2001 Tahoe Reverse Flow cooling system

[Larryjb]

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One other thing -- is the cooling system making its 15 psi? It's pressurizing with the cap on the surge tank?

When you check the cooling system psi, don't forget to test that the cap holds 15 psi as well. This is often overlooked.

 

[Scottydoggs]

on the clutch fan, if you grab the top fin push and pull on it engine to rad, and you feel it move, its shot. i killed 2 fans in 100,000 miles, took it off for the last time and put two aftermarket electric fans on.

and the second fan was a dealer warranty replacement. electric fans were on my dime, and cost less to do then a new fan. and worked way better.

 

[LanceLyons]

On the fan, I've learned over and over that "probably" only applies to everyone else, and not to me! One way to test this is to use a piece of cardboard to block the radiator airflow and run the engine until the temperatures rise above 212. You should hear a new roar from the fan as the clutch engages.

Did you install an ACDelco water pump?

When you did the water pump, what did the cooling passages look like?

Also, what model/year are we looking at?

Good questions. I will try the flan clutch thing to see what that does. That is the first time I heard that the clutch engages at higher temps. I am not sure how it would know that since its mechanical but I can certainly try. I have never really noticed a roar from the fan. It spins and produces reasonable amounts of air.

I can remember the water pump but it was from Autozone and has a lifetime warranty. THe passages looked fine. nothing alarming.

 

[LanceLyons]

^^^^ THIS. If the fan clutch passes the test, pull the radiator and either get it to a radiator shop to have them rod it, or get a new radiator (with the integrated restrictor). New ones aren't all that pricey but it's your choice.

One other thing -- is the cooling system making its 15 psi? It's pressurizing with the cap on the surge tank?

i did pressure test the system to 15 psi and only noticed a 1 psi drop off in a hour. I assumed this might be the tester since i have never noticed any leaks.

I did notice that hot water doesnt seem to make it to the heater core well because heat doesnt come out on full heat.. The heater hoses where all replaced by a shop about a year ago. In Louisiana we never really need a heater so its overlooked.

 

[LanceLyons]

Thanks everybody for the replies. I have a good place to start. Fan / radiator.

 

[Larryjb]

i did pressure test the system to 15 psi and only noticed a 1 psi drop off in a hour. I assumed this might be the tester since i have never noticed any leaks.

I did notice that hot water doesnt seem to make it to the heater core well because heat doesnt come out on full heat.. The heater hoses where all replaced by a shop about a year ago. In Louisiana we never really need a heater so its overlooked.

If the pressure drops 1 psi because of the too, you are using a cheap tool. It may drop if you are testing the truck after it's been driven, even earlier in the day. It's best to test it when it's stone cold.

Not all leaks will be visible. It could be a cracked head. Again, it would be helpful to know what year, and any modifications, recent repairs you have done.

 

[LanceLyons]

If the pressure drops 1 psi because of the too, you are using a cheap tool. It may drop if you are testing the truck after it's been driven, even earlier in the day. It's best to test it when it's stone cold.

Not all leaks will be visible. It could be a cracked head. Again, it would be helpful to know what year, and any modifications, recent repairs you have done.

Yep agreed. Its a 2001 tahoe and does have the heads that are known to crack / leak however it runs well so I dont think that is an issue and we have never seen any kind of oil in the coolant or coolant in the oil. Im guess the tool wasnt great since it was a loaner from Reillys auto parts and we had to use an adapter. I assumed we didnt have a leak since I cant see anything and it runs fine.

 

[LanceLyons]

On the fan, I've learned over and over that "probably" only applies to everyone else, and not to me! One way to test this is to use a piece of cardboard to block the radiator airflow and run the engine until the temperatures rise above 212. You should hear a new roar from the fan as the clutch engages.

Did you install an ACDelco water pump?

When you did the water pump, what did the cooling passages look like?

Also, what model/year are we looking at?

I did exactly this covering some 70 percent of the radiator while it was running. The Truck never overheated. I waited some 20 min and it never overheated.

I also did not hear any change on the fan or fan speed when it arrived at high temp. It continued spinning at the same rate. Again when I tried to spin the fan, it would not spin... or it would stop as soon as I stopped spinning it.

I will keep an eye ball on it.

 

[ROGELIO A GUZMAN]

Hey man I had the same issue where my 2004 xl would overheat while stopped air at idle. Also my AC would push hot air on stop lights. This is what I did

Flushed radiator= same heating issue
Changed thermostat= same heating issue
Changed water pump= same heating issue.
Changed fan clutch = fixed heating and AC and heating issue. Also cooled down my trans temp.

 

[LanceLyons]

Today i took the tahoe for a drive and it was doing fine but then after sitting in parking lot for 5 minutes with the truck running it suddenly was over heating. I thought I might be able to get the vehicle rolling down the road and it would start cooling but it didnt. It got to the point I had to pull over and the coolant was pushing out the reservoir with the lid on tight so better than 15 lbs.

i think I will replace the radiator and fan but i am not convinced that is it. Not sure if the water pump is pumping the right flow.