[GringoLoco]

I'm trying to troubleshoot a noise and occasional engine problem and one of the things it's doing is overheating while in a drive through or sitting for a while, and right afterwards I get the occasional engine problem but way worse than normal, so I'm thinking they have to be related. It seems the easiest way to troubleshoot would be to figure out all the possible ways for an engine to overheat. I'm sure I'm missing a bunch of things. Here's all I could think of so far, none of which could also cause the noise and engine glitch I'm experiencing. What else can you come up with?

1. Lack of, or old coolant.
2. Thermostat
3. Water pump

[mdm]

Fan clutch shot - doesn't drive fan in high temp situations.
Radiator full of trash - been in deep mud lately? Front of radiator have trash on it?

When the engine gets hot when sitting or at low speeds these are the first things I'd check.

[Jerry Bransford]

Radiators commonly get clogged from mineral (hard water) deposits which can eventually get so bad that coolant barely flows through them. Every time any of my vehicles has ever had an overheating problem, it's always been from a clogged radiator. Which is why I stopped using tap water to mix with antifreeze, I now only use distilled or deionized water which is sold in virtually all grocery stores.

[HolidayJeep]

You can use the distilled water from your home's A/C drain as well. I'll fill a couple of drinking bottles a day.

[dsavy86]

I just got done fixing mine. Have a 99 Wrangler 4.0 and started with replacing the radiator. Probably didn't NEED it, but it was time. That did NOT fix it. Mine was the fan clutch assembly. Easy way to tell is to start it up and let it get to running temp or just under 210. Turn off the engine, open the lid and give the fan blades a spin. If they spin freely, replace the clutch assembly. There should be a bit of lag. After you replace the clutch, you will know the difference, trust me. It will blow the rug right off your head. Or it did mine anyway. Embarrassing in front of the neighbors. While you're in there, the serpentine belt and thermostat are worth replacing as well. Cheap, you are already in there and the only thing left after that is the pump, which does not fail all that often.

[PoMan]

What about thermostat....that is what happened on my old Dakota, and is currently happening on my 4.0L wrangler. When it overheats in the drive through, I assume it goes back to normal when you hit the street? Is it almost immediately? Next time it happens, if you put it in neutral and rev it up, and it cools off quickly, I'd bet it is the thermostat. When the engine sped is up, the water pump is spinning faster, so it creates enough pressure to force the thermostat open. Just another thing to try. Intermittent cooling problems are hard to find. Good luck!

Another way to check the clutch, I know mine would make a loud "whurrr" fan noise when I first fired it up and took off. I thought the fan was automatically engaged for a bit when you first start them up?

[Drednot]

Originally Posted by PoMan

When the engine sped is up, the water pump is spinning faster, so it creates enough pressure to force the thermostat open.

I am pretty sure it doesn't work that way, it would force it closed.

My first bet would be the fan clutch.
second would be eroded waterpump impeller
and third,clogged radiator

My 90 YJ had been run on straight water for a while and the water pump impeller was just a couple of rusted nubs. I couldn't believe it even pumped at all

[dragginwagon406]

I happened across a great article by Steve Litt on cooling systems the other day and saved the link. This seems to be a well researched and written page and should help sort just about any cooling system woe.

http://www.troubleshooters.com/tpromag/200204/200204.htm

I'll post the article in a separate thread.

http://www.jeepforum.com/forum/f9/cooling-system-knowledge-coolant-antifreeze-overheating-thermostat-troubleshooting-395690/

[Jackle]

the thermostat is never forced open or closed by the water pump......the thermostat opens and closes by temp sensing material it is made of

[GringoLoco]

Originally Posted by dsavy86

I just got done fixing mine. Have a 99 Wrangler 4.0 and started with replacing the radiator. Probably didn't NEED it, but it was time. That did NOT fix it. Mine was the fan clutch assembly. Easy way to tell is to start it up and let it get to running temp or just under 210. Turn off the engine, open the lid and give the fan blades a spin. If they spin freely, replace the clutch assembly. There should be a bit of lag. After you replace the clutch, you will know the difference, trust me. It will blow the rug right off your head. Or it did mine anyway. Embarrassing in front of the neighbors. While you're in there, the serpentine belt and thermostat are worth replacing as well. Cheap, you are already in there and the only thing left after that is the pump, which does not fail all that often.

