Knocking from petrol tank?
Knocking from petrol tank?
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Discussion

Chuffmeister

Original Poster:

3,597 posts

166 months

Wednesday 24th September 2014
quotequote all
Could this be the sender float mechanism? Is it similar to a float in a sistern?

I only ask, because after my little escapade last night with the alternator bolt, I decided to investigate a knocking noise coming from the back end a little further (drop links done, prop UJ's done, exhaust tight, diff bushed okay). At first I thought it may have been the boot lid, however with the boot lid open and whilst applying pushing the back of the car up and down, I've discovered it is coming from inside the fuel tank. It sounds like something that it floating/ bobbing around and is knocking the wall of the tank under movement.

Any ideas? I don't think it is a metal baffle, as it definitely sounds as if its floating.

Cheers
Chuffy!

phazed

22,471 posts

233 months

Wednesday 24th September 2014
quotequote all
I had a knocking from the rear that was audible when pushing down on the rear.

Turned out to be one of my new Nitrons that was faulty!

I also had a loose baffle in the 4.6. This was only heard on sharpish bends as it surfed the bottom of the tank!

portzi

2,336 posts

204 months

Wednesday 24th September 2014
quotequote all
phazed said:
I had a knocking from the rear that was audible when pushing down on the rear.

Turned out to be one of my new Nitrons that was faulty!

I also had a loose baffle in the 4.6. This was only heard on sharpish bends as it surfed the bottom of the tank!
out of interest what was your fault with your nitron dampner, as I have them fitted for 2 years now, fingers are crossed?

phazed

22,471 posts

233 months

Wednesday 24th September 2014
quotequote all
They are the new Pro 46mm.

Faulty components, kept loosing gas pressure.

portzi

2,336 posts

204 months

Wednesday 24th September 2014
quotequote all
phazed said:
They are the new Pro 46mm.

Faulty components, kept loosing gas pressure.
Ekk frown. Not the standard ones then but the fancy ones!!.

phazed

22,471 posts

233 months

Thursday 25th September 2014
quotequote all
portzi said:
phazed said:
They are the new Pro 46mm.

Faulty components, kept loosing gas pressure.
Ekk frown. Not the standard ones then but the fancy ones!!.
Yep, nowt but problems.

Still not happy, great on track but crap on roads.

K4TRV

1,819 posts

281 months

Thursday 25th September 2014
quotequote all
Chuffmeister said:
Could this be the sender float mechanism? Is it similar to a float in a sistern?

I only ask, because after my little escapade last night with the alternator bolt, I decided to investigate a knocking noise coming from the back end a little further (drop links done, prop UJ's done, exhaust tight, diff bushed okay). At first I thought it may have been the boot lid, however with the boot lid open and whilst applying pushing the back of the car up and down, I've discovered it is coming from inside the fuel tank. It sounds like something that it floating/ bobbing around and is knocking the wall of the tank under movement.

Any ideas? I don't think it is a metal baffle, as it definitely sounds as if its floating.

Cheers
Chuffy!
Most likely the baffle plates have let go and move around as you corner - you won't hear them on the motorway ;-) But do check your radius arms and the bracket for the rear ARB - these can crack/fracture and also give a similar noise??

Messy job to pull the tank out, or remove the access plate (a less messy job) to the float sensor and you may be able to confirm/remove the loose baffle?

New/2nd hand tanks are not that cheap or plentiful !!

T

phazed

22,471 posts

233 months

Thursday 25th September 2014
quotequote all
I have a spare tank with a loose baffle. smile

Chuffmeister

Original Poster:

3,597 posts

166 months

Thursday 25th September 2014
quotequote all
Thanks for the replies. I don't think its a baffle TBH. Whilst the car is stationery, if I press down hard on the lip of the boot it can hear it knocking as if it was floating/ bobbing. I could be wrong, but I would have thought that a baffle would sink, unless it is remaining upright? I will see if I can get a borescope in the tank.

I was naturally going to ask about removing the tanks and how to go about it!

davelittlewood

312 posts

162 months

Thursday 25th September 2014
quotequote all
I think that mine's doing the same thing!

When I stop the car I can hear a knocking from the back of the car that continues after the car has come to a complete stop.
Must be some thing being moved as the fuel slops about.

I've listened from under the boot lid and also when the car's been on a ramp from underneath and the noise is definitely coming from the tank.

My guess is either the float from the level sender or a baffle clanging about.