[Tigers] Coolant queston

Wed Sep 9 14:26:06 MDT 2026

Joe,
Yes, the stock system is faulty.  It will blow off coolant down to a low
level in the stock tank.  If you look, that level is not as high as the top
of the radiator, therefore, the top rows of the core don't have fluid, so
no cooling from them!  Shelby put that tank too low, on his Cobras
it is higher up above the radiator... thanks 'ol Shel... Some guys have
success locating it up by the firewall, where they remove the brake
servo. (not recommended)

Adding a recovery tank with the recovery cap will allow the stock tank to
stay at the top.  When the coolant gets hot, it expands which will
just go on the ground with the stock system but now into your recovery
tank.  When it cools, it gets drawn back into the stock tank like it
has a straw and it is sucking it back up.  The port in the expansion tank
needs to be at the bottom so it will always suck liquid.

I would fill your stock tank to the top when cool.  Put just a little in
your expansion tank.  Now drive it to get it real hot. If nothng comes out
of the expansion tank (it should have its own overflow tube at its top),
you are good.  Now after it all cools down, open your cap.. the stock
tank should be full and you should always keep a little at the bottom of
the expansion tank.  A transparent tank like a modern car lets you
see that, your trick aluminum tank doesn't so you need to take its cap off
and look inside.  The expansion tank is not sealed to the atmosphere
so coolant will evaporate over time and you need to add  some to that
tank.  Mine is up under the fender, kind of a pain to add, I use a left
over wine bottle, its skinny neck works great.
Gary Winblad

Gary Winblad

On Wed, Sep 9, 2026 at 11:20 AM Joe Brown <jbbrown1980 at gmail.com> wrote:

