Hi Guys,
I am having trouble getting my temp. gauge to work in the Wasp. I have power to the wire, I have had the gauge recalibrated and fitted a new sender unit to the head.
The only thing I can think is that I have a wrong (or faulty ) sender switch ? Has anybody replaced one recently and have a part number ?
Thanks

disconnect the sender and ground the wire. does th e meter read anything then ? If so its the sender most likely. If not either the wiring or guage

IMHO

glenn

Hi Glenn,
Yes, that's what happens. I have just picked it back up from the sparky's, he's had it for a week, and it still doesn't work.
Do you know where to get a suitable sender ? As I believe they are all have a different resistance.?

G'day 67GT
Pm me your telephone number and I shall give you a call regarding sender units the BCCV have in stock. Cheers Steve

Normal Holden Gemini senders work with Bellett/Wasp gauges.
Both oil and temp.
Readily available.

If you ground the wire, then the temp meter should go to full scale (ie HOT)
If not then I would be checking the wire back to the gauge and also, check if 12v is present when the sender is disconnected. ie you need a hand held voltmeter and connect it to the wire and ground. You need ignition key on of course.
That will tell you that the 12v is connected to the meter and also that the wire is good. A test light will most likely not work for this test though, you need a volt meter.
If that test fails you will need to pull out the gauge panel and check if there is 12v going to the meter. Possibly a bad connection in the wiring plugs too.

Bellett Car club has the Temp. sensors in stock. (not a big seller) Technically you should be a member of BCCV to buy parts (perhaps you are) but I am sure the committee can over ride that for you.

Thanks Glenn,
I will try and get hold of a volt meter, as I have been using a test light. I guess if the voltage isn't high enough it will not read the switch properly ?

silly question is the sender earthed Thread tape ect between the sender and head will not allow sender to earth A test light between positive and the nut part of the sender will confirm.

If you remove the lead and test, you need a voltmeter. A test light has too low a resistance to properly check the circuit through the meter back to the battery supply in the dash.

the post below re ground is valid although it would be unusual i think to lose ground after the sender was there for so long. But stranger things have happened to worth checking also. [the sensor inside the housing may have become detached from the case]

If you get a voltmeter, it will also have a resistance checker which can be used to measure the resistance across the sender (with the lead removed)
I don't have resistance value available but if you get a meter, i can check mine for you.

Perhaps not such a silly question GT Orph.
I will go and check that today.

Ok no thread tape. That would have been too easy.
I have ordered a new switch from Bursons, to suit a Gemini (based on Brett's earlier post) but will have to wait until tomorrow for it to come in. Hopefully it is just a faulty switch.

How did you go Warren, fixed??

Sorry Dave,
We have been a little busy at work and I haven't had a chance to try yet

Nope. Back to square one. I'll have to find out what voltage is coming through the wire.

How B..... frustrating!
It was interesting the information from Brett that the Gemini are the same senders for water and oil.
What is the contact like between the wire and the sender? I fixed my issue by tightening the connection.

Strange issue if a sparks can not help you??

did you try shorting the wire to earth ?
.......with ignition on of course.

these things work using a variable resistance. A low resistance gives full scale on the meter (ie a short to ground) and a high resistance gives a 'zero' reading. Values of resistance in between, give a corresponding meter reading.

I measured the resistance of my Sport sender with the lead disconnected and it is 430 ohms. Engine cold.
I ran the engine for a short time until it got to about 70C and the resistance was 60 ohms. again, wire disconnected
These are rough numbers only as each sender will be a bit different but what it shows is the resistance is falling as the meter rises up the scale.
Shorting the wire will then give maximum meter reading. ie VERY hot!

The system is very simple, the sender to ground (earth), wire to the meter, the meter, then switched 12v from ignition key. A fault in the wire (including a loose connection at the sender terminal on the wire) the sender (now discounted) or the meter itself. Then wiring from the meter to 12v supply via the ignition switch. There are connectors behind the instrument panel also that could be loose. Worth unplugging and plugging back in again which you can probably do without removing the instrument panel. Fault has to be in one of those areas.

[sender]---[terminal]---[wire]---[meter]---[wire]---[multi way conn. on back of instrument panel]---[wire] --[12v from ignition switch]

I don't knowmif it will help much, but I've found that a dull film on brass contacts can cause intermittent failure of circuts. Take your dremmel multitool type machine (mine is Ozito, $50 from Bunnings) and thoroughly clean up all contacts until they shine, even if they look pretty clean. This film was once the cause of my Doris having an intermittent miss that eventually prevented her from starting.
Do the whole car - coil, dizzy, relays, everything. All the slide connectors, including the back of the fuse box. It takes some time, but only needs doing every 20 or so years.
Hope you get it sorted,
cheers, Matt.

I took the Wasp out yesterday ( thought I might pick the young bloke up from school--didn't he love that ) to give it a run and see if the new sender had made any difference. It does seem to bounce up to a reading every so often, but doesn't hold any position for too long. So it is trying to work. Maybe Farmer is onto something.
I also found out that Wasp's don't like rain. As I picked him up from school, the heavens opened up, which isn't good when the wipers fall off the spindle !!
Light weight alloy trays aren't very good for rear traction on utes either.

partially good news then, the system 'can' work. Certainly sounds like an intermittent connection.
Wires in a Bellett often harden up and crack or break from the heat of the engine too over time.