Hi, as my MM1000 lives under a carport on my drive I fitted a lockable petrol cap for security, but now I have a problem with the tank pressurising, could somebody tell me how to fix this problem.
Thanks, Bernard.
Petrol Cap
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
By using this site, you agree to our rules. Please see: Terms of Use
-
- Minor Legend
- Posts: 2953
- Joined: Mon May 16, 2016 4:39 pm
- Location: Kidderminster, Worcestershire.
- MMOC Member: Yes
Re: Petrol Cap
You need ideally a locking cap with a breather to allow air into the tank as it empties. Not all readily available caps have them. The breather is often a VERY small hole drilled through the top surface of the cap, close to the outer edge.
1956 4-door called Max
-
- Minor Maniac
- Posts: 10815
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Petrol Cap
If the tank is pressurising i.e. the air not being able to get out conversely the air that needs to get in to replace the volume of petrol pumped to the engine cannot get in which will make your petrol pump struggle.
If there is no vent the expansion of petrol in the tank will pressurise the tank.
Dependent upon the type and make of lockable cap fitted a hole drilled in the underside of the cap would alleviate the problem of tank pressurising.
If there is no vent the expansion of petrol in the tank will pressurise the tank.
Dependent upon the type and make of lockable cap fitted a hole drilled in the underside of the cap would alleviate the problem of tank pressurising.
Re: Petrol Cap
Not all vented caps have an obvious hole - I have a lockable vented cap which has a "labyrinth " cast into the underside which provides the ventilation, so it's worth looking at a cap closely before assuming it isn't vented.
-
- Minor Maniac
- Posts: 10815
- Joined: Thu Jul 19, 2012 12:05 pm
- Location: Hampshire
- MMOC Member: Yes
Re: Petrol Cap
If the lockable petrol tank cap was vented there would not be a problem with petrol tank pressurisation.
Check that any vent hole (if there is one) in the cap is not blocked.
Check that any vent hole (if there is one) in the cap is not blocked.
-
- Minor Legend
- Posts: 1438
- Joined: Tue Jan 30, 2007 10:09 pm
- Location: Essex
- MMOC Member: No
Re: Petrol Cap
I've heard of petrol tanks being crushed from atmospheric pressure due to the vacuum caused by the pumping out of its contents!
Alan
Alan
-
- Minor Legend
- Posts: 2953
- Joined: Mon May 16, 2016 4:39 pm
- Location: Kidderminster, Worcestershire.
- MMOC Member: Yes
Re: Petrol Cap
That is one of the few thing I remember from by BL / Unipart product training back in 1979
1956 4-door called Max