Observations on the 308 cooling system

Many people have observed that the 308 tends to run a tad warm and I have been witness here for many years that running too cold is as bad as running too warm. Ferrari wants your 308 to run at 195° F which is the smack dab in the middle of your temp gauge. That's where the engine is designed to run best. That's why that number is the middle of the gauge!

For years I had a faulty thermostat that opened too early. In warm weather it was fine, but in cool weather, the car never warmed up. The gauge would never make it up to 195 and the car never ran well when cold, because carb cars don't run right when they are not warmed up. I replaced the thermostat, and now the car comes up to 195 even in cold weather running 80 MPH down the highway. If you car doesn't, replace the thermostat. It needs to stay closed (or mostly closed) until the engine block reaches operating temp, THEN start sending coolant forward to the radiator.

So after I replaced my thermostat, I found that the car would stay right at 195° (as indicated on the gauge) as long as the car was moving, but would creep up a needle width or two above that when I was in stop and go traffic.

Of course, this bothered the hell out of me. If my daily driver can stay right on the temperature that their designers intended, why couldn't my fine piece of Italian hardware?

Naturally, I suspected the fans of not blowing enough air and started considering larger fans. But instead I decided to do a little experiment. Basically, I let the car idle in the driveway and noted when the fans came on as a function of the temp gauge. What did I find? Well, curious...the fans came on when the gauge was well OVER 195. "What gives..?" thought I, as I pondered this over a glass of nice Willamette Valley pinot noir.

The fan switch is in the radiator. It is a 195° switch. Fairly new as well. I replaced it a couple years ago. The thermostat should be opening at 195. The sender for the gauge is in the engine block, closer to the thermostat. Then it hit me.

The switch for the fans is at the bottom of the radiator, and even though the thermostat in the engine opens at 195 and starts sending coolant to the radiator at that temperature, by the time the coolant goes all the way to the front of the car through a hose, and goes through the radiator, it has cooled down. As a result, the radiator/fan switch doesn't hit 195° until the engine is quite a bit warmer than that. So thermodynamic "equilibrium" in traffic is dictated by the fan switch but equilibrium on the highway (where there is a ton of air through the radiator) is dictated by the thermostat. This explains it.

The solution is not bigger fans! The fans are fine. The solution is to turn the fans on sooner! The solution is a 180° fan switch in the radiator! (I got mine from David Feinberg here on fchat who has been running this solution in his Boxer for years and said "duh!" to my epiphany.)

So anyway, the car stays right at 195° now, no matter what--rain or shine, fast or slow. It runs right and never makes me nervous because the fans in the radiator come on well before the radiator hits 195, making sure the engine doesn't drift above this number. My gauge stays right in the middle. You might even think the darned thing was Japanese.

A highly recommended and very inexpensive mod. Want your 308 to run at the right temp?

1. Make sure your thermostat works.
2. Put a 180° fan switch in your radiator (and be sure your fans work!)
3. Bleed the coolant correctly.
4. Make sure your expansion tank cap holds pressure.

Done!

Birdman

 

You also need to make sure your radiator is working. After 30+ of use, most of them are going to flow less than maximum, and will either require bigger fans or a recore/rodding out to dissipate the heat.

Also, make sure the overflow on the expansion tank is free, which allows the radiator cap to do its job.

 

Interesting info. I put a brand new factory thermostat in my car last April. It warms up to about 170 or so and then sits there unless sitting in traffic when it gets up to 195 on the gauge. I wonder how accurate the original sensor is?

 

I've been looking for info like this B-Man! My car stays at 195 if I let it sit idle, but the temp goes up in stop and go traffic. I'm thinking that starting the fans at the lower temp may prevent the temps from running away like that. My car doesn't overheat, but I don't like seeing that temp gauge climb like that.

I found this thread on the switch, is fastradio the right person to contact about the switch?

https://www.ferrarichat.com/forum/showthread.php?t=252001&highlight=fan+switch

-Glen

 

From the "parts interchange" sticky:

-------------------------

New thermostatic electric cooling fan switch, located at base of radiator:

While having my radiator recored, I wanted to go to a "colder" switch so that the fans would come on earlier and run for longer if stopped in traffic.

NAPA FS-193 Switch: On: 82 degrees C / Off: 68 degrees C

This switch originally fitted to early 1980 Peugeot. Less than $25.00 USD. Perfect fit, completely interchangeable in every aspect.

For comparison: OEM Veglia switch: On: 85 degrees C / Off: 76 degrees C

 

Ah yes, to NAPA or not to NAPA, that is the question I think I can deal with NAPA, thanks for the cross-reference reference!

