cooling and waterpump pulley misalignment problems

[Heuer]

Not quite. The original thermostat #C12867/2 was a Smiths alcohol filled bellows type which had a moving sleeve. They were also made by AC Delco, Quinton Hazel and Lucas.


This design meant the by-pass 'slot' is open when the thermostat is closed. The coolant remains within the engine to shorten warming-up time. When the thermostat commences to open the screen moves upwards (to the right on the photo below) and gradually shuts the by-pass. Coolant now flows from the engine to the radiator only.


However these alcohol filled bellows thermostats were not suitable for use above 4psi so when the coolant pressure was changed to 9psi after cars #879043/850656/861090/888240 they used the Waxstat type #C20766/2.

The disc you refer to does nothing on the 3.8 manifold as it is too small and designed to block a by-pass hole immediately below it.

The dual poppet thermostat was used on the S1.5 and S2 cars and will be useless on the S1 manifold:



If you fit the wrong one on the S1 manifold this is what you ger:

[tinworm]

Hello Yves , what David says above is correct .The bellows thermostat he shows is the correct one ideally 74 degrees although higher rated units will work fine it does need to be a bellows type to be right .
Also when I said measure the pump impeller it is the diameter that is different between 3.8 and the later 4.2 - not the depth of it.

regards Barrie

[mgcjag]

As i posted previously from SNG http://www.sngbarratt.com/ProductDetail ... df6f288830 just check to make sure its correct

[Heuer]

Actually Steve that SNGB will not work because the sleeve is positioned just below the upper plate of the thermostat whereas the original version has the sleeve is positioned 1 inch lower. Hence I did not recommend it - it has a * after the part number meaning it is not to original specification:


It needs to look like this very good reproduction when cold:

[Heuer]

Edit: Did some checking on the SNGB thermostat, it works in the opposite way to the original and is wax filled so can deal with the higher pressures of the later cooling system:

434-156 Thermostat, Bellows Type, 160?F - $115
For the Austin Healey 100, 100-6, and 3000. This is a Moss reproduction of the OE type bellows thermostat, with a sleeve to block off by-pass when thermostat opens. Suitable for systems using 4-7 lbs/sq in radiator caps as original. For systems over 7 lbs/sq. in, use 454-155, a wax capsule thermostat which also has a sleeve to block off the bypass. The reason that you cannot use a 434-165 bellows type thermostat with a cap rated over 7 lbs/sq in is the pressure in the system collapses the bellows, opening the bypass, causing increased operating temperatures and possibly, overheating. The original Healey 100 bellows thermostats opened between 158-167? F, or 70-75? C. At engine 3099 the 11K399 wax capsule thermostat was introduced to go with the 7 lb/sq in radiator cap. The new thermostat opened at 154? F or 68?C.

"434-155 Thermostat, Wax Capsule Type, 160?F - showing N/A but ?25 from SNGB.
This is a wax capsule type thermostat with sleeve to block off by-pass. It is suitable for systems with higher than stock pressures (over 7lbs/sq. in). The wax capsule design is not affected by the higher pressure. This thermostat is designed to fail ?open? instead of closed. The sleeve is in the full raised position when cold, nearly touching the top mounting flange. The closure to block fluid flow is between the inner cylindrical body and the top flange. As this unit approaches the preset operating temperature and begins to open, the sleeve moves downward (along with the cylindrical body) to block the bypass port."


Bellows version available here: http://www.mossmotors.com/Shop/ViewProd ... exID=93097

[ralphr1780]

Actually Steve that SNGB will not work because the sleeve is positioned just below the upper plate of the thermostat whereas the original version has the sleeve is positioned 1 inch lower. Hence I did not recommend it - it has a * after the part number meaning it is not to original specification:

David, it could well work because when cold the sleeve is just above the bypass and would not blank it. Look at the picture Yves has put in previous page of his thermostat housing.
Once warm, the sleeve would slide down and close the bypass.

[mgcjag]

Hi Ralph.....David said it would work in the first line of his post above....the SNG one is the way to go.....please do some more translating and let Yves kwow... all the best Steve

[Polse7317]

Thank's everyone, i have Understood, the sleeve must move enough to close the by-pass groove aperture . I have called SNG for the one that steve recommend . I'll see that when i'll have it. I hope that it will support the pressure....!
I saw the "bellows" , some of them can't work Under 85 C? ( Coventry auto components ) Moss seems correct but quite expensive . I have now all the good advices and apologize with my slow brain understanding and poor language.

[64etype]

Yves,

I'm thankful for this discussion. It prompted me to take the intake manifold off the shelf and look under the thermostat cover. I found....nothing. Thermostat was missing in action, and it appeared to have been operating that way for a very long time. So then I examined the spare thermostat on the shelf. It's the type with the small disk at the bottom (which I would have installed without the information in this thread). I'm anxious to hear if this solves your problem as that bypass slot on the 3.8 looks quite small and I wonder how much it influences overall cooling. In any case, as my car is in a warm climate, I'm thinking about that blocking sleeve depicted in an earlier post...wonder where to find one.

