96 4.0 XJ overheating after heater control valve fix - JeepForum.com
 
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post #1 of 15 Old 02-19-2015, 12:56 PM Thread Starter
Svenlylethor
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96 4.0 XJ overheating after heater control valve fix

Here's the story:

I was filling up my gas by the highway and saw that my heater control valve was leaking a little. I jiggled the hose and it cracked... tried to seal it up with some tape and about 3 miles down the road the jeep started overheating. I then found an autozone that was about 5 miles away and I drove the jeep really slowly right before it got to the red line to overheat. I stopped about 5 times and it took me a while because I was afraid that I'd blow the gasket.

I got to the autozone and put in the new heater control valve. I then filled the reservoir and put about 2 quarts of fluid inside and the jeep ran fine. I drove about 30 more miles on the highway and then I drove it again another 70 miles back home a few days later and it was totally fine. I saw the reservoir fluid was a little lower but I figured that's because the radiator had air in it and it took extra fluid from the reservoir. It had no cooling issues going back at all. I did notice when we were getting close to home that the fan made slight screeching noise for a second and the "GEN" light went on for a few minutes. It went on and off for a little bit on the drive. Hasn't come on since.

just last night I drove about 2-3 miles in the city, stop and go, and my xj started overheating. The engine did seem to have a little bit of a rough idle when I was at stoplights for the first few seconds. Once I stopped I checked the reservoir and it was empty. I filled it up again at about 2 quarts of antifreeze and then put another 2 quarts in the radiator. It seemed like the thermostat was making a slight hissing noise... I played with the hose that goes from the thermostat to the heater control valve and the hissing stopped so I'm assuming it's coming from there. The reservoir was bubbling when the jeep was running as well... no bueno.

I drove it back home this morning and it didn't get in the red but it definitely fluctuated for a bit... (maybe because the thermostat turned on or because there was still air in the radiator). It was running more on the hot side by the time I got home. I also hear a faint squeaking noise coming from the serpentine belt. Not the shreaking sound but almost like a faint squeak... it went away for a bit when I was almost home but I think that's because it stopped when I drove past a bunch of slush, which could have gotten the belt wet... I grabbed the crankshaft vibration dampener and it did seem to have a touch of play on it.... it looked to be slightly vibrating when it was running as well. The thermostat area was making that hissing noise when I turned the jeep off and I heard liquids moving around - not sure where though.

I checked my engine oil and it seemed fine - no trace of antifreeze. After searching the forum, it could be several issues:

-new cap (I inspected mine and it looked fine, but it wouldn't hurt to spend $7)
-I need to burp the radiator (Possibly, but how could I have put 2 gallons in the radiator/reservoir on two separate occasions and there not be a leak?)
-thermostat (I put a new one in a year ago so I don't think so)
-Bad radiator (I have flushed it every two years like it says in the manual and the fluid has always looked fine, but I may be wrong)
-Crankshaft pully needs to be fixed (possible... either way I should probably tighten it or try to remove the squeak. I saw
and it makes that same squeaky noise so it might just be the idler pulley)
-bad water pump (could be true - I am hearing a squeak from the front end but I'm not sure how to diagnose this)
-blown head gasket (I really, REALLY hope that it's not this... but it is possible because I drove the jeep on and off for about 5 miles before I put coolant in it and fixed the broken heater control valve)
-bad fan clutch (maybe... I'll have to figure that one out as well)

Because of the GEN light I think it's the alternator or probably something that has to do with the serpentine belt e.g. water pump. crankshaft pully, fan clutch, etc.

I'm going to buy a new cap and more antifreeze after work and get all the air pockets out of the radiator and see if it has any visible leaks. Didn't seem to have any this morning though. I've been using 50/50 antifreeze, btw.

I'm assuming I'll have to check all those things out to make sure, but I just wanted to get some feedback on this. What does everyone think, based on what's happened? It worked totally fine on the highway for several hours after I fixed it... few days later and it's acting up again. Any help is greatly appreciated.

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post #2 of 15 Old 02-19-2015, 08:50 PM Thread Starter
Svenlylethor
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I burped the radiator by the auto parts store and then drove for about 10 minutes. It didn't seem to overheat or anything.

The electric fan never turned on, which is a little weird, but when I opened up the radiator cap I saw some metal dust (or at least it seemed so). After driving the 10 minutes I opened up the jeep to put more fluid in it. I revved the engine and added more fluid till it was just about overflowing from the radiator cap. The thermostat seems to be working because both hoses were really hot when it was warmed up. The reservoir did bubble slightly but it seemed more like it was like the fluid was flowing from it and a few bubbles happened to get out… which is part of the burping process.

