I have a siemens VDO fuel level sender that I was going to fit today. There are 2 mounting rings, one with through holes and one with tapped holes. Given that the hole must be smaller than the ring in order for the ring to seal the hole, how do I get the tapped hole into the tank? There is a small notch on the tapped ring but still, it would need quite a big hole.

rivnuts

best regards

marc

I used the same VDO sender and had similar troubles. Getting the tapped ring in was not too bad, but holding it in place while the internal rubber seal is located, then the external seal, then the sender unit, then the steel plate......not easy



In the end i used a long bolt and threaded it a couple of turns on to hold everything in place, still a very fiddly job.

I should have abandoned the tapped ring plate and used rivnuts as per the reply above. Good tight seal once it is all in place though.

VDO expect you to cut a 59mm hole which the sender plate will then go through. They include a longer screw which is the one they expect you to use to fiddle everything into place. The rubber gasket goes on the tank top and each screw has its own sealing washer. Extract from the fitting guide below but I would use rivnuts.
Rescued attachment sender.jpg