Odd Cooling Problem

[belltom]

My 2001 Wrangler has some heating and cooling issues. Thought someone might know what is going on.

The engine warms up to a hair over 210. Then heat does not come out of the vents until about 10 minutes later, with the temp guage holding steady at 210 the whole time. It used to start giving me heat right away.as the temp was climbing. Thermostat has been replaced, top radiator hose does get warm showing I am getting flow.

The bigger problem than the heat (because I eventually get warm air), is that when driving it 40-50 miles, suddenly the temp guage climbs to 260, stays there about 60-90 seconds, then drops back down to around 215. When I get home, and check, I can hear coolant bubbling in the reservoir. When it cools off and I check, the radiator is low on water, but the reservoir is almost empty. NO VISIBLE leaks or coolant on the ground. There does not appear to be coolant in the oil (checked diptstick, but have not pulled the oil drail plug to check yet - coolant is heavier than oil so it would be at the bottom of the pan).

Thoughts?

[mheath14]

my tj was doing the same thing last year. It ended up being a cracked head. I eventually put a new motor in it.

[belltom]

my tj was doing the same thing last year. It ended up being a cracked head. I eventually put a new motor in it.

That is my major worry, head or head gasket. That is one possibility the FSM indicates. I thought about renting a pressure tester, but with no visible expernal leaks, it could be internal.

[moose73]

Our 01 wj had a bad head and did the same thing. Loss of coolant but no visable leaks. Put a new head on and have no problems since.

[Fred]

fastest easyest way to know is chenage your oil and or Antifreeze.

[belltom]

It is just odd the oil dipstick does not show any signs of water after I run it. Also, no white smoke out of the exhaust (an indicator of a bad head gasket and/or cracked head). I also thought of the impeller on the water pump being bad and not giving consistent circulation. It would not leak in that scenario necessarily, but I would think it would be more consistent. I think I will go ahead and drain a little oil just to be certain there is no coolant in it.

[belltom]

One more piece of info that could be related or not: 2 codes...P0118 (Engine coolant temp high input), and P0300...(Random Multiple cylinder misfire detected).

[Fred]

may not be enough for it to show on the denise (oh dipstick) I would go ahead and check it to be sure. You need to rename this the Why I need a V8 Thread.

Tell Denise yep Head os blown best thing for me to do is get a 350 with matching Transmission and D300/Atlas or heck go for the gusto a Klune TCase. With all the extra power you have better put that 14B and D60 you have been wanting and well now to make up for ground clearance you HAVE to get 42's, Dont forget to make it work you'll have to stretch it, and Comp cut it so a custom 4link will be in order.

Yep Tom heres your chance!!!

[belltom]

Nice idea, but the only way that is happening is if you send me a huge Christmas gift...hint, hint :p

may not be enough for it to show on the denise (oh dipstick) I would go ahead and check it to be sure. You need to rename this the Why I need a V8 Thread.

Tell Denise yep Head os blown best thing for me to do is get a 350 with matching Transmission and D300/Atlas or heck go for the gusto a Klune TCase. With all the extra power you have better put that 14B and D60 you have been wanting and well now to make up for ground clearance you HAVE to get 42's, Dont forget to make it work you'll have to stretch it, and Comp cut it so a custom 4link will be in order.

Yep Tom heres your chance!!!

[belltom]

I estimate that after driving it a few days, I lost about 1/2 gallon of coolant, filled it up, ran it, then added about another 1/4 gallon, unless when I filled it back up the 1st time, it had a lot of air in the system (but it is an open system).

[Fred]

Hate to say it Tom but those symptoms all point to a cracked head like everyone else noted

[belltom]

OK, looks like no coolant in the oil pan. A little glimmer of hope...I added some coolant and a new radiator cap. Until it cools down I won't know if I have all the air out of the system, however this time, I got heat quickly. Iam hoping this means a ton of coolant was overflowed to the reservoir when the thermostat was bad and due to a weak radiator cap, then on the road the overflow evaporated or leaked out without me noticing. More updates to follow...

[belltom]

OK, this time once it cooled I checked it and the coolant was almost full. I consulted my neighbor who is a super mechanic, explained everything to him, and he really thinks the thermostat and radiator cap were bad, overflowed while on a long trip so I didn't notice (plus I had too little antifreeze so it did not give off an odor), then after changing the thermostat when I filled it, the system had a ton of air in it. Now he thinks I have most of the air worked out of the system, thus I am seeing heat from the vents right away. Let's hope this solves it, as I sure can't afford to replace a head or head gasket right now. I will update once I drive it a few days.

Thanks to all for your suggestions. That is what I like about posting these issues, you get a lot of different views and if nothing else, it helps you think in other areas!

[vlemasters]

Low coolant will lead to issues with the heater b lowing cold then warm. If you didn't warm it up till the new thermostat opened and then refilled it you could have been low. Lets hope so anyway!
Vern

[belltom]

Low coolant will lead to issues with the heater b lowing cold then warm. If you didn't warm it up till the new thermostat opened and then refilled it you could have been low. Lets hope so anyway!
Vern

Agreed! It is doing fine now, but I probably won't know for a few days after drivign it a bit.

[red rubicon]

Good luck and i hope it is not a cracked head.

[Paul E]

Air in the line could cause things to get weird too, like your neighbor said. Hopefully that is all it was, along with the other things you changed.