Need help to ID cooling system part

OK, I tried to take a picture to make this easy, but my computer sux and won't recognize the camera. The Jeep is an 89 4.0, and yesterday a hose came off on the way home from the shop and leaked coolant all over. Here it goes: there is a hose that starts at the t-stat housing and runs back along the valve cover until it hits a "T" connector. One of the hoses off the T goes to the coolant bottle mounted near the passenger side rear; the other side of the T has some kind of fitting with a sensor, then a hose that goes right towards the firewall. Our problem is between that fitting and the hose. The inner piece that holds the hose on to the (unnamed fitting) broke off. That's about the best I can describe it. (Note: yeah, I'm an idiot, but at least I didn't say "thingy" or "dealy")

Ah, closed system mixing valve

You have whats called a 'closed' system. The T is a plastic mixing valve for the heating system and I am assuming from your description thats what broke, dealer has them but I have no idea of the price though $45 comes to mind for some reason.
You can also find them in boneyards but they are going to be as old as yours and they get brittle with age. Eagle here is the expert on the closed systems I've only looked and worked on a couple of XJ's with them and not on the cooling part, generally valve cover gaskets
If I am wrong on the location and it broke off at the firewall then you have one heck of a job ahead of you to replace the heater core behind the dashboard.
One recommendation, you should now really replace ALL the hoses HOWEVER do NOT just pull them off, use an exacto or other razor knife to cut them length wise and then peel them off gently to keep breakage to a minumun. Also do not overtighten the clamps on the plastic fittings.

You had the heater control valve fail. But lets make sure. The closed cooling system has two heater hoses with wye or tee feetings in line.

The one hose runs from the thermostat housing to the heater control valve. The two lines connecte to the upper fitting of the pressure bottle or to the heater core.

The other hose runs from the long pipe screwed into the water pump then back to a wye fitting. The one hose goes to the bottom fitting on the pressure tank and the other to the heater core.

Now for the big question, do you have hose clamps or aluminum bands crimping the heater hoses to the heater valve and the other wye fitting.

If you do have the aluminum bands then you have 15 year old heater hoses, time to replace them ALL. I highly recommend you get all 6 sections from the dealer, they will run about $70 but worth it. I tried the Goodyear heater hoses and they were close but did not lay right. I also had to rig some of the goodyear hoses since they did not offer all 6 sections.

On the heater control valve you will need to take it to the parts store. My dealer wanted $140 for the valve. I found the AC/Delco valve did the trick. Back then Delco supplied a lot of components to Jeep.

There is a problem in the parts books, they list the wrong valve for our XJs, that why you will need to take the valve with you. The parts store guys will tell you are wrong but tell them you want AC Delco part 15-5821 and NOT AC Delco part 15-5221. The 15-5221 is a valve with 2 nipples, the 15-5821 has the 3 nipples you need.

I also recommend you replace the plastic pressure tank. You can pick one up for $40 to $50 at the dealer, or order one from Quadratec.com for $20 + shipping.

One more thing if you change hoses cut the old hoses off your heater core nipples, do not yank them off. It a nightmare to change the heater core so I am told. Here a link with good write ups on flushing the heater core and refilling the engine with coolant http://www.olypen.com/craigh/tech.htm

I had the heater control valve break on my 95 4.0. A new one at O'Reilly's was only $15. Don't know if it takes the same part or not.

arhiney said:

I had the heater control valve break on my 95 4.0. A new one at O'Reilly's was only $15. Don't know if it takes the same part or not.

Click to expand...

The 95 uses a completely different cooling system, known to most XJ owners as the "open" system. This poster is dealing with the "closed" system that has problems when it ages.

I believe the descxription fits the heater control valve, and when my brother snapped the one on an '88 we were working on I found a replacement in stock at my local Auto Zone. Don't know the price, but IIRC somewhere around $15 sounds about right.

Now the mystery part has a name, and I have a new question. Our Jeep has nearly 200K miles on it, and what I assume is the original radiator. Also we have some hose clamps, but many things I assume are the aluminum bands (silver, look sorta like a thread spool). I've also read a couple sites outlining the conversion to an open system. My question is, although the only thing broke right now is the heater control valve, would it be better for us to go ahead and do the conversion. We're trying to go cheap as possible on the jeep, but we don't mind spending a little extra to eliminate any future problems. BTW, thanks everybody for the quick help.

Whiskey Jack,

With your screen name I'd figure you lived in Lynchburg, TN

Yes, if you change the heater hoses, remove them from the XJ, then at your work bench use a hack saw to cut through the band and then remove the hose. This will allow you to reuse the wye fitting.

I am still running the stock cooling system configuration but three plus years ago I was in the same position as you, do I convert or stay with the stock cooling system. I found out both radiators are idential in size so installation not a problem. Also you use the same P/N radiator hoses since they will hook up the same.

The main problem is where to put the switch to turn on the electric cooling fan. On the stock radiator there is a fitting for it to mount in the cold tank. It that sensor with 1 1/4" hex on it. The later radiator does not have a openting to mount the sensor.

Chrysler came out with a fitting to install in the lower radiator hoses but in 2000 the part was no longer avaiable. So if you read about the part on the web sites it a thing of the past no longer available.

There have been discussions on brands of radiator GDI vs modine, do a search on this, someone posted GDIs new numbers. They were having quality problems and changed the number once they instituted new quality measures.

The part people over look is the heater hoses. I have never seen this written down but to fully convert to the post 91 configuration you should change out the return tube for the water pump. If you did this then using the post 91 heater hoses and valve should be painless.

With 200,000 miles you might want to install a new water pump since it could be a stock unit. With the radiator out with will have lots of room to change it.

There has been talk on here about sources of water pumps, you can get aftermarket high volume pumps, rebuilts or even new ones. Don't over look the dealer for a new water pump.

I do like the mopar water pump and thermostat gaskets. I recommend you use them regardless where you get the water pump; however, as most people on here will tell you use a Mopar 195F thermostat.

If you go to the dealer ask them about the water pump pipe then can fill you in on the differences between the 88 and post 91 versions.

I personally like having a reservoir of coolant above the engine, it assures the engine if full of coolant/no air pockets. Even with that said the plastic pressure bottle is the weak point of the system. There are people who have replaced the plastic pressure tank with the moroso surge tank. Eagle is the one that comes to mind that has done that.

martin

At 200,000 miles on the original radiator, it is living on borrowed time. Same with those hoses that still have the OEM end fittings. They can be replaced using standard hose and hose clamps, but there are a couple that are 5/8" hose with one end molded up to a 3/4" size -- those are best bought from a dealer.

While I recommend that you replace the radiator, I do not recommend converting to the open style system. If you read through all the threads on this topic, you'll see that most people who do it then have problems controlling the auxiliary fan. Since the new-style radiator doesn't cool any better than your "closed" style radiator, I have never been able to figure out why so many people rush like lemmings to do this conversion.