'88 LSC, 5.0 HO, AOD.
As long as I can remember, the transmission seemed to slip right around 70mph, uphill on a freeway. Not faster and not slower.
It would last only a short moment.. less than half a second.. and happen perhaps once or twice per mile. But sometimes traveling the same road it wouldn't happen at all. On a long uphill it might happen 10 times.. weird.
The feeling is just like the clutch slipping on a manual tranny. But it's just a short slip-pulse and the engine doesn't have time to rev up noticeably, nor does the car slow down.
Then something new... since about 2 years ago.. Whenever in freezing weather in a parking lot, on a cold start the trans will slip quite a bit at less than 5 mph. Once it drove a mile or so and warmed a little, that disappeared.
Just last month, on the mountain freeway, uphill at maybe 70mph, and downshifted to pass someone, the trans really slipped. In fact, I think that if I kept it floored it woulda slipped forever. But laying off the gas slightly allowed the torque converter to lock up again.
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OK.. Sure sounds like symptoms of a low fluid level. "Underfill: slippage, especially in cold weather, parked or being driven on a hill" (paraphrasing the shop manual) It's time to at least check it.. There are no external leaks, but it's turned over a quarter million miles and all that..
On the dipstick, there's a hashed area, below that a hole, and below that another hole.
A cold-check (room temperature, idling engine, go through gears, put it in park and check) showed the level way below the bottom hole.
No way should it be that low. That bottom hole marks the "Do not drive" limit.
So, seeing it's low, I find instructions to top it off in the glove box owner guide..
Add fluid one cup at a time.
Trans Fluid capacity is 12.3 quarts. Over 3 gallons. That's 50 cups. One cup is like nothing. I have to be a quart or two low at least, wouldn't you think?
Well, I added a cup and the level rose almost all the way to the hash area. Another couple ounces and it was at the hash mark area. That's "full" for cold fluid. Hot fluid expands it higher.
Re-checked it on the hot running car shows the level at maximum at the top of the hash area.
I haven't been to the mountains or in freezing weather yet, so can't say if anything is better, but I sure am surprised that being just a few ounces low puts it in Do Not Drive territory.
As long as I can remember, the transmission seemed to slip right around 70mph, uphill on a freeway. Not faster and not slower.
It would last only a short moment.. less than half a second.. and happen perhaps once or twice per mile. But sometimes traveling the same road it wouldn't happen at all. On a long uphill it might happen 10 times.. weird.
The feeling is just like the clutch slipping on a manual tranny. But it's just a short slip-pulse and the engine doesn't have time to rev up noticeably, nor does the car slow down.
Then something new... since about 2 years ago.. Whenever in freezing weather in a parking lot, on a cold start the trans will slip quite a bit at less than 5 mph. Once it drove a mile or so and warmed a little, that disappeared.
Just last month, on the mountain freeway, uphill at maybe 70mph, and downshifted to pass someone, the trans really slipped. In fact, I think that if I kept it floored it woulda slipped forever. But laying off the gas slightly allowed the torque converter to lock up again.
-------
OK.. Sure sounds like symptoms of a low fluid level. "Underfill: slippage, especially in cold weather, parked or being driven on a hill" (paraphrasing the shop manual) It's time to at least check it.. There are no external leaks, but it's turned over a quarter million miles and all that..
On the dipstick, there's a hashed area, below that a hole, and below that another hole.
A cold-check (room temperature, idling engine, go through gears, put it in park and check) showed the level way below the bottom hole.
No way should it be that low. That bottom hole marks the "Do not drive" limit.
So, seeing it's low, I find instructions to top it off in the glove box owner guide..
Add fluid one cup at a time.
Trans Fluid capacity is 12.3 quarts. Over 3 gallons. That's 50 cups. One cup is like nothing. I have to be a quart or two low at least, wouldn't you think?
Well, I added a cup and the level rose almost all the way to the hash area. Another couple ounces and it was at the hash mark area. That's "full" for cold fluid. Hot fluid expands it higher.
Re-checked it on the hot running car shows the level at maximum at the top of the hash area.
I haven't been to the mountains or in freezing weather yet, so can't say if anything is better, but I sure am surprised that being just a few ounces low puts it in Do Not Drive territory.