1992 2.5L Heat Problem

I recently bought a 1992 Dodge Caravan from a friend of mine whos had it sitting in storage for about 2 years and the heat will not work. Its not that doesnt work completely but it'll get kinda warm and then when i turn the fan up more it'll get cold. Not only that but every now and then and i mean really not much at all, the temp gauge goes up to hot and warns me to check gagues then after a min or so it goes back to the middle. I know its not a head gasket cause my friend says he replaced that in the last year he drove it. I checked my coolant and well it needed some and i put some in and it still is not good. Its horrible here in minnesota right now weather wise (i mean getting below zero for the temp and with wind chill well below zero) and its almost unbearable to drive. It gets warm enough in there so i stop seeing my breath but thats about it. Also when i park after driving it for a while i hear it gurgling, sounds like the coolant reserve taking coolant. I know of somethings i can try (heater core spray and cardboard trick) but i want some advice about what to start with. Thanks.

Are you sure that the system is completely full? Some of your problems sound like you could have air in the system. Have you removed the radiator cap? and looked to see if coolant is up to the neck?

A good place to start would be to look at the coolant, does it appear to be in good condition? Is it rusty or any crud in it? You might start by draining out all the old coolant flushing the system real good. It's possible that there is "gunk" in the coolant that is blocking up your heater core and or some of the passages in the engine. On a Chevy Blazer my daughter owns I took the hoses off the heater core and back flushed it with a garden hose it opened it righ up an it heats like mad now. It didn't seem like there was that much gunk that came out but it made a big difference. relatively small particles can block off the flow through the heater core.

It could be a bad water pump but if it was low flow due to a bad pump, I would think that your engine would run hot all the time. Thermostat has nothing to do directly with the Heater, it opens when the engine temp gets high enough and then it send coolant through the radiator. Coolant is always running to the heater core. if your thermostat is stuck open the coolant will never get as warm as it should..but that doesn't explain the over-heating, with a thermo stuck open you should never overheat.

There are some vent doors in the ventilation system that open and close when changing from heat to cool..one of them could be stuck letting cold outside air in.

I would start with simple and flush and change the coolant.

Ill definately give that a try. I have noticed my coolant in the reserve is kinda gross looking. Ive thought about draining that from the beginning. I shouldve maybe done what i thought it couldve been first before i posted on here but ill go ahead and do that and keep this updated. Thank you very much.

Just found out my radiator is clogged up. So im gonna have to get some cleaner for it and drain it, clean it out and refill it. So thats good news.

You my have a bad thermostat, I have seen thermostats cycle (cold to hot and back) rapidly so try and replace the thermostat as that is the least expensive thing to repair or replace.

That's great that you found the radiator problem! Back flush the whole system as best you can. I wouldn't be surprised that you have some of the same gunk in the heater core...it's basicly another radiator that vent heat inward. Don't just clean out the radiator..backflush the whole system

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