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Leaks at Fiter/drier--Dodge B-350 Van

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May 8, 2017, 8:36 PM

Post #1 of 4 (753 views)
Leaks at Fiter/drier--Dodge B-350 Van Sign In

I am working on one of our church's vans. It is a 1994 Dodge B-350 5.9l with dual a/c. The vehicle developed a leak in the front evaporator. I replaced the evaporator. While I had the system open and since I had the entire gasket/oring set, I decided to replace all the gaskets and orings in the area around the evaporator and valve. Bad idea! When I could not hold a vacuum after reassembly, I took my tank and introduced some refrigerant into the system. Using soapy water, my only leaks were at the metal gaskets on both sides of the filter/drier. My first thought was that I did not clean the sealing surfaces well. I disassembled and used a Scotchbrite pad to clean all sealing surfaces. I was meticulous in the cleaning and reassembly with new gaskets. Try again--same thing, leaks on both sides of the filter/drier at the metal gaskets.

To all who are familiar with Chrysler systems of this vintage, the nuts that hold the flanges to the drier are offset and apply force to the sealing areas in kind of a cantilever fashion. The metal gaskets have raised circles around the sealing area which I assume are supposed to compress and complete the seal. Is my thinking correct? The drier appears to be the original one. The church purchased the vehicle new and to my knowledge the only other work done to the system was a compressor replacement due to a leaking shaft seal a few years back. Other than that, the system has performed well all these many years.

My questions are, " What am I doing wrong?", "What am I not doing that I should" and "Is there some type of sealant I should be using?" I intend to replace the drier thinking maybe the studs which the attaching nuts screw onto may be distorted or perhaps the sealing surfaces on the drier have barely visible microscopic pitting which allows the gas to escape. I do not see how the flanges on the lines could be distorted as they are about 7/16 " steel.

Thank you in advance for your help with this problem. It is about to drive me "bonkers" and any help would be appreciated. Thanks again..

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 9, 2017, 2:06 AM

Post #2 of 4 (743 views)
Re: Leaks at Fiter/drier--Dodge B-350 Van Sign In

NO SEALERS! Save me a dissertation on that.
Somewhere in that I don't think the type of Scotch Brite to clean surfaces was the right choice. I don't use that but know it's all around ABRASIVE properties also vary by exact type and too harsh for A/C IMO.

Clean with soft things and solvents not abrasives. Surfaces flawed you should be replacing and new gaskets each time as well.

Soap and water does work testing for leaks but depending on how slow probably would dry out before you notice a leak when under full pressure. Remember that refrigerant gas is a smaller molecule and would leak easier than plain air not suggested for this at all especially systems using PAG oils which this does.

You've done remarkable well for that many years without a total problem from just the oil - can't know this one but the oil is "hygroscopic" meaning it absorbs moisture out of the air and not so special it ruins it and becomes acidic with just moisture. That could be the source problem this time around and age of it will just start eating thru the weakest things all over.

What do you want for now? I suggest new parts and gaskets where you know it leaks.

If ready for more probably time to flush out the entire system and start over with new oil kept out of moisture as marked on the stuff.

Just FYI for model year 94 in particular which is the first full model year that only came with 134a refrigerant vs called Freon or R-12. The car makers all around some just retrofitted the systems brand new to tolerate the then new gas used - behavior and properties work just different. So you may never be sure all parts acquired or originals were meant for which type but seem to have the history down - great. What I'm saying is new it could have been different mid year of production.

Because of that I do suggest the final charge up to the exact proper amount be done professionally taking in all observations and recording the amounts that worked out written down on this. You tell me - it may be in great shape still overall and well cared for. Whole new one would be quite costly - just glance at high passenger vans of the sort out there what they cost now.

The life and trivia of A/C failures is that at least 2/3rds of the problems will be a leak first then the subsequent problems because of that. The tools to find the tiny ones or be proactive are costly for one time use so suggest send those problems out. You should be using UV dye in it now if not in this vehicle already as well,


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

May 9, 2017, 4:40 AM

Post #3 of 4 (739 views)
Re: Leaks at Fiter/drier--Dodge B-350 Van Sign In

Remove the lines and examine the fittings closely. Make sure you didn't try to tighten it when it was not fully seated which would have damaged the nipple portion that slides into the dryer.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Ultimate Carjunky / Moderator
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May 9, 2017, 6:35 AM

Post #4 of 4 (731 views)
Re: Leaks at Fiter/drier--Dodge B-350 Van Sign In

Some of those gaskets for the fittings are junk. They make thicker gaskets that have some sort of felt material that seal much better.

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