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Topic Review (Newest First)
06-19-2011 06:52 AM
Problem solved!

Finally! I flushed and added cleaner again only to find the next day while doing local driving that it was boiling over to the overflow tank. Once home and cooled down I saw I was losing coolant because of this. Checked the radiator cap and noticed it was pretty beat. I'd checked it periodically and never noticed an issue with it before and made a mental to replace it anyway but forgot about it with everything else going on. I replaced cap and haven't had a problem since. Drove over 300 miles interstate and locally the last few days without a hitch.

I'm thinking that "maybe" there was a little clog still left and the cleaner cleared it the problem has been a bad cap the whole time. Could a faulty rad cap cause no inside heat? That was the original problem that which started me on the road to cleaning up my cooling system. Anyway, I now have heat and more importantly A/C without any overheating at all.

Thanks to everyone for their feedback over the last couple of months! It definitely saved me some big bucks taking it to a shop.
06-07-2011 07:14 AM
jimbud Okay, did what rrich suggested and bled the air out through the head bolt yesterday. Afterwards I ran on idle and a/c on high for about 15 minutes and engine stayed around 210/220. Drove around the neighborhood for another 10 minutes and just when I thought all was good the temp jumped up into the red. Dammit! Wondering if I should try it again today in case there's another bubble in there?

Next step - drain and flush system again, fill with cleaner/water and run for a few days. Any suggestions on the best chemicals to use for this? My buddy who works on/races Volkswagons and helped me with the headbolt thing (had the 12pt socket) seems to think there may be a small clog in the heater core. I need to get this resolved before the serious VA summer heat sets in.
06-03-2011 06:55 AM
jimbud If the burp above doesn't do anything I'm starting to strongly feel it might be electronic. Any idea what to start checking there? I've also flushed the heater core in the past and it came out nice in clean once I had flushed everything appropriately.
06-03-2011 06:25 AM
Originally Posted by rrich View Post
Sometimes it's tricky to burp all the air out of a 4.0
Simple trick - right at the front of the head - driver's side, ........
Thanks, I'll try doing it this afternoon. I've got a related dumb question tho, wouldn't the air eventually burp it's way out over time through the overflow hose?
06-03-2011 01:13 AM
Jiffydarren You know... radiator flushes at your local Jiffy Lube can prevent stuff like this.
06-02-2011 11:31 PM
rrich Sometimes it's tricky to burp all the air out of a 4.0
Simple trick - right at the front of the head - driver's side, there's a stud sticking up. That's a headbolt - it runs through the water passage. Note that the engine is slightly higher in the front than the rear, if not, jack the front up till it is. That will become the highest point on the system.
Remove the headbolt - when it's cold, not hot. Fill the radiator till water runs out the headbolt hole. When it does, wait a moment. Repeat until it stays full. The air will come out first, then coolant.
Replace the headbolt, tighten it to the headbolt torque. It's solved the bleed/ airlock problem for me several times.
06-02-2011 09:24 PM
jimbud Had a leaky top hose today so replaced that and installed a new t-stat. Drove around the neighborhood with the a/c on and sure enough the temp started climbing again. Coolant looked good with no rust/sediment like at the beginning of all this. Any idea what step to take next? Since this started in February I did:

multiple flushes & back flushes with and without cleaner
replaced coolant twice
replaced t-stat twice
replaced worn hoses.
05-31-2011 10:33 AM
DevilDogDoc Get a Robertshaw thermostat and be done with that part. You may be looking for a new rad though, that rust and such may well have clogged you to the point that it can't keep up now that it's getting hot...
05-31-2011 09:19 AM
jimbud After several months of it running fine last week it overheated with the A/C on. Now that local temps are in the mid 90s it runs hot at about 220 or so and the temp shoots up almost immediately when I turn on the A/C. Grrrr. I'm going to pick up and install a new thermostat today and thinking if that doesn't do it I'll replace the radiator. Coolant is still a bit rusty after doing all the flushes and back flushes I did back in Jan & Feb. Nowhere near as bad as before but still a little rust/sediment. Anyone have other suggestions? I'll also go back and read all the other threads about similar issues to hopefully get more guidance.
03-20-2011 09:45 AM
jp2611 Glad it seems to be getting some better-the dirty/nasty looking coolant makes me think there is still something in there somewhere. Good Luck!!!
03-20-2011 08:58 AM
jimbud Still not 100% on the heat output but much much better. Even though the last few flushings were completely clear the coolant is now nasty looking (though not as bad) so am thinking some crud worked itself loose. A few days ago I dropped it off and the shop for oil change, tire rotation and alignment and they called recommending I pay them $115 to do a flush. I laughed and told them I'd take care of it, I'm pretty much an expert at this point. ;-)

