Moss Motors, Ltd

Hi Folks - Its been a while since I was here.

Recently I had cause to chase an alarming leakage of coolant. I decided to replace the radiator drain tap/faucet since the original was seized. Unfortunately, there is a persistent but extremely slow leak from the new tap. Has anyone seen this? Any tips? I wondered if it needed to be worked a little, to seat the brass surfaces together for a better seal. Another option is to make a solid plug from the old tap by soldering it closed.

I think the tap problem is minor compared to what I found with the rest of the system on a routine health check of the car. It is annoying though, even if our cars are supposed to leak The disturbing part was that the header tank on the radiator was empty, and took a good pint or so to top it off again. It turned out the radiator header tank had sprung a leak at the solder joint opposite the filler neck, and the solder joint for the threaded drain fitting in the bottom of the radiator was also bad. These problems were fixed easily with the aid of Mr Blowlamp, some plumbing solder & flux. Surprisingly, this radiator was a replacement fitted when we got the car 5 years ago.

Cheers,

Ed

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I want my MGB

Hi.Ed sorry to here about the leaks.

I'd say that the rad fitted to your car was probably a reconditioned one,and not a brand new one.If it was me I'd probably strip out the rad,and all the hoses and fit a brand new set  from moss.Its probably an expensive cure for your leak,but if you want long term reliability,i would go this way.

I might be talking out of tern here,but i have a 73 B with 76k miles on the clock - original engine,which  i use regularly,i hope i don't jinx it here but there is not a single leak anywhere -oil or water.in fact its so dry on the outside of the engine that the block is actually starting to rust a bit.

I'm thinking of actually spraying some oil over the outside of the engine myself.The water level in the rad.never varies from one year to the next,although it is checked regularly.fortunately there is no drain tap on a 73 B rad.

I think once you fit a decent new rad.your leak problems would be solved.

 

 

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phil wilkins

Sometimes those faucets surfaces have to be matched with lapping compound. Some waterproof grease also might help.

 

Alfonso 

Thanks for the suggestions.

I think the Rad itself is fine now, the dodgy solder joints were easily fixed, and for the joint at the top of the rad, I took a "belt and braces" approach. I made a dished plug of brass sheet, and soldered that over the existing joint in the sheet metal surface. Lots more soldered surface to hold things together AND complete coverage of the joint made in the hole in rad top's sheet metal.

I'll take another look at the tap and see if it can't be improved.

Cheers,

Ed

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I want my MGB

I returned to the problem yesterday....

The radiator drain tap had continued to drip, very slowly but persistantly. I also remembered fitting a similar new drain tap to the block during the rebuild. Sure enough, this was wet with coolant. This is a nuisance

I removed both, dismantled them and could easily tell that they were leaky with a readily available vacuum test that requires no additional equipment (The parts got a good wash first anti freeze doesn't taste so good). The lapping compounds I had (for grinding valve seats) were too course for this job, and left grooves on the brass when I tried them on the old drain tap that I'd kept on hand. However, although it was slow, Brasso seems to have done the trick - adding a little, working the parts together for a few minutes, then looking to see how far well contact had developed between the mating surfaces. Eventually I managed to get a substantially better match between the parts of both taps. They were then thoroughly cleaned and reassembled with silicone plumber's grease.

I'll post back in a couple of days with progress. I had no time to even run the car and bring it up to working temperature yesterday, and it needs a thermal cycle or two to give a proper test. 

Happily, the resoldering work I did to fix leaks from the radiator are holding nicely.

Ed

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I want my MGB

Well, so far so good. Two trips and no drips, seepage or dribbles.

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I want my MGB

Ed-

Stay on your toes...It's toying with you!

 

LCJUTILA 

Ha ha, I know you are right... I'll just provoke something else!

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I want my MGB