Foamy Tranny Fluid!!!!

[tiredtiretodd]

Just changed the tranny fluid and filter and fired up the beast and it started to foam from the mouth! Actually it foamed from the tranny dipstick but I must have lost at least a quart or two of fluid. It didn't happen right away, maybe about 5 to 7 minutes after I started it. I looked up possible reasons why and what I think may have happened was that my radiator may be bad. My square sits and is only ran a few times here and there over a few months. I bought it so I'd have a good project to work on I've never driven it anywhere but down my street. I'm finding a bunch of things wrong but that's the fun of making it my own right! I do hope that my tranny isn't bad though cause that would mean I have to wait a lot longer to drive it!

 

[MadOgre]

Its probably not the cause but make sure the breather tube on the top of the transmission is unobstructed. Very well could be the rad

 

[CSFJ]

Doesn't overfilling cause them to foam also? Or am I mis-remembering?

 

[MadOgre]

I think so. Ive never had it happen so I dunno

 

[PrairieDrifter]

is the tranny fluid a milky color or is it still red?

 

[tiredtiretodd]

Still red more like a milkshake. I will check the breather tube, didn't know that it has one. I also haven't rechecked the fluid yet

 

[PrairieDrifter]

As long as it doesn't change colors you probably don't have coolant in the tranny fluid

 

[mistaake]

blocked cooler lines or over-filled?

 

[MadOgre]

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[tiredtiretodd]

I think I over filled it I put 5 quarts in it after the filter change. Of coarse I ran it after I got a low fluid reading on the stick and kept adding a little at a time and it kept reading low so I dumped the rest in. As I poured the rest of the 5th quart it got to where it wouldn't go down the funnel and started coming out until about two quarts where in the drip pan under the truck. I'm gonna check the vent and the cooling lines and I'll post the outcome


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[HotRodPC]

Yes, overfilling will cause foaming. As will blocked breather, blocked cooling lines or cooler, and so will overheating.

 

[chengny]

No, you didn't over fill it. Total fluid capacity for a TH400 (I think that's what is being discussed) is 11 quarts. Stock torque converter holds 5. That leaves 6 quarts. Maybe 1 quart is in the cooler and the connecting tubing. So 5 quarts would be they correct amount to add after a fluid/filter change.

I doubt your vent tube became plugged up overnight - so that is most likely not the issue.


Was this your first time changing the filter in a TH400? If so, recheck the pickup tube joints at both the top (into the case) and bottom (out of the filter). The filter retaining bolt is often very loose against the bottom of the filter and if the tube/o-rings are not nice and tight, the whole shootin' match has a tendency to fall out of position. Result is the internal pump sucks air in past the o-ring seal and eventually the entire ATF charge becomes foamy. The entrained air increases the observed volume of the ATF and it pushes up into the dipstick tube.

The TH400 is quite prone to pulling in air at the pickup tube (esp at the top end where it enters the case). For that reason, I always use two o-rings on the case end of the tube, with no exceptions

 

[tiredtiretodd]

Thanks, I have the TH350 and I re-checked the fluid level today since I don't drive it and I've only driven it down my street once or twice in the 2 years or so that I've had it (It's a project that I'm just getting around to starting) fluid level was @ the hot line and the engine was cold. I did try to drive it yesterday around the block after moving the modulator hose where it goes on the manifold, and the booster hose to the back of the carb, it still wouldn't shift so I know for sure that my accelerator cable is looser then it could be. I have a new one that I never installed so I'll do that soon. Also I will put new O rings in the tranny dipstick tube because I know that when I pull the dipstick out the whole tube moves. I'm also going to replace the modulator and kick down cable just to have the piece of mind of knowing they're new!


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[tiredtiretodd]

Oh yeah, since it overflowed the first time it hasn't done it again when I've started it. We'll see Monday when I get back to work on it.


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[CSFJ]

well, if the fluid was at the hot line on a cold engine you're definitely over filled.