There is a bit chilly outside, and when driving it seems that the thermostat is closing. When I stop and wait at idle for a couple of minutes it opens up and I have heat in the coupe. But just after I start driving again the heater core turns cold again.

1. Is there anyway to stop the cooling fan on the radiator? I know it has a viscosity clutch, but it still turns way to much I think.
2. Is there any tips on how to blend the front grille...some cardbord or anything clever?

Hope some of you have some tips or tricks. Driving around wintertime theesedays is a bit nippy

 

Did you ever have heat? I the coolant temp 195 or so when it's warmed up? I would think that if your heater core were partially clogged you would get more heat when driving rather than at idle. I've driven in -5 to -10 weather and I don't think your problem is the outside temp. When your thermostat closes water circulates through the engine and heater core and not the radiator so the fan shouldn't matter. Anyway the coolant temp is the key here...if it's anything over 140 you should have good heat. If it's not getting up to 190+ then your thermostat is most likely not closing properly.

 

Yes I have heat. I started the car 15 minutes before driving. When the coolant was about 195 I turneed on the heat and it worked fine. I waited another five minutes to let the coupe warm up, since I was driving my inlaws to the train station. But then when I started driving, the coupe air went cold, the engine coolant dropped to about 130-140 and stayed there on the whole trip. Arriving the train station, I let tha engine run at idle. It warmed up again and the coupe heat came back. Started driving home again, the engine temp dropped to 140, the coupe heat dissapeard again, and didnt come back after I let the car idle at home for five minutes in our driveway.....?

 

I meant if you ever had heat working under normal driving conditions when the temp was similar or is this your first winter?

It sounds like the thermostat isn't closing all the way so when you're moving it's overcooling. It's a cheap and easy fix if you have a garage so your fingers don't get frozen. Even at 140 you should be getting some heat so your core could also be partially blocked...or low coolant..or air in system. Do you have a dash control for recirculating vs fresh air intake? It's easier to warm up cabin air than outside air. I'm sure glad I moved to Florida.

 

Thanks dobyken!
well I`ve had heat last winter and so far this winter. No problems whatsoever. But the coldest weather I`ve been driving in is around 0 °F. I notice when I unscrew the radiatiorcap that the level seemed fine, but the expansion tank was very low, about 3 fl oz. I noticed however that the radiator seemed quite brown sluggish inside. I think I have to flush the whole system. And then refill it with the coolant we mostly use here in Europe. Its blue and glycol based. I`ve heard it doesnt go very well with the GM stuff.

I have to say I`m looking forward to flush the system outdoor. -13 ºF
Better find a way to connect the garden hose to the indoor tap, so I can use some tempered water. Hope this will solve the problem.

 

Flushed the heater core and the system. And changed the coolant. I think I was fooled by the expansion tank level. It was actually empty, but some old dried out coolant/sludge stuff was remaining on the expansiontank sidewalls. At first glance the level seemed ok. So I think the main problem was actually to little coolant in the system.
It works fine now!! (exept for the floor heating....another post)
Thanks for all the help!!!

 

The "thermostat" job is to regulate the engine temp. Mine is typical, it is completely closed until the coolant hits 185 and it begins to crack open. On a warm day, it will open completely about 195 d F and let full flow to the radiator.

Whether open or closed, the coolant continues to circulate thru the heater core. So once the engine warms up, if everything is working right, you should have a steady flow of warm air.

A failure which is not very common, but can happen is for a thermostat to "stick open". If that happens, on a cold day, the engine could easily cool way down as you've described.

A good rule is, about once each 3 years, flush the system, install new t-stat and fresh anti=freeze.

 

Are you loosing coolant ? Check your intake for leaks.
I had the same thing happen. Had the heater core flushed in early springtime and the heat worked great for a while because the coolant was filled, then it went out again in the fall. I knew my intake had a tiny amount of coolant weeping but it got worse to the point where it caused too little coolant in the system. Turned out the heater core was fine.