Overdrive issues...please read

When I take my 1971 mgb for a drive the overdrive doesnt work correctly untill the engine and trans are warmed up.
Once operating temps are up it shifts both in and out of od just fine.

When its cold it wont engauge od.
When it is partially warmed up it will shift into od but willnot shift out of od.
Oil is new,correct type and level.

I am hoping a low buck cleaning and oringing the filter/pump and associated valving will cure the problem...maybe its a sticking issue that goes away once the oil warms up?

Anyone ever experience these symptoms?
I have read about other od symptoms but none yet like these.
Any suggestions are welcome.
Thanks

Do the normal preventive maintenance on it and see what you get..

Where are you located? (update your profile) If you are in a region that is cold, that will certainly affect the viscosity of your oil. It is my understanding that the OD is quite sensitive to oil thickness. What oil are you using? Contrary to what everyone believes, the manual does not simply state that 20w-50 is the best oil. It gives a range of viscosities for different temperatures.

So, clear the filter and if the problem persists make sure you have the right oil.

Agree with Terry here. Drain, clean filter, refill and try again. While you're at it, check overdrive electrical connections and may be good time to get a fuse inline with the O/D circuit. Very possible that the solenoid is getting intermiitent (and needs replacing), too. You don't want to melt the wiring harness trust me...

Look under the steering column and find the short harness that comes from the right stalk switch

Cut the wrapper back about two inches or so. Locate the yellow wire and snip it about an inch and three quarters from the gang plug.

Strip the insulation back about a half inch on both ends of the cut wire.

Tin the exposed wiring with a little solder.

Slip a sheath of heat shrink back out of the way over each of the exposed wires.

Now use one of those plastic fuse holders containing a 20 or 30 amp fuse to join the yellow wires and solder the connections as parallel joints.

Slip the heat shrink back up over the joint and apply a little heat from a match.

Wrap up all of the exposed wiring neatly with black electrical tape and put the whole mess back into place, securing with a zip tie if needed.

Cheap insurance against having to buy a new harness or worse in the future!

sometimes an overdrive will work best with the incorrect oil in it. and then a few years later with the correct oil. go figure. sounds like an oil problem of some kind.

I have these problems so don't feel alone. When it is cold here (relatively cool to the Northerners) my OD is reluctant to engage. Correct 20w50, screens are clean and the o-rings are good. Once it warms up the OD engages just fine. In the summer when it is as hot as Hades here, the OD works flawlessly. Just a quirk? Don't see a real problem here.

Thank you for all the imput !
I have always run castrol 10-40 in engine and trans.
I only drive the cars... mg and a/h bj8 during the summer months here in upstate ny...may-- october.
Always acts the same if its a 90 deg. day in august or a cold morning in october.
It takes approx 5-7 miles to warm up .
I would estimate its been approx 10k sence the last oil change/screen clean.This made no difference the last time i did it.

Its done this sence the day i bought the trans and od used from a guy up north for 300.00 back in 1996 .
The first time i pulled the drain plugs i saw the other half of the second gear synchro in a small pile of ground up brass sittin in the trans plug.

Hummm ....i thought .
How bad could it be?
I am now very good at double clutching down shifts but the strange thing is that i now double clutch my 01 Bullitt Mustang just for the fun of it.
Sounds great !! Gives ya that feeling of diving into turn one at watkins glen...And when ya do it just right it makes ya grin !

So i wont get to this work untill this next May but I will write back to inform you with the results.

I will add the fuse (good idea) but im gonna bet its a weak spring and /or stickey ball in one of the valves.
Thanks guys !

I'd drop out the filter and clean it out.