89 marquis trans

[manlion]

are there any vacuum lines or modules that go bad on a 1989 marquis trans that would keep the trans from not shiffting into overdrive? It happened all of a sudden. The bushing for the accelerator linkage was broken and I changed that. Still does not shift.

[FreightTrain]

The linkage groment at the throttle body is the main problem when an AOD wont shift. The early models that have a rod from the carb to the transmission when the groment brakes the rod falls to the firewall and puts the trans into high pressure not causeing further damage, Now the later models with fuel injection and a cable used for trans throttle control when the groment brakes on it the cable stays were it would be at the idle position. The problem there is the transmission line pressure is very low because the cable is not moving and it burns the trans up and I have seen an installer not hook that cable up after a rebuild and the trans is smoked by the time he returns from test driving it within a few miles because of low line pressure and 3rd and 4th are the first to go then no-go if drove long enough.

Now if you have a fuel injected 5.0 and you ever feel real soft shifts on take off put the gear selector in manuel low gear and take it easy on that screamin engine till you can get somewere to get a groment...

There are no vacuum lines on a AOD

SO JUST REMEMBER
The early models with a carb when it happens (Wont shift) They go to high line pressure......No damage

The later / Fuel injected models shift very soft or will stack shift and be in 3rd or 4th by 20Mph. They have extremly low line pressure.....And will fry the clutchs resulting in a needed rebuild unless put in manuel low gear intill the groment is replaced


If you call around your local transmission shops there is a brass bushing that wont ever come off to replace the rubber one but it is only available thru aftermarket transmission suppliers so transmission shops are the only ones that can get em...I think I pay no more than $5 bucks for them so if they want more than twenty bucks for the part alone keep calling around and dont pay more than $50 installed

[corey6135]

where is this grommet???

[Mercracer]

Originally Posted by corey6135

where is this grommet???

You probably changed it already. He is talking about the bushing (grommet) at the throttle lever for the TV cable.