Crappy R4 compressors! - PeachParts Mercedes-Benz Forum

James L · #1 04-08-2010, 09:51 PM

And now it is time for yet another R4 a/c compressor for my 1984 300SD!! Reman Behr R4 with -o rings, installed 4/2007, R12, 300 visc synth mineral oil. Now it is weak and can not get past 150psi high side after full charge and bubbles in sight glass. (this happened on another R4 I had 5 years ago). another R4 got it cold.

In 5/2006 new R4 with GM sealing washers from ACkits.com, R12, 525 visc mineral oil, lasted 1 year.

In my old 1983 300SD, went thru three R4s with 134A. New and Reman, it does not matter. Brands, I have been thru Delco, Harrison, Behr with both short clutch and long.

My 1995 GMC Sierra truck R4 (top mount, serp belt) is a work horse as is the nippondenso in my 1993 Mercedes W124. I wish we had other compressor options for the pre-1986 W126s..like the denso on the 1986+ 300SDL, 420sel, ect or the A6 on the 380se. I have thought about this alot but mounting bolts and a/c hoses would not match.

Looks like another R4. This time maybe a Murray reman from Oreillys for $152. I hope this one has the 0-rings instead of those dreaded GM sealing washers. Going back with R12. Need to decide on type and visc of mineral oil 150-525visc.

samiam44 · #2 04-09-2010, 08:38 AM

Never had such problems..

I always dropped new ones purchased at Autozone on my car. They drop shipped them from a GM warehouse. I always used straight mineral oil- none of this synthetic stuff. You can purchase it at Napa still.
Some say the oil feed for the front brg must be rotated. You can buy a seal kit if you want to do that. Never had the sealing rings leak= perhaps the rear of your hose needs attention. Make sure all the line clamps are correctly there.
The aftermarket rebuilds tend to grenade in a short time.

The BIG question is HOW are you flushing the system and what hoses do you replace. There is a lot of metal when an R4 dies- I suspect you have bits left in the system. I'd add a screen filter and you need a professional power flushing and some component replacement to get back to a reliable system.

M

Hit Man X · #3 04-09-2010, 11:12 PM

Quit purchasing reman ones, that is your issue.

James L · #4 04-10-2010, 08:25 AM

I have purchased new ones, they do not last any longer than reman, just cost more. New ones have GM sealing washers, reman has o-rings.

The MB R4 is a bad design, On my GMC R4 the ports or up and oil feed to bearing flows down unto shaft. With MB ports are down and oil has to flow up which causes bearing and shaft oil issues.

Before, I have always flushed system before. Replaced dryer exp, ect...My compressor did not lock up,it is working. So I am going to just drop in another, vac and recharge.

I am going to drop in an Oreilly-Murray (four seasons), from texas just like the autozone one (compressor works).

One day I am going to get hoses fabricated and mounts to do a denso.

#5 04-13-2010, 01:21 PM

Are you flushing the entire system, replacing the R/D and then putting in the 8 ounces of oil? Has this car ever had a compressor catastrophic failure?

JimFreeh · #6 04-13-2010, 02:35 PM

Quote:

Originally Posted by samiam44

The BIG question is HOW are you flushing the system and what hoses do you replace. There is a lot of metal when an R4 dies- I suspect you have bits left in the system. I'd add a screen filter and you need a professional power flushing and some component replacement to get back to a reliable system.

M

First thought I had after reading the original post...

Jim

James L · #7 04-13-2010, 03:26 PM

Flushing; In the past 15 years, I have broken apart and flushed the entire system on my two W126s at least a total of four times (2 each), flushing evap, condenser, lines, replacing dryer, exp valve and new condenser, new compressor hoses, 8oz oil just like fsm, rotating 15 times before mounting., ect.

Flushing with approved chemicals and dried shop air (more than most shop do). I flushed even when compressor did not fail and was weak (as in now) also when failed, never saw any metal particles at all, just oil and dye. To really flush right you need a two way powerfull electric/air machine like the hellcat power flusher. No shops in my area ever use such a machine. Anybody here use one?

Anyway....My 1995 GMC at 198,000 miles, still has the original Delco/Harrison R4 compressor with oe 134A. Again it is mounted on top of engine with ports up (with o-ring sealing washers) (x) up and refrigerant oil flows down onto the bearing and shaft seal as it is designed.

MY current R4 on my 1984 MB is working but the the clutch/bearing is now making noise beacuse it has been starved for oil after 3 years.

I will reclaim/recycle the R12 freon, change out to the Four Season reman, look at discarge ports and hoses for any trace of failure (black death, ect) if it looks good. I will seal up, pulll a long vac, with my JB 2 stage deep vac pump with fresh oil. Then Clipligt Dry R for moisture and acid, then cliplight super seal Auto, dye/oil, and R12.

I am going to hunt up a 1986 300SDL in the salavge yard and try to fabricate a mount, v-belt pulley and compressor hoses so I can do a denso next year and be thru with this R4 crap and get better performance and lifespan.

James L · #8 04-13-2010, 04:34 PM

samiam44, screen filter? I would have to have my $100+ compressor hoses cut and fabricated for a screen filter to work.

I notice on this forum everyone wants to bash everyones flushing method and blame this for the R4 failure. In the end it may not even matter as long as you get the debris out (if it failed). Sometimes a flush is not needed if compressor does not grenade. Leave expansion valve and rec/dryer alone and button everything up real quick.

#9 04-14-2010, 08:33 AM

I don't think anyone was bashing your methods. They were just making sure that you knew the importance of flushing and you obviously do.

It is way more difficult than most people understand to get all the debris out of a system with flushing. It is also sometimes a problem because a little flushing agent is left behind. From your description, it sounds like you are doing a very thorough job. I have seen very thorough jobs not be enough. Given your frustration level I really think that a suction side filter would be worth the trouble. It's not that big of a deal to add one in the line and it might just be the "Silver Bullet" that you're looking for. Sometimes when a suction side filter is not used, the new compressor ends up being the suction side filter and then the cycle repeats itself.

Best of luck with it.

samiam44 · #10 04-14-2010, 10:53 AM

The reason I suggest flushing is I've never had reliability problems with new R4 compressors. For their size and weight, they have a great flow rate compared to many compressors. I'd say you should be getting 100-150,000 miles to a compressor.

But, I ussually do have the hoses rebuilt. I've found even after flushing- debris at the shrader valves(I ussually replace them as well). They do make screens which fit in the suction side of the compressor.

My suggests were only meant to help, b/c it seems you are frustrated by the results of your prior repairs. A car with sucessive compressor failures to me is harder and harder to make reliable only b/c of metalic debris in the sytem.

M