Observations on the 308 cooling system

There was a service bulletin that went to dealers in areas of California in '84 or '85 which specifically advised something to the effect of the cars running very hot in those climates. Brian Crall posted it on here forever ago as he was the lead mechanic at the dealer when that particular memo was received. Wish I could find his post......

 

You are correct. The increased hp and a few other things were not delt with properly on the QV model and it is that model specifically that has a problem - all other things being equal

 

Never looked at my fan switch but my fans turn on at around 175-185*F. My thermostat is a 71* stat so my fans rarely turn on.

 

Hi all.

I've thinking about the same question that Birdman tell us in this thread, and there's nothing wrong about it. I'm also thinking that there's a little delay between the temperature on the engine and the temperature on the radiator, and that this "delay" maybe runs to overheat the engine in city.

But I have another question:
The Euro QV have the same overheating problem than the US QV?

If not, then I think that the electronics maybe has something to tell us because you know US engines must run hotter than Euro engines in order to pass the EPA regulations -more temp, less pollution emitted-. Also, if you read the owners manual you can see that the "ignition basic advance" is different between Euro cars and US cars. Maybe swapping the US electronics to Euro electronics would help.

Maybe I'm wrong, I'm not an expert; only supposing.

Any thoughts?

 

I was informed that a change was made to the water pump pulley to increase coolant flow. I don't know if that is accurate, nor do i know the details but the person who told me worked as a Ferrari mechanic at a dealer in 84. Perhaps 85s, like mine, were built with that change in place.

 

I am not sure about that but I do know that one thing Ferrari DID do was convert to a two belt set up in late 84 or so. They were addressing a little problem that some single belt cars had of slinging the damn belt off. I have one of those cars. I had lost three in about 6 years.

Dec 83 was the service bulletin update about this. They offered a kit to the dealer to swap to a two belt system if someone was having problems. Several years ago I was able to source one - probably the last on earth - and installed it on my car. So far so good.

BTW, I have always felt that Ferrari's single belt design was more than a little responsible for failing water pumps on these cars. In my opinion the tension required was probably a tad too much for the bearings to tolerate long term. But, again, that is just my opinion.

 

For grins, can you list out the P/N you used (fans, radiator, etc.) to contain upgrade info in this thread? Thanks!

 

A little more on the water pump pulley thing. I was looking at my shop manual for the 308 QV and 328. I has separate figures showing the belt arrangement for the 308 QV and the 328. In the figure for the 308 QV is shows a 2 belt setup with water pump driven off the same belt as alternator. For the 328 they show a 3 belt set up with the water pump driven off a separate belt. It is also apparent that the water pump pulley is smaller in diameter for the 328, thus the pump will rotate faster and circulate more coolant. I also looked in my '85 owner's manual. As owners of 85 cars know, the 85 manual is an 84 manual with a label pasted over "1984 models". The manual also shows a 2 belt setup. However, when I look at my car (85 QV) it has the 3 belt setup, as indicated in the workshop manual for the 328. So, obviously at some point Ferrari did changed the water pump pulley and went to a 3 belt system. But when? Birdman's car clearly has the older 2 belt system with larger water pump pulley. Also, looking at viper_driver's thread, on page 14 it shows a 2 belt setup and the larger water pump pulley. http://ferrarichat.com/forum/showthread.php?t=262409&page=14. As I recall, his car was an 84 QV so it looks like the switch to 3 belts and a smaller WP pulley was introduced in '85 (or late 84?) which is likely why I have not had the coolant temp problems observed by others. Apparently the 3 belt setup with smaller WP pulley was then carried over to the 328.

Oh, 2belt to 3 belt with AC (which is what I am taslking about, cars with AC)

1 belt to 2 belts for cars w/o AC

 

Again, his two belt system is the "newer" old system. The original old system as found on my Jan 84 is a single belt

I did not know about 328's having three belts with a smaller wp pully. I always wondered how Ferrari seemed to fix the cooling problem without changing the radiator or coolant capacity. I guess that answers my question. Thanks.

 

Birdman's (or at least the car shown in his timing belt write up) IS a 1 belt system if you forget about the AC. 1 belt drives the WP and gen. That's most likely the same as your early 84. It is the same as viper_driver's early 84.

When I was talking about 2 or 3 belts I was including the AC belt. I think this is just semantics.

 

You are correct. When I say one belt, I mean one for the alt AND wp. My "upgrade" kit put a single belt on the wp and a single belt on the alt - my definition of a two belt set up.

