MGB Overdrive on, then off, then on, and off .....!!

[1966marden]

Got this frustrating problem on 1966 MGBGT with Overdrive. Has worked perfectly and now engages for a few seconds, then off, then on again, etc. Have checked the oil level, this is fine and wiring to dash switch, also secure. Any other steps needed - are the isolation switch screwed in the gearbox side or the solenoid itself (.....expensive),likely to be faulty? Hopefully this is not "an engine out" solution. Any ideas welcome. Thanks in anticipation.

[marc.l]

I had the same with mine, checked every thing and could find nothing wrong. In the end I switched the o/d in on the switch and notting happened. I replaced the switch as it was found not to be working and it never was any more trouble.

[wildoliver]

It won't be engine out is the good news.

First job check your oil level again. This is classic low oil level. Failing that pull the bottom plate and clean the filter if that is blocked it will cause the same issue.

If it's cutting in and out it isn't "likely" to be a solenoid issue. It could be switch but more likely to be a bad connection/broken wires.