Car: 1982 245GLT, manual transmission with overdrive. The problem is that when the car is cold, I must get the car up to about 75 in order for the overdrive to engage the first time, and this isn't a sure thing either. Below this speed the light comes on, and the overdrive seems like it is disengaging, i.e. the tach reports the engine speed decreasing. More so than the car slowing down. When the car warms up after about 15 minutes of highway driving, the overdrive works like a champ. When the problem first started popping up I changed the tranny fluid, to no avail. I've read the FAQ and it mentions a couple of possibilities:

1) Electrical problems - I think that this isn't the problem, since it behaves as if _something_ is happening.

2) Internal piston seals going bad - The FAQ mentioned that this will make a warm o/d misbehave. This doesn't appear to be the case here.

3) Solenoid malfunction - I think in my case this is the most likely scenario. Perhaps the solenoid is only partially opening and not allowing full pressure into the actuating piston?

I went ahead and procured a new solenoid, thinking it would cost 30 bucks. Boy was I wrong. Before I open the package on this sucker, is this problem most likely the solenoid and can I check this? I thought about taking the old one out and placing 12V across it, but I am not sure what a fully open solenoid valve v. a partially open would look like.

I hope this reaches you before you install that way too expensive solenoid.

It seems to me that your diagnoses is close if not on the money regarding the solenoid. It is either that or poor electrical connection at the solenoid or at the 4th gear switch.

Prior to replacing the solenoid, see if you can clean it out. If the brass end of the solenoid that inserts into the OD body has a snap ring in the end you can open the unit and clean it out.

Send me an e-mail and I'll get the instructions to you.

Duane ODGuru@kc.rr.com

The one thing you didn't mention was cleaning out the sreen oil filter in the o.d.. There's cover on the underside of the o.d. drain the oil rmove the cover clean the filter, that could be all it is. My experience of solenoids in general is they work or they don't. If it's only opening half way usually something is holding it back ( or the shaft is bent) I would also pull a sole from a wreck to check. P.S. How much didi you get dinged for the solenoid?

I did clean out the screen when changing it. the synthetic is a good idea, and I could use that next, but it is pretty expensive per bottle. the solenoid rang me 180 dollars. Like I said, I'd rather return it than use it if possible.

You changed the fluid. Ok. When fluid warms it thins and is able to flow where/how it needs to 'actuate'. Even with new fluid there could be a goob or two circulating in there. Bleed off some fluid and add a synthetic or trans-medic/detergent product. See what happens. Meanwhile, write an E-mail for a quote on the solenoid to andy@importpartsspec.com I bet you will be happier with their price.

Good luck,

Mark

I'll try this out next, thanks ... what exactly is trans-medic? Do I throw a bottle of this stuff in there, run it for a period of time, then change the tranny fluid again?

Trans Medic is made by K@W. I have used the Auto-trans fluid. I'm sure they have something for Manuals. Slick 50, Duralube, etc. also might be a choice.