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2004 chevy trailblazer_ls
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Discussion Starter · #1 ·
I have an 04 tb with the 4.2 and 3.42's. I recently changed the t stat and temp runs 210 flawlessly. Untill I tow. I know it is gonna run a little hot but is this safe? I am towing a 24' pontoon with a single axle trailer. boat weighs 2350 acording to the tag. I have no idea how much the trailer weighs. It was 82 outside and i had the air on, Towing in 3 at about 60mph. Is this normal or should i be concerned?
 

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i never seen that before:weird: my only guess would be that the water pump is starting to fail my :m2:
 

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I have an 04 tb with the 4.2 and 3.42's. I recently changed the t stat and temp runs 210 flawlessly. Untill I tow. I know it is gonna run a little hot but is this safe? I am towing a 24' pontoon with a single axle trailer. boat weighs 2350 acording to the tag. I have no idea how much the trailer weighs. It was 82 outside and i had the air on, Towing in 3 at about 60mph. Is this normal or should i be concerned?
I think I'd be concerned. I've only towed a couple of times - once was on a 1200 mile trip up north. Granted it was fall, but I had a UHAUL trailer loaded to the hilt, and 4 adults and lots of luggage and stuff a couple of young women (my daughters) couldn't "live without" for 10 days! :D

I also towed in 3 about 60 - 65 MPH Max, and even climbing long hills in northern Ca. and southern Oregon my needle never moved off of 210.

I drive out to the deserts of Arizona and Nevada several times a year, and I've seen my needle move up just barely one line to the right of 210 - when climbing a long hill on a hot day (110F) with both a/c running and doing at least 70 - 75 MPH. As soon as I get to the top of the hill it usually drops right back down to 210.

Maybe you got a bad thermostat - it does happen occasionally. What brand was it? Another possibility is one or both of your hoses are collapsing at high temps. I've had that happen on other vehicles.

I suppose the water pump COULD be bad, but most of the time we've seen water pumps replaced here for the bearing going out. What shape is your radiator in? Good and clean?


Do you have or know anyone that has a scan gauge that you could verify the actual temp of the engine? Just to be sure that the engine IS actually running that hot.
I have seen temp. gauges give false readings. Many years ago, I had one car that if you turned the lights on the temp. gauge would move up about 25 percent. Turn the lights back off, it would drop down. I tried several things to fix it - never could so I just lived with it until I finally junked the car about 10 years and 150,000 miles later! :)
 

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I have an 04 tb with the 4.2 and 3.42's. I recently changed the t stat and temp runs 210 flawlessly. Untill I tow. I know it is gonna run a little hot but is this safe? I am towing a 24' pontoon with a single axle trailer. boat weighs 2350 acording to the tag. I have no idea how much the trailer weighs. It was 82 outside and i had the air on, Towing in 3 at about 60mph. Is this normal or should i be concerned?
Agree with Super. That is not normal. His points on other components of the cooling system are valid. Our gauges are basically upscale idiot lights..a scan gauge would help confirm what is actually going on as they pull Data from the OBDII socket that the PCM is seeing. A transmission cooler would most likely help out if you do much towing. Many articles on that aftermarket option available thru search on this forum. Good luck and keep us informed.
 

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Discussion Starter · #5 ·
The trans cooler is on my list. It is the next mod i am doing. I do have autoenginuity for my pc but my code is out of date so i have to wait till monday to get a new code. I will be able to scan it then. Would the fan clutch cause this? I have read posts on it going out and staying on but never not working. My rad is very clean. I flushed the whole system and refilled with prestone and distilled water when i did the t stat change. I dont know what brand it was i bought it at advance.

It did this about a month after I bought it too but not towing anything. I was driving to florida. 3 adults and 2 kids and a hatch full of luggage, 80mph avg with the air on. It did fine untill i stopped for gas in georgia and left it running so the wife and kids could have some air. It went to the same mark or a little higher and the ac went to crap. It was blowing hot. I shut it off and we drove with the widows down for about 2miles and then it was fine. It was fine the rest of the trip?
 

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Discussion Starter · #7 ·
thats the way the prev owner bought it new. I thought it was a little odd too but there are toons at the lake that are 25' with singles. Two guys i work with. I would prefer the double myself.
 

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Would the fan clutch cause this?
BINGO. If your TB is in fact running hot while towing- I've towed a 10,000lb boat 2 dozen times with my Envoy- and it will move up to 210 and maybe one notch over- but never as high as yours. The clutch fan should be engaging (or disenganging whichever way you look at it) and giving full blowing power. I'd def. hook up your scantool, leave it connected, and go tow that boat again to confirm actual engine temp.
 

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Another issue to consider is that the fan isn't the biggest contributor of airflow at 60 MPH ground speed. The fan could be removed and it should cool well at that speed. It would be really useful to scan and look at commanded fan RPM versus actual. The engine may be generating excessive heat due to exhaust restrictions or something else going on.
 

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My rad is very clean. I flushed the whole system and refilled with prestone and distilled water when i did the t stat change.
You did use prestone dex-cool, orange stuff and NOT the green stuff, correct?
 

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it is green but it says it is compatible with all types. I did a full flush with the flush kit too.
Can I talk to you about a bridge that is for sale in New York State?
You might have something that looks like jello in the rad.
 

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yeah that is not normal whenever i tow i never really see it go above 210; what almost shocked me even more was a 24ft boat on a single axle trailer; that size boat should really be on a double axle trailer
it is a pontoon boat it is just long not heavy so a single axle is fine
 

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As a lot of people on this site know, the temp gauge is , well, a lie. These trucks go to around the 210 mark and stay there almost all the time. The truth is that the gauge will read "210" at any temp between ~180 to~220F then it starts to move higher. Thats why a scan is so important so we know what the real coolant temp is. When you reached that level of heat the fan should have started to roar to try to cool the engine. Did the temp come down at lower speeds? Jay
 

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WHAT? even though i flushed it?
If you put green coolant back in then yes you could have sludge buildup. There are some Dex-cool haters but Ive had 0 issues with it in my 02 TB.

You definitely have an issue, both of my boats weigh ~4000lbs and unless Im going up the Vantage hill in central WA (3% grade for 10mi solid) in 100F temps my engine temp doesnt move from 210. That with the AC off and a trans cooler, hottest Ive seen engine temps while towing were around 222-224F. The temps spiked from 218F so the fan took a sec to come on and bring them back in check which it did instantly.
 

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Discussion Starter · #19 ·
When you reached that level of heat the fan should have started to roar to try to cool the engine. Did the temp come down at lower speeds? Jay
I am starting to lean more towards the fan being the issue. I dont remember hearing the usual roar of the plane prop under the hood when it was idling. Yes at idle it would come back down but only if i turned the a/c off. Idle with the a/c on it would stay steady at this temp. Whatever it really is. I will defiantly tow it again this weekend and check everything more thoroughly.
 
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