Phantom Temperature Spike

[jverdes]

Ok, here is a mystery I need solved. My 2007 Redline's normal operating temperature ranges from about 194 to 205. Well on some very cold Texas mornings (about 40 degrees) my car will damn near over heat!! It shoots up to 250 degrees! At that point a little alarm goes off. If I try to turn on the heater the air is not hot at all! It just blows cool air! Also, I can smell burning coolant. It has gotten as high as 259, then just as quickly as it came on, the car will suddenly shoot down in temperature and go back to normal like nothing happened. It doesnt happen all the time, maybe a couple times a week. Any ideas?????

[Bogie]

Sounds like it needs service.

[BigSkyCountry]

Sticking thermostat. Ray

[Bogie]

Originally Posted by BigSkyCountry

Sticking thermostat. Ray

That does not explain the smell of coolant and the non-functioning heater.

High temp, no heat, burning coolant = coolant isn't circulating properly.

[Skip]

Bogie it explains a thermostat stuck closed....Skip...

[marklynn70]

Yep what they said, get it in and get that thermostat replace. It should be a warrenty item to get it done. But get it done before damage occurs because the worst things always happen at the least expected times.

[Bogie]

OK, someone either explain it to me or send me a link. Are ya'll telling me the thermostat is capable of inhibiting coolant flow? This engineer in me doesn't associate thermostat with valve.

[Gerry]

The thermostat regulates minimum coolant temperature in an engine at operating temperature. It's an on/off valve.

In his case, I'd be looking for a low coolant level as well given the two clues of fluctuating temperature and no heater output.

[MidniteBlues]

Originally Posted by Bogie

OK, someone either explain it to me or send me a link. Are ya'll telling me the thermostat is capable of inhibiting coolant flow? This engineer in me doesn't associate thermostat with valve.

Any liquid-cooled car engine has a small device called the thermostat that sits between the engine and the radiator. The thermostat in most cars is about 2 inches (5 cm) in diameter. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.

Howstuffworks "How does the thermostat in a car's cooling system work?"

No matter what, I would take it in for service to get the cooling system checked..

[Bogie]

Thanks folks. I didn't know the thermostat was actually a heat actuated valve. It makes a lot of sense if this thing closes or sticks at the wrong time, cutting off circulation to an engine that is hot, then that is a very bad thing.

Anyone know at what engine temp the RL valve (er...I mean thermostat) opens?

[Skip]

It varies from car to car. Some at 180 some at 190 degrees...The radiator fan comes on at 210 to 220 degrees....Skip...

[Skip]

Actually MB the coolant does flow even when it is cold. It flows around the inside of the block and to the heater iffen the heater valve is open. It just does not flow to the radiator until the thermostat opens up and allows the coolant to flow to the top of the radiator, to the bottom of the radiator, then back to the engine...Skip...

[WishfulThinking]

My initial reaction is similar to Bogie's. I don't have a Sky to look at, but I don't think I've ever had a car that had the heater core's water flow controlled by the thermostat. The thermostat should only control flow to the radiator. I've seen core's with their own mechanical/vacuum actuated valves, but if you turn the heat on, it doesn't leave the passengers cold until the engine is completely warm. It should give you whatever heat the engine has.

Hot engine + cold radiator(/cold upper hose) is what I think of with a stuck thermostat. To me, overly hot engine + no heat from heater sounds more like ... frozen fluid (which shouldn't be likely in a car that new).

Edit: Oops, didn't post quick enough. I second what Skip said.

[NJSKY]

Originally Posted by jverdes

Ok, here is a mystery I need solved. My 2007 Redline's normal operating temperature ranges from about 194 to 205. Well on some very cold Texas mornings (about 40 degrees) my car will damn near over heat!! It shoots up to 250 degrees! At that point a little alarm goes off. If I try to turn on the heater the air is not hot at all! It just blows cool air! Also, I can smell burning coolant. It has gotten as high as 259, then just as quickly as it came on, the car will suddenly shoot down in temperature and go back to normal like nothing happened. It doesnt happen all the time, maybe a couple times a week. Any ideas?????

Exact same thing happened to me a few weeks ago... Took it in for service, they replaced thermostat (took about an hour) - NO PROBLEM SINCE !!

[Gerry]

Originally Posted by WishfulThinking

...but I don't think I've ever had a car that had the heater core's water flow controlled by the thermostat...

None are or have ever been that I've ever heard of. Coolant is circulated through the heater core whether the thermostat is in bypass or not. But coolant won't go through the core if the coolant level is low. The lack of heater output is one of the telltales of low coolant level in the block.

[Skip]

Iffen the thermostat stuck closed and then of course the engine would overheat and blow off some of the coolant. Then you have steam and not water trying to circulate. That is why the heater is not hot air but cool air....Skip...