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MG MGA - Fuel Pipe Leak Warning

A fellow MGA owner came round for a chat last night. He was telling me that he had been experiencing a slight whiff of petrol for some time, but had assumed it was just damp seals at the bottom of the jet assembly. For a totally unrelated reason he happened to lift the bonnet while the engine was running and immediately spotted a very fine vertical spray of petrol coming from the middle of the braided flexible pipe between the 2 carburettors. He thinks that the pipe may have weeping for a while, but that the heat in the area was evaporating the fuel before it became noticable to the eye. It is also likely that the weep had developed into a spray only within the previous day or so and that it was fortuitous he opened the bonnet with engine running when he did.

We believe the pipe is about 10 years old and could be from the same batch as mine - We did our rebuilds over a similar period.

Worth a periodic check!

Steve Gyles

Hi steve I have heard from another source that these pipes can fail, they were all replacements during the last few years, i believe it's something to do with the rubber not being as good as the originals

g c pugh

I found exactly the same thing about a month ago but nothing as spectacular as a spray. All there was to see was a dark patch on the braiding where dirt had been sticking to the damp surface. I'd been trying to find where the smell of fuel was coming from for some time and also suspected a leak on the front carb. The pipe was also about 10 years old so perhaps this is around their life expectancy as I don't think mine came from any of the usual suppliers. I'd heard of the braided oil pipe failing but not the fuel one.

Malcolm Asquith

My pipe failed between bulkhead and carbs, resulting in heavy fuel loss. Obviously, that's the more likely one of the two to fail, due to relative movement. It was I believe 17 years old. I changed the other pipe together with every other rubber hose, seal (and fanbelt) a few weeks ago.

The recent thread on tyres highlights the effects of aging rubber. Unfortunately the rubber composition has a dramatic effect on the aging characteristics, reproduction parts vary enormously in composition as do the manufacturing costs.

The added effects of fuel, oil, brake fluid, coolant, heat, temperature change, vibration, flexing, ultraviolet light, polutants etc., etc. make it impossible to predict the lifetime of rubber parts.

Tyres on the other hand (at least the main brands) are strictly controlled, regarding composition and manufacturing process. Even then it is not possible to give accurate lifetime predictions. However, we have recently learnt that after ten years we should expect lower performance in the wet at the very least!

So in summary, ten years - well done! now go and replace all your rubber parts! And buy replacements of unknown manufacturing origin or age at your peril!

Neil McGurk

According to my dad, the original flexible fuel lines were not that great either. He replaced a bunch of them back in the 60s and 70s until he changed the fittings to push on types for standard rubber fuel hose. No problems after that.
Del Rawlins

My two carburetor fuel hoses are Moss Motors origin vintage 1986, stainless steel braid cover and Teflon lining, lifetime guarantee as I recall. These are now 21 years old with 209,000 miles, perfectly functional and no hint of degradation. Sometimes you get what you pay for, if you don't mind paying. I am a true believer in the Teflon lined fuel hoses for tolerance to moden motor fuel formulations.
Barney Gaylord

Incidentally, I discussed this with some fellow MGB owners at a meeting two weeks ago. One of them told me his braided fuel lines now has a life expectancy of less than two years! Consensus was that there are quality problems with this type of fuel line.


For these rubber hoses the compound is really the deciding factor. Unfortunately to get low volume production of specific parts there is normally a trade-off in quality.
As you can imagine the original suppliers would have to supply evidence of testing to certain standards and also be responsible if anything happened during the vehicles warranty period.
Today's aftermarket suppliers (also for modern cars when you want to fit a cheaper non-OE part) do not need to go through such testing and their quality control is sometimes poor. A wrongly manufactured part being fitted in a garage will not stop a production line so corners can be cut.
I will check my pipe-work tonight as mine is also around 10 years old and I use my car almost every day.

Steve - Inform the group you bought this part from, including taking back the leaking part, as they should feed this back to the manufacturer.

Thanks for the tip-off.

Neil Purves

I bought both the flexible fuel lines from Moss UK in 1996 and had to replace them in 2003. The car had sat for a couple of years for various reasons and when I tried to start it fuel sprayed out of both fuel lines! They both still looked perfect externally.
Keith Morris


My colleague cannot be certain who supplied his pipe. You will see from my post that we were summising that his and mine could have been from the same batch, but we can't be sure.

The difference between his and my rebuild was that his car was a runner, mine was a junk heap. He replaced bits as and when, while still keeping the car running.

My pipe came from Bob West and is still ok.

Steve Gyles

Reading this interesting but worrying thread makes me think radiator and other cooling water circuit hoses. As temperature and pressure are likely to be worse in such application than for fuel, and the age of the rubber pipes probably just as old, is there a similar case to place a lifespan on them and replace early?
Any experience welcomed.
B Mayo

My experience with radiator hoses is that their life span varies considerably. I had a top hose go bad after just 3 years but my current one looks like new after 5 years.

I would suggest carefully checking the hoses each service and replacing when any signs of cracking or hardening are noticed. I don't think there is any need to replace hoses which look fine as they do show signs of degradation - unlike the braided fuel hoses which do not.
Keith Morris

Braided fuel lines were notorious for leaking, especially when cars had intermittent use and the linings dried out. In spite of "unoriginality" I gave up on them years ago and have used conventional fuel hose with complete reliability and safety. I think that it is possible to get longer-lasting braided hoses these days.
Barry Bahnisch

I take my hose ends to the local tractor hose replacement people (Pirtec) and they renew with a teflon inner and braided outer. They are relative cheap,look good and they last!
BM Gannon

This thread was discussed between 28/06/2007 and 01/07/2007

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