Bellkrank

I just got my first jeep last week. 2000 sport, green, all stock, very clean! but she has very little heat. so i started to look into it and noticed that i had a leak coming out from under my radiator cap an it was pissing out a lot of coolent. So my first thought was just a bad cap and a bad thermostat so for 10 bucks i got those and put them on. The leak went away for about 1-2 days then came back a lot smaller its not pissing just dripping out from under the cap and my heat is still only luke warm. Need help its very cold in northern MI!!!!!

Hommersimpson

check heater control valve.. flush out heater core... sounds like you need a new radiator or something.. might be cloged... there is a reason for it to spit out from new cap...

storm101

As stated earlier, I would start with inspecting the system good and a coolant flush. If theres any gunk in there that should get it out (the flush), and that should help at LEAST (unless theres a bigger issue at hand) with the heat issue.

If that does not solve or help a little bit, then at least you have started out cheap, from there test the system (pressure test) and inspect the system for leaks.

That should get you going in the right direction. The findings of them few things should help point out the main issue at hand!

Remember, diagnosing is a step by step logical process, start cheap and easy and work to hard and expensive.

Bellkrank

Thanks for the tips. I was just reading around and i think im going to try to flush the heater core too. and try a reverse flush. il start tomorrow iv got half the day off.

Mike1998XJ

I just flushed out the heater core on my Daughters Cherokee last night. I've done this a few times. The heater cores are a place where crap gets stuck.... In my opinion that's a good place to start. If you do that you don't even need to burp the cooling system.
Just take the 2 small hoses off that lead to the heater core near the thermostat. Flush water with a hose through the long one, then the short one. Then repeat until you see a nice flow coming out. Reinstall the hoses, start the Jeep and turn it on defrost with the fan on high. Let it run until the thermostat opens and you should have good heat. You may need to add a little coolant to the overflow tank after this.
And don't let your pets drink the antifreeze if you spill any!

JSmith0055

hopefully its not a bad heater core, that happened to me b/c the coolant was not circulating due to a bad water pump, but if your not overheating thats not the case... flush it, and start replacing one by one...

captainofiron

Yea but start with the cheap easy stuff first

Bellkrank

So here is some more Q's?

When does the small black electric fan come on? and what does it do?

is it normal for the top hose going into the heater coil to be hotter than the bottem hose?

where are the heater control valevs and what do they do?

danimal

Since I just went through this, I'll take a shot. Someone will correct me if I'm wrong. The aux or electric fan should kick on at around 200 degrees, or if the air conditioning is turned on it will run continuously.

If you follow your two heater hoses along the valve cover they'll come to a black plastic piece, then go on to the heater core (you can't actually see the heater core, just the fittings/pipes the hoses connect to). The black plastic piece is the heater control valve.

I would think there would be a slight difference in the temp between going into the heater core and coming back out due to the heater core being basically like a small radiator. The water temp will probably dissipate some, but probably not a whole lot.

I just went through all this, but mine was due to overheating. When purchased the previous owner was running straight water (no anti-freeze) in it and it was full of rust. I flushed the heater core, the block, replaced all the hoses, replaced the thermostat, and still had the issue. I ended up replacing the radiator and that fixed it. Oh I also replaced the fan clutch. Might not have need it, but while I had it apart I figured what the heck.

I'd go with the suggestion the guys made to flush that heater core real good as well as the block and radiator, then try running it again. You really need to flush every component in the cooling system. Rust and/or deposits could be sitting anywhere in the system.

Be careful when putting the hose to the radiator and heater core to flush em out. The vehicle only operates at 7-9 psi give or take. Your garden hose can put out as much as 50-60 psi when it's on full blast. That's way too much pressure so don't open the spiggot all the way.

Hope you find the problem and are able to fix it. Speaking first hand I know it can be frustrating at times.

fishtaconc

Just a thought when you flush do not be tempted to install those flush tees they lead to problems down the road.

Bellkrank

why no tee? i just saw flushing kit at the store and almost got it?

fishtaconc

the plastic tends to beak and usually going down the road. Thats just been my experience.if you can find the parts out of brass you can go that route.

captainofiron

brass would be good, but the plastic ones are usually good for years, I have had one on my Trans Am at least since 2001, and thanks guys, now I will probably go home, and it will crack by itself. hahaha

fishtaconc

Sorry to jinx ya, ive never had any luck with them, on another note the sell a barb to female garden hose adapter like someone suggested earlier you use this by taking the hoses loose put the barb in.

danimal

I'd have to agree. I've seen more than one of those prestone flush kit adapters break. I just use the garden hose and seal it with a rag (depending on what it is you're flushing out). I'd also flush each individual component rather than trying to flush everything at one time. If there's something in there, you might just be pushing it down the line and into something else (heater core or radiator).