Engine getting too hot when off??!??

[Anonymous]

Here's my conundrum, when running, the engine cools just fine. If, for example, I drive it to the grocery store to pick up a few things for SWMBO, the temp gauge will be waaaay over to the right when I return... not quite into the "overheat" range, but alarming nonetheles. I start the car and it cools back down to the midway point within about 30 seconds. 1) is this a problem I should be concerned about, and 2) if it is a problem, what's the best way to fix it?

FYI - '66 Mustang, 200 CI, new 195* t-stat (tested), original radiator (was rodded approx 6 years ago), hoses good, no coolant leaks, coolant is full (i.e. I can take rad. cap off and coolant is about 1/4 inch below opening).

Also - Timing has previously been off by about 30*... harmonic balancer had slipped. Verified TDC and made a new mark. Now running at 3* initial (6* initial left me pinging under load... In a previous post I had talked about swapping in some new springs in my load-o-matic dizzy... those didn't work out so the originals are back in... but the springs are a bit weak so I've been getting too much advance under load... hence initial timing set at 3*). NOTE: The "overheating" issue described above was present even before I got the timing corrected.

 

[ludwig]

That's because your water pump is not working after the engine is turned off. Fortunately, it is not making more heat after it turns off either. The drop in temp is due to a fresh slug of water running through the cooling jacket when you start up again. There is some convection water movement. The t-stat will close when it gets cool enough again. Just make sure there is enough water in the system so you don't get an air pocket.

This post run heat-up is why some cars have the fan running after you turn them off, to cool them down when the pump is not going.

You know your body will still twitch, emit persperation and the chemicals in your digestion still function after the spark has been shut off. Same deal.

 

[Anonymous]

You know your body will still twitch, emit persperation and the chemicals in your digestion still function after the spark has been shut off. Same deal.

I suppose then I'll find something else to worry about, eh?

 

[Bort62]

Yeah, it's called heat soak. It's not a big deal.

 

[66 Fastback]

Not a concern. But as mentioned some cars have fans kick on to cool it down after the engine is shut down. It can be a concern on turbo-charged cars where that exhaust heat could cook the oil in the turbo. Some turbo applications had a pump to circulate the oil too.
Doug

 

[fordconvert]

Be glad you dont have mechanical gauges, at least with the key off with electric ones you cant tell but mechanical ones are always on so it can really freak you out.

 

[61Futura]

The combination of abnormally high heat soak and premature pinging could indicate plugged up water passages. But since your timing mark can't be trusted, you can't be sure that the pinging isn't from too much timing advance. A 40 year old engine can get alot of rust in the water passages, especially if it sat around unused for a few years.