Im one of those lucky owners who's never had a problem getting HOT heat or COLD air. Well, that changed.


So that changed on a chilly day last spring. I turned the heat on and it was lukewarm. I popped the hood when I got home and the coolant was crappy looking so I dumped it, refilled it and went about my business. I didn't think much about it until this summer when I took far trips on hot days and had minor overheating. By minor I mean, the temp gauge was JUST on the other side of 210 (it sits on 210 always) and a tiny bit of steam coming out of the hood. It was coming out of the overflow tank and it dripped MAYBE half a cup of coolant out of it on 3 different occasions.


I've drained and filled the coolant 3 times since that first time in April. Last week I drove an hour north hunted for the day and an hour and a half back. When I got back it was smoking a little and puked a cup of water out.


So, I did some thinking & research and since I have a pinhole leak in my radiator, my water pump is original (1999) and my t-stat is a couple years old, I figured why not change out everything. I spent $250ish and got a radiator, water pump, t-stat and housing, temp sensor, inlet pipe, and all hoses (I changed my heater core 2 years ago) and just finished up changing it all.


Here's my problem: I put 2 gallons of coolant in it and had an inch in my no spill funnel, so I started her up and started burping her. After a little while I got about another 2 quarts in her (10 total) and I CAN NOT get the temp gauge to 210. It stops on the mark before it (185ish). I cant get any hot heat out of it. The hoses to the heater core are HOT and I cant touch them, but no heat in the cabin. I mean, its lukewarm, but NOT hot.


What gives?

 

Did you flush the heater core and engine when you changed all of the parts.

 

I sure did. And it appears the reason I was getting crappy coolant was the lower radiator hose was rotten and has the wire completely exposed inside. I tested the old t-stat and it opened. Cant figure this out.

 

Probably the water pump. The pump fins are probably rusted away. Its not moving the coolant through the system as it should.

 

Pump is brand new, as is everything else I listed. And the old one was absolutely fine, no rust on the fins at all.

 

With everything you replaced, and the fact that the heater core hoses are hot to the touch, then I would look towards the blend door actuator. It sounds as if it is not fully moving to the "hot" position and stopping you from getting full heat in the cabin.

 

Sorry. Just re-read. Must be tired, had to read again twice before I saw that the pump was replaced as well.

Symptoms match what can happen with rusted pump fins, and my brain locked on to the pump being original.

My bad!

 

Seems like I need to look into the blend door actuator because I cant, for the life of me, figure out how the hoses to and from the heater core or super hot, yet basically no heat in the cab.

 

With the heater on max see if both hoses feel about the same temp and too hot to handle. If so I'd say blend door. If the return hose is notably cooler then it's a clogged heater core.

I don't recall ever experiencing a clogged core on any other vehicle but have had to clear out 2 XJs recently, a '90 and a '97. I don't know if it's just luck or something about the XJ that makes them more prone to clogging. Both cleared up by just blasting them with a garden hose and nozzle set to 'jet'. Hit the outgoing side first (back flush) 'till it's flowing clean then alternate back & forth 'till they both flow clean. Blow the tap water out with compressed air if available and wash all the rusty shat off the car & driveway before it sticks.

 

I have the SAME issue in my 99 XJ.. Just replaced the t-stat with a Mopar 195, new Gates water pump, new hoses all around and flushed core and used CLR too last weekend.

Lukewarm heat and BOTH hoses from core are hot. Had flow when flushing core last week too.

Will check my blend doors later tonite if I get time. Will post what I find...

No heat sucks. On my '92 all it needed was an annual core flush and the heat was HOT..

 

Positive mines clogged up if its anything like what my return jug was with hard caked rust then its shot lol. I put the speed to 1 and itll build up heat but put it on 4 and its not even really warm

 

Not plugged up. I replaced the heater core 2 summers ago AND flushed it when I had everything apart just in case. Funny thing is, I was SURE the fins on the pump were rotted off and my t-stat was plugged after A: Reading similar posts on this forum over the past 10 years and, B: Looking at how gross the coolant was getting after 6 months. Turns out everything was fine, INCLUDING my water pump fins and t-stat (checked it in a pot of water). It was all crappy looking because my lower radiator hose was rotten on the inside and the wire was exposed, so it was making the coolant REALLY bad looking.


Im positive now that the heat issue is the blend door.

 

this metal spring is suppose to be in there lose in a way , its an anti collapse spring.. when the coolant gets hot the hose might collapse if you took that metal spring out i would put it back in.

marc

edit: its not rotten the spring is just twisted inside the hose and holds itself tight

http://3.bp.blogspot.com/_g_f0Y4GJUA...0/IMG_6346.JPG

 

More heat on low fan than high fan is a good indicator that it's plugged, or maybe the valve in the heater hose (if yours has one) isn't opening properly.

 

I have a 95 Cherokee same problem hoses were hot no heat, flushed heater core with clr twice didn't help much, went to put new heater hoses on it and noticed someone had the hoses turned around, since the heater core sets above the engine you want the hose coming from the water pump to go on the lower connection on the core so it pushes the water up through the core and all the air out, now mine will run you out its so hot.