How Hot Does Your 456/550 Run? (Revisited)

Either that or it was a job security move to generate work and parts sales... take your pick, both are realistic and both have merit.

From what I have learned from our conversations on the subject, a whole new path and procedure will now be required.

I think I posted pictures of the F40 radiator I had to cut apart and repair some time back.... shocking what can be found lurking in there!

 

Mark, thanks for posting this up; I'd completely forgotten about it!

By way of background Mark was thinking one day about the possible effects of erosion/corrosion on the bypass port seating surface for the thermostat. That, and what the effects would be if the thermostat didn't seal well at the bypass port?

The answer was obvious, if leakage at the bypass port is allowed to occur at very high running temps when the thermostat is "supposed" to be fully open, you'll have a hotter running engine.

Since Mark & I both have hot running V12's here in Houston, we were excited that we might have found a possible cause/contributor to our problem.

So I began a search for an alternate thermostat that:

1. Had the same form & fitment as the OEM 'stat

2. One which began opening the radiator port, and closed off the bypass slightly earlier than the OEM

3. One which had a slightly longer "stroke" on the bypass disc to ensure better sealing of the bypass port

The Stant 13648 specifications indicated that it had all the above qualities, so I picked up a test sample and physically checked its opening temp, bypass closure temp, and stroke, then I informed Mark of the results so he could try one in his car. Based on the results he's provided below, it looks like we might have a winner. My only concern with using these is that they're made in China, while the OEM 'stats are German, IIRC. Indeed, most "pros" feel that Stant, who used to have a great reputation for high quality products, now only sells junk that is built in the far East.

It'll be interesting to see/hear Mark's results with this 'stat after more long term use.

 

John- How has your modified shroud improved cooling? Plus the 575 pulley and impeller?

I see what you mean about the extra load on the AC from the humidity, but that should be offset by the better heat absorption of humid air passing through the radiator.

 

Is there a cross reference to another supplier Stant number made not in Asia?

 

Taz, unfortunately my 550 is still up on jackstands. Haven't had any time at all to devote to it lately. We recently purchased a fixer-upper home in Montana, 4 miles out of Yellowstone's northeast entrance, so have diverted a lot of time & resources to it.

Carl, I don't know and haven't had the time to research it. Stant provided a LOT of useful, detailed engineering data in their catalog, and I don't have this level of detail from the other manufacturers.

 

I was just there on an annual fishing trip. One day a few of us need to meet there for a fishing trip.

 

The problem I had was getting the thermostat to open. I was generating air in the system under hard driving or at fairly long freeway stretches. As soon as the speed dropped to slow traffic speeds the needle went up near the red, and in one case well into the red.

The air was keeping the thermostat from opening. I've proved this to myself numerous times by very careful bleeding when very hot. Whenever I bleed it cold there was no air, only coolant so I know air bubbles were being generated, probably by the impeller, hopefully not by combustion gases.

After the installation of a steam vent line I never see above 170F, even under the worst conditions. At normal freeway speeds in ambient up into the 90s the needle stays between 120 and 190 on the gauge, so about 150 F.

 

One thing I'd be curious to know from you guys is how long it takes to go from dead cold to the fan coming on at idle. I'll time mine and post. I'm guessing under three minutes for mine. This is how it was when I bought it and the same after I rebuilt the heads. Wondering if I have a big air pocket trapped in there.

 

I know John has your modification. Did he also have your problem? Can you tell me how to make this problem. I took my silver 550 out on track during a corporate event and drove people around up to about 150mph in 20 minute stretches about 7/10ths and never had a problem. It looks to be sold so I'm not driving it until sold. I have the other red 550 never put that car to the test. How long a freeway stretch and at what RPM? I would like to see if I can duplicate your failure conditions.

oh does ambient temp have anything to do with it? In socal it is only about 80

 

Carl, On the track it overheated in 2 laps on a hot day. By this I mean the needle was 3/4 of the way up. I bleed it, refilled, drove home, about 3 hours. After 1 1/2 hours of freeway driving I ran into stop & go traffic. The gauge went into the red immediately.

Later on I drove down to Santa Barbara, no problem until I hit town and traffic lights. Gauge went up but not into the red.

This was a recurring thing until the steam vent line, now I have no more over temps, in fact it runs almost too cool. I have given it rigorous tests over the last two years, no more problems plus it makes filing the system a breeze.

Its really nothing more than what all other cars have, a line from the highest point on the engine (thermostat housing) to the header tank in an uphill run. (Air bubbles hate going downhill in water )

Call it a self bleeding line teed into the other bleed line, all going to a high point on the header tank.

