Community Forums

Petebur · 06-13-2010, 08:20 PM

While working in the open nose area of my MH I noticed that the previous owner had disconnected and bypassed the heater core.

Have any of you replaced the heater core in you 2000 Diplomat? It looks like it is inclosed in the same housing with the A/C evaporator. I think that’s what it is call, the part that does the cooling. Is this a job I could do in my driveway? Perhaps I could remove it and take it to a radiator shop? Do any of you all have experience in removing the heater core?
Any help would be appreciated,

Petebur · 06-14-2010, 08:35 AM

What I mean by open nose area is behind the generator excess door.

Dutch Star Don · 06-14-2010, 01:36 PM

Petebur....Did you look under the passenger side dash. I've never had mine out, but it looks like you would access it from there. Once you get the heater core out, you should be able to find an aftermarket core. Monaco used a lot of GM components.

walt2137 · 06-15-2010, 04:29 AM

Yes I have removed the outside cover and it has two screws that are extremely hard to get to or was on our 99 Dip, I didnt change the heater core but I could have, we had a water problem when we used the dash AC it was blowing on the metal fire wall causing condensation and soaking the carpet under the passenger side of the dash, fix was to insulate the metal fire wall. You can get the hard to get screws out with a little hex screw driver ratchet from harbor freight or use a 1/4 socket set and find a socket to fit the little hex type screw driver

Petebur · 06-15-2010, 06:59 AM

Thanks for the replies.
Walt2137, thinks for your input. With your information I don’t mind giving it a go. I don’t mind tearing in to a job if I think I can get away with it, but I have been bitten a few times and caused more of a problem.
I hate it when I do that.

jwinston · 06-16-2010, 11:29 AM

take some pictures and post as the work progresses..... thx james

Petebur · 06-17-2010, 09:33 PM

Jwinston,
Will give it a try. I have never tried to post pictures but maybe I can figure it out. It will probably be a week or two before I can tackle the job. Just had some service work done today. Oil change , trans. oil change, filters and the like. Have a technician scheduled to change out slide seals next week. Then off to the tire shop for new tires. The heater core will probably be the last job. Can’t leave home without a windshield defroster.

Petebur · 07-23-2010, 05:42 PM

OK! Got around to changing my heater core. After removing the core I took it to a radiator repair shop. They tried but could not stop the leaks. I ordered one from Monaco.
You may be able to see all the silicone that someone used the last time they changed the core. Although it did a good job it made it extremely difficult to remove the housing without damaging it. I used a pocket knife and a flat pry bar. Also had to cut away silicone to remove the sheet metal from the plastic housing. I found some automotive weather striping to replace the silicone. It will be a much easier job if I have to do this again. There are five screws holding the hole assembly to the firewall. The Left two and the top are removed and installed by feel. I used a right angle drill with a long ¼ socket drive and 3/8 socket for those. I had been dreading this job for a long time but all thing considered it all went back together easier than I expected.
Now the hot coolant does not circulate through the heater core. May be a problem with the heater valve as the coolant gets to the valve but does not go though it. Another problem for another thread.
Thanks for the replies to my question as they gave me the courage to tackle this job.

jwinston · 07-26-2010, 08:25 AM

thanks for the pictures. James

concrete1 · 01-27-2016, 12:13 PM

2000 Monaco Diplomat needing a heater core, where did you find the replacement part, and was it very costly.
thanks.

Rburian · 01-27-2016, 12:37 PM

I replaced the core twice on my previous 2000 Dip, the manuf. name and part number was on the core, ordered direct from the factory, sorry Don,t remember who I order from. It,s difficult to reach the nuts on the far side of the housing, I remember using a small racket and extension, other wise , it only an hour to remove and replace. Make sure you plug the hoses attached, or you will have antifreeze spill all over.

barmcd · 01-27-2016, 02:29 PM

The PO might have cut the heater hose and looped it back to the engine. That's fairly common on old cars that have defective heater cores.

That's quite a mess by the way. Good job replacing it.

Petebur · 01-27-2016, 07:47 PM

Yes is was a bit costly. I wound up buying it from a Monaco dealer in north Houston. Paid $274.46 in June of 2010. I recorded a part # E56407. I think that is a Monaco part number.
I took it to a radiator repair shop to see if they could repair it. It was so corroded that it was not repairable. Maybe you will have better luck.

Montanacraig · 02-28-2016, 07:46 PM

I had a dealer quote me around $1500 to do the job a couple years ago. Needless to say, mine is still bypassed. Can you change the core out without disconnecting the AC? I'd like to have a real defroster rather than my hand-held harbor freight heater.