help with overheating 79' 308 USA

The Evans doesn't boil...and neither does a proper mix of antifreeze/water...at least at any coolant temperature that should ever be seen in an engine. BUT both expand (volume increases) as they heat up. So if the coolant level is higher than it should be when cold, it will overflow/spit from the vent tube when the car is at normal operating temp.

From your post, I ASSUME that you had some problem with overheating when the car was in its original configuration and you then made all the changes you described in order to correct the problem. Is that right or did the overheating occur after some of those changes were made?

Obviously it could be a head gasket issue, which your proposed combustion leakage test should confirm or deny. But if air is consistently getting into the cooling system, there is a leak of some sort somewhere.

 

My 308 QV has a bleeder screw and rubber O-ring at the top right hand (passenger) Side of the radiator. Are you sure you have all the air bled out of the radiator? Would think that bleeding the entire system out of the thermostat bleeder would take forever.

 

If it is a head gasket you might be able to confirm with a leak-down test as I show in this video. I had a leak on #4 cylinder. Prior to this I did a number of "block tests" to see if I could detect combustion gases in the coolant but they all showed negative. I believe that when the combustion gas enters the coolant it flows to the radiator and is trapped there so it never shows up at the expansion tank. I replaced my head gaskets and all has been well now for the past two years and 6,000 miles.

 

Of course Evans coolant boils. Why wouldn't it?

 

I've never really understood Evan's claims re engine protection but maybe I'm missing some vital point.

In my view:
The boiling point of Evans is about 100F higher than 50/50 water/antifreeze but the H2O/AF boiling point, - around 260-270F at 15PSI - is much higher than the coolant temp would (should) ever get in a normal engine. IOW, if the engine temp has risen to the point where H2O/AF boils at 15-16 PSI (common coolant system pressure), other damage will have likely occurred due to the excessive heat. The same heat that would NOT boil the Evans can still damage the engine in the same way. IOW, the Evans can't protect the engine from the same temps that would damage it with H2O/AF. At least, that's the way it seems to me; I welcome info to the contrary.

That being said, I would consider using it if, as they claim, you don't have to periodically change the coolant. Also, there would be no rusting/corrosion of components if a slight seep/drip occurs. In that regard, it might be worthy thing to do. OTOH, if a hose broke, clamp failed, etc, and you lose a lot of coolant...it cost a lot more to replace! But heck, the world is full of compromises! In any case, before deciding to use it I would do a bit more research to be sure that the heat transfer capacity of Evans is at least equal to 50/50 H2O/AF.

 

It's called a differential compression tester also known as a leak-down. The piston needs to be at TDC with both valves closed, you control the input pressure with the dial and it shows on the left gauge (I used 100 psi), the right gauge will show how much pressure the cylinder holds and how much leakage either past the rings, through a valve or - hopefully not - through the head gasket. I did the gaskets myself, it's a bit involved, not something I'd suggest trying if you have no experience. I have rebuilt a number of Fiat and Alfa engines over the years and the F106, even though a V8, is similar. The Ferrari workshop manual is quite thorough but it is not a book that is going to guide you in a how-to manner. There is also some machine shop work you would want to have done to the heads while they are off. But first step is to determine if you even have a head gasket problem. It may not be the case in your situation, it could be something far simpler.

 

water temperature should stay below 195 F with the standard coolant and standard old fans, at usual road speed driving: It doesn't require any change nor improvement. It looks you have a leak in an head gasket or somewhere in the heads: I would do a simple compression test at your mechanic shop, to check if there is a leak somewhere, at first. Maybe your car has a lot of mileage and it's the time to change the head gaskets.

Ciao

 

Having used Evans for over a decade on our builds I can offer some insight. It does not expand or boil in normal use and operation of an engine. It does not induce galvanic corrosion that water/coolant does. It does burn if it leaks into the combustion chamber due to headgasket failures.
That said, it requires a complete flush and condition of the system to remove ALL previous water based coolant. The 308 is a right PITA to do this on given the location of the heater cores. I remove them from the vehicle and take the time replace all hoses since we're in there. Left over residual water will cause Evans to not operate correctly, glycol is hygrophobic so it has an affinity for water. That's why the system needs to be dry first.

