It's AC season so I figured I'd post some pics of an R4 that I took apart.

Here it is without the steel shell:



You can see the valve that is held in the cylinder by a c clip. The steel "band" is sort of the cylinder head which connects all 4 cylinders with the hi side port. The 2 O rings seal it to the "crankcase".

The valve removed:



Notice another set of reed valves built into the piston. The "crankcase" is the suction side. The crankcase is a solid casting that has been machined.

You can get inside it by removing a C clip beneath the pulley bearing and removing the 4 "snout" bolts:



There is an O ring underneath the snout that seals the suction side.

The inside of the crankcase:



As far as I can tell there is nothing resembling an oil sump in the case. It's the same no matter how you clock it.

Another view:



It appears as if the connecting rod assembly is put together and then the pistons are pressed onto the rods through the cylinders.

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

Interesting stuff, never seen the inside of an a/c compressor before.

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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Thanks for sharing Jon.

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Jim

I'm guessing that compressor was open to the air for a while?

It always amazes me how compact that compressor is.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

This is the compressor that I replaced last year and it's just been knocking around the garage since then.

A recent post about another R4 failure made me curious about what could have happened to it so I figured I'd tear this one apart.

I would like to get the crank and rods out but d@mned if I can figure out how to do it...

The crankcase appears pretty sturdy but the moving parts look really fragile.

I agree that it's a cool design but other than the nifty machined aluminum crankcase it seems cheap. I cut the "band" off of the case but it sure looks like it just presses onto the case with the rear "tang" holding it in position.

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

yup. that small 3/4" wide metal tab is all that holds the cover on, without the bolts passing through the body of the thing.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

The "sump" is in what you describe as the snout, on the reverse side. It's basically a hole that is perpendicular to where the central shaft passes through. It's visible in funola's thread here in post 43 or 44: http://www.peachparts.com/shopforum/diesel-discussion/280510-dissembling-r4-compressor-3.html

If the X visible in post 42 is up, then oil will theoretically get slung around by the motion seen in the video linked from post 32. It will pool in the hole, then trickle/drip onto the rotating shaft or re-supply the "front" of the bearing with oil. At least in theory.

The questions I'd have about whether this is a sump intended to lube the bearing can be seen in oblique view in post 44. I guess it depends on where the seal ends up. The hole appears to be "outside" the bearing. If the seal is even more forward than the hole and creates a gap, then it might function that way. If the seal is closer to the hole and the bearing, then maybe not.

Later in that thread he says CompressorWorks claims to use a different sealing method and they don't have the "sump." So it might be there, it might be functional, or it may be an artifact of an older design.

Here is a cylinder with the reed valve assembly removed:



The center part is pressed into a hole in center of the piston. I drilled them out.

The assembly with the piston:



I drilled through the valve holes on the pistons to get it apart. I was surprised to see how thin the pistons were.

The crank is made up of 2 (I think) pieces and pressed together:



I cut through the journal to get it apart without tearing up the center parts.

The center section:



It looks like the center block/rods were placed on the crank and then the rear journal was pressed on.

More explodedness:



I found that the pistons were screwed to the rods.

The case with the guts removed:



You can see the cuts I made to get the thing apart.

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

I think you are going to have a lot of problems getting that compressor working again...
best bet is to put it in a box, and turn it in as a core...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

One word. JB Weld...

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

JB Weld , so funnie!

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1982 300SD

The crankshaft:



3 journals that ride on needle bearings.

The counterweights are pressed on:



I'm guessing the slide block is slid over the crank and the counterweights pressed on:



Both of the connecting rods are identical.

From taking this thing apart I can see why the system must be very clean and free of moisture.

"Remanufacturing" one of these things doesn't look impossible. The trick would be getting the crank weights oriented properly. Disassembly would be tough as well because the pistons were screwed onto the rods really tight. Looks like a tool that fit the holes in the pistons could be used to unscrew them.

I'm actually pretty amazed at the d@mned thing! It was fun taking it apart to see how it ticked...

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

Wow neat to see inside it. My 300d has a old Harrison r4 compressor with a r12 sticker on it. It may be the original compressor, works like a champ knock on wood

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

This one was working like a champ as well. The compressor part didn't fail it was the pulley bearing that went out and damaged the housing

You can see why they are so oil sensitive with all those sliding parts.

After becoming intimate with one I'm less of a hater. They did hang in there until '94...

__________________
My occupational hazard bein'
my occupation's just not around...
1980 300SD
1980 300SD

Whenever the discusssion is going on crankshaft, i always like remember the camshaft because I like its simple design and looks like newly born baby when sits besides the crankshaft.

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"Positive attitudes create a chain reaction of positive thoughts." - CurtMaxwall