 

Birdman - I hate to argue with something that seems to work, but it seems like there is a flaw in your logic if I understand what you mean. It starts with the part where the thermostart opens and sends hot water to the radiator. When that happens it forces cool water back into the engine immediately. That water that the thermostat sends to the radiator doesn't needs to come back from the radiator before cooling starts.

The fan switch is located right at the radiator exit so that theorectically water exiting the radiator is always under 195*.

That said both of my 308's have has a wide range that they operate in depending on speed and ambient temp. And I've always blamed the fans after replacing the thermostat...

 

Just a commment, I have read allot of posts here and I have come to a conclusion. I am extremely lucky.The first item on my bucket list was a 308. Not a 328 or 48 or 55 or 60 (458 out of my realm) and the only thing I knew about Fcars was that they were difficult/exspensive to maintain. My point is that I keep reading about failures and poor design and the 2V is slow. First off all 3X8s are slow compared to what's out there. Secondly we drive it allot and it has not let us down in 5K mi. It fires right up and runs 160 -180 highway and 195 in traffic (90+ at BRC this year) The roof does not leak the engine does not smoke. (valves can be wiggled in place with new seals) It will run an honest 140 (27 yrs. old no sense in redlining too often) The seats are not soft but they are right , we can drive longer in the 308 than the Tahoe with heated leather. The fuse block is original and all terminals are clean and functional. I could go on and on--------------- I can only (so far) agree that 2nd is too stiff when cold, engine heat enters the cockpit and the handbrake is marginal at best. I have only changed the EX valves and disconnected the fast idle. I also installed the quad seals on the shift shaft just because I wanted to understand the transmission. Simply a beautiful dependable ride thanks to all the help I have received from this forum. I'm just sayin, Lost
PS I also put new 390s on from Coker and they don't "have the look" but are quiet and afford all the performance that is needed on the street.

 

I suspect your gauge calibration is slightly off. I had a Fiat Punto which for the whole of its life was rock steady at 7 o'clock on the water temp when it should have been 9 o'clock. I knew it wasn't running cold, so it never bothered me.

 

Great thinking, but it won't work. Unfortunately.
I put in a 180 probably in 1999, in fact there is a thread I started on it WAAAAY back in the day. It's a common VW aftermarket part.

Didn't do crap for my 308 QV and I gave her about 40,000 miles to show me

 

Maybe because part of the issue is the flow of water through the system (or lack of it when the engine is idling)? If the pump is spinning slowly then the water spends a long time in the engine block & so it would seem to matter less how much you cool it by (or rather when you start to cool it). Maybe there is some kind of balance to be struck between cooling capacity & flow rate vs heat generation?

Might be an interesting test to see what happens if you idle the engine at say 800, then at 1000/1100 & then again at 1500 (not that you'd want to run the thing that high really but it would provide the "top end of the scale").

It may be that if you knock the idle up a small amount the increase in flow may actually help to hold the temperature down in traffic (despite there being increased heat generated per unit of time). Not sure what would happen in reality but maybe give it a try, see what happens & let us know?

 

I replaced my stock QV fans with aftermarket SPALs, the largest I could fit in there.

No I can run in the hottest of any August afternoon in NYC where heat and humidity is sweltering and my car stays pegged at 195 water temp. It's air flow, and the stock fans just weren't pushing enough air through the radiator.

I also added an aluminum radiator, and one of Gleggy's lower vented panels, but the fans was the single change that made all the difference.

 

This is an interesting discussion, and I more than understand the varying points of view. The one thing I've learned is that old cars do not behave like new cars, especially when it comes to coolant temps and readings on the gauges. First, old gauges are simply not that accurate. Second, the sensors that control the gauges are also not very accurate. I had a problem with an old 12 cyl. Jaguar XKE, with the gauge always looking like it was creaping up to overheating. When we used some accurage instrumentation and took readings of the engine and coolant, it was clear that the car was within normal operating range. The gauge in the dash was wrong and was misleading.

Now, in Birdman's case, I've seen that as well with old cars. They were always notorious for overheating in traffic. I had an old '65 Chevy with a 283 V-8 that would go into overheat mode in traffic. I would have to put it in neutral and rev the engine up a bit to get the water pump moving coolant through the engine as well as to get the fan turning at a reasonable speed, as it was belt driven off of the crank pulley.

Electric fans have resolved a lot of the problems of low airflow when idling. But you do have to be sure they are actually coming on. And in modern cars, some now have electric water pumps that maintain a constant flow through the system. But even the mechanical pumps have better impellers that keep the coolant moving. Our old 3x8s have okay water pumps, but not up to what new cars have.

