Radiator Overflow- do or do not?

Do it. I used a 2" dia x 16" billet tube from Summit if I remember correctly. Mine was only 16 ounce capacity and not quite big enough to catch it all. Ideally 30 to 60 ounces should work.
I mounted it vertically on the aft firewall next to the header tank. Be sure to change to the proper tank cap designed for closed systems.

Since I went to a closed system I never had the need to bleed air from the cooling system more than once a year, if that.

 

The tanks back in 'my day' (70s) were for recirculation, with an overflow.
So all the 'piddle' would be sucked back in when the system got cold again.
But your car's piddle may be you just have a tad too much water. Once
she pees (YOU started the analogy!) enough of it out, she should be
able to hold the rest.

But do NOT rub her nose in it! Your air dam will thank you



Jedi

 

Your car is overflowing because air bubbles trapped in your system are expanding when it gets warm. If there is no air in the system (except the obvious air in the expansion tank), then the factory coolant level (6cm below the filler neck, or what ever your manual says) gives enough room so the thermal expansion of the coolant itself won't overflow. ie no overflow tank needed when working properly.

 

+1 The proper level is approximately 6cm below the filler neck that the cap seals to. Some cars may spit a bit even at that level, but they will find their equilibrium and stop after a few times. Make note of the level (cold) and that will be the appropriate level for your car.

 

Are you saying your 308 does not have an overflow/expansion/recirculation tank in the engine bay??

 

I added one to my 308GT4 to see how it would be. It sits right in front of the crank pulley mounted on the fender liner. I did have to drill four small holes in the fender liner, but I figured this was the easiest to fill and hide if the tank goes away. It is almost invisible in this position, it was hard to take a picture of it.

It is a generic overflow tank from the local auto parts store. It works well, I've not gotten any air out of the bleeder vents since installing it. I find that the car will often flow to the bottle after shutdown when the engine is hot and the pump isn't circulating water. As it cools it draws water from the tank and refills the system.

The car wasn't designed to have it, and it shouldn't need it, but never worrying about burping the radiator before each drive is nice.
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This is what I used. It's the polished "tube" next to the overflow tank.
It collected overflow from the black header tank next to it and then it returned as the car cooled down. The overflow tube would spit on the hot days prompting thoughts a bigger reserve was needed, about 30 ounces.


If done correctly a closed system should never purge onto the ground, EVER.

If your 308 has an open system add the surge tank. It keeps the system from pulling air back in after a hot run.

There is a very good reason why just about every car made after 1970 went to this system.
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The thermal expansivity of ethylene glycol is .00057/Deg C. The change in volume of 18 liters of a 50% solution of ethylene glycol when going from 20deg C to 100deg C is around 850 ml. If you fluid volume is expanding more than that there is a problem, such as overheating, boiling or most commonly air in the system. EPA mandated systems, such as catalytic converters, air pumps and catch tanks are not required for the proper function of the engine.

 

From what I've heard a common cause of this kind of overflow is a bad radiator cap that can no longer contain they system pressure.

 

Rick,

This may sound like a silly question, but after your car has "piddled", do you top up the reservior tank again? If you do, that could be the cause of the problem. The reservior should only be about 1/2 full. I've seen this happen with other people, and I've had it happen on my old Jaguars. If you over-fill the reservior, it will spit out the excess when it's hot. Once the reservior has found it's own level, it won't overflow, even after a hot run. This presumes that the system was properly filled and properly bled so there is no air in the radiator/lines. I've seen some guys who insist on opening up that reservior after every drive (or before every drive, when the engine is cold), and filling up the tank. Then they wonder why it overflows.

Just a thought.

Steve

 

Correct.

 

Also correct but a closed system with catch tank IS better. The requirement to "bleed" the cooling system was pretty much eliminated when I installed the catch tank.
With the open system I had NO overheating problems with mine. It would piss after a hot run before finally attaining it's "operating level" in the header tank. I just got tired of the public pointing under my car and telling me something was "leaking". Note, I was only running 25% Ethylene Glycol at the time.

Ideally there should be NO air in the system anywhere. Air in the system promotes corrosion and with an open system you WILL have air in the header tank to allow for expansion.

