[Tigers] Coolant queston

Wed Sep 9 12:20:37 MDT 2026

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
>>>>>>> _______________________________________________
>>>>>>>
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>>>>>>>
>>>>>>> _______________________________________________
>>>>>>>
>>>>>>> tigers at autox.team.net
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>>>>>>>
>>>>>>> _______________________________________________
>>>>
>>>> tigers at autox.team.net
>>>>
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