temp gauge needle moving around

[timmycharger]

Yesterday I drove my 68 to work, taking it on it's first long highway run since the engine rebuild and car restoration.  I have an aftermarket Be Cool radiator and dual electric fans and a 195 Tstat and had no issues with overheating since getting it back on the road. 

Yesterday morning on the way to work it held the temp steady, around 200 or so (best I can guess with stock style gauge) and had no issues. On the way home, in about 75 degree weather, the temp needle was moving around more than usual. It creeped up to about 220 for a short period then quickly moved back to around 200. I didn't think the needle should move so quickly, sort of a gradual thing?

I then approached some traffic and it stayed in the 200 range until I went home.  Is it normal for the temp to fluctuate so much while on the highway?  One theory I have is that the fans are not going on while I am at highway speeds and when I slow down, they kick on? I don't remember it doing this 20 years ago LOL

[70 sublime]

Almost sounds like the thermostat stuck shut a little then popped open ?

[justcruisin]

I wouldn't rely on the accuracy of the factory gauge, to be sure, it is a good idea to fit up a quality mechanical gauge - even if it is only temporary for testing purposes.

It is possible to get pockets of water that get caught in an area of the engine and heat up then move on, in my experience this is only the case when not using a t-stat though.

A 195 t-stat is too high IMO.

[A383Wing]

Possible cluster voltage limiter is sticking causing full battery voltage through the gauges

[Dino]

If you haven't stuck a solid state voltage liiter on there yet, please do. I fried two gauges just after restoring them because the stock limiter gave out. Not cool!

180 thermostat should work fine in your car btw, but if this works for you then go for it.

[timmycharger]

Thanks guys. I like the idea of another gauge, I think I have one. Yes I did have the solid state limiter installed when I had my cluster restored. I keep reading conflicting opionions about what temp thermostat to use. I may try the 180 in the future.

[TexasGeneral]

 

Possible cluster voltage limiter is sticking causing full battery voltage through the gauges