Dash Heater Core

[Jim Murray]

On a 2000 Marquis has anyone ever had to change the dash heater core? It's located on the firewall just behind the
brake peddle. If you open the small trap door by pushing the spring loaded door down you can see the core. Trouble is
you can't get there from here. If you try to come up from the front under the front cowel you run out of room because of
the taper of the front cap just below the windshield. I can see the leak, touch the leak, I just can't get the core out.
  I've talked to CAT and they advise against putting "Bars-Leak" or anything else in the radiator, the chance of that
working after traveling 40 feet from the radiator to the core are slim and none.

[Marty and Suzie Schenck]

You need to get a small guy to get up in between the front cap and the firewall. The AC evaporator and the heater core are all in one housing mounted on the firewall. I had to fix the evaporator on my 1998 Monterey and thats how I know. It's the same on my 2002 Thunder so I imagine it's the same on your Marquis. It's do-able if your small.
Marty (yes I'm small)

[Jim Murray]

Do you think that there might be some way from the inside dash down to the top of the core?

[Bill Johnson]

We also had a leaking heater core on our 02 Patriot.  Like Marty, the only way we could repair it was by getting up between the front cap and the firewall.  I echo Marty's statement that it helps being small.  While I am not so small, the person that did remove/replace the unit was (smaller, thinner and younger).  At best it is a tight squeeze, but is doable.

[Jim Shaw]

I agree with the others that being small is a must. Had to have mine replaced last year on My 2003 Monterey and after it was replaced they found that the heater valve was leaking and had to replace it also. I guess I have to wonder if it was just the heater valve or really both which would be a rairty. I would be sure and have a pressure check done on the cooling system to be sure. I was on the road and left my pressure tested at home.

[Howard Eiffert]

I also have a heater core leaking on my 99 Patriot Thunder.  I dont't have truoble getting to it to change but I don't know where to find a new one.  Maybe I will be to fix it but would prefer to have a new one.  I presently have it by-passed.  Any ideas would be appreciated.    Howard Eiffert

[Paul Schwalen]

Howard,

How did you access the heater core piping to install the bypass?  My core is still OK but after 7+ years I probably don't have much time left before it springs a leak.  I have looked at the amount of space between the front cap and the rear of the dash and can't see a way to change the core with the amount of space available.  I was wondering if removing the dash from the windshield back would allow it to be done from above?  Any ideas anyone?  :-/

Paul

[Jim Murray]

Howard
I too would like to know where to bypass the core. I can get along without a heater and as long as I have a
clean rag for the windshield the defroster.

[Howard Eiffert]

My 99 Beaver is the old body style with the access door in front and the heater core is directly behind the door.  I was able to use a short piece of copper pipe and hook the in and out together to bipass the core.                                                  Howard Eiffert

[Jim Shaw]

Jim, I also had to bypass my core. It is difficult, but it can be done from under the front of the coach. Be aware that on mine the two hoses had a different size ID. One was 1/2" and one was 3/4". I found a connector at Napa that worked great. I have a 2003 Monterey with the Cummins 350.
Jim

[LarryNCarolynShirk]

I had the heater core replaced a year ago by Richard Boatman in Bend.  He removed the dash from the windshield back to the control panel.  Then cut an access hole in the top of the exposed strand board beneath the dash padding.  He worked from the top while his slim assistant worked from the bottom.  He patched the hole with the part removed and attached it with screws to facilitate removal in the future.  I am glad HE did it.

Larry