Fixed AC Hoses 1985 300D - PeachParts Mercedes-Benz Forum

BillGrissom · #1 05-21-2015, 02:02 AM

The main suction hose in my 1985 300D started leaking (thru the hose), leaving yell-grn liquid (AC oil w/ dye) on my CA air cleaner. The original hose was Aeroquip GH521-12, #12, 5/8" ID, 1-3/32" OD, but I don't see in Aeroquip's catalog. It appears to be non-barrier type, typical of 1980's R-12 systems. The assembly is M-B PN 1238301916 "Pipe line, bracket to expansion valve". Dealer price is $72 (M-B of South Atlanta), but I also found $57 (ECStuning.com, Benzparts) + $19 shipping from most and >1 mo delivery (Germany). There is a clamp under the battery tray. Mine broke off, so I reached under and pried it open to release the hose. Then, pull the hose into the cabin, thru the rubber firewall grommet, after unscrewing both ends.

I decided to repair my hose because: I have a Master-Cool crimper, my 1985 car appears to use a different PN (shorter, for CA air cleaner), I didn't know if OEM hose would be barrier type, it saved a lot, and a learning experience for when my 1984 needs the same work. I bought Aeroquip GH134-12 "reduced barrier" hose because more flexible and elegant. It has the same 5/8"ID, but 0.98"OD. It appeared this would match the 1"ID of the #10 std ferrules I had. The ferrules were slightly larger, but crimped OK, with a little extra ridge. But, I had to drill each center hole to fit the tube.

I decided to replace all hoses but the small blue "liquid lines", so ordered #12 "reduced barrier" ferrules. The later fit much tighter (needed oil to slide hose in) and crimped fine w/ my #10 std dies (screw slightly beyond the "stop" mark). Great, because "reduced" dies are expensive. BTW, #6 std dies also work on #8 reduced ferrules (marked thus). You can buy this crimper set new for $143. I can sell mine when done with hose work on several cars and recover most cost.

RollGuy previously mentioned that the factory hoses have a captive ferrule - search "Coll-O-Crimp" or "Bead-Lock". Aeroquip sells "cage-clip" fittings w/ Oeticker-type clamps for those who don't own a crimper, but fairly pricey ($10 vs $0.50 per ferrule). If you want to pursue new fittings, perhaps Bus & Commercial Vehicle Air Conditioning (PN 313378) or Cold Hose - Metric (Notches in the nuts of fittings indicate that they are metric thread) - Fittings (PN BL9308) fit the engine side. These have M27 nuts on #12 O-ring fittings. It appears that M-B brazed the nut end to Coll-O-Crimps. You must still re-use the special fitting on the evaporator end.

I reused the fittings, as shown in the photos. I cut a longitudinal slot w/ an air cut-off wheel. The first hose I cut the ferrule end at its OD, which worked but "not purty". On others, I cut at the inside corner w/ a hacksaw. Angle ~20 deg from the tube so no risk cutting thru the wall. You can also attack the corner w/ a triangle file. You don't have to cut all the way thru, just thin the metal so that as you pry the ferrule it tears at the corner, then polish with a flat file. It is like opening a can, but without the proper can opener.

I similarly replaced the compressor discharge hose, using Goodyear Galaxy #10 std barrier hose and ferrules I had. I have long been peeved by the tortuous path M-B chose to route that hose. You can buy that assembly if you want to keep that "feature". Instead, I ran the hose straight across to the condenser fitting (M-B not thoughtful to put on driver's side). RollGuy's hose mod does similar. I bent the fitting at the evaporator end downward, being careful not to kink the tube. I attached the fitting to the frame rail w/ pipe strap. If like my cars, the rubber isolator on that fitting broke decades ago leaving it floating (85 CA only?, I'll check my 1984). I supported the mid-section w/ a hose clamp thru 2 factory slots (thoughtful) below the radiator (w/ tygon tube protector), so the hose can't sag down and snag on parking bumpers. After getting the discharge tube off the R side of the engine and removing the EGR valve (RollGuy's block-off plates), I can now easily get at the alternator bolts, making roadside fan belt replacement tractable.

I have 47 ft of #12 reduced hose left (good deal) and ferrules, so I could makeup a new main suction hose for others easily, if you have a 1982-85 300D (or equiv.). Ditto for the other suction assy (long tube across front). PM if interested, but you must do the leg-work - supply old fittings w/ ferrules cut off and state exact length of rubber (incl inside ferrules), mark clocking of 2nd assy fittings, and source O-rings (ex. HF's HBNR kit). All I would do is cut the rubber and crimp new ferrules. PeachParts appears to offer one of these assemblies (photos unclear). I don't have enough #10 hose to make discharge hoses for others, plus deal with those variables. PeachParts (and others) sell it.

