It's 105 degrees outside. Can my cooling system handle it?

[mrblaine]

The needle basically has 5 positions when you get up to temp. Just left of 210, 210, just right of 210, about halfway between 210 and 260, and 260. This is for my 2001, I believe it changed slightly in other years.

Just right of 210 can mean anything from ~215 to ~235-240. It is best to check your real temps with an OBDII since the gauge is pretty garbage.

My Jeep spends most of its life pegged on 210 while it fluctuates from ~200-208 driving around town according to the OBD. Once I hit the highway on a 80+ degree day with AC on, it’ll move up to just right of 210 and run at 215-225.

I’ve been trying to nail my cooling system down for a while. I’d be interested to hear what the Arizona guys are running for real temps according to the OBD while idling with AC on and driving at highway speeds with the AC on. I think those numbers would be able to show what temp a proper functioning TJ should run at when under load.

All I want to know and care to know is if the needle is hovering around the 210 mark, that's it. The rest of that info is useless.

 

[Jamison C]

Good to see! In the hour and a half when I last posted I managed to order a Mopar pump, tstat, cap, and fan clutch (along with some other unnecessary stuff not Jeep related.. kinda bored after work these days). Hoping to have the same results.

It should warrant you the same results. If your radiator is fairly new and in good shape then maybe a sticky thermostat isn’t allowing coolant into the engine from the radiator. Or the water pump is just worn out. You said the system is factory, how many miles on the Jeep?

 

[Joseph]

It should warrant you the same results. If your radiator is fairly new and in good shape then maybe a sticky thermostat isn’t allowing coolant into the engine from the radiator. Or the water pump is just worn out. You said the system is factory, how many miles on the Jeep?

145k just rolled over. I had the head gasket done about 2500 ago. Mopar radiator ~10k. It really takes me sitting for minutes with my foot on the break for it to get a little hot, about 220 I’d say. Rather just get it all done while I have the money though.

 

[TJRick]

Thats my line about winter.
We hit 65 below a few times and no new cars will start unless they are plugged in.

You need a carburetor to start when it gets that cold. I bought my '87 YJ specifically to get a carb.

OMG this man gets it. Yes, you need a carburetor to start when it gets that cold! No, seriously.

I get so tired of seeing "better cold starts" as a reason given by someone who would rather have a fuel injection system. Anytime you see an aftermarket fuel injection system advertisement, you will see "better cold starts" as a benefit.

There are many reasons to prefer fuel injection, but "better cold starts" isn't one of them.

 

[TJRick]

It is quite annoying though that there are actually people out there who think that Jeep (or any auto manufacturer) would have designed a vehicle and forgot about the areas of the country where it gets much hotter.

You'd have to be a pretty stupid automotive engineer if you designed a vehicle thinking it would never see these sort of temperatures.

I agree with you about the cooling system.

But does that mean I don't need an auxiliary transmission cooler, as long I stay within the load limits specified by Jeep?

 

[Chris]

I agree with you about the cooling system.

But does that mean I don't need an auxiliary transmission cooler, as long I stay within the load limits specified by Jeep?

Technically you don't need one as long as you aren't towing.

If you are towing (even within the load limits), a transmission cooler isn't required, but it will extend the life of your transmission.

 

[CodaMan]

So I went ahead and hooked up my scanner today. When I did my flush the other day I also changed my thermostat. The needle sat right below the tick so I figured while I had everything apart I’d check the thermostat. Interestingly enough, it was a 195* unit, but I went ahead and swapped it anyways since I was in there.

Cue today after driving it around for a bit and then sitting in a parking lot with the AC going. I decided to hook up the scanner since the needle is still sitting in the same place. We’re at 101* outside today.
View attachment 171898View attachment 171899

After giving it a few good revs I could only get it up to 206*. Just thought I’d share my findings and also help reiterate with @CodaMan that the factory cooling system is more than capable when properly maintained.

Looks perfect

 

[billiebob]

OMG this man gets it. Yes, you need a carburetor to start when it gets that cold! No, seriously.

