Vehicle is a 97 2500 suburban with the 454, 180,000 miles. when I bought it the coolant temp was a bit low, in the 150 ro 190 range all the time..I did have heat, not super hot but sufficient for summer. We recently had a hot day in the 80's. My Coolant temp in the dash climbed to about 210 while on the freeway. Then when in the city was about 220 or 230 ish. Hard to tell the incraments. It seemed to me that it was acting like there was no tstat installed so I went and purchased one. OEM 195 deg. When I removed the TSTAT housing. I was indeed correct in, there was no thermostat. My first thought was. There must be reason. Well..its easy to R&R so I installed the new one. So now..The temp settles in at 210 at Idle. Driving it reaches about 230 or the last big hash mark before the 260 mark. On the freeway its about 210 or a bit higher. So. I know there is a problem. Here are observations i have made that a shop i think will also.
1) radiator cab when removed was very very rusty...red Flag for me
2) A intermittant rattling when driving..sometimes is there sometimes isnt. the Isnt is when under power and not idling or moving slowly. Sounds like a bad pulley. I checked the pulleys and noticed the fan is a bit wiggley at the shaft to the clutch pack..another red flag

So questions are...if the clutch pack for the fan isnt working properly will this cause the higher temps?..also..im looking at the radiator not flowing properly due to the rust. when i watched the coolant flow after the TSTAT install.it seemed to have a heave firm flow from the upper smaller hose into the radiator end on the left side facing the truck..so im not sure i can tell if the radiator is a bit clogged form rust or not.

what else should i look for, or is the fan item number one and is there a way to check the radiator itself?

Thanks
Larry G

I think you found both like nailed a few of them and gotta clear those away. The rust is red is that a red flag is more rust than water taking up the cooling factor.

Now you spin that fan clutch and if it does keep resisting and you keep spinning and spinning and all of a sudden it loosens up? Then the clutch is good. If it just spins like breaks clean on a few turns of the blade is she is junk.

I think you found both like nailed a few of them and gotta clear those away. The rust is red is that a red flag is more rust than water taking up the cooling factor.

Now you spin that fan clutch and if it does keep resisting and you keep spinning and spinning and all of a sudden it loosens up? Then the clutch is good. If it just spins like breaks clean on a few turns of the blade is she is junk.


well..the rust is ont he cam..the inside of the rad looks like i would thinnk after 10 years but the water is nice as the coolant should be..ill check the fan s you explained

well..the rust is ont he cam..the inside of the rad looks like i would thinnk after 10 years but the water is nice as the coolant should be..ill check the fan s you explained

the blades have little resistance and spin not freely but litle resistance and nothing changes if you keep doing it..thats an easy change so il look at the temp when i replace it..next is to look at a new radiator or recore..

update on the cooling system...bought and installed a new fan clutch..temps had no change...so i back flushed the cooling system...and also ran the water pressure the corrent way..all seems like it flows very well..odd..i have the 195 degree tstat(new) installed when it opens the temp climbes to 210 or 215 hard to tell what the incraments are..so the 210 is straight up the next big hash i assum is 240?..well it stays religously in between the two marks..sitting in the city trafic it is near the next hash mark..then if you start moving it goes back to the 210..on the freeway it sits just off(above) 210.so is there something else that would cause such a consistant reading? I have good heat from the front and rear blowers..at 400 something for a new radiator im not wanting to start throwingparts at it hoping i get it..what next??:runaround:

210 is not really hot, especially when there is guess work on the actual temp. get a scanner on it and see what the real temp is.

i agree 210 isnt but its closer to 230 or 240..not sure what the next big hash mark is...it stays between the 210 and the next hash mark which im guessing is about 230 or 240

210 is not really hot, especially when there is guess work on the actual temp. get a scanner on it and see what the real temp is.