97 GM transmission shudder a help!

[Mustangdude86]

Just picked up a 1 owner 1997 GM with 97k miles. I noticed on the way home...driving about 20 miles so its good and hot...I noticed a pretty good shudder from 3rd to 4th. Any ideas?

Is this as simple as fresh fluid, or is OD going out....I sincerely hope not the latter because I'm broke.

[Kodachrome Wolf]

Drop the pan, change the filter, and add fresh fluid. It should be 5 quarts for a filter service fill. Grab some Mercon V from your favorite auto parts store.

If the problem persists, it may be something else.

[sly]

^ what he said. If the problem persists, replace the torque converter. It's lockup shudder.

[Mustangdude86]

I've never done this before yet. Does the filter just pop out once the pan is off? I'm assuming it's wise to buy a filter that comes with a new pan gasket?

If the problem does persist.... What can happen driving it with the shudder?

[Kodachrome Wolf]

After you remove the pan, you simply need to pull the old filter out. It may be a little stuck if it hasn't been serviced before. You should not need to replace the pan gasket unless yours is shot. Our cars have reusable pan gaskets which are superior to the generic ones usually packaged with transmission filters. Only replace your gasket with a new one if it is damaged.

[Mustangdude86]

Okay thanks. I'll give it a shot!

[P72Ford]

If you've never serviced a transmission before... there is no drain plug. If you're asking why, take solace in the fact that everyone has asked this same question for years.

Draining can be tricky. I usually start by loosening the front of the pan, and progressively working my way backwards around the pan, so that the pan "hangs" off the partially loosened bolts. Keep loosening them incrementally, until the fluid has drained enough that handling the pan is manageable. You need a good sized drain pan to do this without making a mess. If the bolts give you grief (had this on rusty cars), be patient and use some PB blaster. Breaking a bolt in the pan rail is less than ideal.

Also make sure that you have the o-ring on the filter, the old o-ring was removed, and you have it (o-ring and filter) fully seated before re-installing the pan.

I would pick up at least 6 quarts of fluid. Add 5, cycle it, check, and test drive. Add more as required. It never hurts to have an extra couple quarts around.

As an FYI, my Dad had a '99 P71 that used to shudder at lock up, and a transmission service fixed the issue. There is hope!

[Mustangdude86]

Thanks for the heads up. That does seem silly that there isn't a drain plug.

Driving it today, I mainly noticed it doing it in 3rd (off and on during acceleration) and a tiny bit in 4th whenever gas was let off and re-applied.

Still sound like lock up issue?

[TecNickal]

Yes torque converter. Especially when cruising and letting off throttle when it's in 4th with locked converter. Then reapply throttle. Torque converter will unlock then lock again.

[Kodachrome Wolf]

FWIW, Dorman makes a transmission pan with a drain plug if you're interested. I'm considering getting one for ease of service in the future.

[Mustangdude86]

Yes torque converter. Especially when cruising and letting off throttle when it's in 4th with locked converter. Then reapply throttle. Torque converter will unlock then lock again.

Ok if servicing it doesn't work that'll be the next step. Still better than the whole transmission I'd say though.

[Mustangdude86]

FWIW, Dorman makes a transmission pan with a drain plug if you're interested. I'm considering getting one for ease of service in the future.

I'm assuming its this guy right here?

http://www.dormanproducts.com/p-73883-265-813.aspx?year=1997&make=Mercury&model=Grand%2520Marquis&origin=&parttype=Transmission%2520Pan&transmissionmfrcode=4R70W

[Mustangdude86]

Also, not to start a fluid brand war, but is an off the shelf fluid, like an autozone, Mercon V sufficient, or should I shoot for something else? I don't want to spend a whole lot in fluid if it does turn out to be the tq converter.

[FordMan77]

I usually use Motorcraft fluid, but I have used Valvoline Mercon V in the past. The only drawback to the Valvoline is it seems to smell burnt right of the bottle. Not sure it's changed since I only used it that one time.

If you can drain the torque converter I'd do that too. Think it still has the drain plug on that year. You'd have to pop off the rubber inspection cover on the bellhousing and rotate the engine around by hand to see if it does for sure. If you do that and drain the pan then you'd get more of the junk fluid out. I'd also suggest the J-mod and a trans. cooler for it. J-mod doesn't necessarily help with the TC shudder, but it provides faster clutch engagement which cuts down on clutch wear and heat generation. The cooler will help keep the fluid alive a bit longer as well. Been through a few 4R70W issues myself and seem to have finally made one live rather well, lol.. so far.

I'd change out as much fluid as possible, new filter and fluid and see what you get. You could probably snag a good cooler for cheap if you look around. All else fails then you just extended the life of it hopefully long enough to locate a used trans. for it. I know how it is to have limited funds and have a drivetrain component start to give up. Rear axle redo #3 coming up for me here shortly. Hopefully for the last time...