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MG MGB Technical - Oil Guage Flex Leaks

I need some help on solving a persistent oil leak on the flex line from the engine block to the guage union on the bulkhead.

Some time ago I purchased a Moss flex line (324-626) to replace the badly deteriorating original one. I have had leaks with this flex line at the block from day one. From what I can see the conical hose end that should mate inside the male block and bulkhead flare is the too large or the wrong shape. I can distinctly see an impression made on the flex end by the male fittings. This indicates to me that it does not really match up.

I've managed to keep this at a slow drip with a lot of tightening but it is getting worse.

Is this just a bad sample from Moss? Are there alternative fixes or suppliers that are recommended? I could buy a new one but if they are the same then it's money wasted. One thought I had was to have one made up from hose and tubing fittings. Does anyone know the description of the fittings used by BMC?

Robert McCoy

Robert,

Sounds like a bad part. I've recently installed a new flex line from Moss (367-180) and it works just fine. My only bitch with it is the nut is metric and not SAE!

Could the union-part #4 in the illustration (460-015) be buggered? For 4 bucks it might be worth the investment. Don't forget washer (324-626)

Cheers

Paul
Paul Hanley

Robert - It could be that over the years the fittings at both ends of the flex line has been overtightened, causing the flairs at both adapters to wear out. You may need to replace the adapters at both ends. I have seen this quite often on fuel pumps.

Paul - I wouldd be willing to wager that the wrench size you need is a 3/16" or 1/4" Whitworth wrench. The next closest size wrench that would fit a 3/16W is 15/32 American or a 12mm. For the 1/4W the closest sizes are 17/32" American or 14mm.
Cheers - Dave
David DuBois

No - not a bad part - they ALL come like that now!

The original hose had a flat mating surface at the block end and conical at the connector end.

You need to remove the block adapter (3/4 inch socket) put it in the vice (vise) and using a 1/4 inch drill or countersink bit, carefully drill into the small end until the centre hole is opened up to a countersink that reaches almost out to the threads.

This will give you a good seal and allow the securing nut to run down more than the couple of threads it is at the moment.
Chris at Octarine Services

Chris, I think I see what you mean. The fitting at the block is not countersunk as deep as it should be, hence it appears the ferrule in the hose just sort of butts up against the flat surface rather than snugging down in the fitting taper. You can see the marks right at the very end of the fitting ferrule.

David, the tubing nut on mine is 13mm. It is just a bit snug but that's better than too loose.
Robert McCoy

Just an update for the records. I used a countersink to drill out the engine block fitting as suggested by Chris. I then used some sandpaper to smooth out the chatter marks from the countersink.

After installation I still had some leaks but further tightening of the nut seems to be setting the ferrule in the fitting.

It does appear that the block fitting was originally made for a flat end on the hose. The new hoses have tapers on both ends. I'm sure my hand made taper is not exact but seems to be working.

Thanks Chris.
Robert McCoy

Second update. The hose still leaks at the block connection. I'll get a new hose and block fitting (with washer).
Robert McCoy

This thread was discussed between 21/01/2004 and 02/02/2004

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