Ford - Tempo - Transmissions :: 1993 - Pronounced Thunk When Downshifts At A Higher Rev

First, the specifics: 1993 Ford Tempo 4-cyl Auto 78,000 miles (the proverbial little old lady car.) From a stop, the car will rev clear up to about 30 mph before shifting out of first into second. It will stay in second well past 60 mph, and even then, I have to kick it hard to make that happen. It's not that it won't shift; bit it seems to delay well past where it should. If I do manage to get it into 3rd, there's a pronounced thunk when it downshifts at a higher rev than it should when I slow down.

Now the background & other info: It's not my car. My B-I-L lent me this car because I ride a motorcycle all winter, & he took pity on me for the rainy & snowy days. In return, I offered to fix an annoying rattle. The problems went well past that, of course. The second day I drove it to work, it overheated and spewed clouds of steam in the parking garage. I had to have it towed home. That turned out to be a split in one of the heater hoses.

Disturbingly, however, the temp gauge on the dash never rose off of "C" on the ride in. I had expected to be replacing a water pump, but the heater hose seemed to be the only issue. Just the same, I replaced the thermostat and the temp sensor because I suspected the burst hose was a symptom, not the cause. Sure enough, after it's all put back together, the dashboard temp gauge is working better, and a short hop to the grocery store showed no overheating. At least that problem seems solved.

Prior to the coolant issue, the car drove fine (for one day); the shifting problem only surfaced afterward. As a last piece of info, I'll add that I had to add an entire quart of transmission fluid to bring the level between the marks. I didn't check that previously, so I can't say if that was a pre-existing condition. So then - what's the fix here? Could an overheated engine cause the tranny problem? Any chance this can be fixed simply? (FWIW, the rattle is the A/C pulley.)