but you still get heat when you don't want it, try clamping off the hose that comes out of the aux pump and goes to the thermostat housing. This hose is on the other side of the inner firewall near the coolant expansion tank. Use padded vice-grips to clamp that hose and the flow of coolant will be shut off. If that stops the heat then the valve is definitely leaking.

Unfortunately the valve in the '95 E300 is unique to that one model because it is a two-way valve (a very few late 1993 model year 300D-2.5 cars used that valve too). Here's a picture of the monovalve taken apart:

Some of the rubber parts may be common with other 124 monovalves but I'm afraid that if yours indeed has a leak rather than a stuck solenoid you may have no choice but to replace the entire assembly.

Jeremy

So the solenoid is the part cut off in the top of your photo? and it that the leads that I should put 12v to?

How does the valve work exactly- does the current push the valve up which pulls the pointy thing out of the way and allows the coolant to flow?

Jeremy5848 · #39 07-01-2013, 03:41 PM

Quote:

Originally Posted by freesoul

So the solenoid is the part cut off in the top of your photo? and it that the leads that I should put 12v to?

How does the valve work exactly- does the current push the valve up which pulls the pointy thing out of the way and allows the coolant to flow?

The part cut off in the photo is the motor for the aux pump which in the '95 E300 is made as a unit with the monovalve. The monovalve solenoid is on the left in the photo. The 1995 E320 (possibly also 1994) has a similar combined valve/pump but it has different plumbing and does not replace the E300 version, alas (I own one).

The solenoid pulls the brass pointy valve up, yes, allowing coolant to flow through the heater core. Notice also that the middle of the valve assembly also has a brass pointy thing pointing in the other direction. When the solenoid is not energized, that section allows coolant to flow through the bypass line (runs behind the engine, in parallel with the circuit through the heater core).

The idea is that there will always be coolant flowing out of the back of the head, whether through the heater core or through the bypass line, and returning to the thermostat housing on the right front of the block. My guess is that this helps keep the head at a constant temperature, which helps smog control.

If this were a electric switch it would be generically called "SPDT" for "Single-Pole Double-Throw." I can't think of a plumbing analogy.

Jeremy

freesoul · #40 07-01-2013, 03:56 PM

Quote:

Originally Posted by Jeremy5848

The part cut off in the photo is the motor for the aux pump which in the '95 E300 is made as a unit with the monovalve. The monovalve solenoid is on the left in the photo. The 1995 E320 (possibly also 1994) has a similar combined valve/pump but it has different plumbing and does not replace the E300 version, alas (I own one).

The solenoid pulls the brass pointy valve up, yes, allowing coolant to flow through the heater core. Notice also that the middle of the valve assembly also has a brass pointy thing pointing in the other direction. When the solenoid is not energized, that section allows coolant to flow through the bypass line (runs behind the engine, in parallel with the circuit through the heater core).

The idea is that there will always be coolant flowing out of the back of the head, whether through the heater core or through the bypass line, and returning to the thermostat housing on the right front of the block. My guess is that this helps keep the head at a constant temperature, which helps smog control.

If this were a electric switch it would be generically called "SPDT" for "Single-Pole Double-Throw." I can't think of a plumbing analogy.

Jeremy

how does that brass pointy thing allow coolant to flow when it is not directly connected to the solenoid?

I will try the troubleshooting you related above, thank you!

So I guess if I buy the new monovalve I end up getting the whole shooting match in your photo above.

gsxr · #41 07-01-2013, 04:26 PM

Jeremy, I thought the monovalve closes when not energized... therefore defaulting to max heat if there is no electrical signal. So when energized, it should block off the hot coolant flow. Right?

Disclaimer: I've never taken one apart to experiment with.

freesoul · #42 07-01-2013, 05:12 PM

the monovalve is only $95, I will have it tomorrow

Jeremy5848 · #43 07-01-2013, 05:14 PM

Quote:

Originally Posted by gsxr

Jeremy, I thought the monovalve closes when not energized... therefore defaulting to max heat if there is no electrical signal. So when energized, it should block off the hot coolant flow. Right?

Disclaimer: I've never taken one apart to experiment with.

Correct, I had it backwards.

Jeremy5848 · #44 07-01-2013, 05:16 PM

Quote:

Originally Posted by freesoul

the monovalve is only $95, I will have it tomorrow

It will be interesting to see what you get for $95. The correct factory part, 001-830-40-84, is closer to $500. Please keep us informed.

Jeremy

freesoul · #45 07-01-2013, 06:27 PM

Quote:

Originally Posted by Jeremy5848

It will be interesting to see what you get for $95. The correct factory part, 001-830-40-84, is closer to $500. Please keep us informed.

Jeremy

maybe its just the valve and not the whole assembly? The guy has been around forever, German guy with thick accent thats why I stopped in last Saturday with a photo. His son usually handles the parts but he is on vacation