Hi all,

No coolant comes out of the plug at the back of the engine when I take it off.. I've stuck some wire in there to try to clean it out, and I think there might be a very very small trickle of coolant getting through now (or possibly it's just the water I sprayed down there in an attempt to loosen the dirt), but I would have thought it should be pouring out..

Also there's definitely coolant in the head (I took the temp sensor off and it was flowing out pretty fast..)

The only reason I can think of that would explain the lack of coolant coming out of the hole at the back of the engine is a blockage somewhere.. Does this seem reasonable? If so, what are some things I can do to confirm and fix it?

Also my temperature gauge never moves off a point below cold.. I know the gauge works (when I touch the wire on the temperature sensor to somewhere on the fuse box it slowly goes up to hot), so is it likely that the sensor is broken? I've only ever run the engine for about 5 minutes at most though, so I thought maybe it just never gets hot enough.. how long should it take for the gauge to read anything above cold?

Any help would be greatly appreciated..

Cheers,
Harry

Cheers Pete

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A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Apart from very early motors that had a brass tap on there, most others had a brass plug which never got taken out since new.
The back of the water jacket there fills up with rust flakes, casting sand etc and it's a bugger to clean out.
However it won't usually affect the motor, there is very little coolant circulation needed in that spot for cooling to be normal.

Often you can clear it with a twist drill and a pair of pliers...

If rebuilding the motor though it's worth getting it cleared properly while motor is apart. A chemical clean will do it (but is expensive now).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The gauge goes to hot when I put the sender wire to earth. What does this mean?

So should I just not worry about the lack of coolant at the plug for now (I will hopefully get around to rebuilding the engine sometime.. but not yet)?

If the gauge goes to H when you ground the wire, that is normal.

Don't worry about that block drain plug for now. Whether water comes out or not doesn't matter. It will not affect engine temp.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

That means that the gauge is working correctly, if you think the engine is running hot get a kitchen thermometer and put it in the radiator and see what it reads.
If it reads 80 deg+ I would replace the sender unit.
Cheers Pete

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

By the way, thanks for the help guys - it's much appreciated.

I had a play with a multimeter and the temp sender.. The voltage across the sender was jumping around pretty wildly between about 1V and 6V, even while the engine was off.. Is this supposed to happen?

Harry

Should be no voltage at the sender as it is the earth side.
The gauge gets power from the voltage regulator and the sender causes resistance.
Cheers Pete

_________________
A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Sorry - I was talking about the voltage between the nut on the sender (which I assume is earth) and the wire (when the wire is attached to the sender).

The gauge and sender are powered by a +10V supply. This is `regulated' by 1950s technology (a glorified bi-metal strip). With the sender taken off the head, there is voltage on that line. A digital voltmeter may read a bit funny though as the regulated output is pretty choppy.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

That's an understatement

The one I took off my car a month or two ago was more like a voltage randomiser than a regulator. Even in AC mode the multimeter couldn't get a lock on the voltage output.. I would have been interested to see what the waveform looked like on an oscilloscope...

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Simon

The adventures of an owner builder in the Tallarook Ranges