[Solved] Overheating while driving

[drburke]

I got a problem. I've thought about it, googled it, and came to my own conclusion, but I wanted to run it by the knowledgable ones as well (all temps verified by scanguage). My engine and tranny temps are skyrocketing. This started well before the 33s were on, and well after the lift/bumper was on. I used to run 190-210 temp on engine, and tranny wouldn't touch 200. All of a sudden now, my engine temp is hitting 230 and tranny 245+ (I don't try to push it beyond 240) on any given day, route, etc. and I have no clue why. It seems to be related to the transmission; my engine temp will hover at 195 and be okay UNTIL my tranny warms up. Once the tranny gets to around 10-20 degrees out from my engine temp, the engine starts getting warmer. Both oils are full and good.

Once they're both at 200, it's purely dependent on speed, tranny leading the temps. Highway, I cannot drop out of OD otherwise the temps skyrocket*. City, it doesn't matter what I do, it's going up regardless. The weird thing about the highway I noticed, is that they're on a very linear path. Going 80, tranny will be at 245, engine 230. If I back off, the tranny cools down and the engine follows. Going 60, tranny and engine will hover around 200. Slipping into another gear at any speed will cause them both to go up, rapidly.

Using that knowledge, I bought a tranny cooler and I'm gonna install it tomorrow. Thinking there's probably something else, but we'll see. Fan clutch doesn't seem to be working anymore either, so it could just be a coincidence that both started overheating. Anyway, any input would be appreciated, it's kinda frustrating.

Final word for future readers: My problem was, once the transmission heated up, the engine and transmission temperature would both climb way too high. Temps verified by ScanGuage II. Before the tranny got to 190, the engine temp was perfect. After 190, they both consistently hit 230/245 engine/tranny. Shifting to third helped very little. Tranny cooler delayed the overheating. It turned out to be the radiator. It was clogged somewhere along the path and once the transmission fluid got too warm, it took the engine coolant's temp along with it. New one fixed it right up. If you're at high mileage and experiencing this problem, you might be better off replacing your cooling system anyway. Otherwise, start with the radiator first so you don't have to go through the steps as I did.

[Trail X]

A trans cooler may help, but keep in mind that the heat from your trans cooler will reduce the effectivity of the radiator - if you place the cooler in front of the radiator. The cooler, however, does not seem to be the root issue. Its probably also been exacerbated by the 33inch tires. What gears do you have?

Are you positive that your torque converter is actually locking up as it should? If you have the SC, you can get codes to read the torque converter slip rpm number.

Also, if you're overheating in city driving, that seems to imply something else. Your fan clutch is certainly suspect.

If you're overheating in 3rd on the highway, then something is definitely amiss. 3rd should generally force the truck into TC lockup 90% of the situations above 60mph, and should bring the temps into management.

Also, if you're hitting 240, your trans fluids life is really short. The fluid is probably fried if you hit it regularly.

[DirtyBacon04]

Are you feeling any slippage? Because your truck is sounding like mine was before i had the rebuild. But like JD said, a xmsn cooler at this point will help, but it'll be more of a bandaid rather than a repair. I'm also willing to bet your fulid is toast. Are you hearing the very loud fan at higher rpms? I know it sounds cool... like an 18 wheeler... but it's a standard clutch failure. Could be water pump, too...

NFL team choice is the most suspect cause, though

[dvanbramer88]

You didn't paint your radiator with standard spray paint did you? therefore effectively insulating it?

Now that is out of the way, I agree with James, check your torque converter rpm number.

Also agree with Bacon, if you suspect your fan clutch is failing, start there. That is defiantly hurting the efficiency of your cooling systems and might be most of your problem.

A bad water pump could be the culprit too.

What kind of coolant do you have? If you still have the factory Dex Cool, when was the last time it was changed? In our jeep, we've had massive cooling problems and basically had to replace the radiator, water pump and heater core from old Dex Cool breaking down and turning into an orange/brown sludge. It ate away the fins on the water pump and clogged the radiator and heater core. We had consistent over heating problems like you described. Could be something worth checking into. If your coolant is old or has never been replaced, a good flush and re-fill with brand name green anti-freeze could do you some good.

