TH400 Whining... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Figuarus · 02-24-2016, 06:04 PM

So, I just serviced the filter and fluid on the Th400 I have in my 64, and it has started whining when it's cold out.

After it warms up, or I drive it for about a mile or two, the whining goes away.

The filter and fluid are both brand new, and when I changed the fluid, there wasn't any real sediment in the pan.

I'm thinking front pump, but Im not too educated in this transmission to make any kind of diagnostic.

I do have a cooler on it, and the hoses are new(er) too.

Any help?

clinebarger · 02-24-2016, 08:26 PM

If it happened right after the filter change?

Double check the fluid level.
Check the plastic pick-up tube for cracks.
Check the O-ring the fits over the pick-up tube.
If no issues are found....Switch filter brands (Filtran make good ones).

Figuarus · 03-11-2017, 04:08 AM

Ok...ANOTHER update.

My truck has been sitting for the last 4 and a half months due to a BAD engine oil leak.

Two days ago, I got down to fixing the oil leak and went to pull the truck out from under my carport. There was some SERIOUS whining from the trans when I got it to fire up.

I tried shifting into gear, but there were no gears to be had.

At first, I thought that I had lost all the fluid from the trans, but further inspection told me that there was PLENTY of fluid in the pan.

Yesterday, after letting it idle for a minute or two, the whining started to go away, and I had gears again. I took it for a drive today around town and it's now driving just fine, albeit thought I do have a whine if I manually shift into first to take off.

Is it time to consider a swap or rebuild? Is this a case of the front pump going out?
I have a lead on a 350/700r4 from a late 80s van, and it makes sense to upgrade, but if I can keep this trans alive as long as I can, that would be awesome. (I've got a weird emotional attachment to it as it came out of my dad's 71 Monte Carlo )

Thanks guys.

68gmsee · 03-11-2017, 10:09 AM

It's been a year since the first post but did you do any of the checks that clinebarger mentioned?

Figuarus · 03-11-2017, 11:31 AM

Yes. Used a WIX filter, checked the old filter for damage, but nothing presented itself. The fluid level is normal at hot and it's even SLIGHTLY overfilled due to a small pan leak.
We are talking 1/8th" over full mark.

clinebarger · 03-12-2017, 12:10 AM

Sounds like your pump is getting very weak, Along with converter drain-back from worn Stator Bushings/PR valve.
If you have emotional attachments to the unit......Have it rebuilt or build it yourself, Installing a used/unknown 700R4 rarely works out.

02-24-2016, 06:04 PM	#1
Figuarus Registered User Join Date: Sep 2014 Location: Salt Lake City, UT Posts: 346	TH400 Whining... So, I just serviced the filter and fluid on the Th400 I have in my 64, and it has started whining when it's cold out. After it warms up, or I drive it for about a mile or two, the whining goes away. The filter and fluid are both brand new, and when I changed the fluid, there wasn't any real sediment in the pan. I'm thinking front pump, but Im not too educated in this transmission to make any kind of diagnostic. I do have a cooler on it, and the hoses are new(er) too. Any help? __________________ 2013 Malibu LTZ 1996 C1500 4.3/5spd 2wd

02-24-2016, 08:26 PM	#2
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: TH400 Whining... If it happened right after the filter change? Double check the fluid level. Check the plastic pick-up tube for cracks. Check the O-ring the fits over the pick-up tube. If no issues are found....Switch filter brands (Filtran make good ones).

03-11-2017, 04:08 AM	#3
Figuarus Registered User Join Date: Sep 2014 Location: Salt Lake City, UT Posts: 346	Re: TH400 Whining... Ok...ANOTHER update. My truck has been sitting for the last 4 and a half months due to a BAD engine oil leak. Two days ago, I got down to fixing the oil leak and went to pull the truck out from under my carport. There was some SERIOUS whining from the trans when I got it to fire up. I tried shifting into gear, but there were no gears to be had. At first, I thought that I had lost all the fluid from the trans, but further inspection told me that there was PLENTY of fluid in the pan. Yesterday, after letting it idle for a minute or two, the whining started to go away, and I had gears again. I took it for a drive today around town and it's now driving just fine, albeit thought I do have a whine if I manually shift into first to take off. Is it time to consider a swap or rebuild? Is this a case of the front pump going out? I have a lead on a 350/700r4 from a late 80s van, and it makes sense to upgrade, but if I can keep this trans alive as long as I can, that would be awesome. (I've got a weird emotional attachment to it as it came out of my dad's 71 Monte Carlo ) Thanks guys. __________________ 2013 Malibu LTZ 1996 C1500 4.3/5spd 2wd Last edited by Figuarus; 03-11-2017 at 04:09 AM. Reason: I accidentally a word

03-11-2017, 10:09 AM	#4
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: TH400 Whining... It's been a year since the first post but did you do any of the checks that clinebarger mentioned? __________________ 68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive...

03-11-2017, 11:31 AM	#5
Figuarus Registered User Join Date: Sep 2014 Location: Salt Lake City, UT Posts: 346	Re: TH400 Whining... Yes. Used a WIX filter, checked the old filter for damage, but nothing presented itself. The fluid level is normal at hot and it's even SLIGHTLY overfilled due to a small pan leak. We are talking 1/8th" over full mark. __________________ 2013 Malibu LTZ 1996 C1500 4.3/5spd 2wd

03-12-2017, 12:10 AM	#6
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: TH400 Whining... Sounds like your pump is getting very weak, Along with converter drain-back from worn Stator Bushings/PR valve. If you have emotional attachments to the unit......Have it rebuilt or build it yourself, Installing a used/unknown 700R4 rarely works out.



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