smoke from overdrive on BN2

[bighealeysource]

Hey y'all,
I had an earlier post about problems out of no where with my overdrive and a couple of folks got back which I appreciated. I was hoping it was just a bad solenoid so put a new one in tonight and took the Healey out for a test drive. Holy crap, it did not go good. In 3rd gear, maybe doing 35 mph, trans tunnel off as working on it, switch on at the toggle and seemed like it was engaging as normal, then all of a sudden, a definite metallic grinding sound, pretty loud, and I immediately toggled off the O/D switch. Continued going forward and seemed okay as I was turning around to go back home, maybe a mile out, and on that mile back at maybe 20 -25 mph, had faint smoke coming out of the small breather on top. Not like on fire smoke, but definitely white smoke. Got her home, let everything cool down and took it back out - I know that may not have been my most brillant decision but if it's broke not going to unbreak - no more smoke and got up to 50 -55 mph for a few miles and turned around to come back. Just before I got back got a louder than normal gear noise coming from what seemed to be the O/D unit but no smoking, just louder than normal. Pulled back in and the engine bellhousing was at about 120 degrees, trans at close to the same but O/D unit about 145 degrees. This all with a laser temp device and simply pointing at the bellhousing, actual trans and then the O/D unit. The O/D unit is well beyond my capabilities to work on other than the basis electrical issues which I thought were the problem. Apparently not ! Other than the obvious of pulling the O/D and trans that will probably have to be done, do you think I can safely drive the Healey without using the O/D ? Not really driving anywhere where speed limit is beyond 55 so no interstates or anything. It's running great otherwise and no issues with trans or engine. I know if I have to pull everything it will be down for sometime just as fall weather is approaching. I have a couple of great sources for getting the work done so that is not the issue, of course the cost certainly will be as semi retired. Any recommendations, advice, etc ??? Would really like to put this off until this winter.
Many thanks,
Mike

 

[57_BN4]

Was the oil level ok?

Drain the oil and take out the big round brass plug underneath. If no major junk in there probably ok to run in non-od. Sounds just like your clutch was slipping- typical of low oil pressure and that is what made the heat.

An easy thing to check is the lift of the actuation valve, it is under a small plug with hexagon head on the top of the OD next to the breather which is usually fiendishly tight. That is also where you'd attach the pressure gauge. It needs to lift the ball bearing off the seat far enough to allow oil to pass to the apply pistons and also the ball bearing needs to seal on the end of the lifting rod which is hollow to allow pressure to discharge when switching out of OD. You can fish the ball and rod out with a magnet stick.

If you do have to pull the trans eventually, run it gently on stands and flick it into and out of od a few times while in 4th gear mid rpm then take it out of gear and pull the lever sideways to operate the OD solenoid a few times as soon as it is stops turning. This makes sure the load is off the clutch/sprag so you can easily get the mainshaft out. If the last time the OD was disengaged was during a kickdown then the clutch and sprag end up loading the shaft in opposite directions and it remains firmly stuck together.

Andy.

 

[bighealeysource]

Thanks Andy, appreciate the detailed advice ! I had checked the oil level and use 30 wt non detergent and believed it to be good. I will drain it as recommended and see if any bits in there and refill. If no pieces of the parts are laying in the drain plug will leave well enough alone for now and see how it drives out. Think your description of the clutch slipping makes sense for the white smoke and heat and makes me feel a bit better that my overdrive wasn't on fire !!!
Good on ya mate,
Mike

 

[Randy Forbes]

Sounds like the ovd clutch assembly is delaminating, which will leave pieces of it flying around the gearbox. I think driving it will continue to make things worse (as in more expensive to repair).

You've been having problems on & off for quite a while, and I think it's time to face up to a total gearbox inspection and overhaul.

 

[bighealeysource]

Hey Randy,
I know, trying to put off the inevitable a bit longer. Sent you a PM about it too. Will drain it and see what's in there and post back here what I find.
Thanks,
Mike

 

[bob hughes]

Randy





Bob

 

[Randy Forbes]

Well, if you can piece together the entire outer friction surface(s) of the clutch cone from the drained oil, you might be able to get away driving it in Normal mode...

 

[bighealeysource]

Drained the trans and OD oil and no big pieces but a few very small particles, about size of a grain of sand. Bottom of oil drain pan had a slight metal flake appearance to it but the particles in suspension were so small could not even separate them out from the 30 wt oil. Did drive it again to heat up the trans and engine oil and shifted fine, no noise or grinding, just normal. Regardless, going to pull it soon and go over both pieces ! Thanks for everyone's comments and advice !!!
Regards,
Mike

 

[Healey Nut]

You dont need to pull the transmission to remove the overdrive . You can remove the rad fan and jack up the gearbox high enough to remove the overdrive from inside the car after removing the tunnel etc . Rebuilding the overdrive is easy you just need to be methodical have patience and take notes .And dont be cheap replace ALL the worn parts . The hard part is getting the double spline to line up when refitting it to the gearbox . Its a royal PITA but it can be done ,again with patience , dont force it it should just slide on if everything is lined up . Theres no big mystery to an overdrive , all it is is a hydraulic pump that when engaged has enough oil pressure to overcome spring pressure and engage a wet clutch .:fat:
You have all winter to do it , take your time.