Another round about question while I am brain storming, have you topped off or re-filled the radiator/cooling system lately? what mix of coolant/water are you running. If you're running greater than 50% coolant 50% water, that is also reducing the efficiency of your cooling system. The water does most of the work as it has a higher specific heat than the coolant. The coolant offers boil over protection and also freeze over protection. Out west the run as much as 70% water in their cooling systems. I personally like a 40% coolant/60% water in my truck.

All food for thought.


Oh, and like they said, your tranny fluid is probably toast too.

[drburke]

A trans cooler may help, but keep in mind that the heat from your trans cooler will reduce the effectivity of the radiator - if you place the cooler in front of the radiator. The cooler, however, does not seem to be the root issue. Its probably also been exacerbated by the 33inch tires. What gears do you have?

No doubt, but I find it odd it started on the stockers. 3.42 gears.

Are you positive that your torque converter is actually locking up as it should? If you have the SC, you can get codes to read the torque converter slip rpm number.

I'll get the rpms next time I drive. Do you by chance know where the code for it is? I couldn't find anything on the website.

If you're overheating in 3rd on the highway, then something is definitely amiss. 3rd should generally force the truck into TC lockup 90% of the situations above 60mph, and should bring the temps into management.

It does the exact opposite-- they skyrocket anytime I'm out of OD [because I'm trying to keep the same speed as I was in in OD].

Are you feeling any slippage? Because your truck is sounding like mine was before i had the rebuild. But like JD said, a xmsn cooler at this point will help, but it'll be more of a bandaid rather than a repair. I'm also willing to bet your fulid is toast. Are you hearing the very loud fan at higher rpms? I know it sounds cool... like an 18 wheeler... but it's a standard clutch failure. Could be water pump, too...

NFL team choice is the most suspect cause, though

No slippage, it was just rebuilt in January. There is no jet noise from the clutch. It stops when I put my hand on it at idle, though.

*ahem* rise up *ahem*

What kind of coolant do you have? If you still have the factory Dex Cool, when was the last time it was changed? In our jeep, we've had massive cooling problems and basically had to replace the radiator, water pump and heater core from old Dex Cool breaking down and turning into an orange/brown sludge. It ate away the fins on the water pump and clogged the radiator and heater core. We had consistent over heating problems like you described. Could be something worth checking into. If your coolant is old or has never been replaced, a good flush and re-fill with brand name green anti-freeze could do you some good.

It was replaced a month ago with Dex Cool. I'll check into it.

Another round about question while I am brain storming, have you topped off or re-filled the radiator/cooling system lately? what mix of coolant/water are you running. If you're running greater than 50% coolant 50% water, that is also reducing the efficiency of your cooling system. The water does most of the work as it has a higher specific heat than the coolant. The coolant offers boil over protection and also freeze over protection. Out west the run as much as 70% water in their cooling systems. I personally like a 40% coolant/60% water in my truck.

I use the premix 50/50.

I appreciate the responses. I'm going to be doing a LOT of driving over these next couple of weeks, so I'm gonna have to find time to inspect this more indepth. I guess the first course of action is to read the TC codes and see where I'm at. Like I said, it was just rebuilt in January and you get bet I'll be PISSED if it goes out again. I have a nationwide warranty on it.. but the closest shop it an hour and a half away.

[dvanbramer88]

If you can stop the fan clutch with your hand that easily, I'd go ahead and say it should be replaced.

How about with the truck off? Can you just spin the fan freely by hand? A new fan clutch will be tight and offer resistance with the truck off.

[drburke]

Oddly enough, when off, it has resistance to it. Shaft has a bit of wobble to it.

Like I said, engine stays nice and cool until the trans catches up, then it all goes to hell. That's why I jumped at the cooler first. I'm kind of confused why I would be checking all of the engine's cooling systems when it appears it all starts with the tranny.

[Moots1288]

Oddly enough, when off, it has resistance to it. Shaft has a bit of wobble to it.

Like I said, engine stays nice and cool until the trans catches up, then it all goes to hell. That's why I jumped at the cooler first. I'm kind of confused why I would be checking all of the engine's cooling systems when it appears it all starts with the tranny.

