Smelly Morris problem

[Oldmogman]

I wonder if anyone could help me track down the source of fumes in the cabin of my two-door saloon?

The fumes leave me with a muzzy head, suggesting they may be fuel related (I previously used a carbon monoxide alarm inside the car to check they weren’t from a leaking exhaust). I experience fumes with or without the heater running.

My car runs a 1275 with HIF44 carb (both reconditioned 55K miles ago), K&N filter and LCB, etc.

I gave it a thorough check-over after reading this MMOC thread:

viewtopic.php?t=47433#:~:text=While%20r ... e%20sender.

However, I found no petrol leaks in the engine bay. Neither the fuel pump nor the carb is leaking and there’s no evidence of leaks from the fuel pipe or hose. (I replaced the pump-to-carb hose years ago with braided hose advertised as E10-resistant after experiencing a strong petrol smell in the cabin.).

Neither is there a petrol smell in the boot – the tank is not leaking, the sender gasket is bone dry and I’ve replaced the tank filler neck tube.

The gearstick has a tight-fitting vinyl gaiter on top of the rubber one, so there are no leaks there.

All I did notice during my inspection, however, was that the large grommet for the heater trunking and the small ones for the heater hoses are perished, so there’s the potential for engine bay fumes to enter the cabin. However, the bonnet is louvred, which I would have thought would mean that fumes are sucked out of the engine bay.

I’ll replace the grommets but, before I place my order, I’d be interested to hear of others’ experiences – is there anything else I’ve not considered?

[Bill_qaz]

Surely you can tell the difference in smell between petrol unburnt and exhaust fumes?
Are you sure nothing is touching the exhaust and melting or oil getting onto it.

[simmitc]

Deceased rodent under the carpet or rear seat?

[exlkrs]

Deceased rodent under the carpet or rear seat?

Many years ago, the long hot summer of 76, when I worked at a distributorship, a new MG Midget bought by a lady had an awful smell. We changed carpets, looked for leaks, tried everything. A chance conversation with the customer, who stated she was annoyed she had bought stuff at the supermarket and left them at the checkout. That switched on a light bulb, and a search between the boot floor and outer wing produced the offending bag of sprouts, now many weeks old.

[Meggie moggy]

Hi
Possibly the same problem that I had with Meggie especially as you are running a similar set up. Have you checked to see if you are running rich? This was mynproblem and a replacement flat and needle valve from SU cured this.
Either way good luck

[svenedin]

So you are pretty sure that you do not have fuel leaks or exhaust leaks. What about the engine breathing arrangements? Does the engine have a closed breathing system or is there a draft tube that vents to atmosphere? It is possible that you are getting crankcase breather fumes in the cabin.

Stephen

[rocco]

Did the fuel smell ever get resolved?

I have a petrol smell in mine but only after I've filled up the tank. Once the fumes escape and I'm down to half, there is no smell.

Seems most likely that the rock-hard fuel filler neck rubber hose is weeping or it's the sender unit gasket. I've bought both but have not seen whether there is evidence of a leak at fill-up because the wooden shelf obscures my view.

20240817_123428.jpg (1.88 MiB) Viewed 2738 times

I removed the boards at the weekend and from the photo above, it would appear that the sender unit gasket is the cause. Is this what others would believe too?

[svenedin]

Did the fuel smell ever get resolved?

I have a petrol smell in mine but only after I've filled up the tank. Once the fumes escape and I'm down to half, there is no smell.

Seems most likely that the rock-hard fuel filler neck rubber hose is weeping or it's the sender unit gasket. I've bought both but have not seen whether there is evidence of a leak at fill-up because the wooden shelf obscures my view.

20240817_123428.jpg

I removed the boards at the weekend and from the photo above, it would appear that the sender unit gasket is the cause. Is this what others would believe too?

Mine has never leaked to the extent of leaking liquid fuel. I have replaced the fuel sender gasket twice and the rubber fuel filler hose but the boot still smells of petrol. The tank was new only a few years ago.

Stephen

[rocco]

I've just bought a neoprene sheet with the intention to cut out a gasket from it. I'll use the cork gasket as a template and make a couple of them while I'm at it.

I saw on another thread on here a cool looking compass-like knife for cutting out circles. I'm going to look for one now, could prove to be very useful.

[svenedin]

I've just bought a neoprene sheet with the intention to cut out a gasket from it. I'll use the cork gasket as a template and make a couple of them while I'm at it.

I saw on another thread on here a cool looking compass-like knife for cutting out circles. I'm going to look for one now, could prove to be very useful.

Yes that was my post with the compass cutter. Moss do sell an ethanol proof neoprene fuel sender gasket but I have not tired it: https://www.moss-europe.co.uk/en-gb/gas ... f-293--401

Stephen

[rocco]

I've just bought a neoprene sheet with the intention to cut out a gasket from it. I'll use the cork gasket as a template and make a couple of them while I'm at it.

I saw on another thread on here a cool looking compass-like knife for cutting out circles. I'm going to look for one now, could prove to be very useful.

Yes that was my post with the compass cutter. Moss do sell an ethanol proof neoprene fuel sender gasket but I have not tired it: https://www.moss-europe.co.uk/en-gb/gas ... f-293--401

Stephen

Indeed Sir. I've since moved on from a compass cutter to a Cricut Maker, having got some more long-term thoughts in my head and that I now have two Minors. However, for just over a fiver for two gaskets, the realisation has set in that I'l need to make at least 100 gaskets of my own to make it worthwhile.

[mowogg]

Going back to the original question, I would change the Flexi fuel line. I have just replaced my ethanol proof hose which has failed. I think this has been causing fumes in the cab for some while which I thought was an exhaust issue.

My hose lasted from 2018

[rocco]

The flexi-hose on mine is like concrete, absolutely no give in it when squeezed. I've bought a new one already and I've bought new rubber for the filler cap to body - it has to make sense.

[svenedin]

When I changed the flexible fuel hose in my engine bay it did not fix the problem of petrol fumes. I then noticed a very slight weep of petrol where the outlet spigot threads into the fuel pump body. Make sure you use proper fuel hose clips and not Jubilee clips. Proper fuel hose clips stay round when tightened. Another place where there can be a leak is the overflow from the float chamber if the needle valve is not seating properly or if the float level is set too high. It pays to be very meticulous and to go round sniffing in various places!

Stephen