temp gauge trouble

[supertweet]

trying to connect coil over tube type temp gauge, 48 truck, the hole in the head is 3/4", was plugged with a bolt. the end of the tube that is to connect to the head doesnt have a bulb, instead looks like a small nipple. connected it to a flared reducer and it leaks coolant. an old head i have around seems to have this same nipple type welded to the head itself. also have bulb type unit but for older truck so wont fit in gauge cluster. any info appreciated, thank you, Dave in squamish B.C. canada.

[TodFitch]

I think you are referring to the adaptor bushing that the gland nut on the bulb screws into. I haven't seen them sold separately but there is usually an assortment of them in the universal mechanical temperature gauge packages at your local bubble wrap auto supply store. Last fall the cheapest one in my local store was selling for US$17, so that should be the upper limit to your cost of buying one if you throw everything else in the package away.

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hey thanks,realized that the bulb is broken off both the gauge and on the parts head, hence the confusion. so now it's solder a bulb to the tube? thx, Dave.

[Dan Babb]

If the hole in the head was plugged with a bolt, it's probably worth checking the threads. I believe that should be a pipe threaded hole, and if a bolt was used, it could have messed up the threads.

Double check my info ( I'm not 100% sure it's a pipe thread hole, but can't imagine that it wasn't).

There's a good post here with instructions on how to solder on a new bulb using an inexpensive replacement gauge as a donor.

[TodFitch]

hey thanks,realized that the bulb is broken off both the gauge and on the parts head, hence the confusion. so now it's solder a bulb to the tube? thx, Dave.

Use that same cheap mechanical temperature gauge that you bought for the bushing to repair the original. As mentioned by Dan there are some instructions on the web to do that. You can Google "mechanical temperature gauge repair" and click on the first unpaid, non-ad link. Or you can just go to my Plymouth web site directly and navigate to http://www.ply33.com/repair/tempgauge

I agree with Dan: If someone had jammed a bolt into the pipe threads on the head you may have to get them cleaned up to get a water tight connection when you go to install the gauge.

[pflaming]

I did not realize that copper stub was a 'mini' tube. Now I understand the sleave. So the either heats up, rises in that copper tube and activates a very sensitive 'coiled tube' in the gauge and registers the temp. WOW. Do all off the shelf have this set up? Are some just a copper wire? DETAIL, DETAIL, DETAIL!!!!

[TodFitch]

I did not realize that copper stub was a 'mini' tube. Now I understand the sleave. So the either heats up, rises in that copper tube and activates a very sensitive 'coiled tube' in the gauge and registers the temp. WOW. Do all off the shelf have this set up? Are some just a copper wire? DETAIL, DETAIL, DETAIL!!!!

All of the "mechanical" type temperature gauges I've seen or heard of work that way. There are electrical gauges that use just a wire to carry the signal but that is a totally different setup than came in older (30s, 40s, etc.) vehicles.

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o.k. back on track, thanks for the help, awesome article, informative and gives one confidence, will proceed and let y'all know how it,s going, will check threaded hole to determine what happened... thx Dave.