Over Heating YJ - JeepForum.com

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post #1 of 27 Old 07-15-2016, 07:58 PM Thread Starter
Zyurazek
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Over Heating YJ

Hey Guys, Its been a while since I've been on this forum, but I am having an issue with my wrangler that I need to figure out before I take it on a 4 hour trip to the beach on Monday morning.

Here's my issue, If I cruise at or much above 70 MPH, which is highway speeds around here, the temp goes up past 210 to around 220-230. It normally sat just bellow the 210 mark. Its fine at idle and if I drop my speed down bellow 70mph, it cools back down just bellow that 210 mark.

Over the last 2 years, Ive replaced the entire cooling system. This includes the Radiator, thermostat, radiator hoses, water pump, heater core and the fan clutch. Both temp sensors have also been replaced along with all the wiring up to the gauge, and the gauge itself has been replaced. So I know the gauge is reading accurate.

The fan clutch works properly, I've also heated up the engine to running temps and have placed my hand all over the radiator to check for any cool spots and all seems evenly heated, the thermostat is properly working, and I don't notice any leaks, or note any coolant in my oil. All fluid levels are where they should be and the coolant is nice and bright green.

I have a winch and stinger on the front of my jeep, but I don't believe it is making much of an impact on cooling it considering last year I drove this baby 14 hours strait only stopping for gas stops going around 75mph through the mountains and the most the temp would be was 210 on the dot.

So right now, I am at a loss of what the issue could be. Any suggestions would be a great help! Also with your suggestion, if you could include an easy way of testing the possible flawed part, that would be great!

Thank You!

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post #2 of 27 Old 07-15-2016, 08:25 PM
bruinjeeper
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Stop whining about the 'ride' - If your YJ ain't wrangling your soul free, then might I suggest you buy a stationwagon... at least you can fit all your bull**** in the back.
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post #3 of 27 Old 07-15-2016, 08:49 PM
Chrisnvegas
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You bought the cheap radiator with plastic tanks?
It doesn't have the same cooling capacity as OEM.

More speed means more horsepower, more horsepower means more heat.

What happens in my Jeep, stays in my Jeep
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post #4 of 27 Old 07-15-2016, 09:11 PM Thread Starter
Zyurazek
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Quote:
Originally Posted by Chrisnvegas View Post
You bought the cheap radiator with plastic tanks?
It doesn't have the same cooling capacity as OEM.

More speed means more horsepower, more horsepower means more heat.
I bought it 2 years ago from napa:

https://www.napaonline.com/napa/en/p...869_0194673290

It worked just fine on my 14 hour drive. I made sure the fins were all cleaned as well. The issue just started about a month ago. I drive it only every couple weeks now since I purchased my home and I just cant throw the gas money into it like I used to.
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post #5 of 27 Old 07-15-2016, 09:52 PM
Chrisnvegas
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If the thermostat is opening and the pump is pumping, the radiator's ability to cool is being exceeded.
What are the variables?
Is it hotter than usual right now?
Did you recently block the airflow?
It's full of coolant properly mixed?


I had one of those radiators.
Switched it out fast. Couldn't handle the heat here.

What happens in my Jeep, stays in my Jeep
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post #6 of 27 Old 07-15-2016, 10:21 PM Thread Starter
Zyurazek
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Quote:
Originally Posted by Chrisnvegas View Post
If the thermostat is opening and the pump is pumping, the radiator's ability to cool is being exceeded.
What are the variables?
Is it hotter than usual right now?
Did you recently block the airflow?
It's full of coolant properly mixed?


I had one of those radiators.
Switched it out fast. Couldn't handle the heat here.
Last time I ran it before the issue occurred, it was in the lower 70's, mid 60's ambient temp. I was pulling my 14 foot trailer loaded down with my motorcycle, with the ramp up. All together it all probably weighed 2800 pounds at a constant speed of 65 mph. The temp stayed right around the 210 mark. No changes has been made to the jeep since my 14 hour ride last year. Going down to Mississippi I had to replace the clutch fan due to over heating issues, but once that was fixed, I had no issues. During my trip last year I had my winch and stinger mounted up front at a constant speed of 70-75mph through hills. Its much hotter in Mississippi than here in Virginia. No modifications have been made since. I checked the air filter recently and it is fine. It was replaced about 6,000 miles ago.

What I'm not understanding is how my radiator would be completely fine cooling before with harsher climates and with pulling loads, but all of a sudden it isn't sufficient?

I took two additional trips last year that were 4 hour trips with the same equipment as I have now, not a single issue. Temp stayed right at 210. Ambient temps were hotter than it is currently. Only issue I had on one of those trips was I lost my brakes going around a back road turn.
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post #7 of 27 Old 07-16-2016, 04:43 AM
Chrisnvegas
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Ok, I was at work.
So... obviously something has changed. Let's try to figure out what it is.