Will drain and do another flush over the next few days before adding fresh coolant again and seeing how it does. Thanks again for all the feedback and suggestions guys.
03-06-2011 06:47 AM
jimbud I've since cleaned everything out, put in fresh 50/50 coolant and burped the air but the incline idea is worth a shot. Frankly this past week I've not bothered with it since the weather has warmed up and no need for heat. I'll have time this week to mess around again and will keep posted. Thanks for all the suggestions, it's appreciated.
03-05-2011 04:50 PM
Nailhead432 Grab both heater hoses after the engine warms up, then reach over and throttle it up approximately 2500 rpms and see if that doesn't get both hoses hot. I've seen air get trapped in heater cores before that is very stubborn to get out. If this is the case, park ur jeep on the most inclined hill u can without falling out of the jeep and carefully remove the radiator cap while the jeep is running so that u don't burn urself and just let it run for a while. U will need to monitor the coolant level and make sure that it doesn't get too low on u. The idea here is that air will travel to the highest point and the higher the radiator cap is in relation to the rest of the cooling system, the easier air will bleed itself out.
When u said that when u first started it, it warmed up and puked about a gallon of antifreeze out. This is typical when air is trapped. Air trying to escape ur cooling system will first displace the coolant that is in it's way, then u simply top it off. By opening up the cooling system again when u installed the thermostat, u reintroduced air back into the system. Good luck and keep us posted.
03-05-2011 07:46 AM
jimbud Makes perfect sense when you explain it like that.
03-03-2011 09:02 PM
CapnDean Lets figure the obvious> It was working fine til you flushed it: Hint #1, now it does not heat.

Jeep does not overheat on the highway: If it does not overheat on the highway under load.
A) The thermostat is good B) The water pump is good C) The radiator is not clogged (or at least not clogged up too bad to cool the motor).

Now...since you are not getting heat.... and assuming that in flushing the radiator you did not screw with your heater vent door.... You my friend have an obstruction SOMEWHERE in your cooling system that is blocking water flow through your heater core. The only other rational problem would be that the heater vent door chose this exact date to crap out on you.
03-03-2011 08:28 AM
Originally Posted by jimbud View Post
I'm thinking this is a water pump issue but wanted to get other opinions.

A month ago I flushed cooling system, changed coolant, burped system but found my inside heat barely worked. Figured I didn't burp properly. When trying to burp the line the radiator backs up slightly and over flows.

I figure might be bad thermostat so I replace it. Try to burp the system after replacing the thermostat and radiator backs up slowly as engine heats before sputtering coolant everywhere once it gets hot. Water doesn't appear to be circulating through it.

The weird part is my engine isn't over heating now and staying right at about 210 degrees but still have little to no inside heat. Heat hose feels to be empty with no water circulating.

Am I right in assuming the water pump went bad and needs replaced or could it be something else?

if both the hose's are hot ,you have a problem your heater door under your dash
03-03-2011 08:25 AM
hookuspookus use a stant t-stat
03-02-2011 12:06 PM
linuxjacques I'm having the same problem.

I changed a bunch of cooling system parts (radiator, water pump, fan clutch, hoses, and thermostat).
I put in a fail-safe thermostat and everything was great for three days and then it stuck open.