I wasn't including the a/c belt on either of the above

Glad that is cleared up for others reading this

 

You can not conclude that the engine runs cooler with the fans on. Assume the fans come on at TH and switch off at TL. Typically TL will be 15 to 20 degrees below TH. So first of all, for the fans to come on the coolant temp must exceed TH. There are 5 possibilities:

1) The coolant temp never exceeds TH and the fans remain off. The coolant temp could be any where below TH.

2) The coolant temp rises above TH and the fans switch on. The additional cooling provide by the fans is sufficient to reduce the coolant temp below TL and the fans switch off. After the fans switch off the temp will again rise to above TH and they will switch back on. Thus the temp will cycle from somewhat above TH to somewhat below TL.

3) The additional cooling provide by the fans is sufficient to reduce the coolant temp below TH, but not below TL. Thus the fans continue to run and the engine temp will be between TH and TL.

4) The additional cooling provide by the fans is not sufficient to prevent the temperature from continuing to rise above TH. In this case the coolant temp will continue to increase and may (should) stabilize somewhere above TH but below the maximum allowed operating temperature.

5) Same as 4 but the coolant temp fails to stabilize below boiling point and the engine over heats.

For any given car, which of the 5 scenarios happens on a given day depends on the ambient temperature. If you lower the fan turn on temperature you are just making the 5 scenarios trigger at lower ambient temperature. In the case of scenario 4, lowering TH will have no affect on what temperature the system stabilizes at.

 

Spot on. One of the first things I noticed when I bought my 328 was the same "feature" as previous Lotus Esprits I have owned, which have the same cooling system layout. Idle in traffic, temp goes up (but not to excessive level). Put your foot on the gas to increase idle, still stationary, and the temp quickly decreases. Its down to the long path the water has to take to/from the rad I reckon. Needs some water pump revs to overcome the resistance and get the water moving. In this scenario its immaterial whether the fans are on or not, if the water is not moving at enough volume to transfer enough heat from engine to rad.

 

The process is a little more complicated but in simple terms increasing the flow rate of coolant through the system results in making the transfer of heat, both from the engine to the coolant and from the coolant to the air passing over the radiator, much more efficient with the result that the coolant temp drops even though more heat (due to burning more fuel) is generated in the engine.

 

Hey all ... a couple thoughts.

Regarding engine hp, this is only going to be factor when you are driving at full tilt loading the engine. I'd say 99.9% of you are having over heating when you're idling around going on ice cream runs yes? ... making minimal power so engine hp should not be a factor if you're getting hot.

I run my car at full tilt. I was never having over heating problems running around town, idling, etc. ... just when I had the snout of the 308 under the exhaust of another car for a solid 10-15 min under full load she would climb to 240 f. If I drove normally she would go to 195 f and stay there all day ... but never lower unless I was traveling down long hills.

I discovered one of the cylinders was leaking into the water jackets. This leakage was mininimal. You had to wait maybe 10-20 seconds to hear a bubble in the water jackets (shop had to be silent ... even a leaking air line would mask the bubble) and the leakdown number was only 6% so no one would have thought the gasket was leaking from compression or leakdown numbers.

I made my own head gaskets out of aluminum so that kind of changed the experiment a bit because of the heat exchange from head to block thru alumium is more efficient. I noticed this when a leaking aluminum head gasket was running way cooler.

With aluminum head gaskets that are sealing properly my car seems to be nowhere near over heating even under full load for 15 minutes. The water did not go over 195 f. I also shoot the tank with an IR pyrometer to double check temps and I have aftermarket oil and gearbox temp gauges to double check everything. It is pretty hard to load an engine for 15 minutes continuously on a typical road but I have some good mountains for testing this problem. The last couple of runs my fans didn't even turn on.

Getting hot at idle is nothing to do with horsepower of the engine ... it's either water flow rate, air flow rate, or hot air getting right into the water jacket via leaking gaskets. My buddy has a big block El Camino that is acting like a 308. I thought I was going to discover a blown head gasket but turns out he had his tranny rebuilt and it is binding up ... we could barely turn the engine over by hand so that is what his problem is (sigh).

I guess apart from JohnK on here I'm the only one with a 308 that doesn't get hot? ... interesting. Looking for a leaking head gasket is not something everyone looks forward to and I basically avoided looking at it because I thought my car would have run hot all the time with a leak ... wasn't the case.

My consipracy theory is Ferrari distributed that TSB instead of replacing head gaskets . Wasn't there an Aston Martin or something in the 70's that was wet sleeve that almost put them out of business 'cause of head gasket problems?

I was all set to put a high flow water pump on because I thought my problem was localized boiling since it was only an issue under sustained full load. I am really amazed at how cool she runs now.

