O/D won't disengage when hot

[glemon]

As stated above, engages fine, disngages fine, but after 15 minutes or so of driving out doesn't disengage. After it sits and cools off it does self disengage (but this freaks me out as you are not supposed to go in reverse with O?D engaged, and it is hard to "know" it is engaged).

All of the above behaviour is very consistent and has been replicated several times. I can hear the solenoid click when it is stuck, electrics seem fine.

It is supposed to be rebuilt, could the new linings on the cone clutch be sticking? Any ideas, my previous experience with these is that they work or don't engage, never had one that sticks on, am thinking only fix will probably involve taking it apart, am hoping something is tight and wear and time will fix it.

I have a J type O/D on my TR250 tranny.

 

[Deleted member 12470]

Make sure that the gearbox oil level (shared with the OD) is up to the fill opening. When "hot" the oil is splashed around the gearbox and overdrive and the OD hydraulic pump may not have enough oil to operate if the level is low.

 

[Deleted member 8987]

Yeah, but lack of oil and pressure CAUSES disengagement, right? Oil issues can cause overheating of components, expansion, and sticking, unless something is put together "tight". Have you tried a thinner viscosity oil?

 

[TR3driver]

Have you checked the pressure? That's certainly where I would start. I had similar problems with my J-type when I tried to shim the 'idle' pressure up a bit too high. The unit would work fine when cold, but hang in OD when hot.
https://www.geocities.ws/jholekamp/

The good news is that the relief valve that controls the idle pressure is accessible without removing the unit (but you will have to remove the bottom plate & one of the plugs under the plate, which takes a special tool).

Could be the solenoid hanging up; but they are kind of expensive to just replace on the off chance it's the problem. There's also a special tool for that (but it's just a really thin, short, 1" open end wrench).

 

[Deleted member 8987]

If I recall, the last time I needed that special thin 1" open end, I took a GM fuel filter wrench and cut it in half. They are THIN, 1", one end angled opening, one straight.

That's a fuel filter wrench like for a quadra-flush.
To hold the fuel filter nut tight while removing the fuel line, and then to remove the nut to replace the filter.

 

[TR3driver]

Sounds better than what I did, which was to buy a 1" combo wrench @ Harbor Freight, cut it in half and mill off the sides.

Might not need to be so short on a TR250, but on a Stag there's no room to swing a longer wrench.

 

[glemon]

Tha have not tried anything yetnks for the ideas, I have not tried anything yet, looks like I will be crawling under the car this weekend.

Greg

 

[Minesweeper]

If the problem appears to be with the solenoid, the solenoid is dead simple to refurbish. The thin 1" wrench (available at McMaster-Carr), some electronics cleaner and a few o-rings are all that is needed. I had the same non-disengaging problem last year. After eliminating low gear oil, clogged filters and electrical issues as possible causes, I rebuilt the solenoid -- o/d now shifts in and out with no hesitation.

Scott

 

[glemon]

I jacked up the car and looked about a bit Sunday, I did not want to take too mcuh apart because I had a car show to go to Sunday night.

I discovered I was way low on oil (topped it up), discovered my semi thin 1" wrench was not thin enough, will go to the downtown pawn shop and get one to grind down.

Good news, balky 2nd gear downshifts are gone with the topped up tranny, bad news, I am losing oil through the vent hole that in trsnny, not sure why, was told you need a vent hole with O/D.