Hot-running LS6

mmcporter · #1 08-28-2003, 01:51 AM

Anyone have any tips on lowering the highway speed temp on an LS6 with 4.10 posi, M22, polyglass rubber and otherwise stock? The car runs at 190-210 at speeds of around 65-70. Plenty of coolant in the radiator, car has never overheated or belched up coolant. Everything seems to be functioning okay. Am I driving too fast with this gearing? Any thoughts?

**Mr70** · #2 08-28-2003, 01:59 AM

Is Your Fan Clutch working properly?
What is your Thermostat rating?
What weight engine Oil are you using?
Also try Flushing the Entire Cooloing system.Get it all out of there.You'd be amazed what kind of Crap can accumulate.

mmcporter · #3 08-28-2003, 02:04 AM

[ QUOTE ]
Is Your Fan Clutch working properly? I think so 
What is your Thermostat rating? Don't know, good question 
What weight engine Oil are you using? 20W50 nonsynthetic 
Also try Flushing the Entire Cooloing system.Get it all out of there.You'd be amazed what kind of Crap can accumulate. Makes sense, although the coolant looks fine and it was changed recently 

[/ QUOTE ]

**MrMotion** · #4 08-28-2003, 02:14 AM

This seems to be the normal heat range for an LS6. If someone knows how to get them to run cooler I'm listening.

**Mr70** · #5 08-28-2003, 02:38 AM

My 70 L78 TH400/4:10 was running 210+.
I checked all I mentioned earlier,and then Changed my gas blend.I run highest the station has at the pump,then add Protek Lead/Octane boost.By verying the mixture,I found it actually showed an Increase/decrease in my cooling system Temp.
Albeit slight,but still a difference.
Today I found the best is 20 Gallons of Mobil gas,with 11 oz.Protek additive.
I only run 185-190 degrees now.

hvychev · #6 08-28-2003, 02:47 AM

Interesting guys. I am running between 200-210+ with my LS5 TH400. Rick I have done all the fixes you mentioned including boiling the tanks & recoring my original radiator, changing to a Mr. Gasket 160 thermostat, and am running 20W50 Penzoil. Would the timing be an issue?

**Mr70** · #7 08-28-2003, 02:52 AM

Yes Frank.
Timing is a Factor.What are you at?

hvychev · #8 08-28-2003, 03:01 AM

Rick believe it or not I have never adjusted the timing under my ownership for over 2 1/2 years and 12000+ miles! The car has run perfect and has had not had ONE mechanical failure or problem in that time! (knock on wood) So I am not really sure. [img]/ubbthreads/images/graemlins/blush.gif[/img]

BBIGG BLOCK 396 · #9 08-28-2003, 03:50 AM

I would check the Gauge first to make sure it is correct!Sometimes the gauges are not CORRECT! then the timing,and then use a 160 or 180 degree ROBERT SHAW thermostat.I had a slight overheating problem and worked with the timing,and change to the Robert shaw thermostat and lowred my temp 10 degrees.Please do not try the coolant additives such as WETTER WATER and PURPLE ICE,They do not work!If you have not flushed your coolant system in the 2 years I would think you should do that also and use a good brand of coolant.Hope this helps

Bobby

**k92** · #10 08-28-2003, 04:16 AM

I have similar setup as yours,but with more cam, 11.5:1 no clutch on my fan and my car never over heats,I have a 160 degree thermostat,38 degrees total timing and run pure 100 octane fuel, the car never gets over 185 degrees no matter how hot it is....