Hyperborean

I bought the jeep last August. It ran just fine and the temp gauge was working until this past November. It showed a proper temp and heat was good. Then it just stopped showing a reading yet I had good heat. This spring I replaced the thermostat and got much hotter heat. However, the gauge still didn't show a reading. I found the sending unit had been broken and replaced it. The gauge worked fine for a couple of days then started showing the same signs as before. Sometimes the gauge will simply read nothing or peg out on its own. Also, when I turn the key to the "on" position the gauge will rise a quarter of the way. This is with a cold engine. Once the vehicle is started, over 1-3 minutes, the gauge will slowly rise to peg out. Could I have broken the violet wire enough to be causing the gauge problem?

I do not smell antifreeze indicating an overheating problem. There is no leaking anywhere, no signs of leaking on the garage floor, no strange noises from the motor indicating an overheating, no lurching, no loss of power, nothing. The jeep runs just as it always has.

When I remove the radiator cap, with the jeep running, the coolant does not flow. If I squeeze the upper rad hose the coolant moves. If I squeeze the lower rad hose the coolant moves. The lower rad hose appears to have a spring in the first third or so of the hose. This hose is a flexible hose, but I don't know if it's an OEM hose or replacement. The upper rad hose is hot to the touch, but the lower hose is cold. The radiator itself is cool to the touch as well except near where the hoses attach on the backside. It's warm at both places, but not hot. There is no coolant in the oil and nothing coming from the exhaust pipe. I don't see any leaks around the water pump either.

With the engine hot I can turn the fan, but it will not spin freely. If I give it a good spin it will move a short bit and stop. It does not continue to spin. I take it that means the clutch is OK? The radiator overflow is at the "full' mark as well.

I have replaced the radiator cap with an OEM from CT. The temp sending unit, the one from the rear on the drivers side, was replaced just a couple of weeks ago. It came from Napa. The thermostat was replaced this past November and came from CT.

I need to know:

Why the gauge is not working properly/at all
Why coolant does not appear to be circulating yet the engine does not appear to be overheating

Specs:

95 YJ
2.5 Litre
No Custom Mods. All Stock Parts.

Hopefully I've offered enough information for someone to give me a good idea of what the problem is. I really appreciate the time, effort and any information you can provide.

Jonathan

oldfart

did you try measuring the resistance of the sending unit when the motor is cold and also when it is hot?

Hyperborean

No I didn't. That sounds like a skill I would need. I wouldn't even know what to do, what to use or where to start.

oldfart

Ok, in that case, ask around your friends if any of them has a v o m and knows how to use it. it's not rocket science but it's really the first thing to check.

Hyperborean

V O M? Voltmeter perhaps? If so, I have one. If you could explain what I need to do I'm sure I could figure it out. I didn't spend the time explaining in detail the problem I'm having to be shut down so fast. You're the only person who has responded and I get the feeling you can help me sort this problem out. I understand doing a diagnosis online is a PiTA, but I really need some experienced help.

Thanks again.

Hyperborean

Tonight I drained the radiator with the intention to refill it and give it a good try at burping the system. I also tightened the temp sending unit as it was a little on the loose side. Everything was going quite well until I noticed a lot of smoke coming from the oil filler cap. I shut the jeep down and pulled the dipstick. It was cream-colored and foamy. I took the oil cap off and confirmed the creamy colored sludge on the inside of the cap. So I take it the motor is now pooched and the jeep is now guarding the U/G parking.

So, if anyone is from Kelowna and knows of a good replacement for a good price please send me a PM.

Jonathan

oldfart

Don't assume the worse until you have performed some basic diagnosis. If you could make it to the sunday night chat it would be easier to try to sort out some of basic things you would need to check. If you are coming to the chat, have your vom at hand and I'll see if I can give you a quick course on what to do with it. The chat starts at 8:30 est,
The snot on the oil filler cap can be caused by a number of things, not getting up to temperature by only driving very short trips can be one cause. I would change the oil and see what comes out, if there's no coolant in it and the motor is not overheating to the point of boiling over there's good chance is ok.

Hyperborean

The oil dipstick is covered in cream colored sludge. There isn't any shred of oil on it. The oil cap itself didn't have just a coating of it, but a good 1/8 of an inch of cream on it. I took a good sniff inside the valve cover and smelled anitfreeze in it. I don't have a Sunday for a few weeks at least. When I have a few minutes I'll pull the oil plug and take a look. The odometer shows ~315k on it. The motor looks like it's probably the original one. The PO never mentioned anything about a rebuilt. Not too broken up about this though. Would like to have a 6 cylinder in it though. The 4 cylinder is just too weak for the area. I usually only drive it to work and home, but do take it out on the highway from time to time.

Hyperborean

Thought I'd leave a note about this problem as I just posted another issue.

I replaced the motor with a used one. Used one had 100k on it and a transmission with unused tranny for $650. Turns out Peanut, the Jeep, needed a few other things too. Shocks needed replacing as one was broken. Radiator, hoses, serpentine belt and a pulley, rear brake cylinder (it was leaking), 4 tires (2 were bald anyway), muffler and a new temp gauge. Runs like new now! Aside from the oil gauge problem now...