Reluctant temp gauge sending unit

[cliffpeters]

My temp gauge has been acting up, reading full H at all times, even when keyed on cold. If I remove the wire connector from the sending unit, the gauge returns to C. My first assumption is that the sending unit has given up the ghost. I thought I'd replace the sending unit, but it doesn't want to come out. As it's brass, I'm afraid of shearing it off if I get too aggressive with the spanner. Has anyone experienced this? Can you offer any tips for removing the old sending unit? Or am I barking up the wrong tree? Could it be the voltage stabiliser? I REALLY don't want to remove the dash to get at the gauge!

 

Thanks,

Cliff Peters

1971 TR6 YNK 99K

[jean]

Cliff, if it's the voltage stabiliser the fuel gauge will also show wrong.

 

For the sender problem, soak it in WD40 for a day or two. The procedure to remove a stubborn bolt is, after WD40, to first try to tighten it a little further and then untighten. Tighten, untighten movement should be continued until the bolt is free. Once it moves freely untighten it completley. This is the best, and mostly only way to safe the thread.

The problem with untightening a rusted/corroded bolt in one sequence is that a lot of heat will be generated, and that more and more force will have to be applied with the risk to shear it off.

Jean

Edited February 7, 2006 by jean

[cliffpeters]

Thanks, Jean and Alec, for the advice. I've been away, which is why I haven't replied sooner. Will give your advice a try! I'll let you know how things work...

 

Regards,

Cliff

 

Hi Cliff,

 

WD40 is fine, as Jean suggests, and his logic is impeccable, but there's also the corrosion/calcification effect from hard water glueing it all together. In this situation I use WD, then some very hot soapy water, then neat kettle descaler, then repeat all over again, and finally WD - each applied with a very small paintbrush, you're not trying to soak the engine !! And do it over a couple of days. Hasn't failed me yet.

 

Cheers,

 

Alec

[grmills]

Excuse my ignorance but is there any reason not to get the butane out???

[Guest ron]

Cliff

These sender units are actually quite tough, try a sharp hit with a hammer and a brass drift on the spanner flats to see if it will help 'break the seal' before trying to remove it with a socket.

At least at the end of the day if you do shear it off it's relatively easy to drill brass out of cast iron.

Ron

Edited February 13, 2006 by ron

[cliffpeters]

Thanks,

 

I must admit that I haven't had the courage/gumption to take this project on, so I will try your method. Do you think it would make a difference if I tried this after the engine was hot? So far, I've just been working on the car in the garage, stone cold.

 

Cliff

Cliff

These sender units are actually quite tough, try a sharp hit with a hammer and a brass drift on the spanner flats to see if it will help 'break the seal' before trying to remove it with a socket.

At least at the end of the day if you do shear it off it's relatively easy to drill brass out of cast iron.

Ron

[Guest ron]

Cliff

I don't think it'll make a great deal of difference, I think you'll be surprised how easy it comes out if you're confident, and as I posted before if it shears off it isn't the end of the world. I'm pretty sure they are threaded 5/8" UNF, so if you think it's going to shear off, scrounge a tap before you start, the tapping drill is 14.5 mm, if it does shear drill it with a smaller bit first, say about quarter inch to make sure you're centralised before drilling it with the bigger drill, if you don't fancy that the water pump housing is removable to take to an engineering company to do it for you.

Ron