 

Start back at the begining....(this thread is slightly hijacked)

Have you bled your system? Mine required bleeding 2 or 3 times before I got all the air out last year. She has not even dribbled a drop since. Once you have that done, then fill the expansion tank to the level that the manual states. I believe that my GT4 is 6cm below the top of the tank. I have that marked on a 2' long dowel that I keep in the trunk. At any time when the motor is cool, I just drop the dowel in and voila, I know if my level is correct or not.
IF after bleeding a couple times she still spits up, then its off to step 2 of your troubleshooting.....

FWIW, YMMV.....but this is what fixed my problem with spitting up last year.

JIM

 

Fill expansion tank to the level recommended by the service manual.....warm her up with the cap on, then bleed from the screw at the thermostat housing AND at the radiator itself. Open slowly until fluid starts to flow, then close. Once you think she is bled, open the cap (on a cool motor), refill and repeat atleast once.
The 308 motor tends to hold lots of air in the system once introduced, so you really should get used to bleeding it. Its super simple to do!

ALSO, make sure your cap is good. If it looks old, then go buy a new one. They are cheap and they do fail. I bought a new one for mine right down at NAPA.

JIM

 

The black tank in your photo is your "overflow" tank (expansion tank). If you need an overflow tank for your overflow tank you have some other problem. The hose to the ground is for when there is a problem causing the cap to open. Excess coolant level, excess pressure, weak cap etc. It routes the water to the ground instead of spraying the engine compartment.

The top half of your black tank is nothing but an air pocket when the coolant is not hot. It gives space for expansion of the coolant ("overflow") as things heat up. I would not worry about any air getting sucked back in. If this does actually occur it's only getting sucked back into the air space at the top of the tank.

I've got two mid-engine cars (front mounted radiators) and when I change coolant or open the system to change a hose etc. I always run the engine to full temp. with the coolant tank cap off, then bleed. Increase engine speed a few times to increase water pressure. Then I put the cap on and bleed again. I've never had issues where I've had to bleed many times to remove air. You probably... know but always make sure your heater controls are open all the way (full heat) before starting the procedure.

I think on more modern cars they use air blending to adjust temperature instead of regulating coolant flow (coolant flow always at max. in the cabin heater core) so turning heat to full is probably not needed.

 

I do it both ways and of course start with cap off because you don't want to remove the cap when the engine is hot :-( It certainly can't hurt and you will never have an overheating problem with the cap off when you're not driving it (not loading the engine).

Yes, then I put the cap on and bleed at the radiator AND at the thermostat outlet between the heads. A drive around the block is not a bad idea either just to make sure things get moved around well, but probably not essential. Again, with heater on full heat. Not sure if your car has a bleed point at the thermostat outlet or not. If not, that might explain why it seems more difficult to bleed 308's than 328's (from what I've read). Verrell make a better mousetrap (bleed screw) for the outlet. It allows you to bleed without removing the whole screw and getting sprayed.

Finally if your cooling system is marginal I would run one third anti-freeze and two-thirds distilled water (instead of 50-50). Water transfers heat better than anti-freeze.

You can also get a coolant system pressurizer from Mityvac and others. Great way to check for leaks or help expel air with the system cold. Only thing to keep in mind is if you're trying to track down one of those really elusive leaks the cold pressurizing of the system does not fully simulate an engine under normal circumstances (you don't get the expansion and contraction caused by heating and cooling).
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I definitely do not want to highjack this thread but I discovered I also have a pin hole in my 328 GTS 1986 radiator.
What is the material for the original radiator? Is it aluminium?
Just want to know so I can talk on the phone with radiator shop in my area.
TIA to all.

 

I would tend to think it's old school copper/brass. I really doubt it's aluminum. Well, one thing I can tell you for sure is that mine says Ferrari on it and also says "Made in Spain." (all embossed in the metal)

If your radiator is otherwise known good (not clogged, no overheating) I would try some J-B Weld on the pinhole if you can reach it. Possibly a much cheaper/faster fix and definitely better than introducing some leak sealant into the cooling system.

 

Yep, I agree. No liquid chewing gum will into that radiator and that's a fact!
Thanks.

 

Mine has the "made in spain" stamped on it as well. I would say it's made of brass/copper as its somewhat heavy, certainly not made of aluminum. As far as a pinhole leak, the best thing to do would be to take it to a good radiator shop and they can fix it right up, good as new.