Overheating...

[dmich2]

What's a new forum w/o an 'overheating' thread? The wife and I were de-Christmas decorating and ready to wring each other's necks when I said, "It's nice out, let's take Sweet Pea for a run." Well we cruised some back roads and a limited access and cruised for miles at 60. Awwwww. She purred, (Sweet Pea I mean) But as I glanced over, the wife was smiling too. She kept say, "Let's go down this road", or "Turn here." We were having a ball and as the sun starting setting it got a little cooler. I had been watching the thermo and it never went over 160 even at slow speeds. Oil pressure was great. Well I could tell the boss was getting cold so I reached up and threw on the heat. Almost immediately Sweet Pea went up to 190+. had me worried due to the rate of climb, but she stayed there. When we got home, wife still smiling.. , a good thing, I checked the radiator level and added about a quart of 50/50.

So...? I always thought that if a car was overheating you were suppose to turn on the heater to lower it. I hear about that when you're driving in hot weather and you start to overheat.

Any thoughts?

Suppose to be 70 here tomorrow... can you say...Tee-Time?

Dennis

 

[Wombat]

Maybe there was an air lock in the heater core? The heater core is pretty much the highest part of the cooling system, so air will collect here. A friend of mine has a Mk 2 Jag that also has the heater core higher than the engine and he has installed a bleed valve on it to let the air out.

 

[61Alpine]

70 Tomorrow.

Hah. Supposed to be 28 here tomorrow.

Drove my Alpine on Monday and Tuesday (taking it to and from upholstry shop) is was about 28 degrees. With the heat on I was just right, even though I barely got it warm before I arrived.

 

[dmich2]

Thanks Bob. I'll check that. If I did not mention it, the temp gauge moved immediately up when I turned on the heater and dropped as soon as I tirned it off.

Dennis

 

[Bill Blue]

Dennis, very interesting.

But an even more interesting question is "Why is it running so cold?" Should be running at 180, minimum.

Bill

 

[Jim E]

Would verify it with a temprature gun. Could just be something touching or not touching under the dash and when you move the knobs it changes or make a circuit.

I am running one of Coolcats instrument voltage gizmos and find they work very well and remove a lot of ghosts from the gauges.

 

[Tom H]

First thing I looked for on the new forum was an "Overheating" topic!!

My suspicion, just like Jim's is that when you moved the heat lever it somehow caused a change in voltage applied to the temp gauge system. The temperature and fuel gauges both run off a small regulator behind the dash. And if moving the heater cable caused a short to appear or disapper in that regulator circuit you could cause a reading change. Did you notice if the fuel reading also changed? Jim's reference to a "Coolcats" is, I think, a modern replacement for the old regulator I referred to above.

Tom H

 

[slippery_biscuit]

I have to concur with the folks suspicious of an electrical bug. Even under extreme conditions (which it sounds like you weren't) it should have taken Sweet Pea a bit to heat up and subsequently cool off if the coolant were actually fluctuating 30+ degrees. A mechanical device interacting with an electical one.... you just never know.

And 160 deg does seem a tad cool. Is that the thermostat temp you've installed?

Jeff

 

[dmich2]

Bill. At speed she always ran at a nice temp. Even when we go those really HHH days here in NC. The only time she would get hot in the past is when I'd get stuck in stop and go city traffic, but that was before the Volvo fan. I did install the Volvo fan and moved it close to the radiator. Jim, I'll consider the gauges being funky and do some checking.

Dennis