So, I guess what all that means to me, and what I was getting at is that if the gauge goes up a needle width or two when idling in traffic, and it comes right down when you start moving, and the car is not overheating, it ain't broken. There is nothing wrong with having the fans kick on at a lower temperature, but at highway speeds, the fans are worthless even if they are running. Changing the fan switch may be fixing a problem for something that doesn't need fixing at all.

 

In 26 years of ownership I have never found it nesessary to fool around with my car's cooling system. Fans come on when idling on a hot day and temp does rise, just like it did in '85.

 

I think that you all are overlooking what I feel the key point in this thread is - if you have never knowingly had your radiator core rodded and cleaned, you are dealing with 30+ years of assorted crud in the radiator. And no amount of twiddling with fans / switches / thermostats / etc. is going to be an effective fix.

I pulled my radiator years ago and had the core replaced - you'd be astonished to see the build-up inside of your old one.

Now, several years on, I've had a cool running car which -never- shows any signs of overheating.

Point is that, if your radiator itself is flowing well, then you won't have any subsequent need to jump thru hoops to keep it cool.

Thanks and Cheers - DM

 

Mine was silted up years back and a lot of sludge certainly came out of the rad when we attended to it.

Whilst you'd have thought you'd notice a progressive deterioration, that wasn't my experience. The overheating-in-traffic symptoms came on quite suddenly and it was only evident under load.

I guess there are different degrees of crud and it can push around / sit in the system in different ways.

 

My radiator was boiled out, rodded, etc, etc,


Twice.

180 switch went in and no improvement. Remember I have one of those "hotter running" QVs and I have owned it since 97. The switch has been in for 12 years. I also, when the temp trips the switch, both fans blow (I only mention this because this is how it has always been - I don't know if it is supposed to be one on with the a/c off and both on with it the a/c on.)

Additionaly I have replaced the themostat with the STOCK FACTORY replacement part, not and aftermarket item. 1.1 bar cap. Bleed properly.

Nothing made a difference.

 

Rodding out 308 radiators DOES NOT WORK. The passages are very small and cannot be cleaned properly. If the radiator core is replaced for a correct unit (ie. similar to original and not a American car core) then the car will cool well. I've seen it a ton of times and a new rad always does the trick.

 

I'm no expert, but I think Ferrari knew what they were doing when they decided to put the temp switch in they did.
I would think there is a problem else where.

Someone changed the core of my rad to what seems like a gm one and it works. I'm not to happy with it, but one thing at a time.

I had the water pump rebuilt twice, the first time wasn't done right and temps were not perfect, after the second time the cooling works spot on.

 

Even chemically? Since we are on the subject, what's the general view on chemical flushing/descaling of cooling systems and/or dismounting the radiator, laying it down & then filling it with a descaler & leaving that to do its thing (rinse and repeat as necessary!). Its probably not going to do any good if the thing is blocked solid, but is it sensible preventative maintenance or can it do more harm than good?

I've also often heard the issues to be more about blockages caused by bits of rubber flaking off the inside of coolant pipes - if that's an issue is there any kind of chemical treatment that could dissolve/remove that too?

 

This might work ok for the early carb cars but the later cars are recognised by Ferrari themselves that they are inadequately cooled! Love that haha

 

The owner's manual for my '85 QV says the thermostat opens @176-185F, and fan switch is on @ 183F, off @ 167F. At any rate, I don't think the 15 degree temperature shift you're talking about is going have a meaningful positive effect on performance once the engine is warmed up but it conflicts with the conventional assumption that more heat (after proper warm-up) is usually not a good thing.

Have you noted any change in oil temp after raising your engine temperature; i.e., is the oil cooler staying ahead of the hotter engine? I wouldn't do anything that made my oil run hotter than the nominal 195-200F that I see after my engine is hot.

I also suspect (but haven't verified) that coolant's ability to transfer heat becomes less as it gets hotter, so running nominally 15 degrees hotter reduces a critical margin for keeping the engine temp down when stressed, e.g., a long grade on a hot day.

 

Is that a fact?

 

Correct, and if you read the first paragraph under the section Cooling System it clearly states that max permitted temperature is 230 to 240 F.

 

I'll stand by my 26 year owner history without an over heating problem and having done nothing special. When I purchased the car I was told emphatically by the Ferrari tech who delivered the car to me that these cars do not over heat and if it did to shut it off immediately because something must be wrong. So far so good.