In a message dated 1/19/98 5:34:45 PM !!!First Boot!!!, dswope@ix.netcom.com
writes:
> Hi folks. A member of our local MG club here in Austin TX has a
> problem, and has asked me to post it for him in hopes someone can give
> him some advice! I have told him how good you all are at giving advice!
>
> "A couple of years ago, I broke the little spade connector off the
> temperature sensor on my '76 B Roadster. I got a new one at a local
> parts house, but after I installed it, the temp gauge pegged on "hot" as
> soon as the engine warmed up (the engine was definitely *not*
> overheating). I took it back for a replacement, which they provided,
> and I got the same result. I got out my soldering iron and tacked on a
> glob to the old sensor that I could get an alligator clip on, modified
> the wire to end in a clip, reinstalled the old sensor, hooked it up, and
> things were back to normal. Fast forward to the present. I had to
> replace my head gasket, so I took the head in for a valve job, and I
> forgot to remove the sensor. The machine shop managed to whack it
> beyond all possible repair, so I ordered a new sensor from Victoria
> Limited (the unit specified for my model year), and I'm back to the same
> problem. Pegged on "hot" when the engine comes up to normal temp.
> Since I've just had the cooling system all apart, I am reticent to drive
> around very much with no data from my temp gauge -- any ideas?"
>
> Responses can be sent to me, and I will pass them on, or to Gordon Gunn
> at ggunn@texas.net
>
> Thanks folks!!
>
> Donna Swope
Hi Donna:
I just put a new one on my '71 B. I purchased it from Victoria British and it
works fine.
First time I've ever seen the gauge get up to normal.
When these things go bad they usually cause the gauge to read low. The room
temperature resistance of the new one measured 830 ohms. The resistance should
go down as it gets hotter. Another thing to check is the bi-metal voltage
stabilizer.
It is supposed to provide a regulated 10 Volts for the gauge circuit. If it is
bad it could
be putting out full battery voltage (12V engine off, 14V engine running) and
that will make
the gauge read high. A good way to check the voltage stabilizer is to unplug
the wire
from the sensor and measure the voltage from the wire to ground. It may bounce
around
a little, but it should average 10 Volts.
Bob Donahue (Still stuck in the '50s)
EMAIL - BOBMGT@AOL.COM
52 MGTD - under DIY restoration NEMGTR #11470
71 MGB - AMGBA #96-12029, NAMGBR #7-3336
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