evaluating an AC compressor when system is currently discharged - Page 3 - PeachParts Mercedes-Benz Forum

kuene · #31 05-03-2018, 11:00 AM

even though my compressor isn't seized, I wonder if I should just as well replace the compressor with one that I know the history of. I'll know how much and what kind of oil is in there. I'm replacing all the seals I can get to, plus the drier, and the expansion valve - might as well get new compressor right?

A few folks on here have mentioned using the 4 season "heavy" compressor part 58231. When I check compatibility on 4 seasons website, they say it's not compatible with the 1982 300d. The only 4 season compressor that matches according to them is the 58228.

Does anyone know if the heavy (58231) is indeed compatible, and what benefits might the heavy version bring if so?

Does anyone know if either of these, when purchased through pep boys or other distributors, comes with the various sealing washer set?

Would either or both of these require a different kind of belt/pully that what would normally be on a stock 1982?

Separate question, should I absolutely replace the pressure sensor with new when I replace the drier?

Thanks all - taking my time, really absorbing the advice given here. Looks like i'm in deeper than I had planned, but I'm learning.

funola · #32 05-03-2018, 12:26 PM

Quote:

Originally Posted by kuene

even though my compressor isn't seized, I wonder if I should just as well replace the compressor with one that I know the history of. I'll know how much and what kind of oil is in there. I'm replacing all the seals I can get to, plus the drier, and the expansion valve - might as well get new compressor right?

A few folks on here have mentioned using the 4 season "heavy" compressor part 58231. When I check compatibility on 4 seasons website, they say it's not compatible with the 1982 300d. The only 4 season compressor that matches according to them is the 58228.

Does anyone know if the heavy (58231) is indeed compatible, and what benefits might the heavy version bring if so?

Does anyone know if either of these, when purchased through pep boys or other distributors, comes with the various sealing washer set?

Would either or both of these require a different kind of belt/pully that what would normally be on a stock 1982?

Separate question, should I absolutely replace the pressure sensor with new when I replace the drier?

Thanks all - taking my time, really absorbing the advice given here. Looks like i'm in deeper than I had planned, but I'm learning.

I would replace the compressor. I tried to reseal a used light R4 and it didn't perform well and didn't last. Based on my experience, I would recommend the reman in Mexico 4 Seasons R4 heavy compressor, and not a new 4 Seasons light compressor. On the box of compressor I bought from Pepboys, pics showed a light compressor but inside the box was a heavy. So make sure you open the box to look before buying. I think new 4 Seasons are lights but the rebuilts can be either light or heavy. IMO, the heavy R4's runs smoother with the bigger rotating mass of the bigger clutch.

I would not replace any of the hoses based on my experience, unless you enjoy doing more work/ spending more money than necessary. Do replace all the o-rings, pressure test the system to insure there are no leaks before charging with refrigerant.

ROLLGUY · #33 05-03-2018, 02:08 PM

Quote:

Originally Posted by funola

I would not replace any of the hoses based on my experience, unless you enjoy doing more work/ spending more money than necessary. Do replace all the o-rings, pressure test the system to insure there are no leaks before charging with refrigerant.

I have worked on probably 30 of these systems, and more often than not, the hoses leak. My experience says they SHOULD be replaced. So often there is enough time and money to do things over, but not enough time or money to do it right the first time. Why is that?

kuene · #34 05-03-2018, 02:15 PM

How would one be able to identify a heavy r4 from a light r4 - what do I look for on the unit? Is there a measurement? Just part number confirmation?

ROLLGUY · #35 05-03-2018, 02:26 PM

Quote:

Originally Posted by kuene

How would one be able to identify a heavy r4 from a light r4 - what do I look for on the unit? Is there a measurement? Just part number confirmation?

The heavy is the left photo, light is the right. I doubt there is any difference with the internals.

funola · #36 05-03-2018, 03:40 PM

Quote:

Originally Posted by ROLLGUY

I have worked on probably 30 of these systems, and more often than not, the hoses leak. My experience says they SHOULD be replaced. So often there is enough time and money to do things over, but not enough time or money to do it right the first time. Why is that?

How did you determine that the hoses leaked? Did you test each hose individually?

I tested total about 15 x W123 AC hoses with a digital pressure gauge with the hose submerged underwater and they were all good. Those hoses were 35 to 40 years old. 2 of the hoses (taken from an 82 300D), looked rotten on the outside but still tested good and did not leak.

An important point I am making here is: unless you do a proper test on each hose, you do not know if the hose is good or bad.

edit: I did not and would not use the rotten looking hose, even though it tested good. W123 AC hoses are thick with 2 layers. Even though the outer layer is rotten, the inner layer could still be good.