Now, when it comes to the engine, the cooling, the fuel and ignition, I stick to original Mopar replacement parts. Period.
A couple years ago, I also redid my cooling system at the same time I did the harmonic balancer.
It took some digging, but I found an original Mopar water pump, thermostat, radiator cap (16 lb) and fan clutch.
The fan clutch is actually made by AC/Delco.
In my not so humble opinion, they are better quality than the aftermarket and are better calibrated.
The radiator I got is a test radiator given to me by a manufacturer for testing. It passed! It's similiar to the Champion radiator except was hand made in the USA because they only made 10 for testing.
Anyway...

The radiator cap is important not only to hold pressure to raise the boiling point, but to force coolant into passages in the block to help eliminate localized hot spots from cavitation and spot boiling. If a spot is boiling, it's not cooling.
Did you know desert trophy trucks run their cooling systems at 35 psi and up? I believe Nascar does too.

Thermostat.
We all know what they do. I have had crappy aftermarket ones. I very much prefer Mopar.

Fan clutch.
Strictly Mopar (AC Delco) only. Period.
They come on at the right time and freewheel at the right time. Made in the USA. Enough said!
I don't trust the calibration of aftermarket. The cooling system is always trying to play catch-up.

Radiator.
It originally came with an all brass and copper radiator with metal tanks which also provide some cooling.

I think we can rule out the fan. Even with the winch, 70 mph should provide enough air!
If it didn't overheat before and the coolant looks clean and you don't think there is a blockage anywhere, the radiator can be ruled out too.
Especially if you were towing with it.

So that leaves us two things, the cap and thermostat.
So maybe the thermostat is no longer opening up all the way?

What happens in my Jeep, stays in my Jeep
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post #8 of 27 Old 07-16-2016, 05:09 AM
1320yj
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The OP didn't mention replacing the radiator cap , even tho the cap looks new it can be bad so have it pressure tested.
Also check the system for combustion leaks into the cooling system , a cracked head or a blown head gasket can cause a high speed overheat even if no cross contamination is present. There is a commonly available test kit for this.
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post #9 of 27 Old 07-16-2016, 08:30 AM
shaggyjim
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I would check the cap first and if that isn't it replace the t-stat. I'm with Chris in that it sounds like thermostat is only part way open.

Jim...

"That's more fun than watching a hippie get mauled by a bear!"
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post #10 of 27 Old 07-16-2016, 09:51 AM
fishadventure
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Quote:
Originally Posted by shaggyjim
I would check the cap first and if that isn't it replace the t-stat. I'm with Chris in that it sounds like thermostat is only part way open.
I'd agree.
A 'runable' head gasket leak generally doesn't raise temperature, at first. After a time it gets worse and it raises pressure so much it /appears/ to be "boiling" over when in actuality combustion gases are entering the cooling system blowing coolant out cap into the overflow buffer tank.

Eventually this WILL cause overheat because there won't be enough liquid enough of the time to absorb and carry away the heat of the engine.

How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #11 of 27 Old 07-16-2016, 09:58 AM
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Oh, and I forgot to say:
If your gauge shows 230/235 and you're NOT boiling over at least some of the time and you are running green stuff at 50/50 then I wouldn't believe the gauge until I confirmed with a thermocouple.
At 12-15# cap rating and with 50/50 coolant 230-240 is a sketchy place as it usually will be pretty hard for it NOT to boil in that case. An new OEM cap and t-stat are pretty cheap insurance policies.
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How many old threads actually convince *you* to read all 36 pages? http://www.jeepforum.com/forum/f12/length-envy-build-thread-629700/
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post #12 of 27 Old 07-16-2016, 08:40 PM Thread Starter
Zyurazek
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Alright, Today I went to replace the thermostat, and while reinstalling the housing cover, it cracked. So tomorrow ill have another shot at replacing the thermostat.

As for the radiator cap, I replaced that 2 weeks ago. I was supplied a 16 psi cap from the auto store. As for boiling over at 230-240, I believe I read on the bottle of coolant that the boil over is rated at 255 plus.

Anyways, after I broke the housing, I decided to pull the radiator off and flush it out. I didn't notice any chunks or anything come out of it. Water flowed great through it. I purchased a new set of radiator hoses to put on, just in case since I pulled the radiator. I figured it was cheap insurance. I also flushed the entire system, again. So once I get the new housing tomorrow, Hopefully the jeep will run well.

Also, I noted that the last thermostat installed was rated at 195. The auto store gave me one rated at 180 to put back in. Should that help at all?

Over the past few days that ive called to look for OEM parts strait from jeep, they've told me that everything ive asked for is discontinued. I can no longer buy OEM fan clutches, or radiator hoses from jeep.
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post #13 of 27 Old 07-16-2016, 09:51 PM
Chrisnvegas
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Quote:
Originally Posted by Zyurazek View Post
Alright, Today I went to replace the thermostat, and while reinstalling the housing cover, it cracked. So tomorrow ill have another shot at replacing the thermostat.

As for the radiator cap, I replaced that 2 weeks ago. I was supplied a 16 psi cap from the auto store. As for boiling over at 230-240, I believe I read on the bottle of coolant that the boil over is rated at 255 plus.

