Back to the thermostat question

As winter and cold weather is approaching. (after the warmest Halloween on record today at 20° plus!) I am starting to re-visit the issue of having a thermostat and whether was the cause (or main contributing factor) of the blown head gaskets.

Some really useful information out there, but in summary, my issue could be a combination of things, rooted in the basic old design of the cylinder head bypass port. There is a great source of info here: http://mgaguru.com/mgtech/cooling/cool_103c.htm

Although written about MGA's, it's equally applicable to the Somerset. In summary, the newer type of thermostat on the older engine design does NOT stop the flow of hot water back around the head through the bypass port like the original bellows style thermostat would have done:

Despite not being a performance car by any stretch of the imagination, with it's pre B-series design and inherent weakness across 2&3 anyway, the old Devon/Somerset A40 engine could be hyper sensitive to that problem. Pretty much what I pondered about the thermostat issue causing flow issues in the first place, but with some reasoning behind that now clear (i.e. highly likely to have been the case due to the different designs.)

So I really feel I should try to crack it. Have ordered the blanking sleeve mentioned in the article and will fit that as shown in the picture. (from the article mentioned above and contribution acknowledged)

That - in conjunction with the lower temp thermostat, drilled with a couple of small flow holes should overcome the incorrect flow experienced when just fitting the new style thermostat.


(Still awaiting seats, but no rush. Austin day at White Lion next Sunday, so planning to attend that as the last activity of the year, rather than the previous visit being the last as originally expected!)