I've got a few more questions before I tackle the job of replacing the compressor and flushing, refilling with r12 this weekend.

When I took my 300cd in for evacuation of the r-134a and new valve cores, the old valve cores were covered in black funk. That definitely means the compressor seized and puked throughout the system. I now have the correct r12 mineral oil, and a quality flush agent as well. Got these from an A/C shop open since 1954, they should know what they're doing. They said I didn't need a flush gun, that I would pour in the solvent, and blast it out with my air compressor. I have a good dried/filtered air compressor so that should work. I have a few hoses to attach to the evaporator hoses so I can flush through there too. I also have the r12 and a vacuum pump/gauge station. I'll take out the Condenser to a car-wash place to blast it clean (the outside of it). I'll take the old o-rings to a parts place to match up with new ones.

Just got my new Delco R4 compressor in the mail today. It came with the stepped ports, Im wondering if I have the correct sealing rings for the job. I think people use the fat yellow ring for the Suction hose, and the green one for the Discharge. The delco manual says this is the correct configuration for compressors with 3/4" suction and 5/8" discharge ports, which is what the MB uses, right?

Replacing the R4 won't be fun. This new Delco has a smaller clutch than the other one in the car so it'll be further away from the oil cooler hoses. I think I have to remove the PS pump belt to get the compressor belt off? Still confused about the belt situation, there should be an adjusting nut on top of the compressor to loosen/tighten the belt, and loosen the compressor bolts to move the belt?

As for flushing, I'll break the lines to and from the drier, to and from the condenser, remove the expansion valve to expose the evap. lines and the two other ones, break the line where the low side valve is, the line where the high side valve is, and the suction/discharge from the compressor, and flush those out well. Am I missing anything? Diesel Giant has a decent guide on this rebuild.

The new Delco r4 has a shorter clutch than the older one in my car. So I'll have to set the spacers differently, or adjust the belt up or down?

Tips/tricks on compressor removal and other things are appreciated before I screw up tomorrow trying. I have the whole weekend to do this though.

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1980 240d
1999 SL500

A flush gun would be better. A pulsating flush gun would be best. But you can do it that way. It would be better if you can remove the evaporator from the car, so you can change its attitude during flushing and purging. Otherwise, you are not going to be able to "pour it in" very effectively. I don't know if removing the evaporator is an option for your car; it sure was not for my W210.

When purging, I found that I had to connect an air dryer right next to the part or I was getting water that condensed in the air hose. The idea is to get the liquid out, not put more in. Nitrogen would be best, but I don't have any.

You'll find a guide that is much better than Diesel Giant's here: http://hecatinc.com/flushing_tech_article.htm

Good luck derburger, I have been following this project few a few threads. I am still hoping to start on Sunday on the wagon, but my 240D ignition tumbler decided yesterday was its last


So, hopefully my new tumbler will be in tomorrow and I can be done with that before I start on the AC.

If you are changing the belt you do have to remove the PS belt. Otherwise, you can just remove the end from the old compressor.

I am using a flush gun - it was $25 from a supplier on ebay. seems like a small price to pay considering all the other expense!

How much was your mineral oil? Did you decide to go with mineral oil or Frigiquiet?

Are you going to bump the clutch to distribute the oil?

Good luck! Take pics and post them ASAP so others (like me) can benefit!

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

I bit the bullet and bought a $225 pulsating flush gun. It sends rather violent pulses of fluid through the system, helping to dislodge crud. It does work very well, but I admit that most people wouldn't pay so much for a tool that they only expect to use a few times.

I'm considering purchasing one of the pulsator flush systems.

I have been struggling with a '94 Prelude and will be going through it again this weekend. This time I have another compressor, a new discharge pipe (dryer and evaporator) and evaporator. The condenser has already been replaced. I've been having a hard time getting all the little balls out of the system.

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Jim

I bought the Mineral oil from the guy who owns the 50 year old A/C shop. McParts places would have Mineral oil but I wanted the best possible for the job. It was 10 dollars for a quart, flush was $10 for more than a quart too.

The A/C guy says alot of people don't cycle the clutch by hand 10 times before starting the system, and that "hammers" the compressor (and runs it without oil) and it takes alot out of the life of the compressor. So put oil in it and turn it by hand when it's on the car, then bump a few times before putting refrigerant in to make sure the oil is circulated correctly.

Without a flush gun, the hard part would be flushing the evaporator, but I have a hose to connect to the evaporator, where I can put flush in and blow compressed air through. If it's too difficult without one, I'll go to a Mcparts and pick one up. The A/C guy said it wasn't really necessary. Otherwise a funnel and lots of compressed air works fine. I got the old "good stuff" (environment destroying) solvent for flushing that evaporates really fast so it'll help.

Little balls, little metal shards . I have to flush the system really really good. If I screw up or can't flush something, or can't turn the compressor the A/C guy said he was happy to help. I'll take plenty of pictures of my progress this weekend.

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1980 240d
1999 SL500

To save a big mess inside the car, drill out the restricted side of the old expansion valve (surely you are replacing it!!!) then reinstall it. That way, you can flush the evaporator from under the hood.