(Stunning paint job).

[Heuer]

Yves

The bellows type is not strong enough to resist the pressure of a 9psi cooling system but was OK with the 4psi of the early cars. So the expensive one from Moss would not work for you anyway - the SNGB one will be fine and cuts in at 75C.

[Simonpfhc]

I have recently bought one of the SNG thermostats in question for my 3.8 but not yet fitted it. I've just put it in a pan of water and heated it. At about 76 degreesC it opened and indeed the sleeve lowered. Once fully opened, I quickly sat it in the water manifold and the sleeve is in exactly the right position to cover the bypass slot :-)

The sleeve is not a very close fit in the bore of the manifold, so it may not stop all coolant flowing into the bypass, but will probably stop most of the flow.

Glad this is now confirmed - I was beginning to wonder where everyone was getting thermostats for their 3.8's from!

Cheers.

[Polse7317]

I wait for the sngb one .....

[Heuer]

Well that was a hell of a ride! Increased my knowledge of thermostats no end. Thanks to all who chipped in. I have added a post to the Factory Fit thread based on what we collectively found out. Please report back if you find anything new.

[PeterCrespin]

I have added a post to the Factory Fit thread based on what we collectively found out. Please report back if you find anything new.

Unfortunately, you have posted incorrect info about blanking sleeves etc. You need to strip that out and add the correct info, including the current SNGB part working as described in this thread. Someone could also tell SNGB to alter their 4.2/3.8 listing to show that tstat is for all S1 E-types, not just 3.8 as shown in Steve's screen grab.

[64etype]

Yes, the cooling system explanation in the Knowledge Base cautions that a blanking sleeve would need to have some controlled "leakage" to the pump for the short period when the thermostat is fully closed. Probably why the one shown in the photo has some holes in it. Obviously best to have the thermostat do it automatically. If you decide to leave the blanking sleeve portion, I'd recommend adding a reference to the Knowledge Base discussion.

[ralphr1780]

A nice example of team brainstorming, glad of the guidance brought forward.
Sorry David our messages had crossed.
Yves, my suggestion is to get one correct thermostat and simply run the engine shortly to check for no leakage, of course keeping an eye on temperature. Then put your stress aside and continue your project until you can take the car out on the road for a first test ride.

[Polse7317]

Thank's everyone for that discussion , i am sorry if i have irritated some of you by my ignorance in the cooling and by-pass system, i am raring to fit the"new" part and tell you that everything is OK ... !
It will be in some days, i am busy in my work .

[Heuer]

Unfortunately, you have posted incorrect info about blanking sleeves etc. You need to strip that out and add the correct info, including the current SNGB part working as described in this thread.

Done! I will contact Julian Barratt and point him to this thread. The only outstanding question is that the Waxstat #C20766/2 was also specified for the 4.2 cars. It is no longer available and supersedes to #C27650 which is the generic sleeveless one. Anyone have a 4.2 manifold on the bench to do some checks and confirm this thermostat actually does anything useful in the 4.2 manifold or is the #C20766/2 (SNGB #C3731/1*) required for proper operation? The S2 SPC specifies #C28067.


I also found this on the Wat-Jag site:


This is the one XK's Unlimited sell:

[Robert Hiland]

Here are a few tips you may find useful:
- buy your new thermostat from one of the "usual suspects".
-install thermostat with piddler valve up.
- when installing the fan belt pulley tighten the bolts sequentially. Due to the small tolerance it is possible to have it tight but not straight.

Good luck

Bob[/b]

[PeterCrespin]

The only outstanding question is that the Waxstat #C20766/2 was also specified for the 4.2 cars. It is no longer available and supersedes to #C27650 which is the generic sleeveless one. Anyone have a 4.2 manifold on the bench to do some checks and confirm this thermostat actually does anything useful in the 4.2 manifold or is the #C20766/2 (SNGB #C3731/1*) required for proper operation

Not sure I follow.

The spares lists call for the same part for both 3.8 and 4.2 S1 because both use the peripheral slit bypass port, as does my Warneford triple Weber manifold for that matter. The same sleeve thermostat available for the 3.8 should be used in all these cases.

This is quite different from modern cars and is a good reason to carry a spare on long trips.

Starting with the S2 it all changed and the slit (through still present on RoW triple SU cars) was no longer used. Instead, a separate housing was bolted to the front which has a coaxial poppet valve port, as do the twin V12 housings. For these cars a normal 'non-sleeve' modern thermostat is indicated and should be checked for poppet protrustion when fully open, to ensure it projects far enough to seal the port.

Anyone who has converted a twin Strangleberg S2 to triple SUs either needs to fit the S2 housing or use an S1 sleeve thermostat. Using an S2 thermostat in a triple SU conversion manifold doesn't work, just as Yves found with his 3.8.

Incidentally, as Ralph pointed out, leaving an S1 idling for half an hour is pretty stressful, especially with the original type fan. Yves should do exactly as Ralph said (plus check his pressure cap reaches to the correct neck depth).