| I would like to address a
rare, but it does happen, electrical problem. When I was working as a young mechanic at an
MG dealership in Roanoke, Virginia, I was bringing a brand new MGB into the shop for a PDI
(Pre-Delivery Inspection). It was a 1976 MGB, and believe it or not, when I pulled on the
handbrake the starter motor would crank over! The very same problem happened to me many
years later when I was working for European Sports Cars here in Sacramento, this time on a
1975 MGB. The problem is a bad DIODE, of which there are two, located inside the car on
the passenger side firewall by the wiper motor. The wires to the diode in question are
color coded White-Red and White-Orange. A diode will allow electricity to flow only one
way, so they are very easy to check with either a voltmeter or a test light.
Working as I have for twenty years on MGs, the repairs I try to cover in
my tech articles are the rare ones, not the obvious. So here is a situation that happened
to me while I was working at a fully authorized British Leyland dealership in Roanoke,
Virginia. A dual carburetter MGB was brought into our dealership running on only two
cylinders. I checked all the usual problems but found everything to be OK.. Then I found
the problem. On the intake manifold there are two freeze plugs at each end of the
manifold, and yes, the rear plug had fallen out. So if your MGB should all of a sudden
start running on two cylinders, check your intake manifold. This problem does not happen
on the single carburetter MGB.
In another tech article this month, I
would like to help you pinpoint the mystery vibration in your MG. You have checked
everywhere, under the car is nice and tight, no play in the drive shaft U-joints. Well, go
back to those U-joints, they may be frozen, not allowing the drive shaft to flex. To
check, just simply remove the drive shaft from the car and feel for any binding in the
drive shaft yokes. If so, replace both U-joints. If one is bad, the other one cannot be
far behind it for replacement. I came across this problem a few times while working at
European Sports Cars.
Paul Lewis
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