I guess a lot of you guys know the problem .
When i fill up my gas tank over 3/4 full and the split is standing with a light right side down , the gas starts ro leak out of the cap into the drain . Making a mess underneath.
The gasket looks good . But as far as i see it , it can’t be fully closed as the tank doesn’t has a vent to let air in, so this has to come via the cap i guess.
Anybody ever got this problem solved ?
Thanks in advance
Sam

Yes common problem. Tank behind engine. Petrol comes from below ground.. In warm weather the petrol is cold. Heat sink from engine radiating causes fuel to expand and force against the seal. Tank is not vented.
I never park facing the wrong way. Never fill to the top and never fuel before I aim to park up.
I never fill to the top.
My son brought my bus back saying returned and filled and parked outside.
I said oh dear went out and yes fuel flowing out of tank onto the road. I short run and parked on correct side.. cured it.

Thats exactly what i do too , always just 3/4 , so i have to live with it then.
I thought there might be something i could do as the tank is out for the moment.
But in that case ...
Thanks a lot

You're lucky. When I bought my bus the overflow was blocked. If I jacked it up on the left side the fuel would run into the engine bay....eeck!! Soon sorted and as others have said - I never fill it up....

Wonder if nobody ever designed a checkvalve to put into the filler neck

might be a problem with expansion in the tank. Would need to let gas escape but not liquid and even then if it was filled right up the expansion could cause the tank to rupture.

I've always wondered why bath plugs don't have adjustable pressure valves too.....

Right the expansion would cause a problem. Gues thats why the bay had this fancy tubes
But at least i know that we all have to live with it

Yes guess VW altered the design for that reason.
Seen an almost brand new VW polo fuel tank sucked almost flat by the vent being blocked and the fuel pump suction pulling it in. Neighbour asked me to look at his wife's car because it would only accept less than 1gallon before fuel appeared in the neck. She was really puzzled. I asked if it had made any strange noises she confirmed. I had the pleasure of phoning the Main dealer and asking them to collect it for repair. The Service Manager would not believe my explanation and came out in the loan car to examine and collect it. Turned out they had blanked the vent to underseal it and not removed the blanking plug! He was not amused. Thanked me politely and then asked what I enjoyed to drink, sent me a bottle of whisky as a thank you!