Water temperature of engine changed

[jake_crew]

The bypass hole in an A series goes between the head and the pump directly below the thermostat, is about 3/8" in diameter, has a horrible corrugated hose and was eliminated on the A plus engine as it was unnecessary

 

Richard

The horrid crinkly hose is an aftermarket "easy-fit" item intended to be fitted conveniently at the roadside, though I reckon that's still a mare of a job.

 

I've always used a piece of hefty twin-wall pukka heater hose, with proper Jubilee clips, and replaced that whenever the head or water pump is off.

[TimYoung]

The evil bypass hose replacement hose was always bad news on minis (yes I was there).

Avoid crinkly, easi- fit sic, hose if possible.

 

Tim

[RLWP]

Running an A plus head, I have fitted a screwed bung into the water pump inlet

 

No more leaky bypass hoses

 

Richard

[Colin North]

I moved her yesterday. At a little higher speed than I normally do. Normally I drive very slowly, not much above tickover because I am not in a hurry and enjoy the scenery etc.

Yes, the temperature did climb a little quicker but it did not climb to the point of thermostat opening.

The calorifier water was lovely and warm.

If there is an air-lock in the calorifier feed, my engine boils very quickly and the hot water does not heat, so that can be eliminated.

Then I drove home, that is the time for thinking...

What has changed?

I remembered on the way home.

The calorifier has a second coil for central heating to heat the calorifier. I have recently, for the first time ever, filled the 2nd coil and there could be a short loop for a thermal syphoning of hot water to the central heating circuit. I have not confirmed that the CH pipes are getting warm as I only thought of this on the way home. I would be surprised if this is the answer but it (along with the cold) might just answer it all.

If that is the case then I am sorry I bothered you all.

I am grateful for all your thought and replies.

Merry Christmas & a Happy New Year to you all!

Colin

[Stilllearning]

Ah, there had to be something else going on! That may well be the answer.

[David Mutch]

I can't see how, or why it should have changed, but nothing to do with wrong type of thermostat, is it?

 

BMC 1.8s typically need the less usual type of thermostat, known as a "bypass" thermostat, (on right, in picture below), that has an extra part not present on the more usual non-bypass type, (on left).

 

 

If when you look down the thermostat housing there is a seat and hole at the bottom that would be covered by that extra "penny washer" shaped bit at the bottom of a bypass stat, that is almost certainly the type you should have.

 

Fitting a non-bypass stat in a system designed to have one might give unpredictable results, as it is possible for water to end up bypassing the cooling circuit.

Hi guys. Had an overheat yesterday, and it appears my stat was the cause. On opening up the housing, I found a non-bypass stat (left one in the pictures), but the head appears to have a bypass (as pictured in the post below) The engine has run happily like this for years (at least 4), so I'm wary of just changing to a bypass stat. I have a spare 83C bypass stat from my car, would it be OK to fit this?

Fair enough!

 

For the benefit of anybody who has no idea what I'm on about (!), the type of housing that needs a bypass stat, looks like this at the bottom.

 

(Once initial warm up is complete, it covers and closes that hole at the bottom).

 

Edited September 25, 2016 by David Mutch

[David Mutch]

I changed the thermostat for a bypass one (not the one from my car, as it turned out not to be quite the correct size). Now the engine seems to be over-cooling. Weirdly, it seems to run cooler that with no stat in at all! Any ideas what's going on there?

 

PS - I don't entirely trust my temp gauge. It's a Smiths analogue gauge. Is there any way of calibrating these, or is it a case of a new gauge/sender if it's wrong? Is there any way of testing whether it's the gauge or the sender which is faulty?

 

Thanks

[Tony Brooks]

 

I changed the thermostat for a bypass one (not the one from my car, as it turned out not to be quite the correct size). Now the engine seems to be over-cooling. Weirdly, it seems to run cooler that with no stat in at all! Any ideas what's going on there?

 

PS - I don't entirely trust my temp gauge. It's a Smiths analogue gauge. Is there any way of calibrating these, or is it a case of a new gauge/sender if it's wrong? Is there any way of testing whether it's the gauge or the sender which is faulty?

 

Thanks

 

1. No idea unless its a lower temperature stat, some marine use ones are around 60 to 70 degrees. If its a bypass stat having no stat or a cooler one would allow water to bypass the cooling system so the engine MIGHT run hotter.

 

2. Smiths used to make a little test box to test the gauge but all I can think of today would be to take the sender out, reconnect it and heat it in a water bath with a thermometer. Then repeat with a new sender. May as well just fit the new sender and see. You could heat the sender in a water bath and plot its resistance on a graph but how you would get the test values I have no idea. ASAP publish the resistance at a hot and cold temperature in their printed catalogue for European and UK gauges. Smiths will be European.