328 no heat at idle

Thought I fixed this problem with a thorough bleed of the radiator, but I get no heat from the heater cores at idle. Once engine revs are up to 1500 or more, no problem, tons of heat...like in HOT. But, stopped at a light, the heat will slowly go cold...once I start off, heat again. I have had the car for 1.5 years, and it has always done this for me. Car has new water pump and radiator was "rodded out" and cleaned. Perhaps the heater cores have a mild restriction? Just weird that once the revs are up a little, the cores pump out a TON of heat, even at the lowest settings.

My friend says he has the same problem with his 328 and 512TR.

Anyone?

Dave,
Short of having a low coolant level, or still some air trapped in the cooling system...there's really not much else that comes to mind that will cause this problem.

The water pump isn't very efficient at idle...so if the idle speed was a bit low, this would only accentuate the problem.

My BB, as well...doesn't make great heat at idle, but becomes quite hot once rolling. As every component is new, I just attributed the modest heat output at idle as just a "normal" part of the ownership experience.

Regards,
David

Hmmm, my previous 78 308GTS didn't do this...and the idle is set right at (an indicated) 1k rpms.

I had my mechanic bleed the system twice, then I did it, per JRV's procedure, and did get more air out...I am wondering if there is still a pocket of air in there still?

Here's my idea:
Not sure about the 328, but the Mondial 3.2 has an electric boost pump for the hot water to the heater. A failure would be most noticible at idle.
look at this

Now THAT is interesting! I will look into this, and check the diagrams. Thanks.

Boost pump, eh?

I guess the BBs weren't subject to those "modern convienences", but what a great idea!

Checked the diagrams of both the cooling system and heating system on the Ferrari UK spare parts link on the Ferrari Owner's Site, no luck. No picture of such a pump, and nothing described as such. Damn!

A hose comes off the port (flywheel) side of the rear bank and runs into a small electric pump.
Yours may have it, so check the engine compartment.
Of course, you could always install one.

Nope, there isn't one...I know there isn't, that's why I checked the factory drawings, thinking maybe it was removed, but it is not part of the 328....yes, I could add it. I will look at the drawings of the Mondial now.

I looked at the Mondial 3.2 drawings both for the heating system, and engine cooling system and no such "booster pump" or any electric pump as you describe is seen in either in the engine compartment or the forward comparment up front. Could you possibly post a picture of this part?