Finishing Samson the M120 R107 - Page 4 - PeachParts Mercedes-Benz Forum

vwnate1 · #46 04-17-2020, 02:45 PM

You're making very good use of this down time .

Roncallo · #47 04-20-2020, 09:03 AM

Quote:

Originally Posted by vwnate1

You're making very good use of this down time .

Just waiting for an air pump and my manifold to come back from plating. Then I can assemble.

If the plague lasts I might be able to get a 6 speed manual trans installed.

Roncallo · #48 04-21-2020, 01:01 AM

Progress report for today. While I had the subframe out, I decided to address a few issues and naturally as you address one issue you find three more. In any case my diverter valve I call it some call it a gulp valve, Mercedes calls it a check valve for the air pump went out several months ago. Since that is one of those parts that requires removal of the subframe to replace I just disconnected the air pump relay for the moment. Unfortunately while the pump was disconnected with a bad valve, exhaust was now being routed into the air pump. Consequently the air pump was frozen solid. So I got a message from UPS today, the air pump is scheduled for delivery tomorrow. Of course I also ordered a new valve and that came in Saturday.

I also had oil leaks which appeared to be the front seal and the oil level sensor. I did the front seal a few weeks ago, pulled the pan and replaced the level sensor seal today. When I pulled the pan I found several large, non magnetic, metallic chips in the pan see picture. These chips do not look like anything wearing. they actually look like drilling chips that Mercedes did not get out after final machining of the block. Needless to say next time I change the oil I will be sending it out for analysis.

Another issue I had was a chaffing sheath for the wire going to the oil pressure sender. After removal of the sheath, alternator and oil level sender wires, I realized that the biodegradable wires Mercedes allegedly fixed by 1996 did not happen on this car for that harness. So I repaired the part of the wires that I could get to and replaced the sheath. But who knows what is further up the harness. Fortunately that harness is not too expensive and looks like it may still be available for about $210. It also looks like I wont have to pull the subframe to get at it. Hopefully the replacement wires are made with the good stuff.

I have also been well aware that the replacement of the air pump and alternator require dropping the subframe. While I was taking these parts out I thought of way to redesign the mounts to that at least the air pump could be removed without dropping the subframe and maybe if I'm lucky the alternator as well. The original pump alternator mount was a weldment. I have now taken the opportunity to redesign it so that the front plate comes off and allows access to the air pump and possibly the alternator from the front. That wont be going on for this time but I will probably make it in the near future and install at the next opportunity.

So now wiring is fixed for the moment, leaks are all addressed and this week the air pump and AC manifold will arrive and be installed. That will at least give me back a running car. Next step will be to hook up the controls, which should be fun. It will also be an opportune time to replace the bad wire harness.

pic 1 - Chips found in oil pan
pic 2 - oil pressure sender wire sheath
pic 3 and 4 - bad wires.

Roncallo · #49 04-23-2020, 12:49 AM

Compressor is now in. I didn't do in without a fight. I had to press a pilot bushing into the manifold. With that pilot bushing installed the brace I made for the tubes would not clear the manifold to install it. I had to cut the brace and weld on a tab for a screw, making the brace a two piece unit. That's done and the test fit went OK now the compressor is back out so those parts could be painted and the compressor and manifold will the reassembled and tested for leaks before the subframe goes back in. So still a ways to go. I also tried out my AC line fitting crimper which I will be using shortly. That works very well.

vwnate1 · #50 04-23-2020, 12:13 PM

What you are doing here is the very essence of Hot Rodding, I enjoy seeing how you address each situation .

Roncallo · #51 04-24-2020, 01:49 AM

Vacuum and pressure testing of manifold and compressor assembly before installation is now complete and passed test successfully. So I went ahead and did the final installation of the compressor and subframe. Next is to reinstall the power steering pump and button up the engine. Then it gets down to the final fitting of the rest of the AC components. I will need to test the Aux fan as it hasn't been run in 13 years.

Roncallo · #52 04-24-2020, 01:53 AM

Quote:

Originally Posted by vwnate1

What you are doing here is the very essence of Hot Rodding, I enjoy seeing how you address each situation .

Well I try. Years ago the focus was on getting the car running. Now the focus is on getting all the systems in place that weren't addressed at the time. AC will be a major milestone and really is the most difficult challenge with the lack of space available.

vwnate1 · #53 04-24-2020, 02:33 AM

What's in the large black bottle with two gauges ? .

Roncallo · #54 04-24-2020, 07:29 AM

Quote:

Originally Posted by vwnate1

What's in the large black bottle with two gauges ? .

That's Argon from my TIG welder. I used it to pressure test the compressor and manifold assembly.

vwnate1 · #55 04-24-2020, 01:43 PM

I didn't know you could use Argon .

Thanx .

Roncallo · #56 04-24-2020, 03:02 PM

Quote:

Originally Posted by vwnate1

I didn't know you could use Argon .

Thanx .

Most AC professionals use N2 because its the cheapest noble gas. But really for pressure testing you can just use air. I use Argon because I had it available in a source that I have for my welder and I can get 200PSI from.

Roncallo · #57 04-28-2020, 02:07 AM

Electrical hell is about to begin. So while I was down waiting for parts, I decided to take a look at the wiring diagrams. It turns out that in order to turn the compressor on, I need a signal from the N6 compressor relay or as some call it the "Klima relay". The challenge is the N6 relay needs inputs from the fuel pump relay and the idle control module. I believe the idle control output just gives it the engine RPM signal which is easy. The fuel pump relay I'm not sure, I believe that is just +12V but who knows it might be + 5V. I will need to figure out some way of faking it, but I would like to understand what it needs and why. Then there is the cold engine lockout switch. The M120 does not have one so, I may just have to install an ambient temp switch so I don't turn on the AC when its -20° out.

vwnate1 · #58 04-29-2020, 05:43 PM

Well ;

In fact running the AC in the defrost mode clears the windows *much* faster, that's why all modern vehicles set it up like that .

In any case, I see no real purpose to retain the cold lockout .

Just wire it via a relay via the ACC. circuit so the relay will kick out if you start the car on a hot day........

Roncallo · #59 05-02-2020, 01:49 AM

So the past several days I have been evaluating the electrical systems of both the 107 and the 129. Turns out, I have everything in place to use the R129 electrical system and only need to connect one wire to the Evaporator Temperature Switch. Of course finding the end of that 1 wire requires removal of the dash and possibly the heater box. So for now I will connect it to the beginning of the wire at the pressure switch on the Receiver Drier. So electrically that is all that remains to be done. I will go down to the auto parts store and pick up some 18 ga wire and complete the wiring task. Mean while my AC fittings just shipped and my Freon is due in today. I have enough confidence with my compressor installation that I will be reinstalling my front end as well. I can see the light at the end of the tunnel.

vwnate1 · #60 05-02-2020, 01:26 PM

Great ! .

What will you use as a charge, R12 or R134a ? .