Trouble Shooting a bypassed heater core

[mattman079]

Hello,

Hopefully someone has gone through this problem or has some helpful information. I bought my 83 Spider and noticed the heater core was bypassed entirely (Tubes never run to holes in firewall, but just connect to each other).

I would love to drive this fall and was curious if anyone has any tips on how to test the heater core without draining the coolant and hooking the tubes up correctly? I'm assuming the previous owner found out it was leaking and decided to just bypass it rather than fix it, but want to find out without pulling my entire console out or draining all the coolant and testing for a leak the normal way.

Thanks for the help in advance!

[lglade]

I pressure tested mine with a couple of rubber stoppers/bungs (purchased at Ace Hardware) and my compressor regulated down to about 15 psi. I was able to pressurize the heater core while my wife got in the car and listened for hissing. In the end both the control valve and the core were shot. But given the amount of work to replace them, I would have replaced both parts regardless if one had tested okay.

[klweimer]

I'm going to guess the reason the heater core was by-passed was because the core or the valve was leaking. If they are original, they are probably toast. Having the heater is great and really expands the driving season. I don't know of a good way to test these components that would give you the peace of mind to leave them in place. I'd bite the bullet and replace both, along with tubes that attach to them. The new valves require a different tube than was used on the original valve. My two cents.
Kirk

[mattman079]

Thanks for the replies. Was hoping I didnt have to pull the console out, but looks like that's my option

[Nanonevol]

These are never easy. I did one on a Volvo once and just about had to remove the whole dash.

[TX82FIAT]

Before pulling the console see if someone has a radiator test kit. You could use one of the smaller attachments and a plug to pressure test the system as suggested. I would consider filling the system with water to test right from the two ports on the passenger firewall.

A couple questions: Does your heating fan work? Have you looked at the valve to the right of center console near where your left foot toes would be if sitting in the passenger seat? Is there any sign of coolant leaks in the past like the oxidation of coolant. Do you have an ultraviolet coolant flash light? Turn off the lights and see if you have coolant stain on the carpet. Also check the cables to turn the valve on and off. These cables can have

The heater core itself is not hard to replace but if it is the valve you will need to get a new valve and tubes as the tubes and valves are slightly different that EOM with respect to angles.

Take the passenger seat out to make the work easier unless your a contortionist. The time taking the seat out is well worth the positioning to do the other work.

[mattman079]

Hi Tx82FIAT,

I will see if I can find someone with a radiator test kit. How would you test the heater core? Just plug it into the firewall holes and see if the pressure holds?

A couple questions: Does your heating fan work? Yea the heater fan works fine.

Have you looked at the valve to the right of center console near where your left foot toes would be if sitting in the passenger seat? Is there any sign of coolant leaks in the past like the oxidation of coolant. Do you have an ultraviolet coolant flash light? I have checked and I don't see any signs of leakage or rust of any kind. I don't have a ultraviolet coolant flash light, but might be worth picking up one if they are cheap.

Also check the cables to turn the valve on and off. - Valve was a little stiff to begin with, but have some WD 40 has been moving fine.

[PhillySpider]

I replaced the heater core, valve, hoses and tubes last weekend...err, i mean all last week . Was worth it, already doing heat on, top down driving here in the mid-atlantic.

I wouldn't recommend doing the valve or core alone, do them both. My core may have been ok, but when you get the pipes off an look inside trust me, you'll wish you were replacing both.

One note, I bought the kit from AR and really had trouble with the seals (really the short pipe) they provided. Raised seals and a flat face on the pipe (OEM pipe has a different profile) made it difficult to tighten and be water tight. Less torque is more here, if you tighten it too much the seals fail, squirting out the sides...