The heater in my 68 dart is not working to well. It gets a little warm but not hot at all.
I've replaced the thermostat with a 195 but that didnt really help much.
I bought a new heater core thinking my old one was plugged up or something, but i've not installed it yet.

After posting a picture of my engine on another web board, someone suggested that my heater hoses are backwards. Take a look at the attached picture and tell me what you think !

Thanks
Scott
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Typically, there is a different size hose for the supply and return at the heater core. Reversing the hoses should make very little difference to the operation of the heater but would make the hoses harder to hook up. On my 65, the supply is 1/2" and the return is 5/8". There would also be a corresponding 1/2" nozzle on head and a 5/8" nozzle on the water pump.

Rather than replacing the heater core right away, check to see if it's plugged first. You can do this by disconnecting the hoses at the head and at the water pump and blowing through the hoses. If air passes freely through the heater core, the heater core isn't plugged up. While you have it disconnected, hook up a garden hose and flush out the heater core before you put is back together, first one side and then the other. If the core is plugged up, don't turn up the pressure too much as you could easily get 60 psi from the garden hose.

A problem I came across with my car which sat around for a few years was corrosion plugging up the nozzle on the water pump. While you have the heater hose off, check to see if this nozzle plugged up. If it is, clean it out and the short thermostat bypass nozzle while you're at it. Corrosion in the water pump usually means that the corrosion inhibitors are used up in the coolant and it's time for a flush and fill.

Put the hoses back together and check the operation of your heater. If it still doesn't produce very much heat, there is a good chance that the heater core's passages have some scale build up. You can either replace the core now or try chemically cleaning it first. Have fun.

Frank

Backwards heater hoses only matter on systems that use heater water control valves. The non-Aircon heater system in '63-up A-bodies does not, so it doesn't much matter which way the hoses are hooked up. Instead, your heater uses cable-operated air control doors (in the heater box under the dash) which direct the flow of air either through the heater core (temp lever towards "hot") or around it instead (temp lever towards "cold").

Lots of things can cause insufficient heat. A blocked heater core certainly is one of them. With the engine warming up, grab both heater hoses at their midpoints, one with each hand. They should be about the same temperature. If the one connected to the water pump is significantly cooler than the one connected to the cylinder head, the core is probably plugged up.

Other causes include a worn water pump (erosion of the housing), buildup of leaves and debris inside the heater box, a stopped-up heater hose nipple at the cylinder head or water pump, air doors in the heater box that aren't going all the way where they're supposed to go (blocked from closing/opening, bent or broken control cable, temp lever cable clamp slipped so cable doesn't have full travel).

You should get plenty of heat with the correct 180° thermostat. Time for some systematic checking!

Nice clean engine compartment, by the way.

That's not original. Both hoses (and all fittings) were 5/8" until 1970 when the supply was changed to ½" to reduce the possibility of plumbing noise(!). The '70-'72 A-body heater core is identical to the '63-'66 item except for the size of the inlet fitting, and it is common to find the later core in earlier cars, usually with the head fitting changed to match.

SlantSixDan is correct. My 68 IS 5/8" on both in and out connections.

My 71 has 5/8" and 1/2"

Again I learned something new. Now I know that my 65's previous owner changed the heater core. Since the nozzle on the head isn't easily visible and the 1/2" hose slipped over it, I assumed it was also 1/2".

Frank

That's what it's all about!

D/W

_________________

If it ain't broke, fix it!

The coolant flow throught heater core should be into the bottom and out of the top. This is so it can purge any air. When the nipples are side-by-side that makes it difficult to determine which is "in" and "out".

I"m sure that is why they changed to 1/2" supply and 5/8" return hoses on later cars.

Ok, looking at my 75 and 76 service manuals, you do have the hoses reversed at the heater core. The inlet is the passenger side one, the outlet is the driver side one.

Also somestated if water or air flows through the heater core easily that is it not plugged. Not so, it can be partially plugged and still flow well, you just won't get enough heat out of it. I've disassembled some of those old cores and they are always full of all kinds of junk.

Also I just had the core out of my 1987 Dodge truck to fix a leak. It flowed water from the garden hose with no apparent restriction. When I removed the tank opposite the nipples, I found it was full of all the junk that came loose from the radiator and that several of the tubes were not flowing water. I had it cleaned, fixed, and now have it back in the truck and I have heat like I never had before.

That's probably one reason, but the "Chrysler Corporation passenger Cars Engineering Changes for 1970" book says it was to reduce the possibility for waterflow noises (the whistles and rushes one sometimes hears from household hot water plumbing).
'73-up A-bodies use a different heater assembly with a different heater core compared to the '63-'72 item, so don't rely on post-'74 manuals for info on your '68 car.
True, that!

the heater core that I first replaced in my 70 had a large and one small nipple( the head and waterpump nipples were the same way) the one I am running now came out of a 75Valiant and is 1/2" and 1/2".
I had to go to home depot to fix that problem.
Mine also flowed well but no heat. I strongly believe it was the cooling system stop leak that I used more than once(I know, I know everyone gets to smack me in the back of the head for that one) coated my entire cooling system with that crap and heat transfer went bad. I even used cooling system flush 3 times and still no dice. Since then I have replaced the rad and heatercore. now I get plenty of heat and the temp gage barely moves from the middle.

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I went back to my car and had another look at the nozzle on the head. The 1/2" hose does not look like it is stretched over a 5/8" nozzle which was probably another reason why I figured that it was correct. It looks like the previous owner also changed the nozzle on the head when the heater core was changed.

Also, a question for Craig. Since I have never had my heater apart, how do you disassemble the heater core to clean it out? I thought it was a soldered together and not servicable. Or is the tank you are talking about something else?

Radiator shops can unsolder the tanks and brackets from a heater core. Usually they don't bother trying to clean an old core, but simply "re core" the unit, using the old tanks and brackets after making any necessary repairs to them.

The way the heater core is made in your 68 Valiant and in my 1975-76 Valiants and in my 1979 Dodge truck make it usually unrepairable. Sometimes some leaks in those can be repaired.

Sometime with the 1980's trucks (I have a 1987 truck) they switched to a tube and fin heater core with tanks on the ends. The construction is very similar to the radiator in the front of the engine. This core can be disassembled and cleaned up and resoldered. The core itself is only about 3/4" thick and has fins that are very closely spaced (high density fin count) for maximum surface area in a small package.
The replacement cores that are available for my truck are of the old style construction and are about 1-1/2" inches thick for my truck and would not fit like the original core and perhaps not have the heat transfer ability of the original core so I had the old core repaired. I should get a spare from the salvage yard some day for just-in-case.

Craig, I have not found that to be correct. Radiator shops can re-core even the older heater cores. I've had 'em done for my '62, my '65, etc. No problem. Call around to some good radiator shops; you may be pleasantly surprised.

You still have those up in Canada, eh?

I don't know about where Craig lives, but you damn sure can't find any in my neck of the woods. Oh, sure, they'll repair or recore, but they'd rather just sell you a new radiator, mark it up and do nothing. A recore around here is more $$$ than new for that very reason.

D/W

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If it ain't broke, fix it!