308 QV - Correct Radiator / Surge Tank Cap | FerrariChat

308 QV - Correct Radiator / Surge Tank Cap

Discussion in '308/328' started by robo330, Feb 6, 2017.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    What is the correct Radiator / Surge Tank Cap to be used on a 1985 308QV? I am currently running a Cap rated at 13 lbs. pressure (almost 1 bar) and has 2 ears. I have seen the 4 ear type (almost square) and some rated at 9 lbs. pressure. I also have the coolant at about 45 mm from the top of the filler flange. I read somewhere in this forum that the level should be maintained at between 45 and 55 mm from the top of the flange. Comments appreciated, thanks.
     
  2. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    Thank you sir! I am glad I asked the question.
     
  3. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    Sorry folks, but one final question on the subject of Radiator Expansion Tank Caps. Seems that a Stant 10331 (with Red Release lever) or a Stant 10231 (without release lever) are OK to use for everyday conditions. If someone wanted to have the "Appearance" of the original cars and wanted a 1.1 bar cap, apparently the "Square" type is the correct type for cars in the 1985 model year. Prices for these vary from under $20 to almost $60, that's a big swing. Can anyone suggest a "reasonable supplier" if there is such a thing anymore? Thanks.
     
  4. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Owner Rossa Subscribed

    May 4, 2001
    36,599
    Birmingham, AL
    Full Name:
    Tommy
    If you REALLY want to be correct, buy the 0.9 bar cap.

    I may be wrong but I believe the 0.9 was stock but as years passed we have found the 1.1 to be more effective, at least on the QV.

    Try T Rutlands
     
  5. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
    3,153
    SanFrancisco BayArea
    Full Name:
    1983 US 308 GTS QV
    Read that link Tommy provided.

    As I understand it, there was a Factory Service Bulletin issued some years after the car was built specifying a change to a 1.1 bar cap from the original 0.9 bar cap.

    The four-eared Stant 10231 looks very similar to the factory cap. Its a 1.1 bar cap. Shop your big box aftermarket automotive parts stores. They should be dirt cheap, like $10.

    It's what I have on my car now. I have an original Italian-made 0.9 bar cap which I was "saving" for concours events just to look cool. I entered my car at Concorso Italiano this year and forgot to put on the cap. The judges did not (and should not) care.
     
  6. Owens84QV

    Owens84QV F1 Rookie

    Oct 2, 2001
    4,486
    Somewhere in NC
    Full Name:
    Greg
    Mine's a '84 QV (Euro) and I tried a 1.1bar cap and after a relatively short drive (~ 15 miles), coolant was spewing from my overflow tank (never did this before). I had my 0.9bar cap with me, swapped, and the coolant spewing issue went away.
     
  7. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Owner Rossa Subscribed

    May 4, 2001
    36,599
    Birmingham, AL
    Full Name:
    Tommy
    My impression is your 1.1 bar cap was most likely defective from new.

    That is the only way that makes sense.
     
  8. Sigmacars

    Sigmacars Formula 3
    Silver Subscribed

    Jul 19, 2006
    1,241
    The Stant 10331 Red release lever hits the Metal mesh under the lid when closing on the 328 so you ave to use the 10231 Cap.
     
  9. miketuason

    miketuason F1 World Champ
    Owner Silver Subscribed

    Feb 24, 2006
    15,833
    Cerritos, CA.
    Full Name:
    Mike
    Exactly what happened to me. Don't know why the 1.1 bar would spew coolant and not my old .9 bar. Anyway, .9bar is on now and no spewing.
     
  10. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Owner Rossa Subscribed

    May 4, 2001
    36,599
    Birmingham, AL
    Full Name:
    Tommy
    I had to do the opposite.

    That pic on my thread linked here is of a 1.1. I bought that (specifically) because my 0.9 was spewing. I had that 1.1 cap for 17 years.


    The common denominator in all our cases is the factory cap, be it 1.1 or 0.9. Like Rifledriver has said many times, they are crap anyway so none of this surprises me very much.
     
  11. GordonC

    GordonC F1 Rookie
    Owner Rossa Subscribed

    Aug 28, 2005
    4,166
    Calgary, AB, Canada
    Full Name:
    Gordon
    No offense intended to those that had this problem, but I agree with Dr. Tommy - the only way a 1.1 bar cap spews and a 0.9 cap doesn't is if the 1.1 cap is defective - not tightened correctly, weak or broken spring, etc.

    As noted by Brian A, and previously by RifleDriver, Ferrari issued a Service Bulletin with the recommendation to change to the 1.1 bar cap, so that is the proper specification since the mid-80s.
     
  12. Ricambi America

    Ricambi America F1 World Champ
    Sponsor Owner

  13. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    The reason I brought this up is that I had a cap on the Expansion Tank and then the Tank sprung a pin-hole leak. Had it repaired and Black Powder Coated, Epoxy Coated on the inside, and pressure tested. Worked for a while and then the Tank then sprung another pin-hole leak. Both these leaks were in the valley of the re-enforcing grooves adjacent to the Filler Neck. Took it off again. That's when I noticed that the top surface of the Tank looked "puffed up / bowed" as if pressure had de-formed the surface. I have been running a 1.1 Bar cap. I managed to find a re-placement tank and that is when I noticed that the top surface of this "new" tank is flat, no bowing up. To cut a long story short, I have stripped the tank, epoxy coated the inside (again) powder coated the outside (again), had it pressure tested and have now fitted it back. I was wondering if the slightly higher system pressure (0.9 to 1.1) had contributed to the leaks or was that purely coincidental? You can see why I am wary of the pressure rating on the cap. If the Tank can spring a leak, what about other areas in the Cooling System. Maybe someone else has had similar experiences or not?
     