It's easy enough to check the water content of Evans with a hydrometer.

 

Is water temp dial working correctly?

This is surely not the case, as per your comments. But it’s worth checking

 

it probably is ok.
I don’t know how to check it. But maybe get a cheap one from Amazon and hook it up.

 

Minorou the only purpose of the fans is to mimic the airflow through the radiator when you are not moving. So if you are not moving and the fans are running then it should be just as if you were moving - the temperature will be stable. It may be higher than when you are moving but it will stay steady and not overheat. You should be capable of idling indefinitely. So even if the switch were to allow you to get through some intermittent traffic jams it is still ultimately just a band-aid.

 

Yes I understand, I'm just saying that if there is a problem it will not help to turn the fan on at a lower temperature. It will still overheat.

 

I think you should stop modifying a system that should work fine and start finding the cause of your problem. At one point I thought I had a head gasket leak and did the following with the engine cold:

- Pressurized the entire system (through the reservoir cap opening) to 15lb and checked for leaks.
- Observed pressure for 1.5 hours. Pressure dropped to 14lb within one minute but held for 1.5 hours. It initially drops because any air in the system is absorbing the air pressure.
- While under pressure insert a boroscope into each cylinder and inspect for traces of coolant. These are cheap ($35 US)

If you can pass these tests you can be pretty sure your cooling system is tight and you don't have a head gasket issue.

Questions: How much coolant did you drain out when you converted to Evans? How much Evans did you have to add to fill the system? My '77GTB holds 5 gallons of coolant.

Have you observed the behavior of the thermostat in a pot of boiling water? What happens?
What is the direction of airflow through the radiator when the fans are on? (is air blowing toward spare tire?)

 

Minoru, if you dont have a head gasket, maybe you can benefit from this mod... https://www.ferrarichat.com/forum/threads/nickforza-ignition-system-is-it-good.253836/page-2

Nick's Forza ignition and ... read comment on post 38 https://www.ferrarichat.com/forum/posts/138889883/

 

No, that is the bleed line from the engine. Any air in the system will follow that line to the top of the expansion tank which is where it belongs. The problem with the 308 system is that any air that might get carried forward will be trapped at the top of the radiator. Normally systems like this have a bleed line from the top of the radiator to the top of the expansion tank but the 308 does not. The air trapped in the radiator is what causes the coolant level in the expansion tank to rise and can only be removed manually by opening the bleed screw at the upper RH corner. One good mod is to install a drilled bleed screw at the radiator so that you can let the air out by loosening it and don't have to completely remove it.

 

I was one of the ones back then advocating for plugging the small hose to the expansion tank. In my experience, my car would puke coolant almost every time after a drive. No matter how well I bled the system it kept doing it. Even after going through many of the steps you have. It still did it. It got to the point that I started parking my car on some wood blocks when coming home and EVERY time before leaving I'd start the car and bleed a pretty good amount of air from the radiator bleed screw. Every time.

After I bled it again and blocked off that small hose, I never had another problem with getting excess air in the system. That small hose enters the expansion tank well above the level of the water. To my simple way of thinking that was a way, as the car cooled down and the coolant receded it would suck air into the system from the top of the expansion tank.

All I know is, I was basically told I was wrong but my experience is what it was. I just put a hose clamp on that line near the expansion tank and it solved my problem.

Now, if air in your system is NOT the problem then you probably have another issue. BUT also.... If it's not puking out coolant after stopping (or while running for that matter), the fans are coming on and it's not getting above 195 on an 80 degree day, I'm not even sure you have a problem. Don't overfill it, bleed it properly, drive it, let it cool and then check where the level is. If it's normal and not overheating or puking coolant all is good.