Got a 1985 300D turbo - Page 9 - PeachParts Mercedes-Benz Forum

vwnate1 · #**121** 11-12-2018, 07:11 PM

"It isn't magic, it's thermodynamics!"

.

Thanx, I'm trying to work up my nerve to take the plunge but I have 30 + dead Motocycles, a '59 VW, my pickup truck, my Metropolitan Nash FHC and my Morris Minor all waiting and I know I can fix all they need.....

ykobayashi · #**122** 11-16-2018, 09:18 PM

Ok, well I feel like an idiot. I just replaced my monovalve diaphragm with one from an MTC valve. Didn’t work. It leaks worse than before. I have 12v at the monovalve but it is still leaking. Clicks fine.

Just a warm air coming out of vents. Sigh.

Ok, so that’s what I get for paying $20 for a cheap monovalve. Time to get an expensive Bosch one.

Diseasel300 · #**123** 11-16-2018, 10:00 PM

If your original core wasn't all corroded, transfer the diaphragm from the MTC onto the OEM Bosch cartridge. You'll have the spring and plunger from a proper monovalve cartridge with fresh rubber.

ykobayashi · #**124** 11-16-2018, 11:41 PM

Quote:

Originally Posted by Diseasel300

If your original core wasn't all corroded, transfer the diaphragm from the MTC onto the OEM Bosch cartridge. You'll have the spring and plunger from a proper monovalve cartridge with fresh rubber.

Hi,

I actually tried this. The MTC out the box didn’t move at all when energized. So I put all the rubber on the old plunger. This leaked...or at least I think it is. On vents the air gradually warms up. Gets pretty toasty. The valve clicks fine.

My guess is that small dimensional differences (MTC screen looks shorter) are preventing a seal. But I won’t be shocked if I’m wrong. I have an mb unit on the way.

Diseasel300 · #**125** 11-17-2018, 10:23 AM

Possibly a dumb question - where do you have the temp wheel set?

ykobayashi · #**126** 11-17-2018, 06:41 PM

Quote:

Originally Posted by Diseasel300

Possibly a dumb question - where do you have the temp wheel set?

I tried moving the temp wheel all over. When I tried to close the valve it was on MIN aka max cold. I did try moving it to heat and watching the voltage on the valve and it indeed does change. On Min I’m getting 12V and the valve clicks when I connect and disconnect the plug. I can zero the voltage by rolling the wheel to the hot side.

The the bench I can get the valve to click and throw the pintle with a power supply. What I haven’t tried is pulling the entire valve out of the car and blowing through it while applying 12V. It may come to that if the MB part doesn’t work.

The good news is I took your tip and opened the glove box liner and checked the recirculated air flap operation this morning. Works great. And it flips when I push the buttons so I think everything is working as it should...that is the signals from the ACC are coming out on the wires and the vacuum is getting to non. Leaking pods.

But alas I have that balmy air coming out of the vent. I will get my new monovalve next week and report back the result. If that doesn’t work I’m ready to put a ball valve inline with the thing and call it a day.

ROLLGUY · #**127** 11-17-2018, 06:46 PM

Quote:

Originally Posted by ykobayashi

................................
The the bench I can get the valve to click and throw the pintle with a power supply. What I haven’t tried is pulling the entire valve out of the car and blowing through it while applying 12V. It may come to that if the MB part doesn’t work.

I would suggest installing the monovalve in a spare housing, rather than pulling the one from the car.

vwnate1 · #**128** 11-17-2018, 07:37 PM

O.K. ;

IIRC I incorrectly assembled the monovalve and caused it to never quite seal closed, it didn't leak but I got warm AC much of the time, is there a picture of how the parts are supposed to assemble ? .

Then, I've heard about this air re-circulation flap actuator, is there a picture of it in situ and also some details of when it's supposed to open and which cute little relay should I test ? .

TIA,

ykobayashi · #**129** 11-21-2018, 05:04 AM

Quote:

Originally Posted by vwnate1

O.K. ;

IIRC I incorrectly assembled the monovalve and caused it to never quite seal closed, it didn't leak but I got warm AC much of the time, is there a picture of how the parts are supposed to assemble ? .

Then, I've heard about this air re-circulation flap actuator, is there a picture of it in situ and also some details of when it's supposed to open and which cute little relay should I test ? .

TIA,

Hi,

I don’t have a photo of the valve. I just slipped the rubber parts on like the one I removed. I have the new MB valve on the bench. It’ll go in at some point this week.

