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Unread 12-14-2011, 03:24 PM   #1
matrix311
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1992 YJ Wrangler 
 
Join Date: Nov 2011
Location: Tempe, AZ
Posts: 260
Overheating issue on my yj - radiator?

A little history of what's gone on. I bought this YJ 2 weeks ago and god knows how long it's been since the PO last changed ANY of the fluids. So i've gone through and swapped everything out and the last fluid was the coolant. I decided to do a flush. To me it looks like it's still the original radiator just an FYI.

The way I did it was pull the bottom radiator hose and let it drain out that way. Once it completed it's drain I reconnected the lower rad hose and filled up the radiator with water then ran the engine for a few minutes to cycle the water. Then I drained it again via the lower rad hose and did this cycle 3-4 times until the water was clear. Once it was clear I drained the water best I could (i did not remove the drain plug from the engine block as I didn't have a tool to remove it) so I kept draining it from the lower rad hose and also the drain plug on the bottom of the radiator. Once it was free from as much water as I could get it I filled it up with 50/50 pre-deluted mix.

I never drove the Jeep for a few days after I completed this swap, I simply started it up in the driveway and checked for leaks, saw non and parked the Jeep. A few days later I take it for it's first drive since the flush and the temps were in the 260 danger zone shortly after I started driving it so I kicked on the heater and quickly drove home.

First thing I did was let it cool down and then removed the rad cap, started the engine and tried to burp the system of any air that may have been in it. One thing I noticed when the rad cap was off, I didn't see any movement in the radiator. Should I instantly see movement in the radiator or does it pretty much stay still until the thermostat opens and then movement should occur or do you never see movement (like a water current).

So after thinking this may have fixed it I started it back up and the temps just kept going and going so problem not fixed. Yesterday I decided to change the thermostat with a new failsafe thermostat from autozone, new t-stat gasket for the housing and also a new radiator cap (13psi). After swapping all of that I started the vehicle and let it run, burped the system best I could to rid any air in the system and the temps hit 210 and stopped. I felt relieved so I decided to take it for a drive lastnight (drove 10 miles) and the temps hovered around 210 or below the entire time. Lastnight it was about 47 outside and raining. Got home, went to bed and thought the problem was fixed.

Today (sunny, 60ish outside) decided to drive the Jeep to drop off some christmas presents to be mailed off. About 10 minutes into my drive the temp gauge is sitting around 240. If I came to a stop the temps would drop down to 210 but when I started driving the temps would go back up again. I kept driving because it never hit the red zome. Well the longer I drive the more the temps stayed in the higher range of 240-260 and eventually they creeped up into the redline danger zone.

So with all that said, what else could the problem be? Could my water pump be bad? My heater works perfectly fine, it was blowing super hot air into the cabin when I ran it. Also could my radiator be clogged and not flowing anything? When I initially drained the radiator the coolant that came out was so nasty gross. It was brown and thick and looked almost like oil but it wasn't oil. It was just full of contaminants and all sorts of other stuff. So that brings me back to the earlier question about coolant movement inside the radiator? If I take the cap off, start the Jeep, should I see any coolant moving inside the radiator? It just sit still inside the cap from what i'm seeing.

Any help or troubleshooting suggestions would be great! This problem of overheating didn't start until after I did the coolant flush.

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Unread 12-14-2011, 03:31 PM   #2
pasinbuy
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1994 YJ Wrangler 
 
Join Date: Feb 2007
Location: florida
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Radiator is plugged.

WWW.radiatorbarn.com

They had good prices and the best radiators that I could find. No plastic on them. A life warranty.

If you have AC get the three core. Best cooling.

Oldtime, ( below is right) although a plugged radiator does not have to leak. I still say a plugged radiator due to the sludge that you stated came out. You could have the old radiator rodded, but if it is original it will soon be shot anyway. Go with a new one.

Please fill out your profile.
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Unread 12-14-2011, 03:32 PM   #3
oldtime_ironman
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1991 YJ Wrangler 
 
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Did you see the coolant circulating after you changed the thermostat and warmed it up? It should definitely be circulating by then. So I would take off the radiator cap and idle it till it hits 210 and then take a look. If its sluggish or not circulating at all, then you probably have a water pump prob. If you look at the radiator for any "wet" looking spots, in the morning when its cold, then the radiator is starting to go (mine is starting to go, that's how I know...)
.
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Unread 12-14-2011, 03:39 PM   #4
Karma
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HI,
It very easily could be your thermostat. Try it. Your profile does not say what engine or year your YJ is. I use a 190 degree thermostat on my 258. Even if it is not, changing it every couple of years is a good idea. It sounds like it had been in there for many years. I don't think it is the water pump because typically when they go bad its the bearings. You will hear it squeak.

