I smell Petrol - Could it be a leak?
I smell Petrol - Could it be a leak?
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Discussion

herbie hammer

Original Poster:

682 posts

287 months

Sunday 2nd June 2002
quotequote all
Went for a blast yesterday and smelt petrol on the way home but didn't think much of it as we had just filled the car up and I got the usual splattering of Super Plus on my hand.

When we got home, we could still smell petrol and it seemed to be coming from the nearside rear of the car. Had a dekko underneath and couldn't see or feel anything wet, although there was a small liquid stain on the body work behind the rear wheel - but no gushings of petrol or puddles on the garage floor.

Opened the boot and the carpet on the left hand side of the boot was damp and smelt strongly of petrol. I know that I didn't spill any into the boot when I filled it (all the gear that was in there was bone dry so I couldn't have done) - but the carpet is wet.

Anyone out there got any ideas or had the same thing - we don't want to end up as a frazzled wreck on the side of the road on our way to Chatsworth next weekend.

Cheers

Herbie!

kerniki

430 posts

303 months

Sunday 2nd June 2002
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Check the purge tank return pipe by the front wishbone and close to the manifold (passenger side), the heat makes it perish!

Nik

>> Edited by kerniki on Sunday 2nd June 19:08

shpub

8,507 posts

293 months

Tuesday 4th June 2002
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Don't fill it up so much in future. I don't try and top it up as all I manage to do is get the extra into the overflow. This should be vented out of the purge tank into the atmosphere.

steve

nubbin

6,809 posts

299 months

Wednesday 5th June 2002
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Don't want to alarm you, but I had wet boot carpets and a strong petrol smell, 2 weeks after I got my Chimaera (new). I noticed it first when stuck in a traffic jam on the M1. It gradually got worse, until one day, as I took some shopping out of the boot, I noticed the smell, plus liquid in the boot. Sure enough, there ws 2" of petrol swilling about in thwe boot, and dripping through the bolt holes in the bodywork, onto the hot exhaust!! Turned out there was a small hole in the back of the tank/. Needless to say, I was less than chuffed - a human/car fireball had been a distinct possibility. Get it checked ASAP!!

herbie hammer

Original Poster:

682 posts

287 months

Wednesday 5th June 2002
quotequote all
Thanks for the replies chaps.

I am probably being really dense here, but is the tank under the car, or is it the rectangular bit of metal at the back of the boot?

Also, is there an overflow from the petrol tank at the rear of the car? The only reason I ask is that I did squeeze in a the last few drops of petrol when we filled up and I am hoping that I Have just splurted a bit of fuel into an overflow and it is nothing more sinister than that.

I really hate to ask silly questions like this and I have just ordered Steve's book so that I can hopefully pick up on things like this myself, but in the meantime, happy to hear your thoughts!

Cheers

Herbie!

GreenV8S

30,996 posts

305 months

Wednesday 5th June 2002
quotequote all
quote:

Sure enough, there ws 2" of petrol swilling about in thwe boot, and dripping through the bolt holes in the bodywork, onto the hot exhaust!! Turned out there was a small hole in the back of the tank/. Needless to say, I was less than chuffed - a human/car fireball had been a distinct possibility.



If it's any consolation, petrol/exhaust isn't as dangerous as you might think because petrol's boiling point is lower than its flash point - it evaporates before it catches fire. Oil is far more dangerous from that point of view, and hydraulic fluid is downright lethal.

Leadfoot

1,910 posts

302 months

Thursday 6th June 2002
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Pete - IIRC the 'flash point' of a liquid is the temperature that above which, the vapour given off will ignite if exposed to an ignition source. So evaporating petrol, although not able to explode of its own accord, is not a good thing.



>> Edited by Leadfoot on Thursday 6th June 01:13

simpo one

90,765 posts

286 months

Thursday 1st August 2002
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'IIRC the 'flash point' of a liquid is the temperature that above which, the vapour given off will ignite if exposed to an ignition source.'

I think it's the temp at which the vapour catches fire spontaneously - ie it doesn't *need* an ignition source as such, just temp, to make it go bang. Matches set fire to petrol at almost any temp!

Rosso Paul

1,080 posts

288 months

Thursday 1st August 2002
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When I got my Griff I had the worrying smell of petrol. Someone on here gave me a tip to check and it sorted it.

He suggested that I might need to tighten the nut where I think its called the fuel guage sender goes in to the tank. In the Griff its that 'rectagular box' in the boot. Top right had side - easy to get at once you peel back some carpet.

It worked for me!

Paul

Leadfoot

1,910 posts

302 months

Thursday 1st August 2002
quotequote all
quote:
I think it's the temp at which the vapour catches fire spontaneously - ie it doesn't *need* an ignition source as such, just temp, to make it go bang. Matches set fire to petrol at almost any temp!
quote:

Wrong track I'm afraid.
I'll give you an example of a flash point of a fuel I'm familiar with:
Jet A1 (aviation fuel) has a flash point of +23 deg C. This stuff is basicaly kerosene so its a LOT less volatile than petrol. I can assure you that if you spill it onto hot tarmac on a hot day it won't ignite - or there'd be an awful lot of explosions at Airports!
No idea about petrols flash point, but I'd guess it's very very low.

hut49

3,544 posts

283 months

Thursday 1st August 2002
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Let me add my tuppence on this subject. It is vapours given off from a flammable liquid that combust, not the liquid itself. When the vapour from a flammable liquid combines with the correct amount of oxygen and a source of ignition (e.g. a spark) is introduced, the vapour will ignite. (This is what appears to be happening in 7 of the 8 cylinders in my car - the reason will remain unclear until the Optimax is consumed!)

Most flammable liquids have flash points at or below room temperature. Petrol actually begins to release vapours at -43°C. That is, vapour is given off into the air at that temperature, and this layer of vapour will burn when an ignition point is brought near. Liquids like these are called volatile. As ambient temperature increases their volatility increases correspondingly i.e. they become more readily combustible as ambient temperature rises.

The vapour density of flammable liquids determines whether the vapour will rise and dissipate in the air or whether it sinks into low places such as sewers and the bottom of a Chimp's boot. The vapour density of petrol is around 2.5 compared to air at 1.0. This means that very often at head height on a still day you may not smell a petrol vapour cloud even though your tootsie’s might be screaming “don’t light that fag, for Chrissakes”.

Now over to the other issue: what is the spontaneous ignition temperature (SIT) of a liquid, i.e. the lowest temperature at it will ignite without the application of an ignition source. This temperature is higher than the flash point. The SIT for petrol is around 260°C which is why petrol and the hot exhaust is often blamed for conflagrations after RTAs when in fact (as GreenV8S pointed out) the usual cause is ruptured brake/clutch lines since the SIT of this fluid is below that of petrol.

Hutch

zippy500

1,883 posts

290 months

Friday 2nd August 2002
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quote:

I think it's the temp at which the vapour catches fire spontaneously - ie it doesn't *need* an ignition source as such, just temp, to make it go bang. Matches set fire to petrol at almost any temp!



This is the fire point. Flashpoint will do as it sounds. You will see a quick burst of flame and then it will extinguish, if you continue to heat the fluid it will then remain a light. Heating fuel will eventually cause it to self ignite i.e. firepoint regardless if an ignition source is present. This is difficult to do as it will evaporate.

>> Edited by zippy500 on Friday 2nd August 07:58