Check the dmorrison posts for photos of the recirculating flap. It can be checked for operation through the glove box opening. I just flip on the AC on MIN and it slowly closes.

vwnate1 · #**130** 11-22-2018, 08:23 PM

Thank you .

I have taken so many monovalves apart and they're always in different assemblies....

I'll hopefully yank the glovebox out and take a peek soon, there are two vacuum elements visible, I'll just see if either moves .

I just got a delivery from the Machine Shop so I may well be busy away from my W123's for a while.....

ykobayashi · #**131** 11-23-2018, 12:26 PM

New MB OE valve doesn't leak. It was that easy. Just spend the $130 and all is well.

Here is a photo of my "rebuilt" valve that leaked along with my MB OE valve from Pelican. They both look good, but the rebuilt one just puts warm air out the vent. The good one is on the left.

Happy now. I'll have to test my AC temps today. But...my thermometer got repoed last night for the Turkey.

I'll have to hunt for it now.

Strange, both valves look about the same. Some people have good luck using the stock Bosch plunger and putting the new MTC rubber on it but no such luck for me. Oh well, I'm pretty happy that I have a good monovalve, working center vent, functional ACC, charged compressor, working Klima relay. I think I'm going to have to start driving this car now!

vwnate1 · #**132** 11-24-2018, 11:37 PM

Looking at the rubber parts I can clearly see major differences .

I may have to go buy an OEM one too, sigh .

ykobayashi · #**133** 11-27-2018, 03:01 PM

Awww man. My AC hose under the engine is weeping a little oil. I think it was depressurized so long it dried off and looked okay when I got the car. But now, it looks like I need a section of hose. Or more.

Oh boy, more projects. The good news is small amounts of barrier hose can be bought cheap on eBay and the crimp tools can be had for a song a long with half a dozen crimp ferrules. My gut feel is I can get all the stuff I need to rebuild all the hoses for less than $200. A lot cheaper than new hoses...which are not widely available for the 1985 300d California.

I’ve read up on the threads here on hose rebuilding and there is clearly a path forward. In the meantime my system is still holding pressure and blowing cold air.

Not looking forward to disassembling the AC lines bolted to the top and bottom of the engine. It looks almost as bad as taking off the oil cooler lines. But a little patience and stubby ratchets go a long way with these things.

I will probably use the same hose to fix my weeping oil cooler lines as well.

Right now the car is pretty drivable.

ROLLGUY · #**134** 11-27-2018, 04:58 PM

Quote:

Originally Posted by ykobayashi

Awww man. My AC hose under the engine is weeping a little oil. I think it was depressurized so long it dried off and looked okay when I got the car. But now, it looks like I need a section of hose. Or more.

Oh boy, more projects. The good news is small amounts of barrier hose can be bought cheap on eBay and the crimp tools can be had for a song a long with half a dozen crimp ferrules. My gut feel is I can get all the stuff I need to rebuild all the hoses for less than $200. A lot cheaper than new hoses...which are not widely available for the 1985 300d California.

I’ve read up on the threads here on hose rebuilding and there is clearly a path forward. In the meantime my system is still holding pressure and blowing cold air.

Not looking forward to disassembling the AC lines bolted to the top and bottom of the engine. It looks almost as bad as taking off the oil cooler lines. But a little patience and stubby ratchets go a long way with these things.

I will probably use the same hose to fix my weeping oil cooler lines as well.

Right now the car is pretty drivable.

You will need to weld on barbs to the existing hard lines, as the hose is not the same (metric) as what is available now. I can make all the hoses for you for less than the cost of the tools and supplies. The new discharge hose will go over the top, not down underneath. You will also need a W116 R4 manifold (I have one). Of course it will involve evacuating the system, so you may want to wait till next season to crack it open. By then, all the refrigerant may leak out anyway. The oil cooler lines using A/C hose is fine, I have done it this way, and there is not enough pressure to cause a problem.

ykobayashi · #**135** 11-28-2018, 12:12 AM

Wow Rich that is a generous offer.

I’ve read your posts warning about crimping over the steel ends of the lines without barbs. Those barbs are hard to find in 15mm. I had read BillGrissom’s post and thought I’d take my chances crimping to the steel pipe ends with Oetiker clamps. I noted you disagreed with this approach.

My system is still holding some pressure and blowing cold. I suspect it’ll be gone soon. The pressure is down 10psi from when I filled it a few weeks back.

I saw your over the top hose in the white car on Craigslist yesterday. Looks good.

Why is the w116 R4 manifold required? I’m filling with R134a.