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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Mule man on February 14, 2010, 06:47:10 PM

Title: Transmission Fluid Out Dipstick
Post by: Mule man on February 14, 2010, 06:47:10 PM
Just bought an '84 Chevrolet 4X4 with a TH350 tranny.  Runs and shifts great but now it's started blowing tranny fluid out the dipstick.  I did a search and it seems everybody thinks it's the vent tube.  I blew the breather out (and blew tranny fluid everywhere) and put a dipstick with a good rubber seal on it but it's still blowing fluid out.  It is about 1 qt low so no overfill problem.  I  just took my air compressor and blew air into the dipstick and out the vent so I am sure it is open. I need any advice that can be given.  Thanks in advance.
Title: Re: Transmission Fluid Out Dipstick
Post by: VileZambonie on February 14, 2010, 08:13:14 PM
What's the history on the trans? There shouldn't be pressure in the case if the vent is clear.You're checking the fluid level on a level surface with the engine running right?
Title: Re: Transmission Fluid Out Dipstick
Post by: Mule man on February 14, 2010, 08:32:41 PM
Yes, level and and a warm tranny.  It's about 1 quart low now.  I also checked the dipstick with another 350 tranny and they are the same length. The PO said that he had recently changed the fluid and filter.  It has been fine for 100 miles or so.  Shifts fine.  He had installed an aftermarket in the past.  Could that somehow pressure the fluid?  It beats me.  Thanks for the reply.
Title: Re: Transmission Fluid Out Dipstick
Post by: Mule man on February 14, 2010, 09:10:04 PM
That should have said "aftermarket cooler" sorry. I have had one person tell me that it's the modulator valve.  I don't see how that could pressurize the fluid in the pan.  Thanks again
Title: Re: Transmission Fluid Out Dipstick
Post by: Mule man on February 15, 2010, 11:19:42 AM
I've also been pointed toward "lip seals".  Could them leaking cause this problem.  Thanks again
Title: Re: Transmission Fluid Out Dipstick
Post by: VileZambonie on February 15, 2010, 06:18:16 PM
Barfing out of the dipstick usually means overheating/overfull/plugged vent.
Title: Re: Transmission Fluid Out Dipstick
Post by: frito-bandito on February 17, 2010, 02:13:09 AM
My 94 with the 4L60E does the same thing, I've been keeping the fluid about half a quart low to slow this problem for about a year now. I was told that it could have something to do with the torque converter.