***emergency*** get the insulation off your hose - PeachParts Mercedes-Benz Forum

vstech · #1 05-13-2010, 07:44 PM

all 300D owners (TD owners too) with the 617 and R4 A/C that'd be 79-85 I believe.
if you have an overzealous tendency, and installed, or got your car with insulation pipe installed on the suction line that crosses in front of your valve cover, GET IT OFF!@!
I just pulled a good cleaning job on my 83 TD, and found RUST and I mean MAJOR rust on the line nearest the power steering pump!!!!
I took some pics and will be posting them. but I had to get this out there!

vstech · #2 05-13-2010, 07:52 PM

unless the installation was glued on at the part where it goes under the PS pump, and the seam is sealed and the pipe is not torn anywhere, moisture will be trapped in the insulation and wear will eat through the cadmium plate, and start a rust fest, rapidly destroying your line.

good thing I have parts cars...

pawoSD · #3 05-13-2010, 08:12 PM

W126 owners don't have to worry about that problem.

I especially don't, since I pulled my A/C compressor over a year ago.

vstech · #4 05-13-2010, 08:16 PM

nope, the 126 routes the suction line differently! that's why I said D/TD only!
and if your a/c is not working and you never want it to, it doesn't apply to you either.
but if you someday want the line to be leak free, and you someday want a/c. FIX this problem ASAP!!!

JHZR2 · #5 05-13-2010, 09:20 PM

Suggest a fix... I have found closed cell foam but I need the right adhesive to get it on the pipe without leaving gaps for moisture to sit after repair.

I was also thinking of something like brush-on undercoating or something that will bond on.

Thoughts?

vstech · #6 05-13-2010, 09:25 PM

sure.
in the a/c field, we use a rubber cement like contact adhesive. I'll take a pic later for you guys.
I think a bead of acrylic on each end of the hose, and seal the seam with the proper adhesive and you'll be good to go.

babymog · #7 05-13-2010, 09:26 PM

I would expect that a clean surface with a good coating like WURTH rubberized undercoating, would protect it.

vstech · #8 05-13-2010, 09:27 PM

I would also recommend gluing aluminum foil or even roof flashing to the section in front of the valve cover to protect the rubber from tears etc. it'll also reflect radiant heat away from the line.
this will not help cooling at all though.
possible SLIGHT drop in head pressure from the foam.

turbobenz · #9 05-13-2010, 10:02 PM

Maybe this happened to your car but Ive never seen any rust on those lines. Maybe its a rust belt thing though

BlueCrayfish · #10 05-14-2010, 08:50 AM

Don't mess with the hose.

vstech · #11 05-14-2010, 08:55 AM

Quote:

Originally Posted by turbobenz

Maybe this happened to your car but Ive never seen any rust on those lines. Maybe its a rust belt thing though

I'd never seen any rust either. but I've never removed the foam before. on this one, the foam was badly torn, and I have PLENTY of new 3/8nominal armaflex. I WAS going to replace the foam... now I gotta replace the line and do a MUCH better job of insulating it, IF I insulate it at all.

andrewjtx · #12 05-14-2010, 09:53 AM

I just replaced this line with a new Behr part. The insulation looked good and well sealed and was not damaged during install.

And the old line that came off, with its brittle insulation still intact under the PS pump, didn't have any rust on it.

That would suck though to have the line discharge abruptly after a rust spot weakened.

Yikes.

vstech · #13 05-14-2010, 09:59 AM

what were you replacing it for? was the flex part damaged?
I'm just posting this as something to check. I've seen Hundreds of these cars with poor insulation wire tied and open. it never occurred to me to check this line for rust.
I'm out for that one guy that has an unknown issue!

JHZR2 · #14 05-14-2010, 10:13 AM

It is a great point though to check. On my 81, it is all solid, but this stuff just gets brittle with age. On my 82, only one section seemed to actually be glued on - it is fully connected still. The rest has fallen off.

If the engineers thought it was smart to have it insulated, so be it. The line does get quite cold, water condenses on it, and frankly, I would imagine that heat IS flowing into the line, reducing the overall efficacy of the cycle.

Darthgrader · #15 05-14-2010, 10:23 AM

Quote:

I would also recommend gluing aluminum foil or even roof flashing to the section in front of the valve cover to protect the rubber from tears etc.

Is that why I've seen a few hood pads with a little square-shaped section of shiny metal or foil pasted on? I have been wondering about that.

That's a modification equal to my skill set--cutting and pasting!

All kidding aside, anything I can do to extend the life of my AC interests me. I had two compressors replaced in my old 300D and it was far from cheap.