Thunk / Clunk . . .

[Digger]

Ever since I have had her I hear a thunk or clunk noise from the rear near-side quarter of the car. I assume this is something normal but I'm at a loss as to what it might be. As far as I can tell it most often happens early on in a journey, and only when I slow to a stop or I am in slow moving traffic!

Any ideas?

[Pvapour]

I'm going with expansion / contraction of fuel tank

[Digger]

Now that would make sense, so I assume its not temperature related but more to do with fuel being sucked out, and not replaced quick enough with air? Interestingly this evening was the loudest, and I got two thunks, after a 30 minute blat, left the car whilst I waited for a wagamamas t/w and then started her. . . thunk thunk . . .

No, I'm not overthunking this!

Edited by Digger on Tuesday 25th June 22:19

[rigga]

Blocked carbon canister or pipework in the osf wing causing poor venting of the fuel tank, this then causes the tank to implode slightly as the fuel is being withdrawn, and when the venting catches up the tank thn expands with a clunk back to its former shape

Just guess

[Pvapour]

exactly that, try running it for a blat with the cap off and see if it still happens, my first two Chims never did it but the latest and the Griff do?? I was wondering if there is a breather blocked somewhere but have never looked any further into it.

[Digger]

Interesting. Will do pva, well, I'll leave the lid loose, as opposed to off!

Hopefully neither my Insurer or Dealer are reading this

[rigga]

Fuel cap is a good shout as my leven item has a particular good seal, and if i tighten it too much the engine does run different for want of a better word, I just don't over tighten it but there is a mod to cut the seal a bit to relieve the pressure issue.

[Digger]

By the way it is very definitely on the n/s rear quarter, if that is relevant.

[Digger]

I assume there is enough info in the Bible on this, so will have a read up.

Thanks Guys.

[GasMunkey]

Just drill a small hole in the first skin off the cap, enough to breath but can't spill any fuel

[Pupp]

rigga said:

there is a mod to cut the seal a bit to relieve the pressure issue.

I'd be wary of that bodge - petrol vapour and sparky old boot release solenoids are not great bed-fellows

[Digger]

Can we confirm that this has been raised before (known), or is mine potentially a one-off?

[rigga]

Pupp said:

rigga said:

there is a mod to cut the seal a bit to relieve the pressure issue.

I'd be wary of that bodge - petrol vapour and sparky old boot release solenoids are not great bed-fellows

Luckily I haven't needed to do it, just put it out there as an option that's been used by others ....

[Hoover.]

there is am issue if you after market caps to make sure you have one suited to your car... I think the orecat ones are diff to the 500s... I stand to be corrected, but I am relying on my memeory from about 8-9 years ago

[rigga]

GasMunkey said:

Just drill a small hole in the first skin off the cap, enough to breath but can't spill any fuel

I ain't drilling no hole in my shiney cap! !

Digger said:

Can we confirm that this has been raised before (known), or is mine potentially a one-off?

Yes its a known issue