The shaft of the fan or the water pump?

[drburke]

Shaft of the fan. I've been under the assumption this indicated a water pump issue, however, it's been doing this since I bought it.

[dvanbramer88]

I'm kind of confused why I would be checking all of the engine's cooling systems when it appears it all starts with the tranny.

With the exception of your auxiliary transmission cooler, Both systems work together. The factory transmission cooler is inside of the radiator and the engine coolant cools the transmission fluid. The fact that the engine cooling system can keep up with the engine, but can't keep up with the tranny indicates that the system is not operating at maximum efficiency. Normally it can keep up with both fairly easily. Not saying it is your only problem, but in my eyes, it seems like there are multiple problems. The fact that your engine and tranny actually get hotter in 3rd gear is probably a good indicator to the actual cause of the problem. I agree your main issue isn't engine coolant related. under normal circumstances, dropping it into third should help cool an overheating engine down on the highway. The RPM's go up, the fan spins faster, and the water pump turns faster cooling everything down. The fact that the higher RPMs actually increase temperature indicate (to me) that the trans has an issue where it is creating extremely excessive amounts of heat for some reason.


More basically, the OEM trans cooler is pretty small and it only drops the trans temp to about or a little higher than the engine temp. The fact that this little cooler is making your engine get excessively hot along with the transmission would make me believe that your engine cooling system is not at maximum efficiency. But the way it appears to me, the reason everything is running hot lies in the transmission.

[Moots1288]

Shaft of the fan. I've been under the assumption this indicated a water pump issue, however, it's been doing this since I bought it.

Could be the shaft of the water pump f'd with the shaft of the fan.

[drburke]

I went out tonight and drove ~45 miles, half highway half city. At 60, 200/210 depending on load. 65 started to increase, I topped out at 80 and they flew up. I backed down to 75 and seemed to hover at 225/231 engine/trans. Faster-hotter, slower-cooler. So maybe it's not necessarily gear dependent, but speed dependent. Also, I noticed when I bumped it into third, my engine temp would drop 2-10 degrees, but the trans would usually remain the same. 2nd would cause both to climb rapidly. Nothing would really cool it down except staying in OD (which brings my speed down to 50-60, because of my 3.42s).

When I was done for the night, I parked and got a little surprise:



Anyway, I went out and bought a water pump before this experiment. It seems the water pump is working, but maybe not to the fullest. I have 175k and no clue when it was last changed.. probably a good idea to hit that and the fan clutch anyway.

edit: The TC Slip RPM code I found does not work. In 3rd and 4th, it reads a single digit value from 1-10.

[Moots1288]

I went out tonight and drove ~45 miles, half highway half city. At 60, the temps hovered at whatever they're at. 65 started to increase, I topped out at 80 and they flew up. I backed down to 75 and seemed to hover at 225/231 engine/trans. Faster-hotter, slower-cooler. So maybe it's not necessarily gear dependent, but speed dependent. Also, I noticed when I bumped it into third, my engine temp would drop 2-10 degrees, but the trans would usually remain the same. 2nd would cause both to climb rapidly. Nothing would really cool it down except staying in OD (which brings my speed down to 50-60, because of my 3.42s).

When I was done for the night, I parked and got a little surprise:



Anyway, I went out and bought a water pump before this experiment. It seems the water pump is working, but maybe not to the fullest. I have 175k and no clue when it was last changed.. probably a good idea to hit that and the fan clutch anyway.

It doesn't hurt to replace the water pump while you have the fan and clutch out just an extra 5 bolts and some 50/50.

[Trail X]

I believe this was the code I used for TCC slip:

Name: TCs
TXD: 6C10F122199101
RXF: 046205190691
RXD: 3010
MTH: 0001000A0000

Source: http://www.gassavers.org/f69/scangauge- ... 10087.html

I also use the TCC duty cycle (I named mine TCd) from that same page. It just helps you understand what the PCM is asking of the TCC solenoid. From that data, you can see how the TCC responds, by reading the TCs. FYI, TCd of 100 = torque converter unlocked, TCd of 0 seems to show up when stopped, and TCd of 10-20ish means that you should see around 100rpm of TCs (expected to be seen when locked into 3rd or 4th gears at highway speeds).

