Testarossa radiator cap, 0.9 or 1.1 bar?

I'm still using the stock 0.9 bar cap (101499) on my TR without issue. My guess would be that F went to the 1.1 bar cap (137644) on 308QV as a way to address customer complaints about excessive overflow discharge (when the real problem was the 308QV cooling system just being somewhat marginal). Interestingly, the 328 original design documents still call for the 0.9 bar cap. If someone's got a copy of that Service Bulletin for updating the 308QV cap to 1.1 bar, please post -- would like to see their state "reason" and which models it applies to.

 

Probably not, but I have no information. I noticed on the RA website that the 1.1 cap is substituted for the 0.9 cap, and the same on the eurosparesUK website (137644 replaces 101499), but they offer a 101499/C at 0.9 bar that looks like the stock 0.9 cap. Are you having a specific problem?

 

For what it's worth, I replaced my original 0.9 with a 1.1 cap several years ago and haven't had any problems. I do take my TR up to redline from time to time. I found, as Steve noted, the replacement parts on the "big" Ferrari parts sites all list the current replacement part as the 1.1 cap.

 

Less than 3psi difference should not damage anything. If it leaks with an extra 3psi, the seal is already a problem.

How hot does your car run?

Based on water:
1.9 bar boils at 245deg F
2.1 bar boils at 251deg F

Likely either cap would work fine for preventing boil over or more importantly, hot spot cavitation/steam pockets.

Just an opinion.... I’d stay with the 0.9bar cap unless running in hot ‘iffy’ conditions, or if availability is problematic. No biggie either way.

 

No problems with using 1.1 on mine for years. FWIW

Jeff Pintler
89 348tb, 86TR, 99 360 3-pedal

 

Hello
What is the original design for the cap? The oval or the square for the model year 1988.5??
I believe 101499 is the original 0.9bar and the 137644 is the revised 1.1 bar
I do have an oval one (that I don’t think it’s the original based on that it reads Motorad 20 that I believe is 20psi or 1.38bar and it works just fine) but I am getting ready for a concours and I don’t want to have points deducted on something like this.
Thanks

 

To add to my previous post because I am (without my knowledge) obviously been running a higher pressure cap than I am supposed to (20psi vs 16psi of the revised cap and 13psi of the original design)
I did some research here about it and Brian said in this 308 thread (post 21) that he would put a 30psi cap if he knew the radiators would take it,
https://www.ferrarichat.com/forum/threads/308-qv-correct-radiator-surge-tank-cap.544597/

I don’t see any bulging of my radiator, nor any coolant leaks, the only problem I had once was a hose that connected to the radiator failed and coolant started leaking, not sure if the higher pressure had something to do with it, or a combination of an old hose plus higher pressure.
Anyways I am preparing for a concours and because I didn’t have the sticker, when I was checking the pictures Steve and Doug sent me I noticed the incorrect cap and then I started wondering if the incorrect cap with the extra pressure could lead to unwanted problems, I have no idea since when I am running such cap, maybe since last year when the expansion tank was refinished (at the major service) or maybe since I got the car.
I want to get the proper cap for aesthetic reasons and also to prevent any issues due to the higher pressure.
Although maybe 20psi vs 16psi is not a big deal, but maybe it is
Brian can you please chime in??
Thanks
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@Rifledriver Brian
In the other threads you recommend the Stant 10331 for everyday use and maybe keeping the original one for concours. But that is a 308/328 thread, IF you tell me the 20psi cap could create issues and I decide to get two caps, one for showing (oval or square depending on the input of which one is original design) and one Stat for everyday driving, is the correct number for testarossas still 10331??
Thank you very much in advance

 

When I researched it was 10230

 

Thanks it seems the 10230 looks just like mine (Motorad and Stant are supposedly the same company) but rated at 16psi.
I believe the ones Brian recommended in the 308/328 forums were the ones with that red lever on top (10331), also after reading all his posts he mentioned it would work for any model pre 355,456,550 (post 27) so I have my answer if it fits Testarossas
https://www.ferrarichat.com/forum/threads/check-your-radiator-caps-now.481195/page-2

Only question that still remains is if my 20lbs one should be replaced before creating issues with those extra 4psi for everyday driving.

As for the concours the IAC/PFA suggested points deduction list the radiator cap as one that can lead to a point deduction, maybe the judges don’t care but maybe they will, and it is not worth it to have a point deducted in something as small as radiator cap.

 

Can you show where I suggested a 20 lb cap?

 

Nowhere, you suggested a 16psi one, in specific the Stant 10331, but you also said that you would put a 30psi one if the radiator would take it.
I happen to have a 20psi installed (I was not aware until today that I applied the missing sticker) so my question for you is if you think these radiators could take a 20psi cap or better get the Stant 10331 for everyday use and get a regular 137644 just for judging.
And in your experience the original design of the cap is the oval (two ears) or the square one (4 ears)?
Thanks

 

Again, can you point out where I said that? Its a ridiculous suggestion.in both cases. No 20lbs is a bad idea and 30 is worse.

 

https://www.ferrarichat.com/forum/posts/145210618/
You said it here, of course you were not serious about the 30psi one, you were just saying a higher pressure cap is always better than a lower pressure as long as the system could take it, I was curious if maybe 20psi was in the borderline of what the system could take or not, but I guess is 16psi.
Just confirm to me the STANT for Testarossa is 10331 with the red safety lever.
Thanks

 

Unfortunately the coolant decal isn't original. It is missing the degree signs. PM me.

 

I am not a fan of the lever - I like the look of the 10230 and is a proper replacement - non venting etc IIRC - just my two cents

 

Here the thread where we first discussed those Superformance reproductions missing the degree symbols:

https://www.ferrarichat.com/forum/threads/repro-coolant-tank-decals-are-wrong-anyone-have-an-original.616078

 

Hahahaha I can’t believe that I totally missed that!! I will PM you thanks

 

Yes I read all your posts in that 308/328 section, can you post a picture of your 10230 to see if it is oval or squared?Thanks

 

Sure - i originally bot the 10231 but it was incorrect in terms of vented/ not vented

 

What do you mean vented or non vented? Its a very rare radiator cap that is non vented and typically only used on race cars.

 

The term I am referring to is better described in pictures

First pic is "non-vented" and second is "vented"


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