Jeep barely gets hot

During normal driving, my stock temp gauge only goes up about 1/4 of the way. Seems kinda low. When I let the jeep warm up in the morning for a couple minutes at 2000 rpm, the temp gauge goes up about half way, and I finally get some good heat. When I blip the throttle and start driving to work, It goes back down to 1/4. I have my entire radiator covered with cardboard. It dosn't matter if its 0 degrees out or 50 degrees out. Is this normal for the 258? Its a fairly new thermostat.

I'll tell ya, I can run my 258 with barley any water in it and it won't over heat. Must be a well designed motor.

 

Re: Jeep barley gets hot

Sounds like the t-stat is stuck open. My 258 has no trouble getting up to temp no matter what the outside temp is.

Are you sure the guage is reading correctly?

 

Re: Jeep barley gets hot

The first thing you will want to do is to confirm your engine temp. Use a thermal gun or a candy thermometer and check to insure the gauge/sending unit isn't the problem. If you find the temp is low, then your problabbly looking at replacing the t stat again.

 

Re: Jeep barley gets hot

Yea, I would say the gauge is working fine. When its low, the heater output is low. When its halfway, I get good heat. One time I sprung a leak in the hose and the temp gauge started climbing high. I guess I'll replace the t-stat. Does the needle on your 258's temp gauge pretty much always hold the same spot?

 

Re: Jeep barley gets hot

It fluctuates slightly but once its warmed up it is pretty constant.

 

Re: Jeep barley gets hot

Mine stays right in the middle, 195º thermostat. Winter down to the teens, Summer, up to 115º, always reads in the middle.

Boring. Just the way I like it.

 

Not to hijack, but I ironically have the opposite problem(sorta). My temp gauge needle slowly progresses all the way to the other side and reads at 300 degreesR)

I know this isn't the case as the jeep runs and has been running just fine. It's been doing this for awhile now, but its been more of an annoyance than problematic. My guess is a bad sending unit because it's been doing this since I put the new sending unit in. Thoughts?

 

I changed my thermostat a week ago and everything is still the same. My temp sits steady at about 1/4 of the temp gauge with low heater out put. If I go on the highway for 5 min. or more, my temp gauge goes half way up and I get some nice heat. My radiator is fully blocked with a piece of cardboard. Its filled to about an inch and a half below the cap (as much antifreeze as it will take without an overflow). I don't know what else it could be. I guess I'll just attribute it to having the stock heater core and a mojave heater. I should be happy the thing never over heats. I was just worried about carbon build up, and itd be nice to get some good heat.

ps my old thermostat wasn't stuck open.

 

What temperature t-stat are you running?

 

195

 

That is just odd. As long as the thermostat is closed the fluid will circulate inside the engine until it reaches the temp of the thermostat. If its in good working order the engine temp should get up to 195 and stay relatively constant. Its hard to believe that the 2 heater cores would cool the engine down that much.

If you turn the fans off on the heaters what does the engine temp do?

 

Mojave heaters are junk. Sorry to have to tell you that, but from my experience with it, that is my opinion. I swapped my stock one out thinking it would cook me out, but that wasn't the case. I don't think it puts out enough BTU's to be a stand alone heater. Maybe in conjunction with the stocker it would work great, but not alone.

Good Luck,

High5

 

Have you flushed your system? My Comanche was not making any heat out of the heater and I had to flush the heater core. Lots of rusty crap and sand (sand?? from where?) came out and after that it started making great heat.

 

that's what happened to an S-10 of mine once. The heater core needed flushing and it was show low temp low temp, wiggle around some. New tstat was no help, then the water pump blew a mess one day from all it's struggling.

I had good heat anyway though. It seemed counter intuitive that it would run cold, yet was somehow blocked up, but that was the story and result.

 

Similar threads come up here regularly, I really think as Jeepdaddy2000 said the starting point is to verify what the temperature really is, without that verified you are really just guessing is it the Gage or is it running cold. While running cold isn't as serious as running hot the engines are designed to run at a certain temperature and problems like sludge and crankcase condensation can develope. You can get a meat thermometer at the grocery store for $12, you can get a digital thermometer at Harbor Freight for $29. This will tell you what is going on and you really need to know what is happening and go from there.

 

One thing to add when you get the thermometer you can test your thermostat in some water on your stove to see if it is opening up at the right temp. Also to see if your old one was bad.

 

Ok, I'll have to get a thermometer. Thanks for the recomendations and prices, as I am, very cheap. I've never technically flushed my cooling system. Not even quite sure how to do it. HopefI think with the pressure from a garden hose, right? That being said, I have drained my engine block a few times and got out alot of brown stuff. I thought that was good enough, since the block obviously wasn't blocked.

 

Unhook both heater hoses and use a garden hose to blow through them until they run clear. Then reverse and blow the other way until it runs clear in the other direction. Lather rinse and repeat. That will flush the heater core. You can kinda do the same thing to the rad by using the garden hose to flush through the upper and lower rad hose. Likewise for the block. I like to flush each separately rather than force the crud from one end all the way through the system. If you've never flushed and refilled with new coolant there's no time like the present. I'd be good money that it at least helps if not solves your problem.