MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Found it! Or have I?

For the last few years I have been cautious about taking out my MGA at all, as it has suffered constantly from an intermittent misfire after a few miles that has, on a couple of occasions early after the rebuild, meant a trip home on a truck. I started a thread about this a couple of months ago, looking, as usual, for an ignition problem, and it seemed likely to be caused by a hot coil. Yesterday, though, was a really nice day and felt likely to be the last summer day available this year, so I took it out for about a 100 mile round trip. Almost no recurrence of the problem all day until I rounded a junction quite near home, and there it was again. It went away again, but shortly afterwards I noticed the temperature rising. On getting home I could see that water was leaking from the heater tap when the car was driven hard and/or it got hot, not at other times. What's directly under the heater tap? That's right: the distributor, and a stain on the vacuum housing showed that this leak had been there for some time, but the fact that it only dripped when hot, and the engine heat nearby would evaporate enough away to obscure the evidence, meant that is was hard to spot, particuarly as i hadn't noticed that the rad needing topping up that much. Plainly I could do with buying a new heater valve, but you may like to consider, if you have this sort of misfire problem (and to judge from the earlier thread, plenty of people do), then it may pay to consider the possibility.
Gus Gander

Alternatively, replace the valve on the block with a bolt and washer - invariably I have found that I need to remove the tap when I actually want to drain the block. IIRC it's 1/2" BSP.
Dan Smithers

Gus

Fingers crossed you got it right. Presumably, you are implying that water migrated along the vacuum adjusting shaft and into the distributor? The alternative is that water dripped onto one of the spark plug leads and caused an intermittent short either in the distributor housing or plug cap.
Steve Gyles

This thread was discussed on 22/10/2007

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.