Author Topic: AC Manifold Hoses Siezed  (Read 134 times)

jtwoods4

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AC Manifold Hoses Siezed
« on: 17 August 2020, 06:48 PM »
Hey guys, I recently purchased a beautiful 1985 300SD. I have a 1980 300sd also that's why I'm in this group. Anyway, I bought the car in Ohio so I did a very thorough inspection checking for any rust or corrosion. The car has been garage kept its whole life and is absolutely immaculate with only a 140,000 miles. I did notice a little corrosion around some of the fittings under the hood and bolt heads in various places but the body and frame and entire car checked out and was in great condition.

The AC of courses didn't work, which I knew before purchasing. Immediately after getting the car I took it over to my trusted mechanics shop to have the AC compressor, drier, and manifold hoses replaced. Norrmally I wouldn't replace the manifold hoses but the fittings and mounting bracket show some ugly corrosion so I decided I wanted to go ahead and replace it.

Well the mechanics called me today and said the AC system is all tested and in full 100% working condition. They put the system under vacuum over the weekend and it held the vacuum all weekend so we're all good there.

However, they were not able to replace the manifold hoses because the fittings were corroded in place. Despite soaking the fittings with penetrating oil they were unable to disconnect the hose from the firewall or the condenser.

So we just decided to keep the existing manifold hoses who knows maybe they could last another 20 years the system holds vacuum great and the AC works now.

They said they could cut the lines but then the condenser and the expansion valve under the dash would need to be replaced and this would be expensive. So we left the original AC manifold hoses is in place.

Anybody have any ideas for how to remove these siezed manifold lines?

1980 300SD

daantjie

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Re: AC Manifold Hoses Siezed
« Reply #1 on: 17 August 2020, 07:19 PM »
I use a pick tool with a generous dollop of dialectric grease then slowly work the tip of the pick under the lip of the hose, you have to be patient and work it quite a bit but they will eventually come off as you work the grease into the corroded binding.
Daniel
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jtwoods4

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Re: AC Manifold Hoses Siezed
« Reply #2 on: 17 August 2020, 07:21 PM »
These are hoses that are screwed on with fittings you're talkin about hoses that are held on with clamps. The fittings on my hoses are seized.
1980 300SD

Jed

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Re: AC Manifold Hoses Siezed
« Reply #3 on: 17 August 2020, 07:45 PM »
Forgive me but If the system is working and the hoses are not leaking then leave well enough alone. If/When they leak, then worry about it. 

The enemy of good is better.

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jtwoods4

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Re: AC Manifold Hoses Siezed
« Reply #4 on: 17 August 2020, 07:50 PM »
Yep that looks like that's the only option for now.
1980 300SD

jtwoods4

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Re: AC Manifold Hoses Siezed
« Reply #5 on: 17 August 2020, 07:53 PM »
The hose is almost 40 years old. That's why I want to replace it instead of waiting for it to fail.
1980 300SD

UTn_boy

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Re: AC Manifold Hoses Siezed
« Reply #6 on: 18 August 2020, 12:19 PM »
I'm sure you mean the evaporator, as the condenser is what is in front of the radiator. 

I understand that you're worried about the age of the rubber hoses, but I wouldn't worry.  I daily drive other Mercedes that are 50-60 years old that have their original a/c hoses. 

Since you're having to keep the current hoses this means that you need to stick with R-12.  If you put R-134 in the system will give poor performance and prematurely damage the r4 compressor.  The R4  compressors are already short lived on these diesels because they literally get shaken to death by the diesel, but they also weren't made to withstand the higher head pressures associated with R-134A.  Also, R-134A will literally leak out of any original rubber hose over time.  R-12 will not.   This is definitely a "pick your poison" scenario. haha
1966 250se coupe`, black/dark green leather
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1971 300sel 6.3, papyrus white/dark red leather
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jtwoods4

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Re: AC Manifold Hoses Siezed
« Reply #7 on: 18 August 2020, 01:46 PM »
I'm actually replacing the compressor and the dryer with new ones. And the new components are getting filled with r134. Yeah I'm leaving the old manifold hoses but the system was evacuated and I'm sure there's minimal are 12 in those old hoses so it should be fine.
1980 300SD

UTn_boy

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Re: AC Manifold Hoses Siezed
« Reply #8 on: 19 August 2020, 01:24 PM »
Well, it doesn't really work that way.  R-12 doesn't impregnate the rubber hoses to act as a "stop leak" of any sort.  The R-134A will eventually leak out.  Since you're going through the trouble of renewing the compressor and drier why not just put R-12 back in?  You're in Atlanta, and R-134a will be tepid at best on a summer day.  R-12 is readily available all over ebay and on a lot of craigs list listings.  It's not too terribly expensive, and totally worth it.  And don't let any shops tell you it's illegal.  The only way it's illegal is if they aren't licensed to perform automotive A/C work....a 609 certification. If they possess an EPA 609 certification (they should have anyway) they can service your car with R-12, and you as a car owner can legally buy R-12 as long as your putting it into the hands of a 609 certified technician.  Some sellers ask that you sign and affidavit stating as such, but it's normal and ok to do. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

jtwoods4

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Re: AC Manifold Hoses Siezed
« Reply #9 on: 19 August 2020, 02:16 PM »
Well, it doesn't really work that way.  R-12 doesn't impregnate the rubber hoses to act as a "stop leak" of any sort.  The R-134A will eventually leak out.  Since you're going through the trouble of renewing the compressor and drier why not just put R-12 back in?  You're in Atlanta, and R-134a will be tepid at best on a summer day.  R-12 is readily available all over ebay and on a lot of craigs list listings.  It's not too terribly expensive, and totally worth it.  And don't let any shops tell you it's illegal.  The only way it's illegal is if they aren't licensed to perform automotive A/C work....a 609 certification. If they possess an EPA 609 certification (they should have anyway) they can service your car with R-12, and you as a car owner can legally buy R-12 as long as your putting it into the hands of a 609 certified technician.  Some sellers ask that you sign and affidavit stating as such, but it's normal and ok to do.

I hear ya but R134a works fine. Never had a problem with it, have it in my 1980 300SD and its been working for 7 years. Shop has already finished the job. R134a will be fine.
1980 300SD