The serpentine belt was chirping a lot still and just when I was going to leave, that's when I looked under the jeep and saw it was leaking. It didn't seem to be coming from any hoses - it looked like it was coming more from the water pump. I'm assuming it's coming from the weep hole.

Given that there was metal dust around the radiator cap, it's chirping, and fluid seems to be coming from the water pump area, I'm going to say that the water pump needs to be replaced. I've read a few links online that when the bearings go bad on a water pump, it chirps and coolant comes out of the weep hole. I also heard that overheating can cause a leak in the water pump gasket… Either way I'm going to replace it. My XJ has about 250,000 miles on it so it's probably due for one.

For anyone who has had overheating issues, Check out this video. It really helped me diagnose the problems.

I'll let you guys know what happens after I replace the pump.

[]IIIIIII[]
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post #3 of 15 Old 02-19-2015, 08:51 PM
chris87xj
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The heater control valve is notorious for becoming brittle and breaking easily. They aren't really necessary and were design eliminated in 97. Many people simply remove the valve and run bypass hoses.

Gen light means not charging, screeching could be belt slipping, belt slipping could mean alternator pully and water pump not turning much. Start with the easy stuff by checking belt tension. If the belt checks good, remove it and test turn all the pulleys by hand while checking to see how freely smoothly and quietly they turn.

***Chris***

"You can set my jeep on fire and roll it down a hill,
But I still wouldn't trade it for a Coupe DeVille."


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post #4 of 15 Old 02-19-2015, 09:33 PM Thread Starter
Svenlylethor
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Quote:
Originally Posted by chris87xj View Post
The heater control valve is notorious for becoming brittle and breaking easily. They aren't really necessary and were design eliminated in 97. Many people simply remove the valve and run bypass hoses.

Gen light means not charging, screeching could be belt slipping, belt slipping could mean alternator pully and water pump not turning much. Start with the easy stuff by checking belt tension. If the belt checks good, remove it and test turn all the pulleys by hand while checking to see how freely smoothly and quietly they turn.
Yeah, I've read about that before. Since I just put it in I think I'll keep it as-is. I think I'll flush the heater core while I'm working on the water pump though. Might as well do it while it's under the knife.

Speaking of which, when I looked up the water pump on advance auto parts, they said I should replace the fan clutch while I'm at it. Any thoughts on that? Also, I wasn't sure if I should buy an OEM or auto parts store water pump. There were a few bad reviews online for the non-OEM ones but you're also looking at a $32 vs $125 fix. I don't even know how much longer my jeep will last.

I'm thinking the GEN light might have come on because the serpentine belt was slipping from the radiator fluid getting on it. The serpentine belt seemed fine but I might replace it for preventative maintenance. Either way I'll check the battery and alternator… it just sucks trying to fix a Jeep when it's freezing outside, there's 4 feet of snow on the ground, and you have to fix it on the streets instead of in a garage.

[]IIIIIII[]
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post #5 of 15 Old 02-19-2015, 09:44 PM
chris87xj
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I don't know if one gets what one pays for when buying parts, but I'm pretty sure one doesn't get what one doesn't pay for.
The fan clutch is critical to the cooling system and replacement is normal maintenance. I'm thinking 60k miles is the recommended interval. A good rule of thumb is if you don't know when it was last replaced, it might be due.

***Chris***

"You can set my jeep on fire and roll it down a hill,
But I still wouldn't trade it for a Coupe DeVille."


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post #6 of 15 Old 02-20-2015, 10:37 AM
1stockjeep
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My money is on water pump bearing or leaking seal, belt squeal plus gen light is more than likely wet pulleys or the water pump itself causing the belt to slip
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post #7 of 15 Old 02-20-2015, 11:34 AM Thread Starter
Svenlylethor
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Quote:
Originally Posted by 1stockjeep View Post
My money is on water pump bearing or leaking seal, belt squeal plus gen light is more than likely wet pulleys or the water pump itself causing the belt to slip
Yeah, that's what I'm thinking. I also saw a thread online somewhere that the bearings squeak when the water pump is about to go out and leaking coolant is one of those indications. All signs point to the water pump. I'm just glad it's not the engine block.

Both advance auto and autozone say I should replace the fan clutch while I'm there. Haven't changed my Serpentine belt in over 6 years so I'll throw a new one on for preventative maintenance.

