200R4 Lockup Converter Clutch problems

[cellblock_g]

I have a 1985 Buick LeSabre (RWD) and am having issues with the lockup torque converter clutch engaging at far too slow of a speed. Car has the Oldsmobile 307 V8 with 200R4 transmission.

The lockup will usually try to engage in 2nd gear, at speeds as low as 15 MPH, even with a cold engine.

It will also stay locked usually, and not disengage at highway speeds when I take my foot off the throttle.

It will also try to force the car to hold 2nd gear when coming to a stop, nearly stalling the motor, but it finally bumps into first at the last moment.

Also, for example when taking a slow turn in town, say turning onto a side street, the lockup won't release and will cause the transmission to bog down and growl until the car gets up to speed.

I pulled the fuse for the TCC but this kills my gages and causes the Check Engine light to come on, and the clutch still engages.

I pulled the plug on the side of the tranny, and hooray!, problem temporarily solves, except i have no lockup at all. I was warned that without the lockup the tranny will overheat on the highway, so i plugged it back in. But note that the car shifts as smooth as silk without the lockup clutch engaged.

For about 20 minutes it shifted beautifully, EXACTLY like it should. The lockup wouldn't come on till 45 MPH in 3rd gear (the way I remember most cars of this vintage being), and would disengage and engage properly when I applied/released the acclerator. After that it started playing the same old game, with all the problems above coming back. It seems to act up the most after highway driving (65-75 MPH), over long distances.

Anyone have any suggestions as to what the problem could be?

The fluid is clean, smells nice and fruity yet, and doesn't leave dark stains on white towels.

The transmission has no external cooler (no lines going to the radiator if I remember right).

Is it something that a simple flush might remedy?

And what would be the lessor of two evils here: Driving with no torque converter lockup clutch or driving it as is with all the above problems?

 

[cellblock_g]

lockup clutch

also, is this clutch supposed to engage in 2nd gear, period?

 

[GNeric]

"Some" lockup strategies apply after 2nd but sounds like your solenoid is stuck or the valve in the pump is stuck. It uses 2nd gear signal oil for apply. If stuck, it will apply as soon as 2nd is applied.

 

[mikestertwo]

You have a bad lockup solenoid. Replace it.

 

[bison]

replace the solenoid

 

[cellblock_g]

lockup solenoid

How easy is it to replace?

 

[cellblock_g]

part #

And does anyone have the part # for this solenoid? And is the 700r4 solenoid interchangeable with the 200r4 solenoid (in case parts stores have one but not the other)

 

[SSedan64]

Solenoid Replacement

And does anyone have the part # for this solenoid? And is the 700r4 solenoid interchangeable with the 200r4 solenoid (in case parts stores have one but not the other)

It's easy to replace, step by step intructions with clickable links/pics here>>>> TH200-4R TCC Solenoid Transmission Problem
Yes, the 2004R & 700R4 solenoids are interchangeable. You can buy the Universal Solenoids much cheaper than GM parts. $15-$20 compared to $50-$60.
Example here>> 2004R Transmission Parts Solenoids Makco Transmission Parts or buy it from local Auto parts store.

 

[snake oil]

 

[cellblock_g]

5 month update

Well 5 months later and I finally had the lockup TCC solenoid replaced along with doing a full fluid/filter change and a flush. Car drives like a dream now, probably as good or better than when it rolled off the showroom floor 25 years ago. It won't be winning many races with its 307 V8 and 2.73 gears, but its a good looking old cruiser and I'm riding in style! Thanks for your help everyone!!!