4 replies to this topic

[Ryan n Angela]

Hi TMF

 

Having a bit of an issue with a Duel Smiths gauge, the oil pressure side is spot on but the water temp side has zero function.

TBF it was a second hand unit when i brought it and the massive spring thing on the back was snapped off but i was expecting to have issues with the oil side not the temp... anyway i had a single mechanical gauge in my dash so i thought take the massive spring thing off that attach to duel gauge winner... erm no the only way to get the spring thing off was to cut it where it was brazed onto the gauge mechanisms and re attach to new duel gauge. now at this point we did warm the sender over the stove to check it was working as when it was in the dash it wasn't, id put it down to a wiring thing as the other side of the dash had a normal temp gauge in that worked fine (no idea why 2 temp gauges... like that when i got her) but after what seemed an age the temp gauge crept up the scale and when down in cold water and back up in hot so we cut it off and reattached it to the duel gauge and repeated the test process but get nothing at all from it. Not even a flutter. 

We stripped the gauge and as far as i can tell everything is connected as it should be, as it is on the sender end. though we did notice something like a bit of candle wax bubble out of the sender as we heated it where the sender and the adapter screw together. I had a look at swapping the mechanisms from the single to the duel but they don't fit

So now im scuppered??? anyone got any ideas where to go from here? Ive had a look for a new sender and spring thingy but it seems they are only available supplied with a new gauge... Am i at a loss here and a complete new unit is required or does anyone have any options?

 

Proper gutted as it allowed me to put a rev counter in the centre binnacle and retain the dials i needed...

 

Any help/advice would be greatly appreciated.

 

Ryan

 

[grumpy dad]

Hi 

well it is now time to put it the bin

the way it worked was that the long spring thing was a tube

in the tube was a liquid that expanded lots (sorry don't know what it is ) and moved the needle at the gauge end

so when you cut the tube you let the liquid out   

also if you kink the tube hard you get low temp reading 

 

thay standard fit on MG Midget

[Ryan n Angela]

Hi 
well it is now time to put it the bin
the way it worked was that the long spring thing was a tube
in the tube was a liquid that expanded lots (sorry don't know what it is ) and moved the needle at the gauge end
so when you cut the tube you let the liquid out   
also if you kink the tube hard you get low temp reading 
 
thay standard fit on MG Midget

cheers grumpy dad, I thought it would be something like that... should have looked into it before I brought it with a snapped off springy thing in the first place... well you live and you learn eh? time for an Ad on the wanted forum me thinks

[carbon]

Would not chuck it in the bin yet...

 

The fluid inside the mechanical temp sender is di-ethyl ether. They can be refilled and repaired, but not an easy job.

[dklawson]

+1 on the above.  NEVER EVER throw out gauges.  Even broken ones have useful parts AND this one can be fixed (maybe) depending on where you did your brazing.  Hopefully it was NOT close to the gauge head but further down the line.

 

If you consider yourself good at soldering and have access to some tiny drill bits you CAN fix this yourself for about 15 GBP or so.  I have used the technique described in the link below to repair at least 1/2 dozen broken dual gauges.

http://www.ply33.com/Repair/tempgauge

 

Before you spend any time trying to fix the gauge yourself, look at the needle for the temperature part of the dia.  If the needle is fully against its stop peg or VERY close to it, this gauge is a candidate for DIY repair.  If the needle is not at the left end of the scale but somewhere away from the stop peg and hot... professional repair is required.

 

The link above uses the salt/ice bath method to chill the expansion bulb.  That works but it is messy.  Even with careful washing salt residue will discolor the zinc plating on the protective coil spring on the capillary tubing.  Instead, during my last repair I purchased a small quantity of dry-ice since I was working on three gauges that day.  Dry-ice is much colder and cleaner as it does not pose any corrosion risk to the expansion bulb parts.

 

Once you have completed your repair, immediately test the gauge by heating the expansion bulb.  Soldering must be done quickly with a minimal amount of solder.  If you are slow or careless solder will wick deeply into the capillary splice tube and can fill the bore of the capillary tubing rendering your repair useless.  If you immediately heat the expansion bulb after soldering you will know if your repair is good.  If it is not, re-chill the bulb, heat the solder until it melts, pull the splice apart and cut both ends of the capillary tubing back further and repeat the repair.  Again, the method works and you can do this yourself.

 

Professional repair is typically not cost effective unless this is a rare unit from a 1950s car.