  14. robo330

    robo330 Formula Junior

    Apr 15, 2014
    608
    Michigan USA
    Full Name:
    Karl Robertson
    I may add that the Expansion Tank was 30 + years old, but pressure testing after repair did not show any leaks until some time later.
     
  15. Rosey

    Rosey F1 Rookie

    Nov 5, 2015
    3,829
    Australia
    Full Name:
    Mark R
  16. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,288
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    The flexing from expansion will cause a leak in all of them after a given number of cycles in the stiffening grooves as you describe. Any rust will accelerate that and they rust worst on the upper surface where you cant see it. No repair will be permanent. Get a new one.
     
  17. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    4,254
    Canada
    #18 moysiuan, Feb 10, 2017
    Last edited: Feb 10, 2017
    If Ferrari had a factory bulletin in the mid 80's going from 0.9 bar to 1.1 bar, why would my 1988 3,2 Mondial model have had the 0.9 bar cap from new? It was original, I have since replaced a few years ago with an identical (but for a date stamp) four ear 0.9 cap just because of the age. But I don't know what problem the factory was solving for on the QV's other than maybe some markets had higher elevations and 1.1 bar across the board made sense for them as a manufacturer? But if it works, surely using the lower pressure than higher one makes sense. I suppose the pressure-difference between 0.9 and 1.1 is not very big, and the range for the caps is +- a bit anyways.

    There are threads on this, but unless I missed it, other than using 1.1 or the Stant equivalent being a common practice by those with experience, which I would defer to of course, I am not sure why one would prefer one verses the other but would think 0.9 is better if your car otherwise works fine at this lower pressure?
     
  18. miketuason

    miketuason F1 World Champ
    Owner Silver Subscribed

    Feb 24, 2006
    15,833
    Cerritos, CA.
    Full Name:
    Mike
    Doc, since my .9bar is holding the pressure just fine, should I replace it again anyway or is it,
    " if it's not broken don't fix it"?
     
  19. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Owner Rossa Subscribed

    May 4, 2001
    36,599
    Birmingham, AL
    Full Name:
    Tommy
    Leave it alone.

    QV's cooling systems are an enigma to me. Some run too hot in traffic (mine), others are just fine.

    Some blow past a 0.9 (mine did) others, like yours, don't.

    I cannot think of any reason in the world to change psi ratings if you are not having a single problem.
     
  20. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    37,288
    Cowboy Capitol of the World
    Full Name:
    Brian Crall
    What is better about low pressure? Higher pressure is a higher boiling point and helps prevent cavitation that destroys wetliner engines.

    Do any of us really believe we know better than the entire world of automotive engineers?

    If you want to live in the 20's and really like sitting on the side of the road boiling over that's fine but leave me out.

    I'd raise it to 30lbs if I thought the radiator would take it.
     
  21. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Owner Rossa Subscribed

    May 4, 2001
    36,599
    Birmingham, AL
    Full Name:
    Tommy
    On second thought, Mike, maybe you should go ahead and grab a 1.1 :)
     
  22. miketuason

    miketuason F1 World Champ
    Owner Silver Subscribed

    Feb 24, 2006
    15,833
    Cerritos, CA.
    Full Name:
    Mike
    I guess you're right Doc just to be on the safe side assuming I'll get a good 1.1bar this time.
     
  23. moysiuan

    moysiuan F1 Rookie
    Silver Subscribed

    Nov 1, 2005
    4,254
    Canada
    Running Evans coolant with 0 pressure actually seems like a good idea, using modern chemistry rather than reverting back to the 20's!

    Was there actually cavitation problems and engine liner damage, so the factory upped the pressures? That would be a serious problem, so I am just curious if that was actually happening. Certainly would explain why they raise the pressures.

    OEM's spec pressures from as low 5 to 42 (eg. Inifinit Q45), so higher is not better, it is clearly design dependent. Although most are at the 13 to 18 psi rating for sure, so 1.1 bar (16psi) would certainly be viewed as typical.

    Upping pressure a bit, and gaining about 10 degrees of boiling point seems pretty benign. But as my owners manual states the system is under 12.8psi (0.9 bar), with a designed max temp of about 240 degrees and with no (known) issues in my instance, I would be staying with the factory spec.

    If I am boiling by the side of the road, I will remember this thread!

    (That said, I recently replaced the coolant hoses under the plenum, no doubt originals, after noticing them bulge out like something I had never seen, normally I would not be inspecting the engine that closely while it is running, but one time I was looking and got out my lighting and thought, yikes that can not be normal! These were the first hoses I have ever seen on the verge of failure like this in my life. So for all the fuss on rad caps, I suspect a burst hose will more likely be the reason for boiling over on road side!).
     
  24. piezo

    piezo Formula 3

    May 27, 2011
    1,533
    Hong Kong
    Full Name:
    Steven

    My tank bulges on the top as well but no leak for all these years. Changing back to 0.9 bar this major service and will see if it causes any trouble at all.
     

Share This Page