Hi folks,

The day before yesterday, I drove to a store and the car was pulling fine. When I started driving back, the transmission would not shift properly. The car seemed to slow down if I opened the throttle anywhere past about 1/4, and the car would rev as if it were in neutral without sending any power to the wheels.

The car can get up to about 40mph, but nothing above that without redlining. The power throughout acceleration is inconsistent. A buzzing/whirring sound emits from the driver side of the engine when the shift selector is in park, neutral, or reverse, but not drive or 3, 2, or 1.

The fact that the transmission stopped working properly so suddenly made me think it is the failure of a single part (which may have cascaded), so I checked the things that were easy to look at. Vac line to modulator was a little rotted, but replacement yielded no improvement.

Any ideas what sort of job I'm looking at here? Replacement of vac modulator? Fluid and filter? Solenoids? Rebuild?

Thanks

I'm no transmission expert, but all this sounds far too familiar.

The important things on the driver'* side of the transmission are the torque converter and the transmission pump, both of which can make a buzzing sound and symptoms like yours when they start to go.

On the 4T60'*, the vacuum modulator is only responsible for controlling fluid pressure during shifts; on all transmissions, the solenoids are what make the shifts happen. Based on what you're telling us, we can rule all of those cheap-ish fixes out — but good call on checking the vacuum line.

If you have the time, crack open the transmission pan and see what the fluid and magnet tell you. If you have both time and money, change the fluid and filter, then hope for the best.

It shall be done. I imagine filter is available at O'Reilly?

The closest O'Reilly'* to me is about five states away, but it'* an easy-to-find part. The entire 4T60 and 4T65 families take the same filter (I believe).

Any good write-ups on this? I'm mostly curious if I need to drain the pan first somehow. It seems like it will just pour fluid on my face if I don't.

Before you change the fluid, and filter, you may want to consider a rebuild of the transmission since you are around 188k miles, unless you do not plan on keeping the car a lot longer, that way you do not spend money on the fluid now, only to find you need a rebuild shortly after.
If that is not in the budget, then you can do as I did when I had a similar issue with 4th gear and reverse, I drained the fluid, replaced the filter, and replaced the so called permanent filter gasket, mine was not reusable, but I hear mostly all the GM metal framed gaskets hold up and are reusable.
I got lucky, or unlucky depending on how you look at it, I found a good sized piece of my forth clutch thrust washer on top of the filter, I also found my fluid had become a lot darker than I like to see it, so I put on a new filter/gasket, and filled it with with some Mobil 1 synthetic transmission fluid, along with a little tube of a good friction modifier, normally I'd not recommend any transmission fluid additive, but for the money this stuff is worth it, after my fluid/filter change the transmission felt like it did before when shifting/not loosing power.

For your gasket I recommend ACDelco 24227477 Automatic Transmission Filter, available at local parts stores, but I recommend ordering from rockauto, or amazon, prices are almost always cheaper than local parts stores.
If you find your gasket is damaged then you want ACDelco 24204624 Automatic Transmission Gasket, most likely yours will be reusable.


When you drain your fluid note the color, and smell of the fluid, also check the fluid for bits of metal, I used a rare earth magnet, and drug it through my fluid after letting the fluid settle in the catch pan a few minutes, you do not have to do it this way, but make sure to examine the fluid for any metal bits, you can expect to see a greasy metallic goo covering the magnet in the pan, clean up the magnet and out it back in the pan after the pan is cleaned up.

I found a write up for you, thanks to Dan, it says 4T65-E, but is still relevant for your transmission.
https://www.gmforum.com/4t65e-hd-147...filter-279685/

Pan has been dropped. I'm not sure what to look for as far as metal "shavings", but the magnet had a good thick layer of silvery goo on it. Does that mean something exploded?

Hey WilliamE, thanks for the response. Unfortunately, I didn't see it until I had already dropped the pan and replaced the filter. Fortunately, I haven't replaced the fluid yet. I bought 8 quarts of Dexron III at the recommendation of a dealership mechanic.

The fluid was a little brown, but didn't smell burnt at all. The pan had a dark residue on it, and the magnet had about an eighth of an inch of the greasy metallic goo you speak of. Curious, I chopped the filter open on the bandsaw and found a big glob of shredded plastic bits stuck in the intake, along with a single little piece of thin copper sheet, maybe from a shim. Does this sound like what happened when your thrust washer went?

If it is the thrust washer, will a master rebuild kit include appropriate replacements?

I really love the car, and would like to keep it going. Even if it means no more peeling out from red lights =(

Filter after chop. The plastic bits were all centered around the hole on the right, until I moved 'em around a bit.

I wonder if its one of those plastic thrust washers that tend to break and usually just fall down into the pan?? If so, this one got chewed up pretty bad and got sucked into the filter which probably clogged it to the point of starving the pump which is a symptom of your no-go.