Gauges

[Stephen Aitken]

Needing to replace an oil gauge. I can see that you can get two types electrical or mechanical - what’s the difference and what is standard for an 81 b?
Thanks
S

[Vic Butler]

Mechanical Stephen. At the right hand rear of the engine near the oil filter there is a flexible hose to the bulkhead and then a pipe which connects to the gauge.
. Vic Butler

[Charles Farran]

Have you checked that the problem isn't with the pressure feed line rather than the gauge itself? Per Roger William's book "MGB & MGB GT problems & how to fix them" - "Most problems are associated with its' (the gauge's) pressure feed line.A weep of oil from between the coupling on the end of the line & the rear of the gauge requires you to check that a sealing washer (part number 2K4936) is in place - the majority are missing! The oil capillary pipe can also become damaged by vibration or during engine bay work" (He refers to the line being made from steel, but i think mine is copper on my 1980 Roadster). Check you have no weeps at the union where the flexible hose joins the rigid pipe & also where the flexible hose is connected to the engine block & also the flexible hose itself hasn't got damaged.
Charles

[Stephen Aitken]

Thanks will check the hose.
Just to confirm all the gauges are mechanical then?

[Charles Farran]

The speedo is mechanical in so far as driven by a cable from the drive,the fuel guage is electrical that takes its' input from the tank sender,the tacho is electrical that takes its' input from the LT side of the ignition process & the temp guage is electrical that takes its' input ftom the temp sender at the top of the block near the thermostat housing.
Charles

[Vic Butler]

Stephen, why do you need to replace the gauge (a question I should have asked initially?)
. Vic Butler

[Stephen Aitken]

Hi have a problem with the oil gauge as isn’t working. Also some time ago I was given a smiths clock in magnolia and was toying with the idea of just getting a complete magnolia set - I quite like it against the walnut.
Is the tach and speedo 80mm I had a measure and looked to be around 85mm but I assume the width is for the back of it.
Thanks
S

[Vic Butler]

Stephen I am a bit puzzled. How is the oil pressure gauge not working. That would indicate to me that there's no oil pressure although it could be that the flexible hose has collapsed internally and it would be worth checking. I presume it's the original gauge.
If you wanted a magnolia set of instruments you would tell the supplier the year of the car to get the right size.
. Vic Butler

[Stephen Aitken]

hi
Problem with the tube going into the gauge can see it’s too loose..have tightened it up and seems to work for now.
Have been looking at new gauges and they say that you need new voltage stabiliser, oil gauge parts (will get a new tube) but surely don’t need all the rest as they should be ok to use ie new fuel sender etc on the new gauge given that the originals are also smiths.
I thought the stabiliser is already on there also temp gauge just trying to prevent an unnecessary purchase if the original parts are ok but not sure if the new smiths gauges are different..got zero advice from the supplier..

[Vic Butler]

Stephen, on all rubber bumper B's the voltage stabilizer powers the temperature and fuel gauges. On earlier cars the temperature gauge is mechanical so just the fuel gauge on these. The oil pressure gauge on all cars is mechanical so doesn't need the voltage stabilizer.
I would have thought that there would have been oil dripping down from the gauge if the tube was loose. However if you have to renew the tube then it's a good idea to renew the flexible hose from the engine to the connection on the bulkhead. On the MGOC forum there is a thread about the poor quality of some of these replacements and the best place to get one is from Stevson Motors in Birmingham. I've ordered a spare one from them as the one on my BGT is the original although it looks OK externally. The Stevson one is braided and for competition use as well.
There is no real need to replace the stabilizer but if you're changing all the instruments it would make sense as access will be easier and it would be worth considering an electronic one.
However the temperature sender under the thermostat housing is matched to the gauge so it's likely you may have to replace it to match the new temperature gauge.