jwillman

Looking at the spec manual it calls out two oil quantities based on year. I have a 79 but have repalced the Bosch compressor with a Nippon Denso 6E171.

I assume I need to use the 280 cm3 quantity but have read some threads calling out 6oz. I have drained the compressor but sure I did not get out everything. I will be using R134 when refilling.

Thanks.

dprantl

A 928 system with a 6E171 compressor should have 280 +/- 20cc of oil in the whole system. Since you are flushing everything while doing the retrofit, you should put 280cc of ester oil into the compressor. If you were just replacing the compressor in an already converted system, there would be varying amounts of oil left in the other components, so you would only have to add a fraction of the total amount of oil. Also, since you are using R134a, you should fill the system to only 85% of R134a refrigerant compared to R12. So that would be 893g without rear A/C, and 1020g with rear A/C with a 6E171.

Dan
'91 928GT S/C 475hp/460lb.ft

Bill Ball

That's the TOTAL oil installed in the compressor in a fully drained and flushed system. It then distributes out to the condenser, drier, and evaporator with some remaining in the compressor. Did your system have R-134 in it already or is it now just flushed out of all R12 mineral oil? If it was R-134 and not flushed and you just drained the compressor, I would add about 5 ounces to the compressor. If the drier is new (should be regardless), it takes 10cc (1/3 ounce or two teaspoons).

jwillman

Thanks Dan and Bill.

Old system was R12 and had been empty for some time. I have replaced dryer and expansion valve and flushed condenser and evaporator. I also have new barrier hoses from compressor being finished today. I also flushed the used compressor with two bottles of ester oil by adding it to the suction side and spinning the clutch with an cordless drill to pump the oil thru. I assume some trace of that is still in the pump even though I let it drain for a couple of days

According to my calculations 280cc is 10 ounces. Should I still add all 10 ounces given the flush process I used?

dprantl

Yes, 280cc. You can add less since the Porsche spec is +/- 20cc if you think that there may still be some ester oil left in the compressor.

Dan
'91 928GT S/C 475hp/460lb.ft