Strange coolant bottle issue

I searched and I couldnt find anything that really matched my issue so I figured Id ask here.

The other day I was driving and smelled coolant. I noticed the inner fender well was wet so I popped the hood and saw that some coolant had overflowed out of the reservoir. No big deal, I just replaced the radiator last week so I figured it may have been a little over full. Over the last few days everything was find.

So today I took the jeep for a ride and when I got home I popped the hood to check everything out and noticed the level in my coolant overflow bottle was almost all the way to the top. I sat there and watched the level coming back down as the motor started to cool.

Over the last few months I have replaced the tsat, tsat housing, water pump and now last week the radiator. The jeep does not over heat and generally runs at around 203 but occasionally bumps up to 208-210 and then comes back to 203. I cant figure out what is going on. I dont have any leaks that I could find and the CSF 3 row I installed is less than 1 week old.

Anyone ran into this before?

Check under the oil filler cap for goop, You may have a bad head or gasket (I hope I am wrong).

What year XJ?

Its a 98. I checked the oil yesterday and the oil looked fine. I will look under the cap right now and tell you what I find.

No goop, clean as a whistle.

Look at the side of the coolant overflow bottle. There are marks for 'add' and 'full'. Keep the coolant level in between those. When the coolant gets hot, it expands into that tank, and gets drawn back into the radiator when it cools.

Ronbo said:

Look at the side of the coolant overflow bottle. There are marks for 'add' and 'full'. Keep the coolant level in between those. When the coolant gets hot, it expands into that tank, and gets drawn back into the radiator when it cools.

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When cold it is at the full mark. How much can I expect it to expand?

It seems to me only a couple inches surely not to the very top or overflow?

I guess if its not over heating Ill just keep and eye on it. In the mean time Ill replace the radiator cap.

When it is HOT/at operating temp, the level should be at/near FULL.

just because you don't see it mixing means its ok. i had a similar issue in my 88 xj with a modern type radiator and didn't officially know it was the head gasket till i rebuilt the motor

88_cherokee said:

just because you don't see it mixing means its ok. i had a similar issue in my 88 xj with a modern type radiator and didn't officially know it was the head gasket till i rebuilt the motor

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One way to check for a bad head/gasket is to use an exhaust gas analyzer (The type used for Smog testing) to sniff the radiator for exhaust gas.
I did this years ago on a Ford Bronco 2 that was overheating & Sure enough there was exhaust gas in the the coolant, The head was cracked!

Just an off the wall thought maybe the radiator cap isn't holding pressure. Most radiators hold 14-16 PSI, if the cap isn't holding pressure it seems likely your overflow surge is going to be more.

8Mud said:

Just an off the wall thought maybe the radiator cap isn't holding pressure. Most radiators hold 14-16 PSI, if the cap isn't holding pressure it seems likely your overflow surge is going to be more.

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Just put a new one on 5 min ago. So Ill let you guys know on that.

stockli said:

Just put a new one on 5 min ago. So Ill let you guys know on that.

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Check the filler neck out real good. Check where the bottom pressure part of the cap seals, usae a flashlight look close. I've seen more than a few with slightly bent bent filler necks or plastic ones with a casting flaw on a sealing surface.

8Mud said:

Check the filler neck out real good. Check where the bottom pressure part of the cap seals, usae a flashlight look close. I've seen more than a few with slightly bent bent filler necks or plastic ones with a casting flaw on a sealing surface.

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Both my Jeeps have CSF radiators about two years apart...same part.
The filler neck is really a weak spot for me. It's hard to push down on the cap to get it off without tweaking the neck. I haven't broken one yet but with my incredibly Herculean strength I could very easily push hard enough to break it...especially on the newer one.

Hahaha, yeah Im always worried about breaking the necks on the rad too.

The new cap seems to have fixed the issue. I think the old spring was just shot. Damn thing was less that a year old too. Cheap pieces of crap.

One other thing that makes me want to punch someone at CSF, the rad came without caps for the inlet and outlet and without a radiator cap. This is a problem because even after I rinsed out the inside of the radiator prior to install, there seems to have been little pieces of freaking styro foam in there.

I noticed a few small pieces floating in my bloody reservoir. That ticks me off.

Why wouldnt you cap stuff to make sure crap cant get in there? And why no cap with the radiator? :gonnablow