Nippondenso A/C Compressor Seal Replacement Experience

[dkirk]

I recently tackled the job of A/C compressor shaft seal replacement on my 1988 911. The Denso compressor model is 10P15C and as far as I can tell, this is the original equipment compressor that was installed at the factory.



Problems exhibited were the telltale track of oil on the underside of the engine lid and gradual leak down of system pressure, all indicative of a failing shaft seal. I went to the Pelican 911 Technical Articles and accessed the well-written article by Rob Walter to reference during the disassembly process…

Pelican Technical Article: 911 Nippondenso A/C Compressor Rebuild

I also ordered the shaft seal kit specific to the 10P15C compressor through the recommended web site. When the seal kit arrived (some two weeks after placing the order) I began the teardown. As no assembly torque values were given for the 5 socket head cap screws, I measured the breakaway torque during disassembly. This turned out to be approximately 18 ft-lbs. Teardown was straightforward and the old seal was easily pressed out of the nose housing using the methods recommended in Rob’s article. However, it was immediately apparent that the seal that I received (2-piece carbon face seal, part # SK-740N shown on the left) was nothing like the seal removed from my compressor (a single-piece lip seal).



I attempted to reassemble using the new seal, but promptly found out that the axial length of the seal was too long, thereby breaking the carbon ring in the assembly process. This portion of the rebuild turned out to be a $27.00 learning experience!

Doing more research, I found another website that catered to Denso compressor parts and had a very good description of seal types complete with pictures…

Automobile Air Conditioning Parts of Tucson Arizona, Century Auto Air, AC Parts, AC Service and Hoses, centuryautoair.com

Here I learned that two different seals were used in the 10P15C compressor, with the changeover occurring during the late 1980’s. The seal that I had first received (SK-740N) was the older style component, later replaced with the one-piece lip seal (SH-935) as was clearly explained on the Century Auto Air website. I obviously had a compressor made during the transition period, or this was a replacement compressor installed sometime during the car’s prior ownership. I then ordered the SH-935 seal plus a seal protector (SPGM) that was recommended for installation. Parts were shipped USPS Priority and I had them within 3 days – excellent service!



The new seal was easily installed in the nose housing using a deep-well socket and rubber mallet. The seal protector is a must when installing the housing-seal assembly over the shaft – without the protector the shaft keyway would have certainly destroyed the sealing material. Reassembly was straightforward per Rob’s article, with the cap screws being torqued to 18 ft-lbs.

Another item noticed was the close proximity of an unused boss on the end of the compressor that comes in line-to-line contact with the intake manifold. Note the finger pointing to this boss…



I took a coarse, flat file and whittled about .060 off of this boss to obtain sufficient clearance such that no potential for contact and possible noise generation could occur.

To summarize:

• When installing a new shaft seal in the Denso 10P15C compressor, first disassemble the compressor to determine which seal is used
• Two seals are available – SK-740N is the early 2-piece carbon seal.
SH-935 is the later single-piece lip seal. They are not interchangeable.
• If using the SH-935 seal, order the seal protector, SPGM from Century Auto Air
• Torque the 5 cap screws to 18 ft-lbf on reassembly

[Jim Sims]

I use Century Auto Air in Tuscon as a source of A/C repair and conversion parts; recently I rebuilt a Sanden and a Nippondenso compressor with their parts kits. They are very DIY oriented and some of my online orders with them have arrived in two days - regular shipping. They also carry the 90 degree rotatable R-12 to R-134a conversion fittings that greatly assist in the conversion of the original York compressors if one wants to keep the York installed. Jim

[1-ev.com]

Do you have any updates how compressor works now?

[Discseven]

Nice notes Dave... especially on part change.

[Ruben911]

Not to hijack but I also replaced the shaft seal in my Nipondenso, similar to dkirk, back in August of 2008 and to date have not had to add refrigerant. It's my daily driver (12K miles per year) and since I live in FL I use the AC almost every day of the year. I think that frequent use of the AC maintains all seals from drying out, prolongs seal life. Just my 2 cents.

[1-ev.com]

Ruben,
You are correct about lube of any seal.
Also, were your condensor - Under the grill or under the wheel or in the front?

I have unique AC in my electric/gas car :-) you can see on my website 1-ev.com

I see you a bit north of me, you've got nice car!!! We should meet for coffee sometime:-)
-Y.

Not to hijack but I also replaced the shaft seal in my Nipondenso, similar to dkirk, back in August of 2008 and to date have not had to add refrigerant. It's my daily driver (12K miles per year) and since I live in FL I use the AC almost every day of the year. I think that frequent use of the AC maintains all seals from drying out, prolongs seal life. Just my 2 cents.

[Ruben911]

My AC setup has one condensor under the engine grille and one in the front of the car under the bumper/valance. I think this is similar to mid 1980's Carrera setup.

[Porsche 2]

Thanks Dave, very helpful. You provided a link to the earlier description in our hosts site. My frustration is bringing this earlier article up by clicking on the address in your post above also gets me to the heading, but I can't open it. What am I missing?
As a back up, did he also disassemble the compressor in order to press the old shaft seal out from the inside. A Utube video shows the use of two special tools to remove the seal from the outside - trying to a source these tools - to avoid cracking open the compressor.