BillGrissom · #2 05-21-2015, 02:07 AM

Discharge hose photos. 1st is factory assembly. Sanden compressor w/ RollGuy's brackets. Used factory hoses initially w/ Sanden rear head w/ "GM Pad" (search my post). Discharge hose wasn't leaking, but outer shell was swelling and thought prudent to replace rubber while refrigerant was out.

sixto · #3 03-27-2016, 02:45 PM

Do open ferrules reduce around a flange on the fitting?

Sixto
83 300SD

BillGrissom · #4 06-23-2017, 01:36 AM

No. The ferrules just secure the hose to the fitting, similar to hose clamps. M-B used fittings w/ integral ferrules, which is what Coll-O-Crimp offers. The main purpose is probably simpler manufacturing. A secondary benefit may be to keep the hose from sliding off axially, which is likely what sixto refers to, but probably not essential since most hose ferrules are separate pieces. For those without a Master-Cool crimper, search "Oeticker stepless ear clamps". They look slick and you see on many factory designs. A cheap "nail puller" pliers can crimp them. Of course, you can also use screw hose clamps, as most aftermarket 1960-70's AC did. Breeze (smooth) are best. Always use barrier hose today for low leakage, and almost mandatory w/ R-134A.

ROLLGUY · #5 06-23-2017, 12:58 PM

Quote:

Originally Posted by sixto

Do open ferrules reduce around a flange on the fitting?

Sixto
83 300SD

Quote:

BillGrissom
No. The ferrules just secure the hose to the fitting, similar to hose clamps. M-B used fittings w/ integral ferrules, which is what Coll-O-Crimp offers. The main purpose is probably simpler manufacturing. A secondary benefit may be to keep the hose from sliding off axially, which is likely what sixto refers to, but probably not essential since most hose ferrules are separate pieces. For those without a Master-Cool crimper, search "Oeticker stepless ear clamps". They look slick and you see on many factory designs. A cheap "nail puller" pliers can crimp them. Of course, you can also use screw hose clamps, as most aftermarket 1960-70's AC did. Breeze (smooth) are best. Always use barrier hose today for low leakage, and almost mandatory w/ R-134A.

Actually, the factory hoses use what is called a "beadlock" fitting. The barb on the metal pipe is not as course as an actual hose barb, so I would be personally very leery with just crimping hose on with a standard ferrule. The bead on the pipe holds the ferrule in place, and is crimped around the hose on a beadlock type fitting. The best practice is to weld on hose barbs. Also, I believe the factory hose size is metric. Our A/C hose might be close enough to work, but again, I will always use a hose barb welded on that matches the size hose I am using. When I rebuild the large hose going into the cabin, I use #12 hose and fittings, whereas the factory hose has #10 on the TXV side. The only way to make a #10 & #12 work is to weld on the larger size barb on the smaller pipe. The same holds true for the high side hose going to the condenser. I make a fitting that has a #10 on the condenser end, and a hose barb that fits #8 hose. The other end has a #8 fitting. I use all steel beadlock fittings, never aluminum on the Diesel engines. If someone wanted to rebuild their own hoses, and had the ability (or source) to weld the barbs on, all the hose assemblies could be rebuilt for less- even with the purchase of a crimper and all the materials, than it would cost for factory hose assemblies.

BillGrissom · #6 06-23-2017, 03:02 PM

Standard US hose sizes fit fine on mine, -12 for suction, -10 for discharge (or whatever I said). Most hose ferrules are separate pieces, not Coll-O-Crimp or Bead-lock style, and AC hoses don't blow off on those cars. I wouldn't be concerned even w/ screw hose clamps. My 1965 Newport had those (after-market system w/ York compressor) as did most Sears, Western Auto, etc retrofits common back then. When I replaced the hoses (1990's), I had to cut & peel them off the fittings, so they were very secure. You can buy those AC screw clamps on ebay (have locating "finger"), but Breeze are better (smooth) and Oeticker clamps smaller and look nicer. If you do use ferrules and Master-Cool crimper, align the ridges of the crimp w/ the valleys of the metal fitting.

BTW, when I did this in my 1985 I changed to a Sanden compressor, as shown (on Rollguy's bracket). I bought a rear head w/ "GM Pad" fitting, which fit my factory compressor fittings. Another guy did similar. You must bend the discharge tube slightly to clear the oil pan. I am back to an R4 compressor in that car.