Thermostat housing bypass.

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Fuel.inj
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#1 Thermostat housing bypass.

Post by Fuel.inj » Mon Apr 01, 2024 12:07 pm

I noticed that my S2 running cold after a lay up so this morning I decided to replace the suspected thermostat and replenish the antifreeze.
When I removed the outer thermostat cover I was surprised to find that there was no thermostat installed?? and the bypass solid pipe was blocked not only with crud in the pipe but there is this sort of valve like a miniature horseshoe as shown in the photograph which seems stuck also. I am afraid to force it.
Does it come out? What does it do? Can it be replaced as I cannot find a part number for it.
Any advice will help as this job is not going well at all.
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Paul.
1971 S2 FHC (Opalescent Blue)
1990 Mercedes Benz 260E
1972 Saab 96 V4
A number of Nortons.
1939 Triumph T100

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mgcjag
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#2 Re: Thermostat housing bypass.

Post by mgcjag » Mon Apr 01, 2024 12:40 pm

That is not the bypass its the air bleed vent..havent seen that little "jiggle pin" in there before but its quite typical for them to be fitted to a thermostat. It lets air bleed back. The thermostat isn't stuck in the houseing that you've removed is it?.. Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#3 Re: Thermostat housing bypass.

Post by Fuel.inj » Mon Apr 01, 2024 12:49 pm

Hi Steve, there was no thermostat at at all. I just came across this item and part number in SC catalogue. Any suggestions? Do I just fit a new thermostat or do I bite the bullet and get one f these new valves?
https://www.scparts.co.uk/en/breather-valve/207514/
Paul.
1971 S2 FHC (Opalescent Blue)
1990 Mercedes Benz 260E
1972 Saab 96 V4
A number of Nortons.
1939 Triumph T100

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abowie
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#4 Re: Thermostat housing bypass.

Post by abowie » Mon Apr 01, 2024 1:12 pm

You should certainly have a thermostat.

C28067 looks to be the correct part.

I would leave the air bleeder as it is; it doesn't really do much.

I would humbly suggest you consider buying from SNG Barratts, rather than SC Parts.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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#5 Re: Thermostat housing bypass.

Post by Fuel.inj » Mon Apr 01, 2024 1:30 pm

Thanks for the advice Andrew. I’ve already purchased the thermostat and gaskets from SNG and after a little bit of gentle persuasion have just got that bleeder moving a little so I’ll just get it all back together and see how it goes. ATB. Paul.
Paul.
1971 S2 FHC (Opalescent Blue)
1990 Mercedes Benz 260E
1972 Saab 96 V4
A number of Nortons.
1939 Triumph T100

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#6 Re: Thermostat housing bypass.

Post by mgcjag » Mon Apr 01, 2024 1:50 pm

Hi Paul.....you need to look inside your thermostat houseing where the foot of the thermostat meets to block off the bypass from the waterpump...if a prebious owner has removed the thermostat they may well have blocked the bypass....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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#7 Re: Thermostat housing bypass.

Post by Fuel.inj » Mon Apr 01, 2024 2:48 pm

Just checked that now Steve and it’s all clear. I will put it all back together now. Will let you know the outcome.
Paul.
1971 S2 FHC (Opalescent Blue)
1990 Mercedes Benz 260E
1972 Saab 96 V4
A number of Nortons.
1939 Triumph T100

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#8 Re: Thermostat housing bypass.

Post by Fuel.inj » Tue Apr 02, 2024 1:23 pm

Installed the thermostat, filled with antifreeze, run up to temperature, showing normal on gauge, fans kicked in as required. All seems normal thankfully. Thanks for your responses.

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Paul.
1971 S2 FHC (Opalescent Blue)
1990 Mercedes Benz 260E
1972 Saab 96 V4
A number of Nortons.
1939 Triumph T100

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