Cadillac transmission problem.

[PMC the 1st]

I owned a 1987 Cadillac Eldorado (great car!) that eventally saw 280,000 miles of service. It had the old HT4100 engine.
Around the 220,000 mile mark, the transmission refused to shift into 4th gear overdrive until the whole drivetrain warmed up (10 minutes of driving). The car would be cruising down the freeway @ around 50 MPH max with the engine revving @ 3K RPM until it did shift. This happened only on cold mornings (warm socal mornings no problems even @ start-up).

Anybody ever experienced such things with this drivetrain?

[Johnny P]

This really kinda belongs in the tech forum....

The problem you refer to is common on any automatic. Over time the seals get hard and it causes late, hard, soft, banging, slipping or no shift problems.

I believe that car had a 700R4. If so, I'd imagine the servo seals were hard. Oil is directed behind a piston which forces a band to wrap around a drum and hold a member. This is how they overdrive a certain gear. Sometimes it is done which a clutch, but in the 700R4 2nd and 4th are band apply. A mis-adjusted throttle valve can also cause similar trouble.

[F14CRAZY]

Was the engine coming up to normal temperature? My Reatta with a stuck open thermostat wouldn't get above like 120 degrees after half an hour in the late fall and the ECM won't allow torque converter lockup until the system gets to some temperature (I can't remember).