collant boilling over

89 xj 4.0 closed coolling system....

Recently the collant started boilling in the coolant reservoir at about 195*-210* It only happens in traffic or sitting still.

The engine isn't over heating its just boiling out through the cap on the bottle.Is this just a pressure issue?
The cap has always hissed a little since I've had this jeep(4years) but never boilled out like this....I wonder why it started all the sudden???.Is there any way to test the cap?How do I go about pressure testing the entire system and how much pressure does it run at?

Does it sound like the cap is the problem and where can I buy just the cap?The bottle itself is not leaking.

I should mention that I was wheeling last weekend and wasn't paying attention(fans wired to a manual switch) to the temp gauge and it got as high as 260* before I caught it.So that could be related....
Any help is appreciated....Thanks.

Oh and one more question:How high should the coolant level be in the reservoir at operating temp?

Pressure cap.

Check the coolent boil temp also.

Rev

thanks rev the cap is probably the prob....I was just freaking out...took a deep breath and reread my post and it has to be the cap.Is there anywhere I can buy just the cap?

Are there any other vehicles that have a closed cooling system with pressureized tank that will work the same or better on an xj?

Many places, I am sure 5-90 will chime in.

Me? I would just go to the dealer.

Rev

Get a cap rated for 16psi. Alot of auto stores have 13 psi listed in the computer.

16 is stock. I went through two 13 psi caps before I realized that was my problem!

Disregard, you have the closed system. Re-read it

Probably in your case, you have a cracked pressure bottle.

The cap is plastic and is segemented so it will get soft then allow the threads to slip. I rigged mine for a while with a hose clamp. Tighten the cap, then tighten the hose clamp so the cap doesn't slip. A new one cost 12 or 16 bucks (can't remember, I was just there two days ago for one) and comes with a new gasket at the dealer but he had to order one in. Stupidest system I've ever dealt with in my life I think.

I picked up a reinforced bottle from ebay for pretty cheap when my '89 did the same thing. The bottle design was great, but the cap they sent was very soft, and slipped easily. I went to the local junkyard and pulled a cap off a stock bottle. Never had problems with it again. Here's a link to the ebay store I picked mine up from http://myworld.ebay.com/ebaymotors/tennesseeautosales/

--Jeremy89XJuke:--

outlander said:

Are there any other vehicles that have a closed cooling system with pressureized tank that will work the same or better on an xj?

Click to expand...

Check out:
http://cgi.ebay.com/ebaymotors/ws/e...akeTrack=true&ssPageName=VIP:watchlink:top:us

Add a regular cap and an overflow bottle.

Buy a radiator for a '91-'95 jeep (has a regular radiator cap) as well as an overflow bottle. You will love yourself for it trust me.

I wondered how long before someone suggested that.

Seems every time a cooling question comes up, some knucklehead pipes in with that "miracle" fix.

There is NOTHING wrong with the closed system, maintain it and it will be fine.

Rev

Nothing wrong with updating the system, if that's what you choose to do. If you need to replace the radiator anyway, then it's not much more to do the entire swap.

Having said that, I just put in a new rad in my '88 a few weeks ago. Kept the closed system. It's worked fine for me over the years so I saw no need to swap out everything. I did have a problem with my cap. I'll post about it in a separate thread.

Rev Den said:

I wondered how long before someone suggested that.

Seems every time a cooling question comes up, some knucklehead pipes in with that "miracle" fix.

There is NOTHING wrong with the closed system, maintain it and it will be fine.

Rev

Click to expand...

True, but say you have to replace the radiator anyway - why not just upgrade to the newer system at the same time?

Rev Den said:

There is NOTHING wrong with the closed system, maintain it and it will be fine.

Click to expand...

That is true, the only reason to swap is if you feel more comfortable with a conventional cooling system.

I swapped my red Jeep over and will probably swap the Chief over when the time comes for a new radiator. The main reasons I have for doing so is that I feel more comfortable with a conventaional system, being able to pick up a pressure cap anywhere (the closed system caps can are not generally available to your corner store) and, probably most important, parts compatibility between the two Jeeps.

I will not go back to the closed system with the red Jeep because I have a very compact overflow bottle that fits very well between my intake and inner fender wall and I need all the engine bay space I can muster up because of my winch solenoid pack, mobi-arc, and ARB compressor.

Sequoia

PS - Change both the pressure bottle and cap unless you are absolutely positive the bottle is good.

outlander said:

Oh and one more question:How high should the coolant level be in the reservoir at operating temp?

Click to expand...

Inside the bottle you will see a little tower with two levels (it's split). At operating tempature the water level should be at the high part of the tower, cool (the only time you can fill it) it should rest at the lower part of that tower.

Anti-Freeze is supposed to be changed every 2 years. The anti-corrossion protection depletes in it first, but it also looses strength and coolant will boil or freeze at lower/higher temps closer to regular water.

If you haven't changed your anti-freeze within 2 years, I'd suspect 2 causes here, probably a pressure leak (as mentioned, likely the cap and/or bottle) and probably weak anti-freeze that needs to be flushed and changed.

I think Prestone Green is 100k or 5 years and the Prestone Orange Dexcool is 150k 7 years?

Thats Prestone "Extended Life" Anti-Freeze, which is a derivative of Dex-Cool dyed Green. Prestone no longer makes old Conventional "Green" anti-freeze. They have been sued for calling their new "Extended Life" Anti-Freeze "Universal". If you read the fine print on the bottle, you have to completely drain and flush all the old anti-freeze out of your vehicle before using it. Also in the fine print, under ingredients, you won't find any Silicates or Phosphates, but you will find ingredients that are in Dex-Cool.

Most of the manufacturers have gone away from making the old conventional "Green" anti-freeze. Zerex still makes it, and they say they do not agree with the other manufacturers that using OAT and HOAT anti-freeze in vehicles designed for IAT anti-freeze is as good as the original intended fluid.

The most common opinion on the old conventional "Green" anti-freeze was to leave the OEM Fill in for 3 years, then change it every 2 years after that.

If you have extended life anti-freeze in the XJ now, and its been less than 5 years, maybe its still good, or maybe incompatibility problems with the extended life anti-freeze is causing your problems now.

Thanks for all the advice,guys...I really appreciate it.I think I'm going to fab up a surge tank out of .125 steel with a conventional cap and welded on bungs,screw the plastic turtle:doh: :lecture:

What pressure cap should I get for the steel tank I'm building?How much pressure does the closed system operate at?

why not add in one of the inline filler necks on the top rad hose? and eleminate the tank?? that has worked many times and only really costs a little bit of fluid, filler neck and 2 hose clamps. A lot easyer than fabbing up a tank.

PornstaR's idea does sound much easier than fabing up a new tank. You can use any old plastic bottle for an overflow tank.

BUT, I'd use a 16PSI pressure cap just like the open system. The only difference between the open/closed system is how they handle the expansion of fluid. I'd take the advice of those with Closed Systems over mine, I just have an open system, I only comment because I basically understand how the system works.

The open system has the expanding fluid forcing its way past the pressure cap and then it runs down a tube to the expansion/overflow tank. When the system cools and the fluid contracts, the vacuum formed will pull the fluid back in thru a valve in the center of the pressure cap.

The closed system has the pressure cap on the expansion tank, so fluid expansion/contraction goes to/from the expansion tank under the same pressure with the pressure cap on the tank. No fluid should go past the pressure cap, unless something goes wrong and it has to relieve pressure that gets too high.

Unfortunately, in the closed system, the tank has to withstand the same pressure and heat as the rest of the cooling system. So they fail more often than the open system expansion/overflow tank.