water pump? no hot air until driving

water pump? coolant? no hot air until driving

My heater is doing nothing unless i'm on the gas. Usually i warm up the jeep for 10 min and my aftermarket heater gets everything scorching hot inside but now it doesn't do anything but blow cold air unless i get in and start driving then it blows hot. It seems as if the hot coolant is not cycling to the heater unless I'm applying power to the motor. Engine temps reach normal temps (210ish) within about 7 minutes. Does this sound like the pump goin bad or am I running out of coolant or something?

My aftermarket heater is behind my passenger seat and heater hoses hook it directly to the pump. The stock heater core is unhooked. The heater has worked flawlessly until now.



Thanks

Try flushing out the heater with a garden hose, it may be clogged up.

My water pump failures have all been leaks, but low heat production is tied to pump failure too. As mentioned, the heater could be clogged. How are the hoses?

O/T: which heater do you have? Any pictures?

As you have the heater mounted way back by the rear seat, perhaps much of the coolant
is being cooled (or partially frozen) in the lengthy hoses by the cold winter air, by the time
it finally reaches the heater core?

is it possible that there is an air pocket in the heater core?
i had to change my Rad setup on my off road race buggy due to problems with air that would gather in places that should have no air, that was when the engine was mounted in the rear with long lengths of tubing that ran to the front end of the car with a front mounted rad.

same rad same waterpump, but now rad mounted behind the front seats and much shorter tubing from engine to rad (and elevated from where it was before) solved my problems, my air pocket trouble would come and go any time it chose to do so untill everything was moved around.
just a thought..

Sounds like an low coolant level to me.

I was thinking the same about low coolant. I had a car one time that would lose heat around freeway exit ramps. There wasn't enough coolant in the car to keep the system full, so it would essentially puddle to the side of the block opposite of the heater core and there goes your heat. Your water pump isn't very effective at pumping air.

1. Check coolant level obviously

2. If cab heat eventually gets hot, this is not likely caused by your heater core

3. A weak water pump can absolutely give you this symptom. The vanes on the pump wear out. If it's old, replace it with a new one; they aren't particularly expensive. Inspect the radiator and replace it at the same time if it is long in the tooth.

Thanks for the advice guys.

My water pump failures have all been leaks, but low heat production is tied to pump failure too. As mentioned, the heater could be clogged. How are the hoses?

O/T: which heater do you have? Any pictures?

Click to expand...

I don't think the heater is clogged. It's about 3 years old and so are the heater hoses that I used (high quality hoses).

This is what I got:

http://www.4wd.com/Heating-And-Cool..._c=84&t_s=519&t_pt=3419&t_pn=HCT47-0760-U200H

It has it's own heater core in it so I bypassed the oem heater core and this is hooked up to the pump instead. Worked so much better than the stock heater (never had to use a setting higher than Fan level 1 or else I'd fry lol).

As you have the heater mounted way back by the rear seat, perhaps much of the coolant
is being cooled (or partially frozen) in the lengthy hoses by the cold winter air, by the time
it finally reaches the heater core?

Click to expand...

This is a possibility but I doubt it since I've had way colder nights where it would get hot pretty quickly.

is it possible that there is an air pocket in the heater core?
i had to change my Rad setup on my off road race buggy due to problems with air that would gather in places that should have no air, that was when the engine was mounted in the rear with long lengths of tubing that ran to the front end of the car with a front mounted rad.

same rad same waterpump, but now rad mounted behind the front seats and much shorter tubing from engine to rad (and elevated from where it was before) solved my problems, my air pocket trouble would come and go any time it chose to do so untill everything was moved around.
just a thought..

Click to expand...

Another possibility. I would think I would have an issue with it the past 3 or so years but not even a hiccup since until now BUT I just had my cat replaced and my heater hoses run along the frame rail somewhat near the cats so it's possible that the shop had to disconnect the hoses to make room to remove the cat and didn't bleed the air out when reconnecting.

As far as I know, my radiator was replaced shortly before i bought the jeep (about 4-5 years ago) so I don't think the radiator has anything to do with it. The pump seems to be the original so I'm gonna keep that in mind. I'll go out and check the coolant and see what's going on and hopefully I can figure it out rather easily without having to tear things apart.

I checked the fluid today and it was low as shi$. Took 3/4 of a bottle to fill it and the reservoir. Burped it a bit and kept it full till operating temps hit 210 then I tried the heater. Nothing but cold air. Lightly pressed the accelerator and it got warm instantly.

What I noticed was one hose coming into the heater was warm but the other hose was cold. When I hit the accelerator, the other became warm. Does this mean anything? Sounds like nothing is pushing the coolant through the heater at idle.

Ok sounds like you either have a worn water pump or you have a spot in the hoses not allowing flow unless the pump is pushing harder

1985xjlaredo said:

Ok sounds like you either have a worn water pump or you have a spot in the hoses not allowing flow unless the pump is pushing harder

Click to expand...

This

MY pump has 103k on it. I guess it could be due for replacement. It's not leaking though.

I'll check the hoses for any kinks or signs of blockage but i doubt i'll find anything.

Water pump doesn't have to leak to be failing. My money is on that....

try replacing the thermostat

Milhunter23 said:

try replacing the thermostat

Click to expand...

How is the thermostat involved?

just a tip if your tearing apart your cooling system you should always see exactly what s the problem first, i mean pinpoint it not roll the diagnostic dice. and while your opening up the system replace all the simplest things to keep you from having to drain the coolant and do it again in the future. things like thermostat (extreamly cheap), any hoses that may look suspicious, clamps ect.

birchlakeXJ said:

1. Check coolant level obviously

2. If cab heat eventually gets hot, this is not likely caused by your heater core

3. A weak water pump can absolutely give you this symptom. The vanes on the pump wear out. If it's old, replace it with a new one; they aren't particularly expensive. Inspect the radiator and replace it at the same time if it is long in the tooth.

Click to expand...

This ^^^^ ... I would reckon.

muddeprived said:

How is the thermostat involved?

Click to expand...

In your case ... it shouldnt be.

Coolant flow to the heater hoses, bypasses the thermostat - and is constant from start up ... Its why the CTS is in the heater hose gallery, of the thermostat housing.

muddeprived said:

How is the thermostat involved?

Click to expand...

If the thermostat has failed/stuck open, it definitely won't reach normal operating temps, except you said it DOES reach normal temps in an earlier post, right?

Ronbo said:

If the thermostat has failed/stuck open, it definitely won't reach normal operating temps, except you said it DOES reach normal temps in an earlier post, right?

Click to expand...

Yes it reaches normal operating temps.