Sparky
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Unread 12-14-2011, 06:44 PM   #5
OhioYJRunner
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1995 YJ Wrangler 
 
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What coolant did you use? When I got mine and did my flush I thought the coolant was worse than it actually was, tho was a pretty nasty shade of rust. I don't know if it's all yj's as you don't have any of your mech info on your profile, but mine uses a oil colored coolant that is ethylene glycol based which I read is highly recommended to almost imperitive to use. Getting from a dealership was recommended also, but can be gotten at a part store. Could also try replacing the coolant temp sensor or sender switch. When I did mine I ended up replacing those also, tho don't remember why (Can't remember if t-stat, gasket, and housing corrected overheating issue.) Your cts tells your t-stat to remain closed so your engine can warm to operating temp faster and once at the temp (190 I think) opens to keep at correct temp range. bad cts would not tell your t-stat that your engine has reached the correct temp and therefor would not open your t-stat to allow the coolant to circulate through the engine. Just a disclaimer. I am not a overly knowledgable auto tech guy so I'm just throwing out there what I was researching when it happened to mine
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Unread 12-14-2011, 07:07 PM   #6
oldtime_ironman
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Quote:
Originally Posted by OhioYJRunner View Post
When I did mine I ended up replacing those also, tho don't remember why (Can't remember if t-stat, gasket, and housing corrected overheating issue.) Your cts tells your t-stat to remain closed so your engine can warm to operating temp faster and once at the temp (190 I think) opens to keep at correct temp range. bad cts would not tell your t-stat that your engine has reached the correct temp and therefor would not open your t-stat to allow the coolant to circulate through the engine. Just a disclaimer. I am not a overly knowledgable auto tech guy so I'm just throwing out there what I was researching when it happened to mine

Umm, Bzzzt. Wrong.

Gonna have to correct you on that one. The CTS and the T-stat have little to do with each other - the T-stat works on its own regardless - its a purely mechanical thing. It senses it own temp. The CTS does tell the computer when to start reading the oxygen sensor tho, among other things. The OP had already replaced the T-stat and is wondering why he is still overheating.
.

Last edited by oldtime_ironman; 12-14-2011 at 07:10 PM.. Reason: clarification
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Unread 12-14-2011, 07:10 PM   #7
superj
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radiator is plugged
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Unread 12-14-2011, 07:18 PM   #8
OhioYJRunner
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That is right. I do remember that now that you mention it. Sry OP, not trying to send you on a wild goose chase. What about the sender switch Ironman. Idk if you run one w both as I've read some don't have 2, but that sends signal to the indicator, no? Could it just be a malfunction in the gauge? What about the squeeze test? You might have to help w this one too if I hack it up, but you should be able to squeeze the top rad hose when engine at op temp and watch the level lower right? And if it's hot and engine overheating then its in the water pump, t-stat, belt housing area and if not in the radiator, fan area. Sry if this is all wrong OP. Figuring someone will correct me if it's mixed up or gives you a starting point to research problem area tests
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Unread 12-14-2011, 07:28 PM   #9
oldtime_ironman
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Quote:
Originally Posted by OhioYJRunner View Post
That is right. I do remember that now that you mention it. Sry OP, not trying to send you on a wild goose chase. What about the sender switch Ironman. Idk if you run one w both as I've read some don't have 2, but that sends signal to the indicator, no? Could it just be a malfunction in the gauge? What about the squeeze test? You might have to help w this one too if I hack it up, but you should be able to squeeze the top rad hose when engine at op temp and watch the level lower right? And if it's hot and engine overheating then its in the water pump, t-stat, belt housing area and if not in the radiator, fan area. Sry if this is all wrong OP. Figuring someone will correct me if it's mixed up or gives you a starting point to research problem area tests
Yeah, mine has 2 of them. The one on the T-stat housing is for the computer. The other one on the back of the cylinder head, drivers side is for the gauge. It could be the gauge sender is messed up, or the gauge, etc. But somehow I doubt it in this case. Yep yer right about everything else tho.
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Unread 12-14-2011, 08:12 PM   #10
matrix311
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1992 YJ Wrangler 
 
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Location: Tempe, AZ
Posts: 260
Thanks for all the replies everyone. I have a 92 YJ with 2.5L engine in it. I actually did replace the coolant temp sensor which is the brass piece that screws into the engine. Thats brand new as well. I tested the dash gauge in the cabin of the Jeep by grounding it out and it blipped all the way over to the far right so i'm assuming that is working.

I'm thinking there is a restriction of flow somewhere in the radiator. Maybe I should drain it completely again and do like 4-5 flushes with the garden hose to try to dislodge any additional crud that might be in there.

Also I did hear some squeeling noise when I start the Jeep. It only did it for a few seconds and then went away. I checked the serpentine belt and it was a little loose so I tightened the belt and now the squeel is gone. If the water pump bearings were bad would it be a constant squeel while the engine is running? Also if the water pump is bad would it not cycle coolant up the heater hose to the heater core to blow hot air into the cabin? The heater hoses get blazing hot so there must be some movement going on.

