Hi, all,

Fairly new here, so forgive me if this is a dumb or already-answered-to-death question:

'67 C10 short/fleet LS6 conversion, just on the road. Runs great, but pegs the (Stewart-Warner) temp gauge at about 220 degrees pretty quickly. Heat gun shows 180 degrees at the thermostat housing (running a 180 thermostat). Giant Nascar four-row Superspeedway radiator, so no cooling issues there; twin fans, too. New Edelbrock water pump, as well.

Here's all I can figure: system isn't properly bled; so the temp gauge sender is reading hot air rather than coolant; or temp gauge sender itself is too large (had to run an adaptor in the cylinder head) to fit the hole and is contacting metal directly.

Any thoughts? Your help would be much appreciated.

Thanks,

David Langness

 

Your probably on the right track, you might have air in the system. Try aiming the truck up hill, disconnect the small vent hose, and add coolant through the upper radiator hose until all air escapes thru the vent hose(some call this the steam line)and solid coolant comes out. This tip came from the ls1 truck forum and has helped many. Hope it helps.

 

Are you running an LS style thermostat?

 

Its a long shot but I had this happen to me. When I did my 240SX conversion my radiator was a cross-flow built for the LS swap. My engine wouldn't cool. We eventually figured out that the manufacturer didn't put the divider in the end tank so the coolant was just flowing from the top hose to the bottom without going through the radiator.

 

Did you fill it through the upper hose? If you take the upper hose off and hold it up, you can fill the engine easier. Just pour the coolant in it until the hose is full. Usually just filling the radiator isn't enough and will cause air problems.

 

#1 is your temp gauge mechanical or electric?

If electric:
use a infrared to measure the temperature of the head at the point at which the temp sender is in the head. Remember shiny surfaces will trick an infrared thermometer. If the actual temperature is reasonable vs the gauge then you have either a temp sender with an inappropriate resistance range for the gauge OR you have a ground issue. If there is a different ground potential at the engine block vs the gauge your readings will be false. I usually ground the instruments tot he engine block with a 12 or 14 gauge ground wire in addition to the battery ground to the block or even better tot he starter.

If mechanical:
There is a reading issue with the gauge. Boil water in a pan and immerse the sender in it. Use a known thermometer to measure the water temp and check that vs what the mechanical gauge reads. I hope this helps.

 

I pressurized my radiator with the hose untill water came out the steam hole.....
Are you sure your water pump is turning the correct way?

 

W/ the sensor riding on the head material, it may well be reporting the temp of the head, and not the water flowing thru it. The head is hotter than the water flowing thru it........
Fans wired backward?

 

yep, one thing i learned was fill from the top hose, or the thermostat wont have water behind it to operate

 

Jack up the front end of the car to get the radiator the highest point, then pull the steam vents off until coolant comes out there. That will get all the air out. Shouldn't need to pull a radiator hose that way.

 

I know of a couple of suppliers who have STOPPED selling the new Stewart_Warner gauges because of faulty products, you might check your gauge, but most of the suggestions are certainly on the right track...You will get it figured out, all good stuff takes time...