Your picture above is strange. Your engine is idling, but you don't have any oil pressure? Is that correct?

What is the dash warning light? Is that a check engine? Looks like Check "Gauges"?

[Moots1288]

I believe this was the code I used for TCC slip:

Name: TCs
TXD: 6C10F122199101
RXF: 046205190691
RXD: 3010
MTH: 0001000A0000

Source: http://www.gassavers.org/f69/scangauge- ... 10087.html

I also use the TCC duty cycle (I named mine TCd) from that same page. It just helps you understand what the PCM is asking of the TCC solenoid. From that data, you can see how the TCC responds, by reading the TCs. FYI, TCd of 100 = torque converter unlocked, TCd of 0 seems to show up when stopped, and TCd of 10-20ish means that you should see around 100rpm of TCs (expected to be seen when locked into 3rd or 4th gears at highway speeds).

Your picture above is strange. Your engine is idling, but you don't have any oil pressure? Is that correct?

What is the dash warning light? Is that a check engine? Looks like Check "Gauges"?

He could have something wrong with the oil pressure sending unit? Or the gauge itself

[drburke]

I believe this was the code I used for TCC slip:

Name: TCs
TXD: 6C10F122199101
RXF: 046205190691
RXD: 3010
MTH: 0001000A0000

Source: http://www.gassavers.org/f69/scangauge- ... 10087.html

That's what I found and used. In 1st and 2nd, it shows (what seems like) arbitrary numbers from 1-999, and in 3rd and 4th, 1-10 (usually 1-2), unless I'm just misinterpreting it.

Your picture above is strange. Your engine is idling, but you don't have any oil pressure? Is that correct?
What is the dash warning light? Is that a check engine? Looks like Check "Gauges"?

He could have something wrong with the oil pressure sending unit? Or the gauge itself

Bingo. Yes, that is "Check Gauges", and it's the second time it's come on. When idling, it'll drop to zero (with intermittent pulses back to 42), and when moving, it'll act normally. I figure it's probably the sender going out.

[navigator]

since you just replaced the coolant, any chance there is a little air in there?

[Trail X]

I believe this was the code I used for TCC slip:

Name: TCs
TXD: 6C10F122199101
RXF: 046205190691
RXD: 3010
MTH: 0001000A0000

Source: http://www.gassavers.org/f69/scangauge- ... 10087.html

That's what I found and used. In 1st and 2nd, it shows (what seems like) arbitrary numbers from 1-999, and in 3rd and 4th, 1-10 (usually 1-2), unless I'm just misinterpreting it.

Check those numbers in your SC again. That doesn't sound like the proper feedback. It should be reporting something very close to your idle rpm when parked, with reducing numbers up to 100 or so with TCC locked up in 3rd or 4th. Check out the TCd numbers and see what you get there. It will at least let you know if your TCC is being demanded on when you're overheating.

Another two gauges to check are your trans input and output RPM gauges. It can allow you to calculate the slip, as long as you know the ratio of the gear you're in.

Your picture above is strange. Your engine is idling, but you don't have any oil pressure? Is that correct?
What is the dash warning light? Is that a check engine? Looks like Check "Gauges"?

He could have something wrong with the oil pressure sending unit? Or the gauge itself

Bingo. Yes, that is "Check Gauges", and it's the second time it's come on. When idling, it'll drop to zero (with intermittent pulses back to 42), and when moving, it'll act normally. I figure it's probably the sender going out.

Have you checked your oil level to be sure?

[drburke]

Oil is fine, just checked and it was just replaced in June. It has something to do when it overheats. I'm guessing the sender is cooking itself or something. Anyway, I took pics of the coding for verification.






Did a quick test, found out my radiator isn't flowing.. at all. Took the cap off, let it get to 200, no movement whatsoever. Top hose is hot, bottom is cold, both soft. I'm gonna take it for a ride in a little bit and see again. Thermostat has already been replaced with a verified working one. No water leaks anywhere. Definitely narrows down the possibilities.

[dvanbramer88]

I would replace the fan clutch and water pump. Easier if you do them together. But anyway, sounds like you figured it out, I think.