I guess I'll change it again this weekend. :-\
03-02-2011 07:13 AM
jimbud Yeah it's my understanding the fai safe ones do fail to the open position. After putting on over 100miles on the interstate averaging speeds of 60-80mph all gauges looked fine. Temp sat just below 210 all day regarless of if heat was set on high or cool. Still no real heat though. ;-(
03-01-2011 08:27 AM
Peepers Just curious, but don't the fail-safe thermostats fail to the open position, and don't jeeps normally have a 195 degree thermostat, yet run at 210 anyways?
03-01-2011 08:06 AM
Neil F.
Originally Posted by bheiser View Post
It may also just be a defective thermostat.
If the thermostat was bad, the engine would be overheating or not getting hot at all. He said it's running right at 210 which is normal.
03-01-2011 06:51 AM
Originally Posted by Wdkirk01 View Post
Is the nipple on the thermostat housing that the heater core hose attaches to clogged? either that nipple of the one that attaches to the water pump could be clogged as well.
Thanks for the vinegar idea, I'll look more into that. Both in/out nipples are free of clogs, was one of the first things I checked when I started this all.

The thermostat was the first thing I replaced and I spent a little more for a fail-safe one so I doubt that is an issue. Always a small chance it's defective tho.

I drove it on the highway for about 50 miles yesterday with no issue and need to put on about 140 today. Will have to double check the intake heater hose to see how warm it gets.
02-28-2011 12:43 PM
jeepjones So, have we learned our lesson here yet? Even though flushing the
rad,transmission,engine etc. sounds like a good idea it really isn't, just imagine what would happen if it was a large chunk of carbon released into the engine by using seafoam or another cleaning system pushed heavily by those minute lube type of places? Do you think mister $5hr has any idea what he is actually doing other than what he's been "trained" to do? Or what may actually happen, KABOOM! Half the time it's the gunk that allows an older system to keep functioning.
02-28-2011 12:24 PM
bheiser It may also just be a defective thermostat.
02-28-2011 10:56 AM
Wdkirk01 I've seen people fill their heater core with a white vinegar and water solution and let it sit. The acid content of the vinegar will loosen debris in the core. But a cork in the bottow heater core outlet and fill it from the top opening. Let is sit for a little while (guessing a couple of hours) then flush from the top and back flush from the bottom.

Is the nipple on the thermostat housing that the heater core hose attaches to clogged? either that nipple of the one that attaches to the water pump could be clogged as well.
02-28-2011 07:20 AM
jimbud Thanks for the opinions/suggestions. I attached one of the engine flushing kits and finally got all the gunk out and water running clear. Still no real heat though. ;-( Operating temp seems much lower than before too as well. Didn't have a chance to drive it around yesterday but will put about 50 highway miles on it today which should be a decent test.

Is there any definitive way to know if or where you have a clog?
02-27-2011 09:39 AM
tylerdaly89 I had the same problem a few weeks ago. Ended up being that the radiator is a little clogged up. I did a flush, and it seems to be better, but not perfect. I have been told that since it is still slightly clogged, but operating temp is good I should be fine unless it starts overheating this summer. I live in FL so that will be in about a month.

You might be able to flush it or it might jus tbe time for a new one if this is in fact your problem.
02-27-2011 09:05 AM
jp2611 Just an opinion based on other threads/own experience somewhere between the block and where coolant goes to heater core and returns to block-you have a blockage.

Good luck!!!!
02-27-2011 08:37 AM
jimbud After flushing several times was getting a LOT of sediment (and still no real heat) so figure a clog somewhere. Filled with cleaner and dist water and ran for a few days. Will be flushing again today and refilling with new coolant. Hoping this will be it.
02-19-2011 07:13 AM
jimbud Yeah, t-stat was open when I filled it that way. Drove around the neighborhood afterward for about 10 minutes with no engine overheating. Gonna flush it out again this morning and see what happens. Read a thread where several people had similar issues and it took a few flushings to get the heat back. Got nothing to lose.

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