01 Yukon overheating

I have a 01 Gmc Yukon SLT with the 5.3 Vortec with 203xxx miles on it took a trip to las Vegas from socal and going up the mountain on i15 the truck wanted to overheat water temp went up to 225F and i turned off the A/C to keep it from going higher. After passing the mountain it went back to 195 F and stayed their even with the A/C on it did it Only underload it would increase temp i have 285/50R22 idk if the heavy rims affect too or if its normal or i dont know ive never done a coolant flush.....


Funny thing tranny temp didnt even pass 195F at all but i will be adding a tranny cooler soon

It is possible that the added strain on the engine from the larger rim and tire package was enough while climbing that grade that it worked harder than normal. But, you can double check the coolant PH balance with some test strips from the local auto parts place and see if the coolant needs replaced. If it is old then it won't work properly while the engine is under load like that. Another thing you can do that will cost more, but will reduce the overall amount of long term strain on the engine is upgrade the differential gears to a lower gear than you have now. Doing so will help that 5.3 better handle the increased rolling mass of the larger rim and tire package for the long term.

Tranny cooler could help a bit. Has it been flushed lately?

Dumb question,

Have you checked coolant level? both cold and hot.
Whens the last time its been flushed?
Also pay attention to your fan noise. Does it change as the engine warms up?

What should the PH be in order to know if i should replace it or not? the truck has the stock 3.73 gears

---------- Post added at 11:25 PM ---------- Previous post was at 11:21 PM ----------

The transmission never tried to over heat actually even under load it didnt past the 195F but im still thinking in adding a trucool tranny cooler and the transmission was actually rebuilt 2-3 years ago and after the rebuilt it has roughly 12k on it

Gonna service it at 15k?

---------- Post added at 11:28 PM ---------- Previous post was at 11:25 PM ----------

i only checked it when it was cold it never gave me trouble or concern to check it more til now i always just add water or coolant but its always full

Ive never had the coolant flushed at all so it might be all dirty

aguila852 said:

What should the PH be in order to know if i should replace it or not? the truck has the stock 3.73 gears

---------- Post added at 11:25 PM ---------- Previous post was at 11:21 PM ----------

The transmission never tried to over heat actually even under load it didnt past the 195F but im still thinking in adding a trucool tranny cooler and the transmission was actually rebuilt 2-3 years ago and after the rebuilt it has roughly 12k on it

Gonna service it at 15k?

---------- Post added at 11:28 PM ---------- Previous post was at 11:25 PM ----------

i only checked it when it was cold it never gave me trouble or concern to check it more til now i always just add water or coolant but its always full

Ive never had the coolant flushed at all so it might be all dirty

Click to expand...

They sell test strips at auto parts stores. It will tell you if it's good or not.

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If you've never had the coolant flushed, I would do that first. It may or may not solve the overheating problem, but it needs to be done.