Closed coolant system problem

[cykaaro]

Got the heating core flushed out yesterday. Took me about 30min of flushing water through it back and forth until it would only push out clean water. [on initial putting water through it would push out crap then run clean until leventually it was all clean] Well, thanks for all the help! I know have heat again!! and it heats up as fast as my GF's '02WJ!
The plastic end of the valve broke off, so just took it out entirely. Just not sure if I'll put it back in or not. Mine wored ok, so still have the diaphram/valve assemply, as the diaphram can be unscrewed if it ever goes. We'll see about adding a new one or not.

The one issue I do have though, which I had before I flushed the core, is the slider for cold/hot how does it actually function? and what may not be working? Doesn't matter where the setting is, it doesn't change the temp of the air blowing at all.

 

[lawsoncl]

The slider should move the blend door in the dash, which directs the air over or around the heater core. The actual design and path depends a bit on the year. It also directs vacumn to the plastic heater valve under the hood, which cuts flow to the heater core when vacumn is applied. A replacement valve is about $20-25 at the local auto store, but you can leave it out and plumb directly to the core. Since the blend door blocks off the core, you really shouldn't notice any heat from this. Later models are setup this way as cutting flow to the core for half the year tends to cause more clogging.

 

[cykaaro]

I figure it's an issue with the blend door, but this is a new area I've never dealt with before. My XJ is a '90. Is there any write up or such perferably with pics so I know what I'm looking for that can aid me to see if my blend door isn't working as it should? Would be greatly appreciated.

 

[lawsoncl]

The blend door is cable operated and pretty easy to check. I was just outside so I looked on my 89 to refresh my memory. Look under the passenger side of the dash up near the tranny hump. You should see a cable attached to a rod sticking straight down. It's almost level with the bottom of the edge of the dash and kind of look like the crank on the side of a jack-in-the-box. That's the rod for the blend door. If you move the temp lever you should see that move. If not, then the cable may be broken.

 

[cykaaro]

Thanks. Will take a look. Guess it's either broken or cable has come off at one end.

 

[twoksl2]

The service life of the OEM RENIX radiator is 150-180Kmiles, and I've not heard of one going past 200K. Get a quality aftermarket replacement (CSF or Modine) and put it in - then forget about it. Keep on your flushes every other year or so as well.

just FYI, i have over 250k on my jeep and its still on the factory rad. (i'm pretty darn sure) no problems so far, i can't even get get it hot enough for the the elec fan to turn on. had one small pinhole leak, but a quick patch with jbweld and sofar all is good. holds pressure like a champ. fins aren't in the greatest of shape, but until it runs hot, i'm not real concerned.

also, i had a bear of a time burping the system, so i tried drilling holes in the t-stat and it worked like a charm. highly recommend doing this

 

[Maz]

I've seen aluminum with sight glass.($155) Not cheap but Final fix & forget.

Where? Link?

 

[Harlee&Tahoe]

These are what I've found 1 2(Mac's can add a sight glass for extra$ but fits like oem)

 

[langer1]

filled it up, and good to go. went out the following week and had no issues

Well to me that don't sound like air in the system, you simpley have a small leak somewhere.
No system will work with a leak open or closed.
What about the heater core and water pump, both of those can be hard to spot.

 

[Maz]

These are what I've found 1 2(Mac's can add a sight glass for extra$ but fits like oem)

Thanks

 

[stealth919]

Don't mean to depress anybody on the system boiling in the bottle but my toyota did this every time I parked it for a month before I tore the motor down...bad head gasket and cracked head just enough to over pressurize the system into the overflow bottle, had to top off between drives to keep it full, luckily it had a cap on the radiator. Just an idea...although not a happy one.

 

[megabyte5689]

I've said it time and time again - taken care of properly, there is NOTHING wrong with the closed cooling system.

If it overheated without the thermostat, my first suspects would be the radiator and the thermal fan clutch for the mechanical fan (I've posted extensively on both of those.)

As far as purging air from the system, I've also detailed how you can modify the thermostat (you drill two holes - and it takes about a minute and a half...) to make the system purge itself of air without help from you at all.

The service life of the OEM RENIX radiator is 150-180Kmiles, and I've not heard of one going past 200K. Get a quality aftermarket replacement (CSF or Modine) and put it in - then forget about it. Keep on your flushes every other year or so as well.

I still have my original radiator and I have 201,000 miles on the 90 XJ. The previous owners kept all the maitenance up on the car.

 

[89xj]

I still have my original radiator and I have 201,000 miles on the 90 XJ. The previous owners kept all the maitenance up on the car.

on my 89, i found that the single core radiator was the weak link(in terms of flow) in the closed cooling system. after replacing the stock radiator back in the early 90's when i bought my 89, i have never had a cooling problem associated to flow. ive had the usual expansion tank cracks and waterpump deaths, but never a problem with flow/circulation(which caused high engine temps when idleing)

 

[90Blue_XJ]

I have a 90 that was having cooling problems this past summer. It had a hairline crack in the plastic tank on the passenger side of the radiator.
Went to a real radiator shop and he had the copper tanks for my radiator. Changed the tanks and had the core "hot tanked" while it was apart. No cooling problems since related to the radiator. Took a trip just about 6 weeks ago (over the Christmas holidays) to N.C. and coming back it started to overheat. Let it cool and pulled into a country store. There I decided that the problem was the T-stat,so it being Sunday and me in the middle of nowhere I pulled the offending T-stat out and made a silicone gasket. Put it all back together and headed down the road.
Again no overheating and still have not put a t-stat back in yet. I know that it takes forever to get to operating temp and thats bad for the fuel mileage but have been too busy to work on the thing. I'll get around to it sooner or later.

