Trans Acting Up

I have an 85 with the 305 engine and the 700r4 trans. 421,000 miles on this trans. No work done to it. I was driving to work a couple days ago, driving down the hiway at about 65 to 80 mph, for about 30 miles. Got off the hiway onto secondary road. At one of the red lights, the problem happened. Firrst gear was fine, second gear was fine, but it didn't want to shift into third. I moved the gearshift from O into D, and that worked, to put me in third. Kept it in D and drove the last 2 miles to work, and it shifted normally.
After work, drove cautiously home, with gear shift in the "O" position, and all was well, but I didn't go over 65 mph.

Drove it around town today, about 7 miles, in "O", and all was well.

The fluid level is OK, could use about a half pint to bring it up to full.

I haven't changed the fluid and filter in a long time because I have to add a pint of trans fluid every 2 weeks, due to a leak at the front pump seal, so it stays fairly fresh. I guess particles could still be accumulating though.

Another thing I've noticed in the last few months is that sometimes it takes a few seconds to engage, after moving the gear selector into O or R.


Any clues welcome.

Thanks,

RC

A check of the line pressure would confirm it, but I'm guessing the pump is worn. I'd almost guaranty the pump bushing is long gone, and it's a good bet you don't have even a seven vane pump to begin with.

More than likely, when the trans oil is cold, it is more viscous and can get the job done (barely). As the trans oil heats up and loses viscosity, it can no longer maintain adequate pressure. When that happens, the pressure is too low to overcome the spring in front of the 2-3 throttle valve. Line pressure is a function of the pump, the TV, and the PR valves. There is probably already plenty of wear in the governor, accumulator, and direct clutch. The lower line pressure is simply unable to overcome all of these points of wear.

In other words, it's probably time to spend a few hundred dollars on freshening up the trans. You can get a rebuild kit, 10-vane pump kit, separator plate, repair manual, and a band for under $200.

I have an 85 with the 305 engine and the 700r4 trans. 421,000 miles on this trans. No work done to it. I was driving to work a couple days ago, driving down the hiway at about 65 to 80 mph, for about 30 miles. Got off the hiway onto secondary road. At one of the red lights, the problem happened. Firrst gear was fine, second gear was fine, but it didn't want to shift into third. I moved the gearshift from O into D, and that worked, to put me in third. Kept it in D and drove the last 2 miles to work, and it shifted normally.
After work, drove cautiously home, with gear shift in the "O" position, and all was well, but I didn't go over 65 mph.

Drove it around town today, about 7 miles, in "O", and all was well.

The fluid level is OK, could use about a half pint to bring it up to full.

I haven't changed the fluid and filter in a long time because I have to add a pint of trans fluid every 2 weeks, due to a leak at the front pump seal, so it stays fairly fresh. I guess particles could still be accumulating though.

Another thing I've noticed in the last few months is that sometimes it takes a few seconds to engage, after moving the gear selector into O or R.


Any clues welcome.

Thanks,

RC

the govenor gear is a plastic part that this vintage of transmission had wear issues,,,but with the mileage on this type of transmission I would say it will require a overhaul which will depend on many factors as to the cost ...in addition the location of repair shop.

Thanks for the replies. I may be saying goodbye to this car in a few months. Would a bottle of Lucas trans conditioner in the meantime do any harm ? Maybe it would thicken up the fluid and add some pressure to the lines.