Aircooled VW South Africa

Think maybe you have an earth problem on your engine.

It looks as if when your voltage regulator kicks out from full charge, you get a spice to the temp gauge.

Put a heavy earth from your battery to the engine and try again.

Also look at all your connections.

Herman

Gauge and sender not calibrated.
Remember VDO works the wrong way round ie if you earth the sender it reads zero on the gauge and open circuit shows full deflection

Doesnt sound like either to me.
From memory - VDO uses two distinct resistance ranges for their gauges and senders. I'll put money on the fact that you have incompatable parts and the 60deg that you are reading isnt actually 60deg and when the gauge goes out of range, you are in fact going out of the gauges operational resistance range.

No. The sender and gauge worked many years together. When the gauge goes wrong it is very sudden jump to full. Will try a direct earth to the sender body as suggested

Sent from my SM-G930F using Tapatalk

And the winner is.................Herman

Cleaned my earth strap between body and gearbox with wire wheel and the associated studs, washers and nuts making contact, and abra cadabra, gauge sorted.

Who would have thought of such a gremlin.

Thanks Herman - great faultfinding/experience.

You more then welcome, you on you way, that's all that matters.

Enjoy

Herman

Subaru sells a bung to the same dimensions as the relief valve screw. It has 1/8 npt hole for sensor