Non-vented fuel cap

Hi all

I've bought myself a fancy polished aluminium fuel filler cap for my 76' MK1 Golf. Just realized my old one was vented vs the new one non-vented. Does anyone know if it will cause any problems ie. bad fuel suction, fuel pump running hard etc? Thanks

Hi. I think you have answered your own question. Your new cap might not seal completely.

If it does, check and compare with your original cap and see if you can modify the new cap to create a vent maybe by drilling a hole on the inside of the cap.

Regards

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From what I have picked up along the way when trying to solve a pressure issue with my fuel tank the early models like your '76 model has a non vented fuel tank so needs a vented fuel cap. I have a 1983 GTI which has a vented fuel tank (through the gravity valve up inside the rear wheelarch next to the filler pipe) so it needs a non vented cap. I think you will probably find that you will have fuel starvation caused by lack of air being sucked in through the cap. I don't think early models have the gravity valve in the wheelarch, but then I'm not sure if carb models do either but if your car should have had a vented cap then using a non vented will cause problems.
I hope this makes sense.

Well I realize I didn't have to ask about this, as the cap is designed with a vent for a reason.. I just thought I'd seen a lot of pictures of early MK1's with this polished cap, but I guess they must be vented GTI's. Might be able to swap the locking mechanism from my old cap though.. Thanks for the input

I would just stick it on and keep the old one in car and drive the car to see what happens.. If it plays up when out and about use the old cap and mod the new cap.