Coolant escape

Most cars do not run fans after shut down. If the radiator cap is good the car will determine for itself what the proper coolant level should be by purging coolant as described. It is how they were designed to be. Cars with mechanically driven fans have been operating that way quite well for many decades.

 

Well, sort of. I had the same problem in my 308 QV. Shut off with engine hot, depending on how hot, it would blow some coolant out the expansion tank. It would do this time and time again until the expansion tank was empty and coolant level was low. I replaced the cap with the factory spec 0.9 Bar. Problem continued. The 0.9 Bar was not a high enough pressure to prevent a little boiling in the engine somewhere due to the latent heat. I replaced the cap with a 1.1 bar problem solved. Now it operates as you describe. Not uncommon with 308 QVs I'm told.

Could also be a problem with using too low a percentage of antifreeze since antifreeze raises the boiling point up to a point.

Either way, doesn't do much good to run the fans if the water pump isn't running.

 

And that is why Ferrari went to 1.1 bar caps just a couple of years after the car was built.

 

Yes, but Ferrari never told me, nor did they ever change the cap. I have had the car since new and they serviced it for years..

Also see my edit about antifreeze.

 

So your dealer was doing a bad job and Its Ferraris fault? Thats like blaming Exon Mobile because the guy spilled gas on your car.

 

I do not think it is so much about boiling as it is about thermal expansion. I have no idea comparative expansion rate water/antifreeze.

Also from needing to cool off cars in shop leaving fan on does cool off water in radiator and that does keep expansion down but you are correct, it does nothing about engine heat.

 

The car gets hotter after shut-off. I do have an auxiliary cooling pump that I keep runing for 12minutes (!) after the car stops. After approx 30s, the fan start (even if they were off when stopping engine). So there is definitively a burst of heat.

Read the 365 manual for the proper coolant blend : this manual is much more exhaustive. (I had great results with water wetter an no anti-freeze) .

The expansion tank is a one way tank: whaterver gets in cannot get back to the system. I modified one so as to slide an 8mm aluminium tube in the inlet. This tube goes to the botton of the tank and when the liquid cools down in the engine, whatever is in the expansion tank gets sucked back.

Generic caps do work great. In Europe calorstat/vernet are nice. In the US its Stant. No point in making an €8 economy with a 40 year old cap! I prefer the one with a free floating valve given my custom 8mm alumium pickup (free valve allows the coolant to flow back more easily).

Check that ignition and camshaft timings are not retarded! When were they checked last?

During an initial fill, we tend to overfill the system. It will discard the excess untill the level is as per the manual (4cm below the cap).

 

The expansion tank was not intended to return water to the system. It was designed to provide airspace needed for expansion since coolant is not compressible.
Coolant recovery tank and expension tank are 2 very different components.
It eliminates the need for a large air pocket at the top of the radiator.

The car does not get hotter after shutoff. The coolant does but thats OK. Its doing is job.

 

Sounds like the "Ferrari way"!

 

Sure, but this design only allows the coolant one way, which is a concern to me! On my steep roads (800m altitude over 7km), when descending , the system keeps on filling the damn tank, which will just split whatever it contains during the next expansionn. If the car looses sufficiently coolant this is somehow stabilized, but below the level of the cylinder head, which I really don't like.

It's a dumb 22cm tubes, 8mm diameter reduced to 7.5mm over a length of 18cm (on a lathe). I slide it in the inlet port. The 4cm that are still 8mm large do stay out of the inlet. then I secure the coolant hose with two clamps (the stock one on the inlet, a second one over the 4cm that protrude out of the inlet port).

€2.50, plus 1/2 hour on the lathe.

Now, regardless of the road I take, coolant stays at the factory level, and no more mess in the worst possible locations (my garage floor, my brother's in law new asphalt, etc.).

 

I think you are overfilling your system. The "expansion tank" in our cars is the large tank on top of the radiator core. The correct cold fill point is something 18 mm below the radiator cap. The extra tank should never get fluid only some vapor which will condense. The non-pressure cap goes on the radiator and the pressure cap on the remote tank, so that tank is pressured when running.

 

Just fill it to the top of the neck, drive the car for a while then drain whatever was catched in the overflow tank. Normally the level should be spot-on.

The point is to remove what is in the overflow tank, as it will find its way out at the most embarassing time.

But as I've said, as soon as you go down a steep parking ramp with a super hot engine, be ready for some leak shortly after.

It's a good practice to check the level, as when its low the exhaust ports of the cylinder head do not have coolant when the pump is off. Transparent Gano filters do allow to see right away if the level is correct.

 

Odd. Of all the 400's and 412s I have worked on or overseen yours is the only one that has an issue with the factory cooling system and in very hot climate too.

 

My usage is what it is: low speed alpine roads and parking lots shoe-horned in antique cities. Not exactly what these cars were designed for... If you look at the video I posted after the rebuild of my engine (https://www.ferrarichat.com/forum/threads/365-gt4-2-2-engine-rebuild.667462/#post-148795416), before reaching the top of the hill (1min 22sec on the video) the car is at 110°C on the stock setup. My Father's 365 kept on vapor-locking back then on the same road. The 412 had no issue, but the cooling design is much improved. So these cars can get hot (when running on the usual 50/50 premix). The 365 owner manuals concentration guidelines (20/80) just mitigates my issue but requires to make your own mix and change coolant twice per year.

As far as the design of the coolant system is concerned: from the back of the cylinder head to the neck of the radiator, you've got roughly 140cm. There is an 18mm height between the cold coolant level and the outlet coolant port that feeds the overflow tank. No matter what, if you go down a 13% parking ramp you will fill the tank. And this is assuming the coolant is cold and did not expand, (which reduces the 18mm height).

The reverse is true: when going up-hill you'd better have quite some gasoline in the tanks as you can easily starve the fuel pickups tank that is located in the bottom front of the 2 main tanks, whereas the return line of the k-jets are just pouring the gasoline back to the sides of the main tanks (refilling the pickup small tank would have made so much more sense!). Here again the 412 design addresses the issue.

Our habits have changed and what was acceptable back then seems quite odd today : diluting the coolant to reach acceptable temperature, fuel accumulators that spill gasoline to let you now they need to be replaced, overflow tank that trashes toxic coolant, gas tanks vented without charcoal canisters, antiquated oil catch tank, etc. You guys were lucky that a few mods were made to the cars exported to the US (return line for the accumulators, charcoal canisters in the trunk, higher pressure coolant cap). At least this made the cars somewhat less obnoxious and the garage floor less messy.

These are the sort of annoyances I prefer to address, as it makes the ride more enjoyable. On the other hand I perfectly understand that others can make it do with these few drops and consider that this is acceptable on a vintage car. You may even never experience any issue if you are lucky enough to have 6~7% parking ramps and drive the car on the highway.

I stand by my comment that I like the coolant to sit above the cylinder head exhaust ports. Easy to check regularly and makes me feel better...