I strongly agree that a flush gun is not necessary.

"By hand" usually means with a clutch holding tool. It's typically not possible for the average person to rotate a new compressor "by hand."

I can spin the new compressor by hand. Wouldn't I have to engage the clutch for the turning to actually do anything? I think I'm just spinning the clutch disk without it engaged.

I am replacing the expansion valve. Where would I drill it so I could flush from under the hood? Not too familiar with the part, it's 4 connections with a sensor of some sort inside. And if I drill it then where would I flush it from? It would seem to be much less of a hassle and a mess than flushing inside the car. Thanks for the replies.

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1980 240d
1999 SL500

You are just spinning the freewheeling pulley. A clutch holding tool (Autozone will lend you one) will turn the shaft. Most folks are not strong enough to turn a new compressor by hand (no tool) with the clutch engaged.

Drill out the restricted hole in the valve. It should be obvious when you look at it.

From the high side hose where it is disconnected from the drier and the suction hose near the service port.

If you really want to do it properly...
http://www.ackits.com/merchant.mvc?Screen=SFNT&Store_Code=01




.

__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

I really do want to do it properly. I've used ackits.com for learning about general A/C system info, it's a good source. Is there a specific part of the website that I can learn do do it properly from?

I've just looked at the Expansion valve in the factory manual. It appears I drill down through the expansion valve restricted area so the hoses can flow freely. I'll go rent the Autozoo clutch holding tool tomorrow, then I could turn the clutch on the bench to get the residual oil from testing out, and then when it's on the car spin the clutch 10 times to get the oil circulated. I imagine I have to do this before connecting the belt. I'll have more questions when I run into other problems tomorrow.

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1980 240d
1999 SL500

No. The pulley will freewheel if the clutch is not engaged. The holding tool will turn the compressor shaft regardless of whether the belt is connected.

Today I removed the compressor from the car. Removal wasn't too difficult, loosening the adjusting nut on a small threaded rod on the top of the compressor, then loosening three 3/4" nuts, removing the manifold hoses with a 15mm socket, then swiveling the compressor to remove the belt, then removing the bolts and compressor. I've made diagrams of the spacers so hopefully I can remember how they line up.

Tomorrow I'll be removing the expansion valve and doing the rest of the work. Standard wrenches don't work too well removing the txvalve. Is a SAE flare nut set the right thing for the job? Would this kit from HF cover the sizes? Would I use these with a Ratchet or otherwise?

(Wrench sizes: 3/8'', 7/16'', 1/2'', 9/16'', 5/8'', 11/16'', 3/4'')

Then I'll drill out the txvalve, so I can flush the evap. from outside the cabin to not make a mess.




Here's the new Delco R4, and the old Factory Air I pulled from the car. The Delco has a shorter clutch than the other one so it will sit a little further away from the oil cooler lines.



The progress so far, showing the removed compressor and greasy mess where it was. Oil leaks from the engine made the bolts come out nicely. No PB blasting required.



The expansion valve. A SAE flarenut set is the best thing to remove this, right? The upper two nuts are brass and rounding them would be BAD. I suppose I can replace the crumbly foam around the expansion valve when I get around to it.

Where would the best places to put the oil in after flushing be? I've heard 2 oz compressor, 6 oz drier, but it's difficult to keep oil in the compressor. I'll spin the compressor "by hand" 10 times before starting the system to get the oil circulated. I'll go grab some 8oz oil adding bottles from HF when I get the flare wrenches.

Can the connections by the low and high schrader valves be broken and flushed through? Or are they just a solid part? I know the drier, condensor, evaporator lines can be broken and flushed. Can the ones right by the high and low valves be broken, or are they a solid part? I don't think they are serviceable.

If there's anything I mess up on, the nice guys at the A/C shop can do it or show me how to do it on monday.

Any trick to removing the Condenser? I'm taking it out to take to a pressure wash car wash to blast the junk from the fins, and to make it easier to flush it out with solvent.

Tomorrow, I'll post more questions or updates on my progress. Thanks everyone for their helpful advice, so far so good, and tomorrow night I might have cold r12 A/C.

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1980 240d
1999 SL500

Be careful blasting those fins. You can easily bend them with the water pressure. Sorry that I can't help you with removing it; it's nothing like my car of course.

That is a cute little compressor you have, and nice and shiny. Is there any sort of crankcase plug on it? The Desno in my '96 has one, which makes a very convenient place to add half of the compressor oil without making a mess. The plug on my Denso looks like a bolt, but with a 17mm head.

Hopefully those TXV nuts will come off. Again, the later design is much more user-friendly with a single nut holding a plate which retains both tubes. But you work with what you have, as always. I would spray them with some PB or similar and hope for the best. I would also bet that the flare-nut wrenches won't fit very well and you will be forced to resort to an open-ended wrench. I hope that I'm wrong.

Bump, what are the best wrenches for taking off the TXvalve? I'll get some flare wrenches for the work. Should I get SAE or metric, the fittings are standard but metric can get close enough. I can't get the left steel line off because my 7/8" wrench doesn't fit.

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1980 240d
1999 SL500