I wonder if you or someone else can talk about the compressor on my 1984 300 SD. The name plate identifies it as a " Harrison -Mod# 320". Is this 'lightweight' or 'regular', or what? I makes a lot of noise, so I disconnected the belt - I think it needs only a new or remanufactured clutch. But where to get one - that is the question!

Padraig

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1984 300SD TURBO DIESEL

I wonder which GM and NAPA part#s are the $100 R-4 compressors Diesel Giant gets from NAPA ?

This is a quality rebuild R4, but, personally I'd look for new. The R4 is not known as a really "robust" design in the MVAC community.

http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=000113CP


Here's new: http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=15-20206

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Apologies if this topic has been addressed already...down here in MD it is getting hot. I have three vintage MBs that I would like to update the AC in...a 6.3, a 280SL, and a 3.5 cabriolet. Does anyone know a source for rotary compressors and mounting brackets for these cars? I have a friend with an auto AC shop that can help with the changeover, new driers, etc, but I would like to find a source for the parts.

Also, does anyone have an opinion as to whether the systems should be changed to R134 or left with R12 in them?

Thanks in advance.

Jim, I don't understand why you want to change from bullet proof compresors to the higher failure rate newer style compressors. The A6 on your 3.5 is about the most durable compressor you can get. The only reason car mfgs quit using them is, because they weigh as much as a small Japanese engine. The York compressor on your 280SL is also an excellent compressor. I would buy a new one and not rebuilt. If you get a rebuilt from say Sedona or Phoenix, the metal in the rods and pistons is pretty well fatigued. I can't remember what's in the 6.3, but I think it's a York. I'd also stick with R-12.

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Auto Zentral Ltd.

compressor issues
I have been purchasing compressors from the local a/c supply house. They do have the x and it is in the wrong place for the MB application. One of the compressors lasted about 1.5 years.
My question is is it just a matter of removing the four front bolts and rotating the front to the correct position?

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Jim

Essentially yes. I've always had the clutch off, to clear the hex head screws.

Also with the "X" down, the oil to the shaft seal (a NOTORIOUS source of R4 refrigeranr leaks) is obviously less; so overall, it's worth putting the "X" up..

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

I went to the a/c shop where I purchase the compressors today and looked at every compressor they had listed for the '81 300D. There were three different p/n compressors that they had that would work. All were brand new Delphi compressors and none of them had the x where it would be in the "up" position in the w123 once it is installed. I have ordered one that is supposedly only for the MB and will report back on what I see. The guy that runs the shop adjacent to the supply house (a very big and very busy a/c repair shop) said it did not matter where the x is when these things are mounted.

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Jim

I called Delphi customer service today and talked with a 30+ year verteran. He pulled their documentation on the r4 unit and they "recommend" installing it with the x in the up position but on the same hand he said it does not matter. The oil is splashing around in there so much that the front bearing is going to get some lube on it no matter where the x is. He stated that in working there for 30 years that this was the first time anyone has ever asked this question and that they have a MB trained tech on staff and he reiterated the same thing - that it should not make any difference in the life of the compressor. I will be replacing a one year old new "locked up" compressor this coming weekend and hopefully will be able to take the old compressor apart to determine it's failure mode.

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Jim

Threads like this are what makes shop forum great. Thanks guys.

Now I have a question. It seems that the R4s are dogs, especially if they are only lasting 1 1/2 years. Do any of you AC guys have a durable compressor that you can recommend for a W123 turbo? I have two wagons, one of which blows cold and one that does not. I have not diagnosed the bad one, but don't want to do all the work just to have the compressor fail in a couple of years.

I know that the R6's and York piston are solid units but I think they will never fit. Has anyone put a different compressor than the R4 in a W123 turbo?

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Doug

1987 300TD x 3
2005 E320CDI

Look at the compressor on a euro W123. They are a different type. Unfortunately, the last euro 123 that I saw I was unable to tell what compressor it was. The brackets were pretty straight forward and the car had been converted to 134. I don't know how well the system worked.

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Jim

i've been replacing r4's for thirty years and only now
'am i being made aware of this oil passage issue.
r4's are not a bad compressor. originals lasted
years and years. some over ten years.
its the shoddy repair and use of rebuilts that
messes things up. plus not adding oil when servicing them.
if one comes apart then you got something i refer to as
black death. almost everything needs
to be replaced. the evaporator can stay as its single
row and can be flushed. condenser is double row and needs
to be replaced. after everything is done you MUST
install a filter on the suction line just before the comp inlet.
or do the job again.
the r4 comp was designed to be lubed by the oil in
the freon so i'm just not sure that the x is a real issue.
won't hurt though. i'm gonna see if i have a genuine
mb one around and check.

george

george has more experience with MB than Daimler, himself; so I listen.

I'm not so sure, though, a genuine MB R4 (even though made by someone else) would need an "X" to identify which is up since they would be identified for one specific use already by MB. It's the AC Delco, Harrison, Delphi models (aftermarket OEM) that would need it since they are used in many different applications, both high and low mount, for different auto makers' marques. On the MB unit the channel/"hole" may well be there, just no identifying mark, since they already know which way it's going to be used because of the manifold port position and the specs on the box.

The lubricant is in the gas so the compressor gets its share, maybe even the front bearing gets enough, but...... the A6, R4 H6 incarnation series has undergone many shaft seal issues over the years. Steel/steel, ceramic/steel, caged/uncaged, single lipped, double lipped, heck, even triple lipped. The admonition to run the A/C once a month to "lube the shaft seal". All of this points to, at least an issue, with lube to the shaft seal which they apparantly tried to address with the extra "port" to the seal area. The oil mist would "stick" to the solid surface and tend to go downhill to the seal. I wouldn't tear a system apart to check it, but if given the choice (and mine had an "X" (my old ones didn't, I'm pretty sure, now)), I'd go "X" up, on a new install.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

This is really interesting! I have a generic question for the AC experts. Is there anything that one can do to prevent premature compressor failure? And what about the "black death" failure, how do you prevent it?

Hi George, Yes the R4 - the 'workhorse' compressor of its time was designed for efficiency, but not for durability.

The R4 on my 84 300SD (Harrison #320) might even be the original one, but I don't know. Anyway, it recently started to make great noise 'though still cooling (not squealing type noise ) whether the AC was engaged or shut off. I suspect that the prob. is a the clutch. Question : Can one replace the clutch without benching the compressor?

I take note of your recomendation in replacing a compressor (highlighted above) to replace the Condenser and install a filter in the suction line. Why would one replace a condenser if it weren't leaking, and what type of filter would one install - are you referring to the Dryer, perhaps?

Finally, George, how does one indentify a 'genuine MB compressor"?

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1984 300SD TURBO DIESEL