[WillieMacG]

I need some help diagnosing a problem that recently popped up with Woodstock. Since I’ve owned it, the running temp has been rock solid at a needle width under the 210 mark. This is always the case no matter the outside temp. Recently, this has changed. Now, it runs at the same mark for twenty, maybe thirty minutes until a red light or slow neighborhood driving pops it up to around the 225-230 mark. Typically now, my Mike’s Fan comes on as always and the temp will begin to drop, but, never back to 199-200 or so. Close, but not all the way back down. It always stays above the 210 mark now. I checked the coolant levels, pressure caps, surge tank, etc., and all appear to be functioning fine. Since I’m running the AC on “Max” all the time, the slow speed on Mike’s Fan is always on. I suspect this may be a thermostat problem, but I confess I’m stumped. Any ideas?



:yellow:
Willie

 

[BlueStreak]

Make sure the radiator is clean so air can get through, especially between the A/C condenser and the radiator. You have to separate them and clean it out.

 

[Aqua Blur 05]

I would suggest you check your gauge against a data reader to ensure it is reading correctly. My gauge reads higher than yours when stuck in traffic on a hot day. I used my contact thermometer at the T-stat housing and it read at least 10 degrees cooler than the gauge.

 

[xoxoxoBruce]

The thermostat housing should read cooler as that is the coolant being fed to the engine. The gage reads the temperature in the head, where as I understand it, there should be a 10 or 11 degree rise. Someone smarter than me(there's a lot of them) can jump in here if I'm wrong

 

[Mike in AZ]

Be certain that the coolant level is “at or slightly above” the “cold level” in the tank. Very low coolant will cause higher temps.... very, very low coolant will cause overheating.

It’s not necessary to run the A/C on recirculate..... Just having it on will cause the main fan to run all the time.

If the engine operating temperature above 35mph is higher than normal (and you have correct fluid level), you have a “system” problem and not a fan problem. ~85% of the time, this is due to a thermostat problem. ~10% of the time, it is related to the system not pressurizing properly.

If the problem is present above 35, the simplest solution is to go to my web store and order a “Cooling System Tune-up” package for $30. This will get you:
1) A new GM pressure cap (the sealing O-rings on yours are probably flat after 15 years). If the system is not running at 15psi, the engine temp will run a little hotter than normal.
2) A new GM thermostat and seal. (This is most likely the source of your problem) GM changed part numbers on the V8 thermostat (all Silverado, Tahoe, Corvette, Escalade, SSR, etc. use the same one) several times between 2000 and 2008. The regulating temperature remained the same, but they made some engineering design changes that forced release of new part numbers each time. The last t-stat was released in 2008..... that is why I know that we can ALL use a new one.

If you want to get the parts locally, here are the GM part numbers:
Cap = 15075118
T-stat = 12600171
Seal = 12570307

Hope this helps......

Mike

 

[WillieMacG]

Thanks guys for all the input. I'm gonna start the process of elimination by getting and installing a Mike's tune-up kit. Yes Mike, it is a problem above 35 mph after driving for a time. So, a faulty thermostat was my first guess. Again, it doesn't "overheat," it's just running a bit hotter than it has in the past. And, at 13 plus years old with 70,000 miles, it's probably time for a system tune-up.



:yellow:
Willie

 

[tennesseecozydog]

Mike in AZ ... mine stays at 210 since Mike Shaunnessy put on the "Pusher & Puller" fans 7or 8 years ago. THANK YOU Mike !!! tennesseecozydog :ssr

 

[SSR Rob]

Mike in AZ... Mine also stays at a needle below 210 since I replaced the thermostat and installed your direct replacement main fan. I'd also like to say... Thank you Mike!!!!!!

 

[WillieMacG]

If the problem is present above 35, the simplest solution is to go to my web store and order a “Cooling System Tune-up” package for $30. This will get you:
1) A new GM pressure cap (the sealing O-rings on yours are probably flat after 15 years). If the system is not running at 15psi, the engine temp will run a little hotter than normal.

This is what Mike means. Before and after of the old and new caps. Kinda obvious. T-stat next.

:yellow:
Willie

 

[Dicktator]

Yes, replace cap on reservoir or soak in CLR for 30 minutes.

Cap has to keep 15psi for system to work right.

Dicktator

Check in AM when engine is cool, if upper radiator hose is collapsed, cap is bad!

 

[WillieMacG]

Thermostat did not do the trick so I took it to the Chevy dealer and said, "When ya figure it out, lemme know." Two days later it turned out to be the water pump. Getting it replaced as I type this. Hopefully this will be the end of the saga. Stay tuned.


:yellow:
Willie

 

[Donaldo7]

I've been having the same problem. I was wondering, did you finally get your overheating problem solved by replacement of the water pump? Also, did you replace the reservoir cap or was your o-ring in good shape?

 

[Mike in AZ]

I've been having the same problem. I was wondering, did you finally get your overheating problem solved by replacement of the water pump? Also, did you replace the reservoir cap or was your o-ring in good shape?

What are the symptoms of your problem?

Mike