Petrol?

[Chris Card]

Although this story concerns our MGB, it could have relevance to Bentleys that don't get regular use.

Our, or more accurately, my wife's MGB does not get regular use and it has always been run on "cheap" supermarket petrol.

Roy Baker and I took the car on an MG event and on the way home it suddenly went onto two cylinders. We started chugging back to a workshop that maintains classic cars and, after a while, the car went back onto four cylinders.The garage could find nothing wrong and we set off home again. At exactly the same spot in the road it again went onto two cylinders - it picked up again shortly afterwards.

Roy remarked that on both occasions we had just gone over the same "bump" in the road. On turning into our drive, we hit a sunken drain cover, the engine stopped and petrol was overflowing the carburettors onto the drive. This had happened once before, when Liz was driving.

Under the bonnet, everything was fine and, on both occasions, the car restarted and ran perfectly.

The garage mechanic had suggested that we should use one of the "expensive" petrols that include a cleaning agent, so I drained the tank of cheap petrol and filled it with the expensive one. By the next morning, petrol was leaking from one of the pump unions and I discovered that at some point it had been overtightened and the thread was damaged with a tight spot that leaked a bit and a loose spot that leaked a lot. I replaced the pump and all is now dry.

My supposition is that with little use, gum had accumulated in the float chambers and around the loose pump fitting and after a certain "bump" the float would either stick at the top and cause starvation, or at the bottom, and cause temporary flooding. Using the petrol that "beats as it sweeps as it cleans" had dissolved the gum and allowed the petrol union to leak. It remains to be seen if the other symptoms have now been resolved.

Has anyone else experienced anything like this, and could some of the "vaporisation" issues that Derby cars experience be related?

Chris

[Dan Suskin]

Chris,

I dont have any better suggestion than yours - but I did fond it interesting how many WO owners also have an MG. My wife has an MD TD, that I mostly drive!

[John Murch]

My sister has a TC that never gets driven, I really don’t understand why she doesn’t part with it!

[Chris Card]

As a follow up to my MGB experience, I filled the 4.5L with expensive "cleaning" petrol and took my son and grandson to spectate at the Benjafield Racing Club's Goodwood Sprint meeting. Brilliant day out!

YV9608 was running beautifully all the way there but, when we came to leave, she started missing badly and we could only crawl in 2nd gear. I ran all the usual checks and found that the float chambers weren't filling and identified a fuel supply problem. I have a pressure regulator fitted between the pumps and the filter and by temporarily increasing the flow through the regulator the obstruction was flushed through and the problem cured.

I suspect that the "cleaning" petrol had dislodged some debris from the fuel tank/line which had then blocked the regulator. I have now opened up the filter and found nothing untoward inside so, presumably, it was a bit of gum that has dissolved. I know that the filter should come first in line, but . . .

From now on, I will be using the expensive "cleaning" petrol in both the MGB and the 4.5L and, hopefully, no more gum will accumulate in the fuel systems.

Chris

[John Murch]

Have you tried using 'Sta-bil' or similar additive to the fuel? Its supposed to stop fuel going stale and depositing gum.
eg
http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=162913601901&category=179492&pm=1&ds=0&t=1511966344000&ver=0
I did use it for my spare can in the Bentley as I could never remember how old the contents were. However I have no idea if it actually worked.

[Chris Card]

Thanks for that info, John. I'm hoping that this even more expensive petrol that "beats as it sweeps as it cleans" won't gum up the works again. We'll find out in due time . . .

Chris.

[Robert Zannetti]

I am unable to stop myself commenting as :-

I was also at Goodwood for the Benjafield sprint and can be seen (well my car can) in Chris' picture, NT 8694. It was a first class day!

I also have an MG (1958 MGA Twin Cam)

I also had fuel problems on the way home. I do not know if it is relevant but I, too, had Roy Baker with me at the time!!

The MG magazine, Safety Fast is running an exhaustive analysis of modern fuels and their effects of old cars currently. The test were carried out at Manchester University and tackle problems of volatility in hot weather conditions with respect to engine running and hot start problems. The author is Paul Ireland. It has been a long running and fascinating series and he has now moved on to possible solutions. I recommend that you read them. Better still get Head Shed to see if it would be possible to run the articles in Review.

Finally and in answer to another thread I found that BBQ paint is excellent for coating exhaust manifold. ( I am pretty sure that it not an ingredient but a high temperature coating for the BBQ unit itself!) The colour, a matt grey, is restrained and very neat. My 3 litre has had the treatment for the last year and still looks as good as the day I put in on!