Noise after turned off car - Advice please

[Dave Eastwood (Gadgetman) - Club Chairman]

It’s not a bad idea, but I’d be really uncomfortable about doing it on a Westfield, (with their typically smaller batteries and charging systems), without some safety over ride that would stop it before it could flatten the battery too much. I do appreciate I’m being paranoid though.

i must admit, I do also have a bit of an aversion to systems that can run on, on a car, with the ignition key removed.

As for the possible tank issue. Yeah, as has been said, check the venting if it sounds like gurgling! The vent hoses are notorious for creasing and collapsing in on themselves over time, blocking things up - don’t forget tanks vent both ways, both positive and negative pressure, so when the tank is under partial vacuum, if the hose is part blocked, it can actually cause more of the hose to “collapse” in on itself and block further.

Then, I guess just the action of drawing petrol fumes through the valves, can gum them up a bit, long term, and stop them working properly. (I know I need to replace mine, it’s sort of working, but definitely not as well as it should!)

Dont forget though that you want a proper vent valve, that lets air pass in either direction. (Some of the ones you see advertised are just one way valves, they’ll stop fuel coming out if you roll the car, but not vent both positive and negative pressure changes.

[Rhett Turner - Black Country AO]

I had problems with tank venting when I first built my Westi, I checked and checked the venting system but it would still do it. With mine if I'd been on a spirited drive and then pulled up as it dropped to idle it would cut out, it would start again and run OK afterwards. I spoke to Westfield about the problem and from what they said my conclusion was that the vent pipe was collapsing on it self when the tank was under negative pressure, thus blocking the pipe. when stopped it would slowly release and all would be OK. I ended up drilling a very small hole in the fuel cap, not ideal I know, but I have not had an issue again.  

[Stevemarsh]

Thank you all :-) 

[Kezman]

This roll over vent at the top of the fuel tank... to get at it, do you have to remove the bootbox?

[TableLeg]

1 minute ago, Kezman said:

This roll over vent at the top of the fuel tank... to get at it, do you have to remove the bootbox?

You may also be able to get at it from underneath reaching your arm up but taking the bootbox out would be easier.

[WINGNUT]

I removed mine the other night without removing wheel or bootbox, assuming your running a standard tank you can see it easy through the arch even with the wheel on.

[Kezman]

Feel foolish now. Had a look this morning and sure enough you can get at it no problem with your arm under the wheel arch. 

This subject has interested me because like the OP I have noticed the same noise after a journey but realised pretty early on that a quick flip of the fuel cap (mine is I believe the unvented cap with the half moon clasp on a standard 2009 build) as you guys say quickly equalises the pressure and stops the noise.

....But I have one of these rollover vent valves which with my arm under the arch this morning unscrewed (by hand actually so it wasn't nipped up very tight) and had a look. Now, some of you have said it may have a hose coming off it. I think mine did at one stage but apart from the tell tail, cable tie, around 2mm worth of rubber at the neck otherwise I haven't got one. So questions here are is it essential or optional?

Then turning to the valve. A shake of it produces a rattle which I assume is something like a ball bearing in a little chamber, and you can blow with a little effort through it, so mine doesn't seem blocked or gummed up or anything.....so what is it with these things that can fail? Because they don't seem cheap for what they are?

[Dave Eastwood (Gadgetman) - Club Chairman]

It's all very well blowing, but can you suck? (alternatively, just blow from either direction!)

A proper valve should vent both ways, this is most important. Yet at the same time, prevent fuel getting out if the car should turn over.

As a little bit of fuel vapour can vent out of the valve in normal operation, it's good practice to have a hose to carry the occasional condensed dribbles of fuel safely away under the car. (On traditional bodywork cars, having the large upwards run of vent hose actually allows most dribbles to run back to the tank.)

[WINGNUT]

@Kezman I shook mine, sure enough as yours did it rattled. I then sucked and blew as @Dave Eastwood (Gadgetman) - Club Secretary mentioned, from both ends to make sure. Both ways pass air, whether adequate each way I am not sure without having a brand new one to compare too. I then cleaned with brake cleaner to decrease if any fuel vapour has turned tacky over time. Refitted and went to work in it, got to work and lifted the flap on my filler cap and the air noise was still there, mine doesn't have the noise you speak off after a run but does make the noise when cap released. I guess I'd have to try a new valve to see if it cures the air noise on cap release but with it passing air both ways I'm reluctant to throw £30 on something for the tank that isn't unleaded and flammable!

[Kezman]

I get your point Dave about it needing to vent both ways. I will see if I get any noises, now I’ve had a tinker but I think I’m as wingnut in the sense that I’ve not got a new one to compare. I’ve just a sneaky feeling a new one wouldn’t alter a situation anyway and I'm ultimately wondering if one of these vents and the small aperture involved is enough? Almost like it needs two or a bigger one. I know it’s a crude example but a farming friend had a brand new tractor and it’s plastic fuel tank even though was vented was ‘sucking itself’ in as fuel level came down. Tractor dealer had to modify with extra venting to cure the issue.

[Quinten]

9 hours ago, WINGNUT said:

@Kezman I shook mine, sure enough as yours did it rattled. I then sucked and blew as @Dave Eastwood (Gadgetman) - Club Secretary mentioned, from both ends to make sure. Both ways pass air, whether adequate each way I am not sure without having a brand new one to compare too. I then cleaned with brake cleaner to decrease if any fuel vapour has turned tacky over time. Refitted and went to work in it, got to work and lifted the flap on my filler cap and the air noise was still there, mine doesn't have the noise you speak off after a run but does make the noise when cap released. I guess I'd have to try a new valve to see if it cures the air noise on cap release but with it passing air both ways I'm reluctant to throw £30 on something for the tank that isn't unleaded and flammable!

Save yourself £30 and drill the tiniest of holes in the filler cap.  If you have one of these

then lift the unlock tab and you should be able to drill diagonally into the other side (past the seal of the cap).  I did this over 4 years ago and I've not had any issues since.  No spillage, smells or pressure...

[Kezman]

I do indeed have that fuel cap, so I might end up drilling a tiny hole like you say.

[WINGNUT]

@Quinten Uijldert - Northants AO do you have any pics you could share for the hole location? 

[Quinten]

Not at this time, but I'll try to make some for you at the weekend.  You can dismantle the cap quite easily which shows you how it works.  From that you can sort of 'plan' the hole....  but a picture may help

[maurici]

On 09/08/2018 at 09:00, stephenh said:

Good practice is for the cooling fan to be wired directly, in the sense of not being wired via the ignition switch, so when you stop the engine the fan can still work until the temp cools down.

That is by all means useless,  unless you have an afterrun electric pump to move water around...

No point at all about cooling the water In  the radiator if this water will not go to the engine block that is where all the heat is generated...

Some old road cars use to do that,  and was the most useless thing ever. I always found it really amusing. 

In modern cars,  however... there is an afterrun pump,  mainly to go through turbo units, and they can benefit of going through the rad... but im afraid that is not how a Westfield works.