Hmm, so far that sounds like the most likely thing, and would also explain the noise I'm getting (which is irritating the crap out of me by now). When I start it up I get a metallic squelch (don't know how to describe it) noise, and I was starting to think it was from the starter or flywheel (it's sounds like its coming from under the engine up front). BUT, it also makes this irritating squeeking noise from 20-40 mph, like a metal to metal rubbing sound, I thought it would be exhaust rubbing on something but it wouldn't explain the startup noise. It also won't make any noise sitting still and revving the engine, only starting the engine and driving.

So, the fan clutch would explain the overheat and startup noise, could it possibly cause squeeking noise while driving 20-40 mph but NOT while sitting still revving it? I'm stumped.

Thanks for the help!

edit: Yes, I have been in deep (about the bottom of my grill slats deep) watery mud lately, and in fact right before (hours before) the first time it overtemped in a drivethrough.

[mdm]

Originally Posted by GringoLoco

...So, the fan clutch would explain the overheat and startup noise, could it possibly cause squeeking noise while driving 20-40 mph but NOT while sitting still revving it...

Could be your front drive shaft. The centering ball assembly has a habit of getting noisy when it gets full of mud. Pull the shaft and see if you still have the noise. You can just remove the front end of the shaft from the yoke and tie the end of the shaft up. Just make sure you stay in 2H.

With a '00 you could be due a drive shaft rebuild - http://www.stu-offroad.com/axle/driveshaft/driveshaft-5.htm

[GringoLoco]

Originally Posted by mdm

Could be your front drive shaft. The centering ball assembly has a habit of getting noisy when it gets full of mud. Pull the shaft and see if you still have the noise. You can just remove the front end of the shaft from the yoke and tie the end of the shaft up. Just make sure you stay in 2H.

With a '00 you could be due a drive shaft rebuild - http://www.stu-offroad.com/axle/driveshaft/driveshaft-5.htm

Cool, thanks. While I do believe that my fan clutch is shot (combo between startup noise and when I give it a spin it spins for a while), I've found that I must have some sort of driveline related noise as well. I love it when two things go wrong at the exact same time, just to mess with your troubleshooting, lol. I shut the engine off while doing about 35, still squeeking, started it back up, and got the startup screech while at the same time my going 35 squeeking didn't change. It also sounds like it's coming from up front, so that must be it (driveshaft). I even thought it might be something to do with the driveshaft up there, but I don't know enough about them yet to know HOW it could be making noise. I'll look around the writeups.

Is that centering ball assembly a part that's checked and/or repaired during a front driveshaft rebuild?

[mdm]

Originally Posted by GringoLoco

...Is that centering ball assembly a part that's checked and/or repaired during a front driveshaft rebuild?

Did you take a look at the link I gave you in post #11?

[dsavy86]

Originally Posted by GringoLoco

Hmm, so far that sounds like the most likely thing, and would also explain the noise I'm getting (which is irritating the crap out of me by now). When I start it up I get a metallic squelch (don't know how to describe it) noise, and I was starting to think it was from the starter or flywheel (it's sounds like its coming from under the engine up front). BUT, it also makes this irritating squeeking noise from 20-40 mph, like a metal to metal rubbing sound, I thought it would be exhaust rubbing on something but it wouldn't explain the startup noise. It also won't make any noise sitting still and revving the engine, only starting the engine and driving.

So, the fan clutch would explain the overheat and startup noise, could it possibly cause squeeking noise while driving 20-40 mph but NOT while sitting still revving it? I'm stumped.

Thanks for the help!

edit: Yes, I have been in deep (about the bottom of my grill slats deep) watery mud lately, and in fact right before (hours before) the first time it overtemped in a drivethrough.

Not sure on the noise a bad fan clutch could create. I did not have that issue. Diagnosis of a bad fan clutch is as easy as letting it run up to temperature, then turning the engine off and giving the fan blades a spin with your hand. If it spins as freely as it does cold, replace it. Worth the $45 dollars @ AutoZone, although they may need to order it, and is an easy do-it-yourself job. I'm not all that great at diagnosing weird noises and have a couple myself at the moment to work on, but at least if I do not overheat every time I drive, I can troubleshoot the other stuff a bit better!

[GringoLoco]

Originally Posted by mdm

Did you take a look at the link I gave you in post #11?

You caught me, lol. I was on my way out the door to go to work, didn't have time to check out the write up and was hoping for a quick answer, lol. Thanks for the link though, I'm home from work and getting ready to check it out now.