[Mook]

69 GTO with 468 stroker Edelbrock aluminum heads round ports. Timing locked at 35*. Auto meter temp gauge reads 205 to 210, infrared thermometer registers 168* at thermostat housing, 192* inlet to radiator and 148*-153*outlet of radiator. The rally gauge is about halfway. How concerned should I be with these readings? Readings were taken in June of this year.

Thx

[AG]

When the car is fully warm take the cap off the radiator and put an accurate digital thermometer in to check the temp.

[69 Limelight]

I'd go with reading of aftermarket gauge and OEM Rally gauge. They seem to be about the same and Peter Serio (gauge restorer on this forum) posted in the past that halfway on a properly calibrated OEM Rally Temperature Gauge is 209.

[ZeGermanHam]

Originally Posted by AG

When the car is fully warm take the cap off the radiator and put an accurate digital thermometer in to check the temp.

This seems like the most sensible approach.

Also, OP it appears you are not using the infrared thermometer in the most accurate way possible in some instances. Although the laser dot shows you generally where you are pointing it at, the actual infrared light that measures temperature is emitted from the device in a cone shape. The farther away you are from the object being measured, the larger the cone will be and you will get less accurate readings as a result. I usually try to get within 3-4 inches of whatever I'm measuring. In the instance where you measured the t-stat housing, I'd get much closer and measure the actual metal housing and not the rubber hose.

[Mook]

Let the car run 20min…. Once turned off it was so much pressure or I have too much antifreeze in the radiator…. I had to wait to cool off (even after relieving the pressure with the cap release) to open the Radiator cap the reading were directly above the antifreeze was about 150° while inside the car the gauge read close to 180°

Needless to say the temperature of 210° at idle concerns me as I attempt to go to the car show in Ocean City,MD next week….SMDH

[70GS455]

There is one piece of important info left out. What is the thermostat rating?

Sent from my SM-T817V using Tapatalk

[Murf]

Maybe more than one. Where is your sending unit for the Autometer gauge. If it’s in the head, I could see it being a little higher than the others.

Maybe your engine would like some advance at idle.

Good luck!
Murf

[Mook]

SMH… 160 Mr Gasket stat with cutouts to relieve air pockets….. auto-meter gauge sending unit is in the driver side front of the intake…..

[Mook]

Don't believe I left that info out, sorry!

[Mister Pontiac]

None of those numbers would concern me at all. If she sits there middle of the (Rally) Gauge at idle, that's perfect.

All mine run up there all the time. Even hotter during summer days as you might expect (Phoenix).

If you let it idle 20 min and 210 was all the hotter it got, I say drive it, and enjoy it. Nothing to worry about.

Hope that helps.

[65madgoat]

I love the numbers on the temp gun.

How positive are you the gauge is even reading correctly?

[OCMDGTO]

Marcus, you need to figure out which reading is right. The temp gun numbers are great. 210 at idle sounds high to me and I thought halfway on a Rally Guage was 175. When my RG worked my cars usually ran halfway with multiple different engines. I thought on a hot engine you pull the cap while it's running not off.

[tjs72lemans]

I never knew you could pull the cap on a hot car. I thought the pressure would always spray. And burn!

[AG]

Must be done slowly if a non-vented cap. If you have a vented cap, vent and remove.

[Mook]

Today I installed a non-thermal fan clutch let idle for 30 minutes temp never roes over 170°. Still have remnants of hurricane Ian here dropping rain won’t be able to road test till next week….. keeping my fingers crossed.

Thx PY For all the replies and advice, by far the best Pontiac forum on the net!!

[dataway]

Curious what you mean by "non-thermal" fan clutch? I thought all the fan clutches engaged based on temps.

[ZeGermanHam]

I'm assuming that means he removed the fan clutch and installed a fan spacer? Just a guess. If so, that suggests to me that the old fan clutch was either defective or insufficient. I don't like fan spacers with no clutch since they kill tons of power and an HD fan clutch will work just fine.

[Mook]

Originally Posted by dataway

Curious what you mean by "non-thermal" fan clutch? I thought all the fan clutches engaged based on temps.

Something like this….

[dataway]

Jeez, didn't know they made such a thing. So basically a little reverse torque converter in there. Going by the picture I'm guessing it's viscous drive ... more shaft speed heats up the fluid, thins it out = more slip, lower rpm the fins cool the fluid = less slip? Sounds like a very good idea ... I never trusted those little clutch fan thermostat coils.

[tjs72lemans]

I have that on my 55 Chevy and works great.