Mixture Control Switch - What's that for???

[Peter Mueller]

Dear All

Still having trouble with the erratic overheating problem we turned up with at the National, the next little troublemaker I am going to tackle is the thermostat - don't worry, the water pump and the radiator are also on the list.

However, when I looked at the appropriate section in the workshop manual I discovered on the following page that there is something called the Mixture Control Switch . I am sure it will turn out to be self-explanatory and I will look stupid - again. But what is the blasted thing for? Does it give trouble? Could it have anything to do with the overheating problem?

Also, the manual talks of three nuts/bolts that hold the thermostat housing in place. So far I have only managed to feel two. One at about 2 o'clock and the other one at about 10 o'clock. Please don't tell me the third one is underneath and I have to dismantle half the car to get at it (wouldn't be the first time).

Peter

[harvey]

The mixture control switch is the "otter" switch on the top of the manifold which is secured by 3 bolts. (It's the same switch that gives the temperature control for the manual choke warning light, if fitted.)

As far as I know the thermostat housing has only ever been secured by 2 bolts. (And they're 5/16" not 1/4" as it says in the book, all I can think is they've confused it in the book, with the 3 litre which is retained by three 1/4" studs and nuts.)

[Deleted]

The Otter switch is merely a switch to turn on the warning light on the dashboard to warn if the choke has been left out too long. It is not used if you have an aed. The screws are usually siezed and break off- so leave it alone unless you are looking for trouble. The part on the front of the with two 1/2" headed screws is the thermostat cover.

[Peter Mueller]

Looking for trouble - moi? Never.... ;D I must have misread/ -interpreted the text in the manual regarding the three nuts. That was obviously about the mixture switch and not the thermostat housing.

Well, thermostat here I come

[Deleted]

Try loosening the bolts first with the engine hot. There is less chance of them shearing off as the ally will expand.
If they are tight then that is a sure sign that the thermostat is old.