Took my 85 300D for a drive today in 90 F weather with nice cold AC.

funola · #37 05-03-2018, 09:30 PM

Quote:

Originally Posted by ROLLGUY

The heavy is the left photo, light is the right. I doubt there is any difference with the internals.

A good reason to use heavy is heavy use o-rings on the manifold ports, light use stepped washers which are a pain to get right.

ROLLGUY · #38 05-03-2018, 09:45 PM

Quote:

Originally Posted by funola

How did you determine that the hoses leaked? Did you test each hose individually?

I tested total about 15 x W123 AC hoses with a digital pressure gauge with the hose submerged underwater and they were all good. Those hoses were 35 to 40 years old. 2 of the hoses (taken from an 82 300D), looked rotten on the outside but still tested good and did not leak.

An important point I am making here is: unless you do a proper test on each hose, you do not know if the hose is good or bad.

edit: I did not and would not use the rotten looking hose, even though it tested good. W123 AC hoses are thick with 2 layers. Even though the outer layer is rotten, the inner layer could still be good.

Took my 85 300D for a drive today in 90 F weather with nice cold AC.

When the system is pressure tested with 250 psi of nitrogen and sprayed with soap, many have leaked. They also leak at the crimped end often. Yes I agree that the hose used in these cars is very good quality, but they still have leaks, and often in my experience. "I did not and would not use the rotten looking hose, even though it tested good." I am the same way. I don't want to gamble on a 30+ year old hose even if it looks good. With the cost of refrigerant, labor, and time, it is just not worth doing the job twice.

funola · #39 05-03-2018, 10:02 PM

Quote:

Originally Posted by ROLLGUY

When the system is pressure tested with 250 psi of nitrogen and sprayed with soap, many have leaked. They also leak at the crimped end often. Yes I agree that the hose used in these cars is very good quality, but they still have leaks, and often in my experience. "I did not and would not use the rotten looking hose, even though it tested good." I am the same way. I don't want to gamble on a 30+ year old hose even if it looks good. With the cost of refrigerant, labor, and time, it is just not worth doing the job twice.

I do not see how you can spray soapy waters onto every square inch of a hose and be able to see every square inch of it while looking for bubbles. I tried it and it plainly does not work well. That's when I went with testing the hose submerged in water, and to my surprise, none of my hoses leaked.

Regarding ""I did not and would not use the rotten looking hose, even though it tested good.", I should add that's because I had better looking hoses. If I didn't, I would have used the rotten looking hose since it tested good because the part that is rotten is just on the outer abrasion layer.

BillGrissom · #40 05-04-2018, 11:07 AM

You don't save much effort by replacing the compressor at the same time as the hoses. I never replace parts unless I know they are bad - if it ain't broke, ... Of course, rubber seals are an exception where preventative maintenance can make sense. You started the post with "how to evaluate?", now at "I'll change it regardless". Need to pick your battles first.

kuene · #41 05-04-2018, 12:39 PM

yes, I started my questioning/thread around evaluating the compressor. I've since learned much from this spirited group of mechanics and I've evolved my planned approach. If my compressor was seized or had imploded, and possibly contaminated lots of other components - I wasn't going to pursue the project.

Now that I'm feeling more educated, a little more confident in the state of my system, I want to tackle this with more gusto. I'm just thinking that I'll I spend a couple weekends tying up leaks, replacing some other components, adding in expensive r12 - It would be a real shame for the compressor to crap out sometime shortly after and cock the whole thing up.

i really appreciate the help and advice I'm offered here.

97 SL320 · #42 05-04-2018, 04:59 PM

As stated in my post 5, the evaporator must be tested for leaks before working on the rest of the system as replacing the evap is a labor intensive repair.

kuene · #43 05-04-2018, 05:42 PM

thanks. yes - I will be pressure testing the system - if there is a leak I can't find, then it will be in the evap/dash somewhere.

vstech · #44 05-04-2018, 07:06 PM

Quote:

Originally Posted by kuene

thanks. yes - I will be pressure testing the system - if there is a leak I can't find, then it will be in the evap/dash somewhere.

Doubtful...

Pre 124 chassis coils are bulletproof... it’ll be leaking at the compressor, or a hose.

kuene · #45 05-04-2018, 07:43 PM

I think I was misunderstood vstech. I’m going to do a full leak search on hoses/compressor/drier/expansionvalve. IF after checking all those things and I haven’t found the leak - then I will assume it’s where I haven’t checked yet - In the evap or somewhere else under dash.