Engine: Hawk over heating

[Yogi]

My 1960 Hawk-289 4 barrel has been sitting for over a year while I was doing body work. I replaced the old gas and fired it up. Problem is, the heat gauge went out of sight in just a few minutes. My first thought was the thermostat was stuck. Replaced it yesterday but no change. It has a new radiator with electric fan. All suggestions appreciated.
Thanx, Yogi, slightly smarter than the average bear.

[62champ]

A good help are those small and affordable infrared temp gauges - want to confirm how close to accurate the gauge is being.

[jpepper]

It could be a bad temp sender on the back of the left cylinder head. Disconnect the wire and see what the gauge does. It should just sit on cold. If it does not, The wire to the sender is grounded somewhere. It could be in the length of the wire or at the back of the dash gauge. Disconnect the wire from the gauge. With both ends disconnected the wire should have no continuity to ground. If that is the case, the trouble may be the gauge itself. Use an ohm meter on the sender from the center terminal to a ground like the sender body. It should be about 240 ohms cold and about 33 ohms at 220+°. You will not get to that point (at least you should not). The resistance should drop as the engine heats up. If the resistance is very low cold, replace the sender. Make sure your engine to chassis ground at the right motor mount is in place and clean. There should be a ground tab grounding the metallic oil pressure line to the firewall which grounds the instrument cluster to the body. I also add a wire from that ground screw to an engine bolt grounding the body to the engine/chassis assembly. Let us know what you find.

[jg61hawk]

My 1961 Hawk has a strange habit of putting the temp. gauge pegged on hot sometimes when the headlight switch is on. Be sure you are really overheating. I asked about this at an International Meet where the Co-Operators were. It's not unheard of, and Jon Myer explained to me what was probably happening. If it happened as fast as you say and yet the engine started right back up, no overflow of fluid.... etc. I'd check the actual temp. On the other hand could be a simple air bound problem from sitting and the new work on the radiator.

[Mark L]

Since you say it has a new radiator, so that means the coolant was drained and refilled. You may have a large slug of air trapped in the cooling system. I flushed and replaced many of my cooling system parts last spring, and my 259 ran hot like that until I was able to bleed all the air out.

[doofus]

I always drill a 1/8 th hole in a new thermostat to allow air to purge out while engine is warming up. once engine is burped, your OK. Luck Doofus

[Jeffry Cassel]

I bought my 61 Hawk in 1970 while in San Antonio. It did not overheat. Since then I've recored and replace the radiator twice with the HD 3 core core. That helps a lot. It generally doesn't get too hot now but it is Minnesota and global warming seems to have overlooked us. I still believe it is the gas. My lawnmower guy says it burns hot and is really tough on air cooled mower motors.

[Paul Keller]

All the above solid. The non-contact temperature sensors are not expensive and very helpful in locating the source of a high temp. - Is it at the heads, the thermo, the hoses, the radiator (top, middle, bottom). One of the best $15 investments>

Track down, narrow down the problem - you will find it - At far less cost than replacing a bunch of parts that do not need replacing.

Stay with it, PaulK

[Yogi]

Hey Y'all.
I appreciate all of the replies. I'm not positive, but pretty sure that the problem is the heat gauge. I have bought a new mechanical gauge. I have my old gauge out but haven't put in the new one yet. I will let you know how that works out.
Thanks again, Yogi