I lit off my Hayubusa throttle body motor yesterday in the car vs. on an engine stand with a remote radiator. This motor has aluminum head gaskets and an upgraded water pump. This was the first time running 'er with the factory radiator, etc. Once she got hot the fans shut themselves off sitting in my shop ... something my other car didn't do when I had this radiator & fan switch installed so it was an interesting observation/comparison. My driver has aftermarket fans ... the car with the Hayubusa throttle bodies has the stock fans AND the a/c core sitting in front of the radiator just to include all the variables at play .

cheers

 

You bring up an interesting point. I track my car. Less now, but years ago I would drive the total **** out of it. Often they were in the summer too with temps in the 90's and up. I could stay on the track, bouncing the needle off the redline for 25 min sessions all day long and the only problem I ever had was oil temp. In fact it was the oil temp that limited my time out there. The water stayed dead on normal but I would have to pull off to let the oil temp settle.

Moving in slow traffic in Atlanta on the way over in the evening, the water temp would nearly want to swing to full right and the oil would always stay normal or at least barely rise.

 

A baisc question but when the car is running at highway speeds is the car primarily cooling because of the air pushing through vents and under the car, or the air pushing through the radiator which is cooling the coolant flowing through the car?

 

By air pushing through through the vents, do you mean in the engine compartment? No, the engine is cooled by cool water returning from the radiator. Air through the engine compartment provides minimal and inadequate cooling for the engine, but the headers and cats are likely to get a bit too hot (and cook nearby components) with no air flow.

 

So if the air at highway speeds is cooling the car sufficiently but not in stop and go traffic the issue would have to be fan efficiency. The only other variable I can think of a highway speeds is that the water pump may be working to push the water more quickly through the system. So wouldn't the solution be larger fans and electric water pump? Just trying to resolve issues in my own car and these worked on vettes overheating.

 

From my perspective the issue would seem to be more along the lines of rate of water circulation that air flow. That is why Ferrari change the QV water pump in 84 to one with a smaller driver pulley, thus increasing the pump speed and water flow rate at idle.

The idea that the water temp rises when the car is idling isn't unique to Ferrari or other exotics. All cars do it. These days all cars have electric fans which switch on and off based on water temp. Those switches generally have a 15 to 20 degree difference between on and off. So that means in any car with eclectic fans which cycle on and off at idle the water temp is varying by 15 or 20 degrees. It may not be apparent in the gage because the electronic may be designed to show a longer time average temp so unless the temp goes up (or down) and stays there the gage won't respond to the cycling.

 

Are there electric water pumps that can be used in place of the mechanical pump? I still remember qv owners of all years having overheating issues though I was not aware of the upgrade in 84. I guess another issue would be the belts if one went with an electric water pump. The belt routing would need to be modified or a dummy pully incorporated on the electric pump.

Something else though, other fchatters have reccomended pushing on the throttle to increase engine speed in stop and go traffic, and subsequently increase pump action, but this has never resulted in my engine temp decreasing. So I think there is something to fan efficiency in conjunction with water pump speed. I guess what I am saying is if you held your throttle in neutral at 4K rpms in 90 degree heat what are the chances the car would cool sufficiently.

The problem with 308s is there are not enough of them out there to warrant real vendor support. The muscle car vendors have such a large potential client base they constantly develop tech to improve performance and reliability. 308 cooling should not be such a hit or miss science. There are only a few variables (pump, radiator, hoses, fans, and thermostat).

 

I read this thread started by Birdman with interest. BTW, I got his fuse boxes installed in my 308.. I had cooling issues since I bought my 308 6 years ago. I tried most of the solutions discussed here and even after I rebuilt the engine with higher compression pistons ann a few performance enhancements, the car would still overheat. My main worry was heat soak after tracking the car at the Mont-Tremblant racing track (ex-F1 track for the Canadian Grand Prix). I had the original rad restored at a specialty shop. No real improvement. A Ferrari Master Mechanic that I met at the track told me that the rad/fan set-up as the weakest point of the 308QV.

I finally got a custom aluminum rad made for my 308 with pull fans. No more overheating. Car runs cool under extreme conditions. Even after tracking the car at high speed close to the RPM red line for 15-20 laps, the temp is back at 168 after one cooling lap. I can be stuck in traffic for hours in 90 degrees weather, the temp never goes higher than 195. My oil temp is always 195-210 even in the most extreme tracking days.

I will redo the front in carbon fibre this winter.

I've included a picture of the current set-up

Cheers!
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Is 168 your normal temp? That's 75 C. Isn't that too low?