4 replies to this topic

[minilink]

Hi,

 

I was looking to replace my plastic screw-in type gas cap for a locking one. I couldn't tell from looking at this plastic cap whether it's vented or not. But my engine is a 998 HS4 carb setup. I read that carb engines should use vented gas cap, but the locking type vented gas cap i purchased online turned out to be non-screw type. Long story short, i bought another locking screw-in type gas cap w/out knowing it's non-vented until I received it in the mail. 

 

My question is, incase my screw-in type gas tank isn't vented, will it do any harm to my HS4 Carb 998 engine MK3 if I use a non-vented gas cap?

 

Thanks in advance

[Dan]

If you run the car with the tank fully non vented then it will shut down after a while. Won't damage anything especially, it'll just stop. Check the top of the tank if it's a sedan to see if the tank has a vent, if it doesn't then you need to run a vented cap. If it's a van or pickup or an estate with the tank under the floor then you always have to use a vented cap because the tanks are all sealed.

[minilink]

Thank you Dan. I will check the top of the tank tomorrow. Is there any potemtial problem if both the tank and the cap  are vented?

[Guess-Works.com]

no

[Dan]

Although if there is a charcoal canister fitted a vented cap could cause poor running, given where you are this might be a concern.