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No overdrive '88 Grand Marquis Transmission

ExploreFlorida's Avatar
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07-18-04, 09:48 AM   #1  
No overdrive '88 Grand Marquis Transmission

My 1988 Grand Marquis hasa less than 75K miles. I driive it weekly. Recently, when I hit 40 mph, the engine just spins but the tranny doesn't seem to do anything, no acceleration, nothing.

If I let it drop back to 25-30 mph, I can go again as long as I keep it under 40 mph.

I'm able to do fine if I put the car in D2 so that it doesn't go into overdrive. Then I can cruise around without a problem.

Any idea what the cause could be? Hints. Suggestions? I can take it to a tranny shop but have misgivings about their objectivity in these matters.

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Join Date: Jan 2002
Posts: 1,915

07-19-04, 07:37 AM   #2  
I'm guessing you're missing the third gear. D2 means only the 1st and 2nd gears are engaged. Typically 40mph is when the third gear kicks in. Overdrive (or 4th gear) will kick in around 50-55mph.

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Join Date: Jul 2002
Posts: 471

07-23-04, 02:19 PM   #3  
an 88 grand marquis likely has the 5.0 engine mated with the aod.

the aod's are FAMOUS for their overdrives going out, in part I believe to a hollow and very week o/d shaft internally in the tranny.

You can try adjusting the tv cable, but unfortunetly more than likely you're gonna need a new tranny. Don't pay an arm and a leg for it. If you're resorceful, you'll find a guy with a mustang selling a good one for $200 or less (don't pay more than that for a good used aod) and put it in yourself, it's not that difficult.

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