T350 vent question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Paul M · 07-09-2006, 07:26 PM

seems at higher speeds,the vent on the tranny pukes some fluid.checked the level,its fine,if anything a hair below full.not sure if it did this before,but seems after a tranny service(fluid and filter) its either doing it now,or worse...any ideas on this?..thx paul

80 gmc 4wd....hehe

piecesparts · 07-10-2006, 11:00 AM

The vent can and will at times moves some fluid. I had the same issue on a tranny and it was leaving enough mess that I finally bought a plastic container from a vacuum brake bleeding tool to carch the fluid. However, it wasn't long after this started that I had some tranny problems. Ever since I rebuilt the tranny, there has been very little fluid coming out. Just a Note: Watch for some problems to come in the future, that might be causing this problem now.

Slonaker · 07-10-2006, 02:06 PM

Could it be overheating? I heard that GM switched to dipsticks that lock in after the 700R4s came out because people were towing with them in overdrive, overheating them, and catching engines on fire when ATF would shoot out the dipstick. Just a thought.

Slonaker

Jonboy · 07-10-2006, 04:34 PM

Are you sure it is the vent. GM did change the dipstick and tube design, like Slonaker said. In addition to a locking dipstick, they changed the design of the tube seal from an O-ring to a boot type seal. The O-ring sype tube are prone to leaks. The newer dipstick will fit the TH350 and 400 trans. Look for an application of around 1991 or newer. Most likely the leak is in the dipstick tube, though. The best way to check is to clean around the tube, and let the truck sit. The fluid will rise when the truck is parked, and comes up above the level of the bottom of the dipstick, going around the O-ring.

Paul M · 07-10-2006, 06:49 PM

yep..its the vent ontop of tranny ust below where the hump starts...no fluid anywhere from dipstick tube either ontop with the stick or bottom where tube is in tranny..thats all sealed well...i have tranny cover off and can watch the fluid come out when i step on pedal...guess i cant step on it like that anymore

07-09-2006, 07:26 PM	#1
Paul M Junior Member Join Date: Jun 2000 Location: Oakridge, Oregon Posts: 138	T350 vent question seems at higher speeds,the vent on the tranny pukes some fluid.checked the level,its fine,if anything a hair below full.not sure if it did this before,but seems after a tranny service(fluid and filter) its either doing it now,or worse...any ideas on this?..thx paul 80 gmc 4wd....hehe Last edited by Paul M; 07-10-2006 at 12:24 AM.

07-10-2006, 11:00 AM	#2
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: T350 vent question The vent can and will at times moves some fluid. I had the same issue on a tranny and it was leaving enough mess that I finally bought a plastic container from a vacuum brake bleeding tool to carch the fluid. However, it wasn't long after this started that I had some tranny problems. Ever since I rebuilt the tranny, there has been very little fluid coming out. Just a Note: Watch for some problems to come in the future, that might be causing this problem now.

07-10-2006, 02:06 PM	#3
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	Re: T350 vent question Could it be overheating? I heard that GM switched to dipsticks that lock in after the 700R4s came out because people were towing with them in overdrive, overheating them, and catching engines on fire when ATF would shoot out the dipstick. Just a thought. Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

07-10-2006, 04:34 PM	#4
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: T350 vent question Are you sure it is the vent. GM did change the dipstick and tube design, like Slonaker said. In addition to a locking dipstick, they changed the design of the tube seal from an O-ring to a boot type seal. The O-ring sype tube are prone to leaks. The newer dipstick will fit the TH350 and 400 trans. Look for an application of around 1991 or newer. Most likely the leak is in the dipstick tube, though. The best way to check is to clean around the tube, and let the truck sit. The fluid will rise when the truck is parked, and comes up above the level of the bottom of the dipstick, going around the O-ring. __________________ 1974 Jimmy- 5.3/4L80e/NP241

07-10-2006, 06:49 PM	#5
Paul M Junior Member Join Date: Jun 2000 Location: Oakridge, Oregon Posts: 138	Re: T350 vent question yep..its the vent ontop of tranny ust below where the hump starts...no fluid anywhere from dipstick tube either ontop with the stick or bottom where tube is in tranny..thats all sealed well...i have tranny cover off and can watch the fluid come out when i step on pedal...guess i cant step on it like that anymore



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