Which AC compressor to use?
05-01-2011, 04:06 PM
#1
Rennlist Member
Thread Starter
Which AC compressor to use?
I am rebuilding the AC system in the 79. I am converting to R134 and have a flushed the condenser, will flush the evaporator and am replacing dryer, expansion valve and all the seals.
I have 2 6E171 pumps. One has a pulley that spins very smoothly and clutch looks good. Seems to pump well but when draining the old oil out the top it is a luminecant green. Is the green color dye? other than that the oil is clean, no particles.
The other pump has a brownsih oil that is also clean of containimants but the pully drags a bit and has a rubbing noise. It also makes a strong pumping noise when turned by hand.
Should I bite the bullet and pull them apart to replace seals even though i saw no evidence of leaks and the oil is clean or just go with one?
I have 2 6E171 pumps. One has a pulley that spins very smoothly and clutch looks good. Seems to pump well but when draining the old oil out the top it is a luminecant green. Is the green color dye? other than that the oil is clean, no particles.
The other pump has a brownsih oil that is also clean of containimants but the pully drags a bit and has a rubbing noise. It also makes a strong pumping noise when turned by hand.
Should I bite the bullet and pull them apart to replace seals even though i saw no evidence of leaks and the oil is clean or just go with one?
05-01-2011, 05:26 PM
#2
Nordschleife Master
If you're converting to r134a, and are going to use PAG synthetic oil, you'll need to clean the compressors out of the old oil, as PAG + mineral oil = sludge.
I've re-sealed 6E171's twice using gasket kit and shaft seal kits from http://polarbearinc.com/. First time had a leak from between the two halves of the compressor (large o-ring pinched), second time was leak-free and still going strong.
Your other option is to drain as much as you can out of the compressor, and use POE oil (polyolester) which is compatible with mineral oil. You then just need to make sure any AC technicians who service it in future use the same type of oil.
I'd go with the one with green dye (it is dye - used for finding leaks, with UV light and glasses) - that's less scary than brown filthy stuff
(pulling them apart is cool - the internals look pretty neat, and the 6E171 is relatively easy to get back together).
I've re-sealed 6E171's twice using gasket kit and shaft seal kits from http://polarbearinc.com/. First time had a leak from between the two halves of the compressor (large o-ring pinched), second time was leak-free and still going strong.
Your other option is to drain as much as you can out of the compressor, and use POE oil (polyolester) which is compatible with mineral oil. You then just need to make sure any AC technicians who service it in future use the same type of oil.
I'd go with the one with green dye (it is dye - used for finding leaks, with UV light and glasses) - that's less scary than brown filthy stuff
(pulling them apart is cool - the internals look pretty neat, and the 6E171 is relatively easy to get back together).
05-01-2011, 05:56 PM
#3
Race Car
+1, use the one that turns easily. The green stuff is just dye to help find leaks. I would never use PAG oil in a car converted from R12 <-> R134a. You can never be 100% sure you have gotten rid of every last drop of R12 mineral oil, and PAG really doesn't mix with it well.
FWIW, I have seen many 6E171 compressors and have never ever seen one leak from the middle o-ring, so when I reseal I usually do the gaskets, the shaft seal and the two end o-rings only. It's also easier since the middle o-ring requires complete compressor disassembly.
Dan
'91 928GT S/C
475hp/460lb.ft
FWIW, I have seen many 6E171 compressors and have never ever seen one leak from the middle o-ring, so when I reseal I usually do the gaskets, the shaft seal and the two end o-rings only. It's also easier since the middle o-ring requires complete compressor disassembly.
Dan
'91 928GT S/C
475hp/460lb.ft
05-01-2011, 07:48 PM
#4
Rennlist Member
Thread Starter
+1, use the one that turns easily. The green stuff is just dye to help find leaks. I would never use PAG oil in a car converted from R12 <-> R134a. You can never be 100% sure you have gotten rid of every last drop of R12 mineral oil, and PAG really doesn't mix with it well.
FWIW, I have seen many 6E171 compressors and have never ever seen one leak from the middle o-ring, so when I reseal I usually do the gaskets, the shaft seal and the two end o-rings only. It's also easier since the middle o-ring requires complete compressor disassembly.
Dan
'91 928GT S/C 475hp/460lb.ft
FWIW, I have seen many 6E171 compressors and have never ever seen one leak from the middle o-ring, so when I reseal I usually do the gaskets, the shaft seal and the two end o-rings only. It's also easier since the middle o-ring requires complete compressor disassembly.
Dan
'91 928GT S/C
475hp/460lb.ftI am using Ester oil per your previous guidance. I am draining the pump now and will run a 8oz bottle of ester oil thru and redrain before servicing to clean it out best I can. The compressor looked good and only dirt on it appeared to be engine oil sludge.
I replaced the seals under the suction and discharge valves as well as put new stems in the two test ports. rest of the system will get new orings. Biggest issue now is the HVAC control head.
Thanks for the input!
