Getting ready to get the AC working - PeachParts Mercedes-Benz Forum

Yak · #33 07-27-2010, 12:42 AM

Quote:

Originally Posted by funola

It's a very fat o-ring. more like 3.25 x 20.5 by the convention you're using.
The black o-ring in the pic actually looks pretty good after I boiled it, smooth with no nicks, not flattened or crushed. It was made with some good rubber in it's day. This o-ring came from the bad R4. There are 2 more in the good R4 which is in the car being pressure tested. They are holding pressure but I'd take them out to let them stretch out a bit then inspect them and put them back in if I can't find exact replacements.

I was about to say "that's 1/8 x 7/8" but then I found the Delco site:

"

During the 1988 model year, the design of the A/C Compressor O-Rings was changed from the standard “Round” type to an “Oval” type design
on all GM HR-6, R4 and V5 Compressors.
The reason for the design change was to improve the durability of this refrigerant joint, thus increasing your customer’s satisfaction with the
vehicle A/C System.
It is important to understand that due to the “Cross Section” shape of oval vs. round design, the Oval O-Ring does not completely fill the
machined o-ring grooves in the compressor rear head. A gap between the Oval O-Ring inner diameter and the machined groove inner diameter
is correct and expected.
In addition, the Oval O-Ring does not fit freely in the o-ring groove. The O-Ring must be coated with approved refrigerant oil and inserted all the

way into the o-ring groove prior to joint assembly.

http://www.acdelco.com/pdf/appcat_buyers/orings_gaskets_snaprings.pdf

You want the Santech MT0036-2 kit.

http://www1.autozone.com/autozone/accessories/Santech-2-pcs-7-8-in-green-HNBR-O-Ring-for-GM-A6-R4-LT-R4-H6-and-V5-oval-discharge-suction-ports/_/N-26fc?appQuestionId=4294832246&counter=29&itemIdentifier=147371_0_0_&nysQFromType=nysQuestions