Buzzing sound from TF727 trans in 88 GW

FrozenCajunAK · Post by **FrozenCajunAK** » Thu Aug 18, 2016 2:25 pm

So my 88 GW learned a new trick today. It is making a loud buzzing sound when I accelerate from a dead stop. The noise quickly goes away and the transmission seems to shift and hold fine, even at highway speeds. The 3-2 kickdown is a little harsh (I know this is actually not a bad thing) but not too terribly bad. Is it time for a rebuild? Could it just be the front pump cavitating? I plan to change the filter/fluid and adjust the bands this weekend. If the odo is correct (and I have no reason to believe it isn't), this TF727 has 196xxx miles on it and I doubt it has ever been rebuilt in the past.

For the record, I managed to successfully rebuild a TF727 once before. It lived behind a nicely built 360 with a D300 transfer case on the other end.

This might be a good time to tear into the transfer case to clean out gunk and change out bearings and seals as necessary.

REDONE · Post by **REDONE** » Thu Aug 18, 2016 2:37 pm

Does your speedo do anything funny when the trans is making the noise?

FrozenCajunAK · Post by **FrozenCajunAK** » Thu Aug 18, 2016 2:39 pm

Nope. The noise is only when accelerating from a dead stop and it appears to come from the front area of the vehicle. I am wondering if it is a trans valve chattering...or worse...the torque converter buzzing. It does have nearly 200K on the ticker. The engine is in great shape.

REDONE · Post by **REDONE** » Thu Aug 18, 2016 2:47 pm

Gotcha, only time I could relate is when the speedo cable at the t-case had mostly unscrewed itself. Only buzzed until I got up to speed, but the speedo would bounce until then.

FrozenCajunAK · Post by **FrozenCajunAK** » Thu Aug 18, 2016 2:55 pm

I have been researching this a bit and the problem may be in the converter. The Tom Hand TF727 page said that high mileage converters will often buzz. I am changing the fluid and filter this weekend. I'll adjust the bands too. If the fluid and filter change doesn't help and the noise gets worse, I may be taking it out for a new converter. If that's the case, I'll drop another $100 for an overhaul kit. It's good insurance with a transmission with nearly 200K on it. I'll probably overhaul the 229 t-case too since it'll all be taken out and ready to work on.

FrozenCajunAK · Post by **FrozenCajunAK** » Tue Aug 23, 2016 8:22 am

Update:
I did the fluid/filter change and bad adjustment. It did help quite a bit, but the noise is still there when accelerating from a dead stop. It isn't as loud, though.

will e · Post by **will e** » Tue Aug 23, 2016 6:14 pm

Turn up the volume on the radio.. problem solved!

But that is an interesting symptom. I have never heard of a 727 buzzing. You learn something every day.

letank · Post by **letank** » Tue Aug 23, 2016 6:27 pm

will e wrote:Turn up the volume on the radio.. problem solved!

mine seems to buzz in neutral

FrozenCajunAK · Post by **FrozenCajunAK** » Wed Aug 24, 2016 3:22 pm

I am starting to think this is something to do with the torque converter. It may be time to take the thing out and just do a complete rebuild on it. If I am taking it out to do a torque converter change, it would be good insurance to go through it and change everything out that can be changed. The rear band looked good from what I could tell when I was changing the fluid and filter a few days ago.

Curly · Post by **Curly** » Wed Aug 24, 2016 8:33 pm

Last time I had a buzzing sound from an Auto Trans, the psi valve in the front pump was the culprit. Usually did it when shifting from P to D.

wewillsurvive · Post by **wewillsurvive** » Thu Aug 25, 2016 7:04 pm

candymancan · Post by **candymancan** » Fri Aug 26, 2016 10:53 pm

Buzzing could be a sign the pump is going bad.. aka the torque convertor. Also buzzing in the 46re transmission on my 5.9 ZJ but only in reverse is due to some kind of spring and the material it was made out of. There was a TSB about it..

FrozenCajunAK · Post by **FrozenCajunAK** » Sat Aug 27, 2016 11:43 am

I am afraid it is the torque converter. If that's the case, then it's just gonna get a full rebuild while it is out to replace the converter. If I can find a new/rebuilt pump for it, I'll replace that too.

candymancan · Post by **candymancan** » Sat Aug 27, 2016 12:16 pm

The pump is the torque convertor fyi..

Mine in my 46re only buzzes when i put in nuetral tp start the pump because my cooling lines have a deleted check valve so all the fluid drains out and it has to pump it again and it stops buzzing when its full again

REDONE · Post by **REDONE** » Sat Aug 27, 2016 1:36 pm

candymancan wrote:The pump is the torque convertor fyi..

The pump and the torque converter are two separate things. There is a positive displacement sun-and-pinion gear type pump that provides the valve body and band solenoids with the hydraulic pressure they need to operate.

FrozenCajunAK · Post by **FrozenCajunAK** » Mon Aug 29, 2016 3:03 pm

The pump is the torque convertor fyi..

No it really isn't. Not my first rodeo with an automatic transmission. This will be the 4th (or so) 727 I have rebuilt. I was just asking for diagnostic opinions. I really think the converter is going. If I am going to the trouble of dropping it to change the converter, then I may as well refresh the clutches and seals. May go ahead and replace parts in the transfer case too. With 197xxx on the clock, it is just about time to refresh them both.

candymancan · Post by **candymancan** » Mon Aug 29, 2016 7:44 pm

Ok i guess its diff in these transmissions then, because on the 42-48re the pump is in the torque convertor.. HENSE why i said the torque convertor is the pump.

And since a 727 is basically a 46re with no overdrive and less electronics.. i would assume the torque convertor has a pump in it. And the only time my 46re buzzes is when the pump aka convertor is dry because my convertor seems to drain when its parked

http://auto.howstuffworks.com/auto-part ... erter2.htm

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