Why isn't it COOL?

[thechadzone]

My car is really running well, but runs hotter than it should. Even when its fan kicked on and off it wouldn't stay at or below 190 on the temp gauge while at traffic lights. I did a two liter engine swap on the '69 AS and used the 1.8 head, intake, and exhaust manifold. Is the radiator the same between the 1.8 and Spider 2000 engines?

My radiator is in good shape with good fluid, and I have a new slim line fan mounted right up against the radiator that blows toward the engine. It's not the original fan because of the new engine sitting further forward than the old one and reducing the space between the radiator and engine.

Many thanks for your ideas,

-Chad

[TJC]

Firstly, don't believe your stock gauges (if that is what you're looking at and not at an infrared thermometer), they're not known for their accuracy. But, how high does does the stock gauge get sitting at a light, anyway? How hot was the ambient? I assume your fan never turns off when sitting at the light, so have you ensured your cooling system is properly debubbled?

[mbouse]

Chad,

1. the rads are different for those two engine sizes.
2. did you perform a complete burp of the system to ensure there are no air pockets inside?
3. the fan is blowing in the correct direction when it sucks air thru the radiator.
4. TJC is correct about the inaccuracies of the stock gauges. thorough checking cannot be accomplished relying on that particular reading. they are good indicators, at best.

my cooling fan does very little to reduce the reading of my two litre temp gauge as well. i seriously doubt the fan effectiveness, but that is my personal opinion. and, i have swapped to a different stock gauge, and recently changed sensors when i changed heads.

with my '78 1800cc engine, i can see a difference recorded on the gauge when the fan kicks on/off.

if you are not postive you have properly burped the air pockets out of the head, i would start there. getta written procedure if it helps (i can email you one). if you are sure there is no air, then getta laser thermometer and find out exactly what temps you are REALLY looking at before getting too excited.

[So Cal Mark]

an undersized rad wouldn't cause hot running at idle, that has to be an airflow problem. I've found the slim line fans don't flow enough air for cooling above idle. For example, if your idle speed is set at 1400 rpm, the fan won't cool the car when sitting still. First step is to confirm what the temp really is

[thechadzone]

Hi guys, thanks for the feedback. I'm curious about the burping procddure mentioned, and I'd like to take a look at it, either posted, or to thechadzone@hotmail.com.

I think that my gauge is at least reasonably accurate based on the amount of fluid in my overflow resivor at the end of a longer dirve, and because it has boiled over after I loosened the radiator cap right after parking the car. Still, these are the original style chrome bezel "eletronic" gauges, and they don't look quite German in their precision...

Is there an aftermarket fan that is known to work well in this application? The damn fan costed me close to a hundred dollars, but if it doesn't work... I originally had the fan tack welded on the other side of the radiator between it and the grill of the car pushing air through the radiator, and it had about the same results as my slimeline set-up on the other side of the radiator.

Still, my '69 is running well enough to have given me one hell of a speeding ticket today. 86/55... DAMMIT!

[TJC]

When fully hot, your car will always boil over after removing your cap.

Cooling systems are designed to work under pressure in order to raise the coolant's boiling point above 212 degF. Remember, 190 degF is just the temp that the stock thermostat opens, it's not necessarily the engine-out coolant temperature seen at all (intended) operating conditions. Therefore, if you take off the cap when the system is very hot (i.e., top water temps >212 degF), the pressure drops to atmospheric and she'll boil right over.

Again, don't believe the absolute numbers on the gauges. Their for reference only. However, is the gauge going into the red? There is a separate switch (the oh sh** switch) that will pin the gauge needle into the red when the temps get too high. In other words, what, besides the gauge's actual reading, are your indications that something is amiss in your cooling system (i.e., is it boiling over without taking the cap off? How much coolant winds up in the bottle after it's hot? Is the engine knocking? Does the fan come on, but never shut off?.....etc.).

If it is boiling over on it's own, before you do anything like doubting your fan, I'd do a search here or on the Mira FAQ's for the proper debubbling sequence:
http://www.mirafiori.com/faq/content/co ... lbleed.htm

[mbouse]

email sent

[TulsaSpider]

I think it is much harder to push air through a rad than to pull it through. Also you could try the water wetters, they really work!!