Having an issue with a Th350, out of nowhere the trans started spewing oil out of the dipstick tube. First thought was a blocked breather but this was quickly ruled out, if you blow in the breather tube it easily pushes oil out the dipstick. Has anyone had similar experiences or suggestions that might help
How full is it? and was it being driven often right before this happened? or has it been sitting? my guess is that if it sat for a while, and the converter drained back into the pan, it might be doing weird things. but usually they just leak all over the place.
Squirrel Your right I have experienced the same thing with the TH 350,s .After the car sits for awhile they will begin to leak.The converter drains into the pan it it starts to leak .In the Spring after the car has sat all Winter there is always a big puddle of oil on my shop floor under the ******. The nature of the beast... Never had it come flowing out the dipstick tube though ??? Gene
Mine used to leak like crazy after four or five days sitting (draining the converter), but it leaked out of the bottom. You are in Australia (upside-down) Leaks go up.....? Just jokin'. Sounds more serious though.
Seems that this is a common issue with the GM 350Th Trans after the car sits for any length of time .It's odd that this is such a popular trans for the street rodders ??
Well we replaced the dipstick rubber seal and the problem is gone. 2 days of thrashing around the suburbs and not a drop of oil lost
Not to scare you off T/H 350 GM Trans. .I do have several and happy with them but they will leak after the car sits for awhile...Ask around from those that own them..
My avatar has a TH350, it will sit all winter (Minnesota) with a drip pan under and not leak a drop, the fluid level is correct and has 7,303 miles on it. Must be a rare transmission.
Hey nice looking shop , truck project and Family... I'm just mentioning this as a personal experience with these tranneys ?? Gene in Mn
Mine must be rare, too. I have 3 of them that are parked each year from around Halloween to around April Fools day and none of them has ever leaked.
Only a quarter of them dump the fluid out when they sit for more than a week. It usually has to do with being worn out.
I've noticed this winter that mine is leaking at the speedometer gear after it sat for a week. It is in need of a rebuild,however.
A leaking speedo after sitting is often caused by the aluminum speedo gear holder wearing pear shaped. Take it out of the trans and pop out the gear and look down the hole. Find an old cast iron holder from the 50s-60s-70s and change it, or buy a new replacement. Just re-sealing the aluminum ones won't work. Oddly enough, the plastic gear never wears in the holder area, but instead is a great lap. The abrasive is coming from inside the trans.
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