ATF is Foamy

L

LittleJeep

New Member
Joined
Apr 27, 2020
Messages
4
Location
Newfoundland
Hi all,

Our transmission fluid looks like a delicious smoothie/milkshake.

99 Wrangler, 32RH auto transmission.

I've done a lot of looking into this to discover the rad likely failed causing antifreeze to mix in there ..BUT.. after installing an external trans cooler and bypassing the rad, I expected to see antifreeze drip from the open cooler line connections at the bottom of the rad as the motor ran to 210 degrees. That didn't happen. Totally dry. Also, the only possible evidence of ATF mixing into the antifreeze was a thin looking layer of dark grey sludge at the bottom of the overflow bottle. The antifreeze was quite old though so the thin layer could have been the result of that?

Looking around the net further, I discovered that overfilling the trans may cause foaming. I think it was over filled ..BUT.. I also read somewhere on this site that overfilling (by just a quart) was good for the 32RH.

Now, I'm in the middle if a diy flush (pumping out of pressure line while going through the gears) and I'm almost done.

Would anyone have some light to shed on the cause of the foaming? It was very milkshakey looking.

This flushing process is getting pricey. I'm 13 quarts in and the fluid is just beginning to look right. On the island here, the cheapest ATF+4 i can find is $9/quart. Ouch. I'd rather not have to do it again.

Also, no worries on bypassing the rad I think? Our northern coastal climate rarely gets above 23c (73f) and rarely goes far below freezing. 27c absolute max and for just a few days every winter it can go to -18c (0f) absolute min (although windchill can reach -30c (-22f). It's windy here most of the time).

Thanks..
 
Over filling the fluid isn't going to cause it to be foamy.

If you're certain it isn't coolant, I would guess that you've gotten water in the system somehow. Have you been off-roading it at all or taking it through water crossings?

Regardless of eternal transmission cooler, you should still be running it through the stock transmission cooler at the bottom of the radiator, that is the general consensus.
 
I would drain the radiator and look at the condition of the actual coolant but that’s just me. I’d want to rule out radiator failure for certain.
 
Thanks for the quick responses. I checked them out quickly yesterday before heading out to get back at her.

She hasn't been off road lately aside from navigating our record breaking snowfall this winter. Surely that couldn't do it?

I ran the motor to temp again yesterday and all I could see dripping from the open transmission hose connections (bottom of rad) was a very very slow but steady drip of red fluid. Residual atf? Maybe that drip will eventually turn green once the residual atf has drained. I'll be taking her for a spin later and will report back..

So don't do a full rad bypass? I did buy a big 11 1/2 X 11" plate & fin cooler thinking it might work as a decent bypass. But if consensus is not to bypass, we'll replace the rad if needed and will connect up the atf lines.

You're right about the coolant. It needed changing
 
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It takes very little water to make atf look like a milkshake. Foam is often a sign of agitation or air getting churned into the fluid. Think a small air leak prior to pressurizing. This happens fairly often on hydraulic systems that have a pinhole air leak just prior to the pump. I know very little about the internal systems in an auto trans, but hope this bit of info will help you track down the problem.
 
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