Anyways, after I broke the housing, I decided to pull the radiator off and flush it out. I didn't notice any chunks or anything come out of it. Water flowed great through it. I purchased a new set of radiator hoses to put on, just in case since I pulled the radiator. I figured it was cheap insurance. I also flushed the entire system, again. So once I get the new housing tomorrow, Hopefully the jeep will run well.



Also, I noted that the last thermostat installed was rated at 195. The auto store gave me one rated at 180 to put back in. Should that help at all?

Over the past few days that ive called to look for OEM parts strait from jeep, they've told me that everything ive asked for is discontinued. I can no longer buy OEM fan clutches, or radiator hoses from jeep.
Give the thermostat a try.
Here is a source for OEM Mopar radiator cap, 10 bucks, and scroll down for a OEM fan clutch for 50 bucks. They are new parts leftover.

http://collinsbrosjeep.com/NOS-OEM-engine/

I have a new Mopar fan clutch on the Jeep now and an extra in the cabinet because eventually they will all be gone.

I even found original Mopar water pumps and fuel pumps.
When you need something, let me know, I saved the locations.

What happens in my Jeep, stays in my Jeep
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post #14 of 27 Old 07-17-2016, 01:06 AM
Luuca
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Quote:
Originally Posted by Chrisnvegas View Post
Give the thermostat a try.
Here is a source for OEM Mopar radiator cap, 10 bucks, and scroll down for a OEM fan clutch for 50 bucks. They are new parts leftover.

http://collinsbrosjeep.com/NOS-OEM-engine/

I have a new Mopar fan clutch on the Jeep now and an extra in the cabinet because eventually they will all be gone.

I even found original Mopar water pumps and fuel pumps.
When you need something, let me know, I saved the locations.
I would not use the 180 thermostat. It's a bandaid approach to a fuel injected engine that needs to run at 195 to perform properly.

Get the 195 thermostat from NAPA. It will not have a hole in it for bleeding out air so drill one in it before you install it. The only T-stats (aftermarket) that have EVER worked for me properly have been the NAPA branded ones.
MOPAR original would be better, but I could not find one either.

OP: You are on the right track. IMO test the new t-stat on the kitchen stove BEFORE you install it. Boil water in a pot, use tongs to hold the t-stat by the edge, dip it in the water and watch it open up. Don't just drop it in as the bottom of the pot is way hotter than the water. Test it before you drill the air bleed hole.

Also, use the blue goop AND gasket on the t-stat housing and you won't have the fear of leaks that caused you to burn a beast-mode on the bolts and crack it.

Get the non-pressure relief radiator cap from NAPA as well (the one without the red lever thingy) and make sure it's a 16lb rad cap.

The symptoms you describe are in line with a clogged radiator. You did well to check for cool zones; however, that's not 100%. A vehicle that sits, even with good fluid, does still rust. The flush you performed was a good idea. When you reinstall, remember some WATER from your HOSE is going to remain in the block, so get some Pure coolant (not 50/50) to mix in with your 50/50 mix or your mix will be weak and boil at lower temps. They have a tester for fluid mix (titration) and if you are as OCD as you sound (I am too so not a slam) you may want to rent the tester from the parts store and verify you have it right.

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post #15 of 27 Old 07-17-2016, 09:44 AM
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Quote:
Originally Posted by Luuca View Post
I would not use the 180 thermostat. It's a bandaid approach to a fuel injected engine that needs to run at 195 to perform properly.

Get the 195 thermostat from NAPA. It will not have a hole in it for bleeding out air so drill one in it before you install it. The only T-stats (aftermarket) that have EVER worked for me properly have been the NAPA branded ones.
MOPAR original would be better, but I could not find one either.

OP: You are on the right track. IMO test the new t-stat on the kitchen stove BEFORE you install it. Boil water in a pot, use tongs to hold the t-stat by the edge, dip it in the water and watch it open up. Don't just drop it in as the bottom of the pot is way hotter than the water. Test it before you drill the air bleed hole.

Also, use the blue goop AND gasket on the t-stat housing and you won't have the fear of leaks that caused you to burn a beast-mode on the bolts and crack it.

Get the non-pressure relief radiator cap from NAPA as well (the one without the red lever thingy) and make sure it's a 16lb rad cap.

The symptoms you describe are in line with a clogged radiator. You did well to check for cool zones; however, that's not 100%. A vehicle that sits, even with good fluid, does still rust. The flush you performed was a good idea. When you reinstall, remember some WATER from your HOSE is going to remain in the block, so get some Pure coolant (not 50/50) to mix in with your 50/50 mix or your mix will be weak and boil at lower temps. They have a tester for fluid mix (titration) and if you are as OCD as you sound (I am too so not a slam) you may want to rent the tester from the parts store and verify you have it right.
I only said give it a shot for diagnostics since he already had it and it's a 5 minute change.
It'll still overheat with a 180 if it's gonna overheat. Might take a minute longer.

The 2 year old rad threw me. I never had one clog in such a short time.
I was disappointed in the plastic tank radiator though. When pushed hard on a hot day it couldn't keep up.

Mine is similiar to the Champion and I bought my kid a Champion.
They blow off some serious heat.

Still haven't found an OEM thermostat.

What happens in my Jeep, stays in my Jeep
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