'89 Deville 4.5/4T60/fluid q's

Sounds like a friend of mine is going to con me into working on this pile he just picked up. 134K on the clock, states trans fluid hasn't been changed since '92. Says it shifts pretty ok, just hesitates/shakes/shudders on the 1-2 shift. I'm not really sure I want to touch it, I don't like working on pretty 'unknown' stuff. I recommended a basic drain/fill, possibly removing the pan and changing the filter/gasket. I've done that before on an ex's '03 Impala(not fun) and it didn't help. Told him to call the local Cadillac dealership and discuss it with their most experienced tech/writer to get recommendations. I'm thinking he's gonna be out at minimum $100 for this sort of thing. I'm trying to steer as clear of it as possible, but told him to bring it over wednesday after I get home from work to check fluid levels/smell and the TV cable(not 100% sure it has one) and the vacuum modulator. Quick googling says they could both be culprits, but also a sticking 1-2 solenoid.

Thoughts? I hate turning down working on friend's cars, but I'm one of those "Do it once, do it right" kind of guys when it comes to DIY stuff, and I hate working on other peoples stuff if I don't know for certain it will be 100% right. Just sounds too pricey/messy/expensive.

Do not touch it. It WILL fail if you do.

Ranger50 wrote: Do not touch it. It WILL fail if you do.

+1. That thing is on its way out, and whatever goo the trans fluid turned into back during Clinton's run is the only thing keeping it together.

Figured as much. Blasted GM-etry.

I'm not saying you should plunge into this mess with a song in your heart or anything, but what's "blasted" about it? On the evidence, the transmission is full of 21-year-old "fluid" and still "shifts pretty OK." That's great engineering right there, no?

Am I crazy for thinking a GM automatic that shifts decently but has a rough 1-2 shift probably has crud in the valve body and could use a filter/fluid swap, drive a couple weeks, then filter/fluid swap again to bring it back into shape?

Has anyone here actually had one of these transmissions with this sort of maintenance [not] performed and burned one up because of a fluid change?

And oh noes if it does burn up. Not in the most valuable car ever built, the '89 Deville!

pres589 wrote: Am I crazy for thinking a GM automatic that shifts decently but has a rough 1-2 shift probably has crud in the valve body and could use a filter/fluid swap, drive a couple weeks, then filter/fluid swap again to bring it back into shape? Has anyone here actually had one of these transmissions with this sort of maintenance [not] performed and burned one up because of a fluid change? And oh noes if it does burn up. Not in the most valuable car ever built, the '89 Deville!

Nope, you're not crazy. Chances are with that mileage that all it needs is filter/fluid swap. If it's shifting properly then the modulator is probably just fine. BUT, if it's a symptom of something worse, you don't want to be the guy that did that swap cause whatever happens after you finish becomes YOUR fault, no matter how good a friend this is. I'd send him to the nearest qwick lube spot to get the filter/fluid swap done, and tell him NOT to spring for the pressure flush procedure they will try to sell him. Or, tell him to throw in some of that Lucas snake oil transmission fix and drive it till it pukes.

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pres589 wrote: Am I crazy for thinking a GM automatic that shifts decently but has a rough 1-2 shift probably has crud in the valve body and could use a filter/fluid swap, drive a couple weeks, then filter/fluid swap again to bring it back into shape? Has anyone here actually had one of these transmissions with this sort of maintenance [not] performed and burned one up because of a fluid change? And oh noes if it does burn up. Not in the most valuable car ever built, the '89 Deville!

we did. my mom didn't have the fluid done from new to 151k on a lumina. fluid change, trans immediately started slipping bad in all ranges.

however, i wouldn't hesitate to change it out. worst case add some lucas stuff. i had a blazer slipping at 150k due to being run low for a few weeks, again my mom's doing. lucas trans additive, the kind that is as thick as jello, and it's still fine at 199k.