115 240D york failure (?)

[stei7766]

Hello all,

This is my first time actually posting to the forum, but I have been lurking around for a while. After searching for possible solutions to my problem, I finally decided to take a chance and post.

Here we go:

I own a 1974 240D automatic (115kmi) which was converted to r134a by the PO about four years ago. I don't have the specifics, only the r134 fittings and a $75 receipt for "conversion" and "freon." So for all I know the mechanic simply put the fittings on, drained the r12 and recharged with r134. Regardless, the system worked rather well up until several months ago when I switched it off before accelerating to freeway speed (those 63 horses need all the help they can get) and upon switching it on again I noticed that there was no noticeable drop in engine power.

Well, after troubleshooting I came to the conclusion that the compressor had failed. Removal of the compressor confirmed this as the reed valves (the thin ones) had decided to disentigrate (sp.) and chew the crap out of the york's pistons and cylinder walls. As such the compressor was simply chugging away but not really compressing anything.

I ordered a rebuilt york from ebay (a fellow named a9star9x, who had very high feedback, but I was prepared to get burnt) for $115 w/clutch. Installing the new compressor was a royal pita, neither I nor the service manual seemed to know how to remove the big mongo bracket without draining all the coolant. Well the compressor was replaced, along with the high side manifold hose (broke the %$@# fitting off while getting that huge bracket/compressor back on).

Today I just returned from the ac shop which flushed, replaced receiver/drier, expansion valve and recharged (with r134, r12 is 60 bucks a pound). According to him, while road testing it cooled (albeit marginally) but slowly decayed to no cooling at all. He then checked the pressure and found the following pressures:

idle: 100-110 psi on BOTH high and low side
~3k rpm: 65 psi low side/140 psi high side

Which is not good.
He tried switching the new expansion valve with the old one, just to check (they don't fail THAT often from what I've read and from what the tech told me).

Just as an aside, the clutch works fine and everything activates when it should and the system holds a charge (never needed topping off for the ~3 years that I had working ac).

So, the mechanic thinks I have a bum compressor, which I'm inclined to agree with, and my questions are:

Does this indeed sound like a bad compressor? And if so, can I replace it with the damn bracket still on the engine?
Should I go for a new compressor, like from adsitco (because so far I'm not too confident in rebuilds)?
Or maybe do that sanden conversion I've heard about?
If it's not a compressor, that what could it be? I'm ready to tear my hair out ($500 later and still no ac).
And just to satisfy my curosity, what could have cause the original compressor to fail, as it's my understanding that yorks don't worry about lubrication in the system, as they're internally lubricated. It WAS a 30yr old compressor, so I'm just guessing that it was old.

Sorry for the novel, but I just wanted to make sure everyone had enough information to work with.

Thank you all for your help,
Ben Stein

[leathermang]

Well, the easy things first.... R12 is available on Ebay for $25 a lb ( or less )... so I am sorry you did not know that and go back with R12 when you had the chance...

The York compressor does not exactly Ignore lubrication... in the time you had the car did you ever check the level of lubricant inside the crankcase of the York ? You have to have a bent stick to measure it.... but the MB AC manual gives exact dimensions for making one....

I think there are ways to check the compressor for pumping capability before hooking it up and charging the system... like Bench Testing it... for a compressor which is mailed to you that might be worth the trouble next time...

Will have to mull about the rest of the problem....

[stei7766]

Wow, thank you very much for the quick reply. As to the lubrication, I really didn't make myself clear. I was under the impression that other compressors rely fully (or at least mostly) on the oil in the refrigerant, whereas the york has the oil in it's own crankcase which never comes into contact with the refrigerant. Or at least as isolated from compressed gas as it could be.

But, in response to your question, I did check the oil in the old compressor after it failed, and it was okay, according to my trusty bent piece of wire.

Do the valves rely on lubrication from the refrigerant oil? I'm not too sure about the oil content of the previous refrigerant, but the inside of the system and compressor (the pistons anyways) seemed nice and oily to me, for whatever that's worth.

I never had an issue with the r134 cooling capacity, but will r12 give me a more trouble free system? I've never really found a straight answer one way or another to that question, opinions seem to be rather mixed.

Thanks again,
Ben Stein

[leathermang]

The 134a runs at higher pressures.... and there are plenty of people who have had short lives out of their compressors after changing to it...
and on the other side... many people with 20 years use out of their compressors using R12 ( which was designed especially for your AC system).
I don't know if it is the pressures by themselves... or if the oil used with the 134a does not move around as well, or lubricate as well ... but compressors used to last a long time with R12 in them.. and cool better...
The oil which travels around is supposed to mix with the refrigerant... miscible ( spelling )... so maybe that does not do as well as the combo of mineral oil and R12...

you are correct about the R4 not having a crankcase and being more sensitive to lube problems... I will have to research about the oil amount which is supposed to be in the system with regards to the upper end of the York.... your's is an OLD system... LOL

[stei7766]

Heh, you're certaintly right about it being an old system. One advantage though, there aren't too many switches and mysterious black boxes to worry about breaking

However, due to it's age it seems that I might have to accept that I'm, uh, urinating into the wind trying to get this to work.

But you know how it is, I just keep telling myself: "just this one more part, and it'll be perfect!"

[leathermang]

I have an 80 240d... with the manual AC controls...type 1 but mine is the R4.. I expect you have the same system except for the york... they worked for millions of cars... and it is rebuildable... but care must be taken to measure the right things to see if they need renewing...
The York typically lasts longer than the R4 ... but the R4 uses less HP to run it...and is WAY smother... I believe that both your pistons go up and down together... way hard to get that balanced enough to be smooth...

If worse comes to worst... I have a York from a 79 wagon parts car I will ship you...