Do you think I should flush out all the coolant because of the metal dust or should I just fill it up? I drained the coolant last spring and I've practically gone through 2 gallons of coolant since the mishap. I bet a bunch of the metal dust has come and gone.

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post #8 of 15 Old 02-21-2015, 03:30 AM
1stockjeep
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It's gonna be apart so might as well flush it and throw on a new fan clutch as well
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post #9 of 15 Old 02-25-2015, 01:47 PM Thread Starter
Svenlylethor
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So I moved the jeep across the street to fix it. the GEN light went on and the power steering was out for about 15 seconds when I was trying to drive. the GEN light turned off and it was fine... There was definitely some slip in the belt.

I installed the new water pump, fan clutch, and serpentine belt for $100. When I pulled the old one off it looked/seemed fine. It didn't look corroded at all so maybe it just broke the seal. I used a small amount of RTV on both sides of the gasket, but not too much. The chirping has gone, no coolant has leaked, and it seems to be fine. I've only driven it a couple of times but the temp gauge hasn't moved. I'll burp the radiator for good measure later this week but looks like the problem was the water pump.

BTW I don't have a garden hose to flush the heater core. Any way to flush it without using a hose? I'm thinking squeezing a few 2 liter bottles filled with water might do it.

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post #10 of 15 Old 03-08-2015, 08:21 PM
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i just went through this with my sons 1994 cherokee. nipple on the heater control valve was brittle and broke. when trying to remove the broken nipple from the hose it would break into small pieces. i finally crushed it with my hand in order to get the broken nipple out. could some of those broken pieces you spoke of lodged in your water pump?
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post #11 of 15 Old 03-08-2015, 10:05 PM Thread Starter
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Maybe I guess? When mine broke off I did the same thing you did but I made sure to flick them out of the hose. Maybe driving the jeep intermittently for half an hour so it wouldn't overheat could have caused the pump to fail. Either way it works now.

Did you take your heater control valve off and fix it all at once or did you have it blow up on the side of the road like me? If it was the former, I'd be interested to hear what happens to the XJ in the next few weeks. I'd assume that it will be fine though.

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post #12 of 15 Old 04-23-2015, 11:52 AM Thread Starter
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So I noticed the weirdest thing the other day. My temp gauge was going past the half mark but not in the red and fluctuated a little back and forth when I was stop and go. I popped the hood when I got home and the top radiator hose by the A/C had pressure and was hot (meaning the thermostat was working I think) and about 2 minutes later the small hose that goes from the reservoir was leaking from its end where it connects to the radiator cap. The hose was super loose so I put a hose clamp on it. I drove it afterward and the gauge went slightly past half and stayed there.

Do I need to burp the radiator again? Get a new radiator cap? Just when I think all the radiator issues are gone something happens again.

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post #13 of 15 Old 04-24-2015, 12:28 AM
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Quote:
Originally Posted by Svenlylethor View Post
So I noticed the weirdest thing the other day. My temp gauge was going past the half mark but not in the red and fluctuated a little back and forth when I was stop and go. I popped the hood when I got home and the top radiator hose by the A/C had pressure and was hot (meaning the thermostat was working I think) and about 2 minutes later the small hose that goes from the reservoir was leaking from its end where it connects to the radiator cap. The hose was super loose so I put a hose clamp on it. I drove it afterward and the gauge went slightly past half and stayed there.

Do I need to burp the radiator again? Get a new radiator cap? Just when I think all the radiator issues are gone something happens again.
The cooling system is self burping.

Is your rad cap new? Is it set for OEM levels if eighteen pouns? Most replacements only go to 16.

AZ-Jeff
I don't own an XJ any longer, but I still think they are the best of all the Jeep products ever made. My XJ was my favorite vehicle in my 50+ years of driving.
So...I stick around and give advice.
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post #14 of 15 Old 04-24-2015, 09:13 AM Thread Starter
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Originally Posted by AZ Jeff View Post
The cooling system is self burping.

Is your rad cap new? Is it set for OEM levels if eighteen pouns? Most replacements only go to 16.
No. It's the same radiator cap. They're only a few bucks at the auto parts store and they're all 16 lbs. Haynes says 16-18.

I drove it again for a little bit last night and this morning and it seemed to be fine. I'll go ahead and get a new radiator cap though.

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post #15 of 15 Old 04-25-2015, 07:54 PM
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if you havent replaced your thermostat since this happend i would. one time overheating is enough to ruin them.

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