 

[Ecomike]

As of this past weekend, I have officially joinded the crowd of the "I am not impressed with the AMC plastic bottle" crowd.

I replaced my bottle, radiator (radiatorbarn.com all copper/brass 2 row, or maybe 3 row, I forget), fan clutch, and radiator hoses about 2.5 years ago. I also installed a 160 F thermostat at the time, with no bleed holes in it. It never got over 160 F in the winter, and never got over 195 F in the 100 F summer days with the A/C running. So I finally broke down and replaced the heater hoses this past weekend, because of a small leak, and I found a huge lengthwise crack in the 2.5 year old plastic bottle on the rear bottom side, just about to completely give way!:gonnablow:bawl:Only 2.5 years old, less than 10,000 miles on it and it never even got up to 200 F! :banghead:So I am going to start seriously looking at a better bottle, make a better bottle, or start replacing it once a year and just buy them by the dozen.

Oh, and while I am on the rant here, I discovered why they charge so much for those curved, odd, OEM heater hose assemblies. I ending up using $80 in parts to get around them, including 19 hose clamps, 3 hose size adapters, and 4 metal coils for the sharp bends for my 87 Wagoneer.

 

[90Blue_XJ]

As of this past weekend, I have officially joined the crowd of the "I am not impressed with the AMC plastic bottle" crowd.

Oh, and while I am on the rant here, I discovered why they charge so much for those curved, odd, OEM heater hose assemblies. I ending up using $80 in parts to get around them, including 19 hose clamps, 3 hose size adapters, and 4 metal coils for the sharp bends for my 87 Wagoneer.

Please elaborate further. I was wanting to replace mine with copper pipe for the sections that parallel the valve cover. I thought I could do it with a couple of Ts and 90s.
Jon Kelley has done so and was thinking of marketing a set in the near future.
Look at his website under future projects.
Mike

 

[Ecomike]

Please elaborate further. I was wanting to replace mine with copper pipe for the sections that parallel the valve cover. I thought I could do it with a couple of Ts and 90s.
Jon Kelley has done so and was thinking of marketing a set in the near future.
Look at his website under future projects.
Mike

The drivers side tube on the thermostat housing is 3/4" ID, it bypasses the thermostat and supplies coolant to the heater core (5/8") and the side of the coolant bottle, 1/2", while the steel tube T or Y fitting that I reused from the old OEM hose is 5/8" on all three sides. The pasanger side tube goes directly into the water pump inlet, sucking coolant in, and it is a tight fit for 5/8" hose. The T or Y it connects to is 5/8", and the heater core is 5/8", but the bottom of the plastic coolant bottle is 7/8", and curved. The heater core hoses are curved between their inlet and the T-Y fittings, and the side bottle fitting to t-y fiting is curved, and the engine block hoses are curved, its a freakin nightmare to replace with just straight hose, plastic adapters and coil-eze outer coils. I used 19 clamps on the mess! If you did it with copper tubing, and solder it might be nice. If I went that route I might be tempted to use SS tubing.

Hey, PM me your new email address, I never got it.

 

[mlanicca]

I got tired of the jeep bottle and cap and replaced it with a bottle from a Volvo. It worked fine for a couple years, until the plastic started getting darker, and the side looked like it was about to blow out.

I put in an inline filler neck with a 16lb. cap, and an overflow bottle from Autozone. I also took out the heater control valve because I was tired of flushing the heater core so I would have heat in the winter.

 

[BruceB83]

I'm only adding this for future reference so when people are using the search feature...hehe...they can find this.

One thing to note is that when replacing the coolant tank ALWAYS replace the cap too. The system depends on that tank building 16PSI...if it decreases the boiling point of your coolant decreases back closer to 212. Think of it as a pressure cooker...water's boiling temp increases beyond 212*F as pressure increases. Jeep had a problem with a large batch of tanks they produced where the threads of the cap weren't properly meeting the threads on the tank therefore air was passing by and boil overs were occuring. I have a friend who ended up with one of these tanks about 4-6 months ago so they are still "out there" in the market. Best thing to do is ask your parts people if the tank and cap are from a new batch or not. If they can't tell you...go somewhere else where they can.

One more thing...just a technical tid-bit for ya...when the tank is working properly as far as keeping 16PSI...water boils at 260*F instead of 212*F.

 

[scottmcneal]

Does anybody have a pic of the hoses going too the tank? There is 2 3/4 hoses going too the tank, if you look at the t- stat housing standing in front.. The one on the T-sat housing goes to the top (side) of the bottle, Right? the other one goes to the bottom, Right? Thank you for your time...