Question for the R4 compressor experts - Page 4 - PeachParts Mercedes-Benz Forum

sixto · #1 02-25-2016, 12:50 AM

Quote:

Originally Posted by mannys9130

I'm not going to swing on this. The R4 is obsolete, inefficient, and doesn't belong in any AC rebuild. The R4 was done away with when MB introduced the W201. The 84 diesel and all 85+ models got much better compressors. The R4 was still in use by others, so why did MB stop using it? Maybe because it's no where near as good as the replacement.

Anyone who's seen Otto's car admires how original it is. I'm not going to make a compressor recommendation for him but I fully appreciate his pursuit of an R4.

Sixto
83 300SD... call me scarecrow

ROLLGUY · #2 02-24-2016, 07:24 PM

Although I am biased, I say that the O P is doing what his time and budget allows, so leave him alone. I see no problem with using up all the old, cheap R4's he can find. If he has spares, and the time to replace them, more power to him! Heck, I have several compressors I have removed to install Sandens that I will give for free for just the cost of shipping. I could also look at it this way: people like this will use up all the remaining supply of R4's, and the only option left for our cars will be the Sanden! (I say that in jest). I will also add, that when an R4 goes bad, it spreads it's innards throughout the system. A thorough flushing and new drier is required when this happens. If someone is willing to go through this each time the R4 is replaced, then have at it! Either way, I will be here to provide the final solution for any and all your R4 woes.

ROLLGUY · #3 02-25-2016, 09:58 AM

Quote:

Originally Posted by babymog

The experts have made their recommendations, the troll has made his, this thread needs to close.

Yes, what happened with those manifold sealing washers? I too had a major problem finding the right combo when I did my first R4. If you have access to a dry gas to pressurize the system, you can try different ones to get the right combo. There is no sense charging the system every time, thinking you have it sealed (don't ask me how I know this :-).

leathermang · #4 02-25-2016, 11:14 AM

Quote:

Originally Posted by ROLLGUY

....... If you have access to a dry gas to pressurize the system, you can try different ones to get the right combo. There is no sense charging the system every time, thinking you have it sealed (don't ask me how I know this :-).

Automotive Air Conditioning work should NOT be attempted without access to a dry gas.... Nitrogen and Argon being the usual ' tools'. CO2 is also used by some but I am personally biased against it.
Needing the dry gas is not limited to needing to potentially experiment with gasket type which you are not sure of.
Using a dry gas is recommended by the Mercedes Air Conditioning paper manual... which I have a copy of. It is used to blow the Flush out of the items it is put in to.
THEN once a good pressure test after total reassembly is accomplished the Dry Gas is used as a DRYING TECHNIQUE. This is also the same industry standard used on YOUR HOME AC where which is not able to be wet flushed.
The Dry Gas is put under pressure ( always watching the gauges for indications of leaking ) *****THREE SEPARATE TIMES ***** . This is called a ' triple evacuation ' and is NOT for determining if you have a leak...that is done FIRST... then this is done as part of the DRYING process.

Tech Basics: System Evacuation

Of course these things are discussed in the thread in my signature and in lots of other threads in the archives... they are ALSO INDUSTRY STANDARDS.

Yes, many a field tech skips steps due to greed... but on your own system you have an incentive to follow all the standard steps.. which are based on strictly on the PHYSICS of the situation.

This is not due to ' Guru's wanting to make your life miserable.

This is NOT due to an industry trying to get you to pay them to do the work... again...

IT IS THE PHYSICS OF THE MACHINES AND GASES INVOLVED.

It is like the saying about ' do not mess with Mother Nature'... Do not mess with the PHYSICS of the situation unless you are prepared to risk the cost of living with less than ok cooling.. or possibly having to completely start over due to not following ' the rules' ... an example is not spreading the oil around the system when installing it.. or using the wrong oil...or wrong refrigerant... it is your car... but you HAVE BEEN WARNED.

Working on 20-35 year old MB AC systems IS MISERABLE . Accept that and determine to what extent you want to follow the PHYSICS rules to try to get good cooling from your automobile.

Many people assume that pulling a good vacuum will accomplish all the criteria needed.... as a result of watching AC shops do that... skipping the triple evacuation, the total flush, etc... ask how long their warranty is on the work... usually a year at most...

you can skip lots of important steps on many systems and have the AC work for a year...
but my goal is more than five years because I grew up in an era where our automotive AC's typically worked for 6-10 years with no major work needed... at 6 they might need to be topped off... that was cheap and easy since it did not require any vacuuming ....

and that is another reason to use a straight refrigerant... if you use a ' blend' it will escape in a fashion to where the relative amounts in the blend are no longer what was tested to work well.

The R4 compressor , as mentioned many times, is MORE fragile when it comes to good cleaning of the system since ALL OF ITS LUBRICATION comes from the oil being carried around by the refrigerant.

The Sanden and other of that type have their own ***oil reservoir ***.

This also means that the refrigerant in an R4 system HAS to be good at carrying around that lubrication to expect any long term satisfaction from your efforts and money invested.

http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1443&context=iracc

Good luck,
Greg

otto huber · #5 02-25-2016, 12:28 PM

Quote:

Originally Posted by ROLLGUY

Yes, what happened with those manifold sealing washers? I too had a major problem finding the right combo when I did my first R4. If you have access to a dry gas to pressurize the system, you can try different ones to get the right combo. There is no sense charging the system every time, thinking you have it sealed (don't ask me how I know this :-).

I appreciate the helpful feedback that has been offered so far. At the moment, I still don't have the correct washers. The kit most likely to have washers that I can use is listed on the Autozone website, but is not available online or through the local store. This is the kit:A/C Gasket and Seals Mt9518 - Santech (MT9518)

The guy who I recently purchased R12 from worked at a GM dealership for 20 years and has a stock pile of R4 compressor seals. He gave me 3 sets of the AC Delco washers that have green,red and metal washers. Everything else he has appears to be too thin. He is still rummaging through his collection, but I'm not all that optimistic.

The shop that I plan on having a gas charged leak test performed is one of the few shops remaining that is very familiar with these old MB diesels. If I can't find the correct washers before I take it in for the test in a few weeks, I'll just let them figure something out.