I get so tired of seeing "better cold starts" as a reason given by someone who would rather have a fuel injection system. There are many reasons to prefer fuel injection, but this isn't one of them.

yep, snowmobiles were all carbureted, prime twice, pull once, running even at 50 below. The new EFI 4 strokes at 40 below, they all flood and you pull out the generator, plug them in for an hour and..... pray.

My YJ and F250 I kept a pickle jar of gas behind the brake booster. Pull the air cleaner top, dump in some gas, pump the pedal and turn the key. At 40 below it might turn over slow but it always fired.. by the time I got air cleaner cover on and dropped the hood the lifter clatter had stopped and you could drive off letting the engine come to temperature and flex out the flat spots on the tires.

10 years in Yellowknife that YJ never failed. But anyone with an EFI engine HAD to be plugged in at 30 below or colder.

One real painful consequence of EFI, everytime you flood it you need to do an oil change since EFI pumps at 80psi plus and the fuel washes the cylinders and dilutes the oil. Not so with a carb since the mechanical pump only pumps at 7psi.

 

[NDSpeed]

yep, snowmobiles were all carbureted, prime twice, pull once, running even at 50 below. The new EFI 4 strokes at 40 below, they all flood and you pull out the generator, plug them in for an hour and..... pray.

My YJ and F250 I kept a pickle jar of gas behind the brake booster. Pull the air cleaner top, dump in some gas, pump the pedal and turn the key. At 40 below it might turn over slow but it always fired.. by the time I got air cleaner cover on and dropped the hood the lifter clatter had stopped and you could drive off letting the engine come to temperature and flex out the flat spots on the tires.

10 years in Yellowknife that YJ never failed. But anyone with an EFI engine HAD to be plugged in at 30 below or colder.

One real painful consequence of EFI, everytime you flood it you need to do an oil change since EFI pumps at 80psi plus and the fuel washes the cylinders and dilutes the oil. Not so with a carb since the mechanical pump only pumps at 7psi.

I have to put a space heater under the hood with a blanket to keep the heat to turn over the diesel. The grid heater doesn’t want to work right.

 

[jodomcfrodo]

All I want to know and care to know is if the needle is hovering around the 210 mark, that's it. The rest of that info is useless.

I drove across the country with the needle hovering around 210 until I hit Iowa and my Jeep pegged the gauge after turning it off and turning it on again at a gas station. Turns out my thermostat was stuck and I was driving around with the temp at 240, the heatsoak at the gas station put it over the edge. I'm a little more cautious now that I know the gauge isn't all that accurate.

With a fully working cooling system, I don't care as long as the gauge is near 210, but I do hear of people with slightly lower temps than me. I pay attention to the fan noise on hot days now to tell if I have a problem. I also pull out the iPhone OBD out once in a while to make sure everything is doing alright.

 

[mrblaine]

I drove across the country with the needle hovering around 210 until I hit Iowa and my Jeep pegged the gauge after turning it off and turning it on again at a gas station. Turns out my thermostat was stuck and I was driving around with the temp at 240, the heatsoak at the gas station put it over the edge. I'm a little more cautious now that I know the gauge isn't all that accurate.

With a fully working cooling system, I don't care as long as the gauge is near 210, but I do hear of people with slightly lower temps than me. I pay attention to the fan noise on hot days now to tell if I have a problem. I also pull out the iPhone OBD out once in a while to make sure everything is doing alright.

Was it a Mopar thermostat?

 

[Jamison C]

145k just rolled over. I had the head gasket done about 2500 ago. Mopar radiator ~10k. It really takes me sitting for minutes with my foot on the break for it to get a little hot, about 220 I’d say. Rather just get it all done while I have the money though.

Goodness! I’d say you’re due for a refresh! Make sure you flush your block good, and use HOAT coolant. Green isn’t necessarily a specific kind of coolant, a lot of manufacturers use dye. Just be sure to use HOAT. Zerex G-05 is what I use and is readily available. Get the type that you dilute yourself.

 

[jodomcfrodo]

Was it a Mopar thermostat?

I don't know if it was ever replaced in the first 200k miles. I've only driven the Jeep since 182,000 miles were on the clock, but its been in the family since new. I'd imagine it was original from the factory but I don't know.