The last two times I have taken the Roadster out, I have had blow back from the quail with over heating. The first time it happened, I thought that the antifreeze that was in the car originally was the problem. So I drained the radiator which had some chunks in it and flushed some water down into. I refilled it with prestone 50/50 (plenty of it too and ran it in the garage with no problems. I thought I was in the clear (which was foolish because it was just running in neutral so it never got a chance to heat up as in a driving situation). Took it out today with problems again, maybe worse. Got to 200 degrees right after I turned the car off and 210 after 5 minutes. What should I do?
My wife saw something that Les Andrews wrote about distilled water and some additive that I can't remember that made the car run better because antifreeze decreases the freezing point.
The following is what I learned from 6 years of dealing with overheating in my truck that was revived from a 50 year nap in unheated farm buildings, and was not prepped properly for that type of storage. I've highlight key info.
Anti freeze can raise the boiling point slightly in an
unpressurized cooling system. In a
pressurized cooling system like modern cars, it raises the boiling point substantially. Modern cars have been designed and have the cooling systems/materials to run at hotter temps.
The A was not designed to run at the those higher temps. If an A runs at those higher temps it will cause motor damage, some damage due to what is called oil flashover at the piston rings, where the pistons can lose lubrication. Oil at the rings get so hot it burns away instead of lubing the rings/piston.
I consider Boil Over an early warn sign to slow down in hopes the motor temps cool down, or to pull over and let things cool off.
If you do not have one,
I highly recommend installation of a Coolant temp gauge in you upper coolant neck or hose. It allows you to catch the issue before it boils over.
In the vast majority of As, antifreeze is an excellent option, once you have a clean system, it prevents formation of scale rust.
Water actually has better characteristics for cooling than antifreeze. It is better at absorbing heat from the motor, and dissipating the heat into air in the radiator. Some As in mountainous areas where the altitude causes a reduction in the boiling point use water, and in some high heat area like desserts use water.
If using water use distilled water with a rust inhibitor like NAPA 1300 Rust Inhibitor,
in a clean system Red Line Water Wetter can also increase the efficiency of the dissipation of absorption of heat in the motor and dissipation of heat in the radiator. This combination inhibits the formation of rust/scale, but not as well as antifreeze.
Another key is that you cooling system needs to be in great shape. If your radiator is a 2 row core, (unless Brassworks - is OK), replace your radiator with a good 3 row or 4 row core radiator. Insure your system is clean. 1st run some detergent (like Dawn) in the radiator water, and then back flush. It will foam. This cleans out any oil/grease that may have gotten into the cooling system. Typically caused by over greasing the water pump. The water pump only rarely requires a small partial pump of grease.
Run treatments of Thermocure or Rust 911, and backflush, once back flushed and cleaned out,
install an upper hose coolant filter to keep rust/scale/contamination from plugging up your radiator.
So to summarize
A model a cooling system in tip top shape runs cool enough to not overheat in typical summer heat. It can actually run without the fan, except at very low speeds and idle.
Do your trouble shooting with Distilled Water and rust inhibitor. Once issue is resolved try going back to antifreeze. Less damage to paint with water, and easier to clean off.
Insure your system is in tip top shape - backflush as outlined above.
Make sure your radiator is a good model - Brassworks or a good 3 or 4 row tube core.
Install a coolant temp gauge.
Install an upper hose coolant filter.
Antifreeze is good, if you still have problems try distilled
water/rust inhibitor/water wetter.
Hope this is helpful.
