Heater not so warm

Some of you may remember this problem from last winter. 95 Jeep Cherokee. After about -10 it just doesnt produce much heat. Heater fan works fine. Jeep runs plenty warm…but what i neglected to mention and or forgot to consider is… I have a tiny leak in the cooling system somewhere. I added just a small amount of coolant a couple of times over the summer and have witnessed a small amount of steam (not lately for whatever reason) coming from the front of engine compartment. I cant find the leak.

My question is…

Could this cause enough loss of pressure to affect the cabin heating system

Does the jeep take a long time to heat up?

Have you tried adding a bit of UV die to find the leak?
Here’s one but there are many out there: http://www.amazon.com/Tracer-Products-TP34000601-Fluorescent-Detection/dp/B000JFHNTM
You use a UV or black light to find the problem.

Yes, that could be at least a partial cause of the problem. It’s supposed to be a mostly sealed system (expansion tank covers the “mostly” part). Once you start losing fluid, you get air in the system. Air pockets can live in your heater core as well as just about any high spot in the system. They can also produce hot spots in the motor, which can lead to any and all sorts of problems, depending on where they are.

Try RemcoW’s tips, and fix the leak.

No i t doesnt take a long time to heat up…maybe could be faster but seems ok. No i havent tried UV dye but i will check into it,

Thank you both

UV kit ordered through napa. I have to wonder if i wouldnt save myself the money and just pull the radiator and have it pressure tested

Should you need to replace it, you may want to have a look into Radiators.com. I’ve bought several from them. They are quick to deliver and pretty inexpensive.

Thanks for the info but seeing as how im in alaska shipping could change that

$189 in town from O’Reily’s

On the bottom of the water pump is a small hole. Most refer to it as the weep hole. Check there, and make sure there’s no indication of coolant. If there is, it’s telling you the seal is going, and the bearing will follow pretty quickly. Kind of like an early warning system for a water pump failure. Although, it would be unusual for it to fail in the manner you’ve described, I can’t say I believe it would be impossible. It’s worth a free look, anyway.

i replaced the water pump just a few months ago

Does this have the 2.5 of the 4.0 motor? I haven’t been under the hood of one of those in a while. If I remember right, the 4.0 was a motor that would put up with a lot of abuse.

easiest water pump replacement ever.
upper and lower hose were also replaced which kinda leaves the radiator as the leaker

4.0 and it has been a good motor

Yeah, since you’re mechanical enough (just noticed a bit ago your handle, lol), test the rad. Should be easy enough. However, if it’s leaking, I would think you’d be able to find evidence on it, once you get it out.

It’s not something simple, like a weak radiator cap and a hole in an expansion hose, right?

I have not replaced the cap so thats a possibility.
Im not sure what you mean when you say “expansion” hose

The hose from the rad to the expansion tank. There’s almost no pressure there, but if it had a pinhole, it would weep just a little bit, and only when the system was expending coolant or drawing it back to the tank. I don’t think your expansion tank is in line in the system. I could be wrong.

Ah. I know what you mean and no its not inline. I will check that. Thanks

No…but what it can and does cause is AN AIR POCKET in your cooling system. Pressure loss is not your issue…and pressure is what keeps the boiling point of the coolant high.

If you have a leak then you have an air pocket… You MUST find the leak and fix it asap…nothing else will do. A not so hot heater will be the least of your worries if you continue to run with an air pocket in the system. The air pocket is the cause of your heater woes…and it will soon be the cause of your head gasket failure. Find it…fix it… and all the other issues will go away also


if i pull the radiator will the leak (small as it is) be evident?

The radiator is not visible… Shrouds, Fans ect are keeping me from inspecting it. If i pull it will a tiny leak show itself on the radiator…

My guess is YES. Anybody??