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-   -   Help from a th350 owners please. (https://67-72chevytrucks.com/vboard/showthread.php?t=860923)

PbFut 09-27-2025 02:21 PM

Help from a th350 owners please.
 
I am seeing bubbles in the tranny fluid whan it is on the warmer side of operating temperature. I am thinking the added capacity of my system, deep pan and cooler may be expanding to point of overfill but I do not know automatic transmissions very will. Will a overfill induce air into the fluid like a crank does in an oil pan?
The stick shows over fill when this hot, about 210 in pan but don't know if the bubbles are expanding the total volume. In any event I would think bubbles are not good.

truckster 09-27-2025 02:51 PM

Re: Help from a th350 owners please.
 
Where are you seeing bubbles? Is it on the dipstick?

Yes, overfilling can cause the bubbles. You should always check the fluid on level ground, engine running, and transmission warmed up. It should be between the low and high marks on the dipstick.

I would recommend draining off the excess fluid and then checking for bubbles after you've driven it a few miles.

Lee H 09-27-2025 04:39 PM

Re: Help from a th350 owners please.
 
How much overfill above the top hash mark? Start by removing fluid until it's at or slightly below the top hash. Then monitor for bubbles.

PbFut 09-28-2025 05:07 PM

Re: Help from a th350 owners please.
 
I made a suction tube to match the length of full mark on tranny dipstick. Then I warmed the tranny some and got about a pint out. Fully warmed to full 160 operating temperature and got another 1/2 pint. So it was certainly over filled by me after needing to pull the aux cooler to replace a fan. No more bubbles and running at correct temps again. Just a little oops on my part last week.

truckster 09-28-2025 07:12 PM

Re: Help from a th350 owners please.
 
I'm glad to hear it worked out well.


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