[voodoo65]

I didn't have an overheating problem before the recent installation of an Edelbrock performer intake and a Holley 4160.
The temp guage on the 65 has the thin line then a thick line on the hot side. After driving for just a couple of minutes, the needle stay within 1/4 inch of the thin line. Most of the time it's closer. If I stay over 70 mph (near 80), it reaches the thin line. It's slightly better at slower speeds, but gets worse again when sitting in traffic. I don't lose any coolant, though.
I have no fan shroud, a 5 blade fan with no marking other than Made in the USA, 50/50 mixture of Dexcool with a quart of something called Liquid Kool (seemed like a good idea), stock water pump, 3 row radiator, and I used a temperature sender for a 66 because it fit the port in the new intake (was that a bad idea?).
I know it could be an intake leak, but I don't know how to diagnose one. I don't think it's running lean, but how can I be sure? Ignition timing could be a factor, but I didn't remove the distributor when I changed the intake.
I'm stumped on this, but would appreciate any help.

 

[Billgear]

Are you loosing any coolant? It's probably the new sensor has changed the gauge position a little. Did you
install a new thermostat?

 

[Guest]

I asked my friend that owns the Shasta Mustang Supply a while ago because I was having the same problem. He said it is because on the Performer manifold the location of the temp. sender is right above the head and is in a different position than stock. But yours seems to be a lot higher than it should be.

 

[70_Coupe]

Fan shrouds only help at idle and such to draw air through the radiator. You stated you are not overheating there, so you can dismiss this. Driving freeway speeds doesn't require a shroud. Make sure the lower hose is solid and isn't colapsing at high speeds.

But, from your description, you changed the sending unit. The sending units internal resistance lowers with the temperature, causing an increase in current through the gauge, and makes the needle go higher. Are you sure the type you installed is of the proper calibration? Was it new or used?

Just another outside thought, if the connector to the sending unit was corroded or not making good conection, the replacement could have cleaned up the contacts in the connector and or sending unit contacts enough to correct a bad connection, thus causing your gauge to read higher now - although this is the correct reading! (the old one would read lower if the connection had resistance due to corrosion, and seating and re-seating the connector would have wiped away some corrosion)

I don't think lean mixtures or the intake have anything to do with your reading. See if you can locate a thermometer and stick it in your radiator to see what the temperature really is. You can also check a shop manual to see what resistances should make your gauge read low/midrange/high, and substitute these in the circuit with the other side of the resistor tied to a good electrical ground. This proves the gauge calibration and wiring from the sending unit to the gage are in order - and if so, the problem is thus the sending unit or the temperature is running high. ( and that's what I meant before, maybe it always ran high but the bad connection at the sending unit due to resistance made the gage read lower - thus it was incorrect.

If so, you may need a radiator cleaning or a thermostat replacement to correct the overheating.

Tom

 

[fordnut]

Your intake might be leaking, causing a lean mixture. Easiest way to check this is with WD-40. Remove your breather, and with motor idleing, spray a little along the top of the head where it conects with the intake. Do one side at a time. If the intake is sucking air, the motor will speed up. Do this all the way around the intake. Then do all around the base of the carberator. This is the best way to find out for sure that you are not leaning out and causung a heating problem...good luck

 

[voodoo65]

Thank you all, you make very good points. The sender I used was brand new, but it could be a different calibration since 66 used different guages. I got a bushing today to use the old sender. I'm aware that the old sender might not work properly, giving me a false cooler reading, so I may soon get an aftermarket temp guage. I shall also try the WD-40 trick to find any leaks-thanks for the tip. Thank you all.