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MJS170 EA82 Hitachi AC Compressor guide. WIP


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This will be a rebuild/info post for the EA82 Hitachi AC compressor model MJS170. The one the mounts to the inboard of the alternator. Work in progress.

Generally you can rebuild a compressor that leaks, but functions. I have great luck getting R134a converted compressors out of junkers. Generally the system leaks, the PO replaces the hose orings and oil, and charges with R134a. The issue is the factory orings in the compressor are not rated for PAG oil, so they fail. You can grab the compressor, replace the seals for ~$20, and have a working compressor!

Also I recommend rebuilding any compressor you currently have if it works and is quiet. The oil wears out over time, as to the seals, and a bit of preventive maintenance will make it last the life of the car.

This was a factory 250K mile compressor. Second rebuild, don't know what caused that bit on corrosion to push the gasket.

Look at the bores though, like factory hone still!

Seal info:
    >Rear plate to case:
        ID: 118 mm
        CS: 2.5 mm
    >Outer valve body:
        ID: 107.5 mm
        CS: 2 mm
    >Inner Valve body:
        ID: 63 mm
        CS: 2 mm
    >Pass though tube:
        ID: 12 mm
        CS: 2 mm
    >Front plate to case
        Paper
        ID: 107 mm
        OD: 116.5 mm
Bearings:
    >Clutch
        ID: 40 mm
        OD: 62 mm
        Depth 24 mm


If you order a shaft seal these models cross reference: MJS170 MJS130 A5000
Make sure you get both parts of the shaft seal. Some kits only contain the fixed seal and snap ring. You want the complete kit the fixed seal, snap ring, and the spring loaded thrust seal. You should only replace them in pairs, replacing just the shaft seal can cause the thrust seal to wear out quickly.

The rebuilt kit I use. https://www.polarbearinc.com/index.cfm?fuseaction=product.display&product_ID=459&ParentCat=23

Shaft seal. https://www.polarbearinc.com/index.cfm/product/371/ss-0721.htm


Also my #1 recommendation is to upgrade the filter dryer. The factory ones aren't great, and the aftermarket ones are worst. I took the stock dryer, cut the dryer off and braze the bottom closed, so it is just a sight glass. Then take the line that runs from the dryer to the firewall to a hose shop. Get them to install female 3/8 SAE flares on to it. I run a 8 cubic inch drier.

Edited by Ionstorm66
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