I have one kit made up including modified header tank, modified stat housing, all fittings and clamps, everything except hoses. The cost of some of the fittings was exorbitant so we only bought three of those. We never planed on selling these because of costs we couldn't control.

Oh yeah, sorry, I've tested it in ambient temps over 90f

If anyone is interested in the one remaining kit PM me.

 

Mark- Your math is sound and the amount of water in the air is correct. With our IR systems, acquistion was really degraded once you got to 20 gms/m3 and I once launched an IR Maverick at 25 gms/m3, which was the all time high for absolute humidity on an AGM-65D launch. Florida, naturally. Target, a running tank, slowly swam out of the background even though it was very hot. That kind of humidity, which you see in Houston, would only about double the 2% you calculated.

 

This is from the old thread 8/19/2012 and is all I had done.

The car has been running fine on the hottest of days both in L.A. and Vegas.

Never did put in the new fans.

(Hi Bill read the F-chat threads, we are using "No-Rosion" in your car with Bottled drinking water.and 1 liter of anti-freeze )
Regards
Eric

cheers,

Bill

 

Dave's car & mine had/have somewhat different cooling issues; obviously he was getting air entrained in his system from "somewhere" and his steam vent line sorted that and works superbly to help eliminate air pockets. Although my car didn't exhibit the same symptoms as his, I installed his vent line anyway, because it's plainly an improved design for the venting of the system. As expected, it didn't help with my issues, but I'm glad I have it.

Mark & I have/had more similar issues, and as he detailed below, we think it can be chalked up to the hellish summer environment here in Houston and our overworked A/C condensers. Bill (wblink) is in a similar situation when he goes to Las Vegas, however his humidity is greatly reduced from our environment, so his A/C condenser isn't dumping quite as much heat into his radiator as ours do.

So after chasing these overheating gremlins 10 different ways from Sunday and having come up basically dry, we discovered one modification which produced a noticeable and measurable improvement. This was the elimination of the 50/50 premixed coolant, and replacing it with only the bare minimum of antifreeze, and filling the remainder of the system with reverse osmosis purified drinking water, along with the recommended amount of a well known corrosion inhibitor. This had an immediate and very positive effect on our top tank temperatures and is finally keeping our cooling systems out of that dangerous "thermal runaway" situation where the cooling system can't get rid of enough heat being dumped into it by the engine to keep both the top & bottom tank temperatures from rising.

For myself, while the change in coolant has relieved the situation somewhat, my longterm goal is to be able to sit in Houston's gridlocked traffic on a 110 degree day without having the car overheat, which is still impossible with the existing cooling system, even with the improved heat transfer provided by the change in coolant.

To achieve this, the next upgrades I'll implement in the future are a new, higher capacity radiator (I've had both a new 2 pass conventional, and a 3 pass custom unit fabricated), plus a set of SPAL's latest variable speed, brushless motor fans, mounted in a full coverage shroud. It's my sincere hope that these upgrades will finally banish these cooling gremlins completely.

 

John- Is your 550 back up and running, or are you still completing the top end job?

 

I'm like bill but run both 550s with just water and some antifreeze. 550 #1, On race track no problems doing HPDE DOT-R tires and running it 6/10ths 20 min sessions. I wanted passengers to have a thrill not be scared. On 550 #2, I just tried to duplicate Dave's failure after 1 hr hard running then immediately off freeway stop and just idle with A/C running and no problems stationary for 5 mins. My guess is ambient is about 80*F so pretty cool summer in SoCal. I think I need longer heat soak and higher ambient temps. When I have time I will take a trip to the Valley they get 100*F up there.

 

Taz, nope it's still up on jackstands with the heads off. There are 3 cylinders that are still giving me dodgy leakdown numbers without the heads, and it bummed me out, so I pulled off the project for awhile. I'm going to get stuck back into it this weekend and begin the task of pulling the short block and will go into it to see how the pistons & rings look.

Based on Josh's PPI back in 2010, we knew the engine had leakage, so I negotiated a purchase price for the car that was in keeping with the leakdown/compression numbers, and figured I'd sort it out in the future. When I found the worn & out of spec valve guides in the heads last year I was hopeful those were the cause of the dodgy leakdown measurements, and in some cylinders they were, but in these last three cylinders, it appears the problem is down in the block. Always something, eh?

 

John- Unlucky. Hopefully you will find something simple like a broken ring or three.

 

Glass view for Ferrari 456m