Any other thoughts or things to test or try?
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Unread 12-14-2011, 08:30 PM   #11
oldtime_ironman
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Quote:
Originally Posted by matrix311 View Post
Thanks for all the replies everyone. I have a 92 YJ with 2.5L engine in it. I actually did replace the coolant temp sensor which is the brass piece that screws into the engine. Thats brand new as well. I tested the dash gauge in the cabin of the Jeep by grounding it out and it blipped all the way over to the far right so i'm assuming that is working.

I'm thinking there is a restriction of flow somewhere in the radiator. Maybe I should drain it completely again and do like 4-5 flushes with the garden hose to try to dislodge any additional crud that might be in there.

Also I did hear some squeeling noise when I start the Jeep. It only did it for a few seconds and then went away. I checked the serpentine belt and it was a little loose so I tightened the belt and now the squeel is gone. If the water pump bearings were bad would it be a constant squeel while the engine is running? Also if the water pump is bad would it not cycle coolant up the heater hose to the heater core to blow hot air into the cabin? The heater hoses get blazing hot so there must be some movement going on.

Any other thoughts or things to test or try?
You might get better luck with the flushing if you get the hose adapter kit. They got em at walmart and autozone for like $5, just a plastic tee that lets you screw a garden hose into the heater line.
.
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Unread 12-14-2011, 08:47 PM   #12
matrix311
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1992 YJ Wrangler 
 
Join Date: Nov 2011
Location: Tempe, AZ
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Quote:
Originally Posted by oldtime_ironman View Post
You might get better luck with the flushing if you get the hose adapter kit. They got em at walmart and autozone for like $5, just a plastic tee that lets you screw a garden hose into the heater line.
.
Ya i've seen that before. I'll give that a shot tomorrow and see what happens. If it still wont work afterwards i'll buy a new radiator since this one looks to be the original and is 18yrs old.
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Eric - *'92 White YJ, 4.5" custom Deaver springs, 35" MTRs, Tera-Low 4:1, CAI, Rear 8.8, Chromo D30, 4.88s, locked front/rear, full cage and front/rear tube fenders.
*'08 Silver Rubicon JKU 2.5" lift, 5.13's and 35's
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Unread 12-15-2011, 01:40 AM   #13
TA-YJ
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1992 YJ Wrangler 
 
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Location: Pennsylvania
Posts: 533
Did you use the coolant temp sensor from the dealer or autozone/wherever? Just wondering because I was chasing down what I thought was an overheating issue for 2 weeks before I got a mopar temp sensor. I had two from autozone before that. That made my temps sit right where they were supposed to. I confirmed the reading with an infrared thermometer from harbor freight (good investment as well). Before you replace the radiator that would be a good place to start.
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1992 YJ 2.5L
Engine Mods:4.0L TB, Ford Design III 19lb Injectors, Firepower Ignition System, Ford TBird Electric Fan, Pacesetter Header, Magnaflow Cat, Dynomax Super Turbo Exhaust
Suspension Mods:BDS 2" Lift, M.O.R.E. 5/8" HD Shackles, 1" Brown Dog MML
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Unread 12-15-2011, 03:03 PM   #14
matrix311
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1992 YJ Wrangler 
 
Join Date: Nov 2011
Location: Tempe, AZ
Posts: 260
I bought a coolant temp sensor from NAPA. Is there a way to tell if the fan clutch is going out? I have some oil leaking from the front of it. When the Jeep is up to operating temp and i'm parked and raise the RPMs should the fan spin faster as the RPMs rise to cool the engine? What about after I turn the engine off after the Jeep was up to temperature, should the fan spin freely? If so how freely? Should there be any type of resistance? If there is resistance should the resistance be the same whether the engine is hot or cold? This could be the culprit because it seems like the water pump is working fine and the radiator seems to be flowing coolant, maybe just not as fast as it should. But if anyone could chime in on how to test my fan clutch i would appreciate it!
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Eric - *'92 White YJ, 4.5" custom Deaver springs, 35" MTRs, Tera-Low 4:1, CAI, Rear 8.8, Chromo D30, 4.88s, locked front/rear, full cage and front/rear tube fenders.
*'08 Silver Rubicon JKU 2.5" lift, 5.13's and 35's
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Unread 12-15-2011, 03:27 PM   #15
oldtime_ironman
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1991 YJ Wrangler 
 
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Posts: 2,540
Quote:
Originally Posted by matrix311 View Post
I bought a coolant temp sensor from NAPA. Is there a way to tell if the fan clutch is going out? I have some oil leaking from the front of it. When the Jeep is up to operating temp and i'm parked and raise the RPMs should the fan spin faster as the RPMs rise to cool the engine? What about after I turn the engine off after the Jeep was up to temperature, should the fan spin freely? If so how freely? Should there be any type of resistance? If there is resistance should the resistance be the same whether the engine is hot or cold? This could be the culprit because it seems like the water pump is working fine and the radiator seems to be flowing coolant, maybe just not as fast as it should. But if anyone could chime in on how to test my fan clutch i would appreciate it!
Yeah, if you have oil coming out the fan clutch, its gone. Time for a new fan clutch. The resistance should change depending whether its hot or cold.
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