> When I first got the car running I didn't know how much coolant to have in
> the expansion tank so I started out with it filled up.  It boiled over
> pretty quickly so I kept experimenting with it until I found a level that
> didn't puke; maybe about a quarter full.  I added the overflow tank later
> just in case.  I suppose I could fill the expansion tank back but I haven't
> bothered.
>
> I tried using a 13psi cap but it blew a radiator hose off, so I went back
> to a 9psi cap. I also read that the higher pressure could be hard on the
> heater core. I also installed an electric fan that comes on at 190 degrees
> and I haven't had any other issues.
>
> Thanks,
> Joe
>
> On Wed, Sep 9, 2026, 12:35 PM Gary Winblad <winbladgary at gmail.com> wrote:
>
>> Yes, I think it is a recovery type!
>> How high is the coolant in the TIger tank?  If it is full, you are good
>> Gary Winblad
>>
>>
>> On Wed, Sep 9, 2026 at 9:13 AM Joe Brown <jbbrown1980 at gmail.com> wrote:
>>
>>> I went back and looked at my cap.  Everything I've read says that the
>>> recovery style caps have two seals; one at the top of the cap and one on
>>> the spring loaded part.  Here is a photo of my cap.  Can I assume that I
>>> have a recovery style cap?
>>> [image: PXL_20260909_160805998.jpg]
>>>
>>> Thanks,
>>> Joe
>>>
>>> On Wed, Sep 9, 2026 at 7:00 AM michael king <michael.s.king at gmail.com>
>>> wrote:
>>>
>>>> Joe.
>>>>
>>>> You describe how the system works..but without a specific recovery cap
>>>> the water cant get back into the header tank once its out.. it just becomes
>>>> a catch overflow
>>>>
>>>> Regards
>>>>
>>>> Michael King
>>>>
>>>> On Wed, 9 Sept 2026, 19:57 Joe Brown, <jbbrown1980 at gmail.com> wrote:
>>>>
>>>>> I've got the regular pressure cap on the original expansion tank and
>>>>> my understanding was that it would open up if the coolant was boiling over
>>>>> and the excess coolant would then flow into the catch can.  And then as the
>>>>> coolant cooled down it would be sucked back into the expansion tank.  Do I
>>>>> need some other kind of radiator cap?
>>>>>
>>>>> Thanks,
>>>>> Joe
>>>>>
>>>>> On Tue, Sep 8, 2026 at 5:50 PM Gary Winblad <winbladgary at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Joe,
>>>>>> Hopefully you also added the double seal cap?  You need that to make
>>>>>> it a recovery system, not just a catch can
>>>>>> With recovery, the overflow is pulled back in during cool down.  That
>>>>>> is what makes the radiator always full to the top,
>>>>>> for a few more tubes of cooling.
>>>>>> Gary Winblad
>>>>>>
>>>>>>
>>>>>> On Tue, Sep 8, 2026 at 3:21 PM Joe Brown <jbbrown1980 at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Hey,
>>>>>>> I added an overflow tank several years ago and I went with one I
>>>>>>> found on Amazon.  It's called an 800ml aluminum expansion tank from BDFHYK
>>>>>>> and it's around $25.
>>>>>>> [image: image.png]
>>>>>>>
>>>>>>> I wasn't using the remote oil filter, so I mounted this tank in the
>>>>>>> filter bracket.  This tank is slimmer than an oil  filter so I had to
>>>>>>> fabricate a new clamp to secure it.  Here is a photo.
>>>>>>> [image: PXL_20260908_220938306.jpg]
>>>>>>>
>>>>>>>
>>>>>>> Have Fun,
>>>>>>> Joe Brown
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Sep 8, 2026 at 4:51 PM Mark L via Tigers <
>>>>>>> tigers at autox.team.net> wrote:
>>>>>>>
>>>>>>>> So, the plastic kit you mentioned will stand up to the heat of the
>>>>>>>> engine compartment okay?
>>>>>>>>
>>>>>>>> In a message dated 9/8/2026 5:18:10 PM Eastern Daylight Time,
>>>>>>>> winbladgary at gmail.com writes:
>>>>>>>>
>>>>>>>>
>>>>>>>> Mark,
>>>>>>>> IT is worth adding.  Cost and trouble are minimal. You can buy a
>>>>>>>> kit at the auto parts store (plastic tank, dual seal cap, tygon hose) for
>>>>>>>> cheap.
>>>>>>>> Hard to say exactly how much cooling capacity it really adds..  it
>>>>>>>> DOES keep the radiator full to the top, the extra quart doesn't matter.
>>>>>>>> I put the tank in the wheel well behind the headlight, out of
>>>>>>>> sight, out of the way.
>>>>>>>> A very important reason to add is that it stops the leak of
>>>>>>>> antifreeze, which is toxic to small animals.  When we were in Big Sky for
>>>>>>>> SUNI, we stopped
>>>>>>>> into a small museum.  I will never forget the huge stuffed Condor
>>>>>>>> on display.  The placard said he died from driniking anitfreeze from an
>>>>>>>> overheated car... so sad, he was beautiful rare bird.  Please
>>>>>>>> install the system..
>>>>>>>> Gary Winblad
>>>>>>>>
>>>>>>>> On Tue, Sep 8, 2026 at 7:56 AM Mark L via Tigers <
>>>>>>>> tigers at autox.team.net> wrote:
>>>>>>>>
>>>>>>>> I know some have added an overflow to the expansion tank. This
>>>>>>>> seemingly allow the expansion tank to be filled to the top rather than only
>>>>>>>> 1/2 full.  Is the addition of an overflow worth installing?  It appears
>>>>>>>> this would add an additional  1 quart to the system.   How much difference
>>>>>>>> would this make on cooling?
>>>>>>>> Thanks,
>>>>>>>>  Mark L
>>>>>>>> _______________________________________________
>>>>>>>>
>>>>>>>> tigers at autox.team.net
>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>>
>>>>>>>> tigers at autox.team.net
>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>
>>>>> tigers at autox.team.net
>>>>>
>>>>> Donate: http://www.team.net/donate.html
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>>>>>
>>>>>
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