I have a Smith's dual gauge hooked up with a copper capillary line to my 948 block, but it's not reading any pressure. Did these gauges require electricity, too? What is a health pressure reading on these engines?
The water temp gauge isn't hooked up at all. From what I've read here there should be a port below the thermostat housing to thread in a sender, but I don't see it. Was this not available in the 948 head?
It's kind of a moot point since I don't have a temp sender, but I'd like to be able to read the vitals of this engine before Friday
Capillary gauges don't need electricity but the temp side of the gauge will unless that is capillary too (the light will need it though if fitted). The 948 head did not have a sender but you can use midget thermostat housings which accomodate the sender unit instead or drill and tap the block for a sender just below the thermostat.
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ahhhh... The way I read the Haynes manual was to add the sender into the hose and I cuoldn't figure out how that was going to work! Midget thermostat housing makes sense!
The Smiths dual gauge as fitted to the MGB and Midget has an oil pressure gauge which is connected with the oil feed tube to the engine block behind the distributor either by replacing the oil pressure warning light feed wire and sensor or preferably by connecting with a T piece adapter so that the oil pressure light still works.
The temperature gauge sensor fits the hole below the thermostat on engines from 1098 upwards. On the 948 and smaller engines you will require a thermostat housing with a temp. gauge sensor hole.
Neither the oil pressure or temp gauges require electricity to operate, only to power the backlight. The temp gauge capillary tube is fragile and must be treated carefully. If the gauge does not work then the capillary tube is probably damaged. To test it place the sensor in a saucepan of water and bring to the boil
Last edited by mike.perry on Thu Oct 08, 2009 9:19 am, edited 1 time in total.
Matt wrote:Errm the capillary part is normally temperature... oil pressure needs an oil pressure pipe which screws into the back ;)
Just to clarify and avoid confusion here... The capillary tube will have a bulb on the end and will be for temp. The oil gauge could well have copper pipe connecting the gauge to the sender unit. However, most modern applications replace the copper pipe with plastic tubing.
mike.perry wrote:The temperature gauge fits the hole below the thermostat on engines from 1098 upwards. On the 948 and smaller engines you will require a thermostat housing with a temp. gauge adapter hole.
Neither the oil pressure or temp gauges require electricity to operate, only to power the backlight.
This is just a repeat of what I already stated...
mike.perry wrote:The temp gauge capillary tube is fragile and must be treated carefully.
Agreed - be careful or the gauge is U/S.....
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Normal running oil pressure is 60psi for a good engine but will be less for a worn engine when hot. When the low oil pressure warning light starts flickering at tickover it is time to think about a rebuild or transplant.
It looks like the oil line may be damaged. It is copper and it looks like a section was replaced with a rubber hose and some clamps. Might explain why the gauge doesn't work. I have some 1/8 copper tubing, so I can replace it.
you can see it here. The gauge is sitting on a rag in the upper left corner The fitting in the block is unfamiliar to me. It's not like the other units I've worked with.
The thread is the same size for all Minor engines including the side valve. If the pipe was damaged oil would be p-----g everywhere at 60psi. The connection in the photo does not look too clever so a new plastic oil pipe complete with the correct threads would be advisable.
Does your oil pressure warning light come on when you turn on the ignition as it does not appear to be connected?
The copper/rubber inter tube was used on Minis for many years. rather longer overall than shown - and the copper tube had 'bulges' at the ends - to prevent the rubber tube slipping off when the little clamps were tight. I guess it was done to eliminate chance of fatigue break/noise due to vibration - and to make it easier to install!
Check the back of your speedo, you should have a bulb unit plugged in to the orange lens on the right side of the speedo. This should have a green / brown wire attached to it. If you can find the other end of it, it should have an electrical sensor attached and it should screw into the hole where the oil pressure gauge pipe is. You will need a T piece adapter to take both units.
Then US and British 1/8 pipe thread must be compatible. I've always used locally available fittings and since the engine is Austin, which is all US thread, so I never gave it much thought. Odd they didn't use straight threads and a copper washer like other fittings
Might explain why the gauge doesn't work. I have some 1/8 copper tubing, so I can replace it.