[Healeys] Coolant bypass port in the head - 6-cyl
Bob Spidell
bspidell at comcast.net
Tue Mar 29 22:38:08 MDT 2022
Never used any, in this car anyway (for emergencies only, IMO). It was
solder.
On 3/29/2022 7:42 PM, Alan Seigrist wrote:
> Bob -
>
> One thing it might be is stop leak. Stop leak can plug up a system if
> there's air in there somewhere, and stop leak will form clumps if you
> don't drive the car every day. Using stop leak is fine, but you have
> to flush the system out thoroughly after the stop leak has plugged the
> holes in your system.
>
> Best,
>
> Alan
>
> On Wed, Mar 30, 2022 at 10:10 AM Bob Spidell <bspidell at comcast.net> wrote:
>
> It's been years, and my memory is (always) suspect, but I believe
> I put a RS in a pan of boiling water (with a frog, of course). The
> conical top of the RS goes up in the thermostat housing, so I
> think the moving part can only go down. IIRC, the sleeve only
> moved a quarter-inch or so and I thought at the time it would only
> cover maybe half of the bypass port.
>
> I mostly came to the conclusion Michael did: Covering the port or
> not makes no measurable difference; it's certainly not a cure for
> overheating Healeys.
>
> On another note; I drained my BJ8 to install another heater valve
> and block valve and, when filling noticed some crud blocking a
> couple tubes. It was hard to extract, but when I did it appeared
> to be solder that had come off from somewher (by the shape
> probably from around a tube). Rad's not leaking, but I'm not a
> happy camper; this was an 'uprated' core installed less than 6 or
> 7 years ago.
>
>
> On 3/29/2022 7:00 PM, Alan Seigrist wrote:
>> Hi Bob -
>>
>> the Robertshaw thermostats are nicely made, but they open the
>> wrong way around... let me do some measurements as I am dealing
>> with the cooling on my BJ8 now. I have a robert shaw... as well
>> as another sleeved thermostat as well as the bellows.
>>
>> Best,
>>
>> Alan
>>
>> On Wed, Mar 30, 2022 at 9:54 AM Bob Spidell
>> <bspidell at comcast.net> wrote:
>>
>> Years ago, someone--might have been BCS, but I'm not
>> sure--was selling a Robertshaw thermostat with a brass sleeve
>> soldered to it (Robertshaw thermostats have a center portion
>> that moves up and down). The one I bought was 160deg; I
>> desoldered the sleeve and soldered it to a 180deg Robertshaw.
>> I bought one of the original, bellows-type from
>> Kees--whatever happened to him?--but never installed it;
>> heard they were the 'fail closed' type, which could turn a
>> minor failure into a catastrophe (still have it around
>> somewhere).
>>
>> https://flowkoolerwaterpumps.com/products/robertshaw-330-160-degree-thermostat
>>
>>
>> On 3/29/2022 6:35 PM, Alan Seigrist via Healeys wrote:
>>> Harold -
>>>
>>> Thank you, now I understand how the whole thing is supposed
>>> to work. The sleeve works to cut off the bypass so that hot
>>> water is not recycled into the system after it warms up.
>>> FWIW, this only applies to the 6 cyl, the 4 cyl doesn't have
>>> any sort of bypass.
>>>
>>> Yes, I think it would be great if you could share with us
>>> which thermostat to purchase and how to modify it.
>>>
>>> Best,
>>>
>>> Alan
>>>
>>> On Wed, Mar 30, 2022 at 1:28 AM Harold Manifold via Healeys
>>> <healeys at autox.team.net> wrote:
>>>
>>> The coolant bypass plays an important but problematic
>>> role in the Healey’s cooling system. When the thermostat
>>> is closed coolant returns to the water pump via the
>>> bypass. See the red circle on the attached picture. The
>>> bypass is important for three reasons: its allows the
>>> coolant in the block to continue to circulate and come
>>> to a uniform temperature before the thermostat opens, it
>>> prevents hot spots that could develop from stagnant
>>> coolant and it prevents the water pump from dead heading.
>>>
>>> The problematic part is in the original design the
>>> bypass was closed by a sleeve on the bellows type
>>> thermostat when the thermostat opened. The original
>>> Bellows type thermostat used a volatile liquid and were
>>> not reliable and were not suitable for the 7 psi cooling
>>> system pressure. Wax type thermostats are much more
>>> reliable but they do not have a sleeve to close off the
>>> bypass. There may be some expensive wax type replicas of
>>> the original bellows type.
>>>
>>> After looking at many options the best option for a
>>> reasonably priced wax type thermostat with a sleeve to
>>> close off the bay pass is the modified Land Rover Series
>>> ll thermostat. If anyone would like to know about
>>> modifying the Landver thermostat let me know. It can be
>>> easily done.
>>>
>>> Harold
>>>
>>> *From: *Michael Salter via Healeys
>>> <mailto:healeys at autox.team.net>
>>> *Sent: *Tuesday, March 29, 2022 9:17 AM
>>> *To: *Healey list <mailto:Healeys at autox.team.net>
>>> *Subject: *Re: [Healeys] Coolant bypass port in the head
>>> - 6-cyl
>>>
>>> The coolant travels from the bottom of the radiator to
>>> the water pump into the block then from the block into
>>> the head then through the thermostat to the top of the
>>> radiator.
>>>
>>> M
>>>
>>> On Tue., Mar. 29, 2022, 11:57 a.m. Elton S,
>>> <eps2660 at gmail.com> wrote:
>>>
>>> As a related question, what is the direction of flow
>>> through the radiator - up from the bottom or down
>>> from the top?
>>>
>>> Elton
>>>
>>> BJ7
>>>
>>> On Tue, Mar 29, 2022 at 11:44 AM Michael Salter
>>> <michaelsalter at gmail.com> wrote:
>>>
>>> As Gary points out, and far as I have been able
>>> to figure out, the bypass passage is open when
>>> the engine is cold, the idea being that by
>>> "short circuiting" the radiator the coolant in
>>> the heater and bypass passage will warm up more
>>> quickly and the heater will produce heat more
>>> quickly.
>>>
>>> We had a slew of the "shrouded " type
>>> thermostats that I bought when Smiths Canada
>>> closed down. The part number was 43570/28 and we
>>> used to sell them to customers who reported
>>> overheating problems.
>>>
>>> I stopped promoting them as a potential solution
>>> to overheating issues after being taken to task
>>> by a customer who did an extensive study of the
>>> issue and proved, at least to my satisfaction,
>>> that they improved cooling not one iota.
>>>
>>> M
>>>
>>> On Tue., Mar. 29, 2022, 10:47 a.m. Alan
>>> Seigrist, <healey.nut at gmail.com> wrote:
>>>
>>> I don't know if this has ever been answered
>>> before, but where does the little bypass
>>> port begin?
>>>
>>> What parts of the head does that bypass come
>>> in contact with?
>>>
>>> When do you want to cover the port with a
>>> sleeve (when coolant is hot or cold?)
>>>
>>> I ask because the old bellows style
>>> thermostat will cover the bypass port when
>>> the thermostat opens
>>>
>>> then I have another wax thermostat and the
>>> sleeve actually cover the bypass when it is
>>> cold, and doesn't cover it when the
>>> thermostat opens.... so it works exact
>>> opposite to the old bellows style thermostat.
>>>
>>> confused....
>>>
>>> Cheers,
>>>
>>> Alan
>>>
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>>
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>
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