afartinthewind

I have a habit if checking my rig every Saturday morning and I noticed a acceration in my trans fluid color darkening over the last few weeks. As I just hit 220k and I have a radiator of unknown age, I decided to drop in the cooler bypass and was thinking that if my internal stock cooler had begun to corrode, wouldn't I begin to see my trans fluid go dark sooner as it began to run hotter from the poor radiator cooler?(I don't have a gauge yet) I went from fairly clean to probably 7/10 on the dirty scale in around 1600 miles. The fluid was old anyway so I just changed it but I was thinking that this may be a rare early sign of the dreaded "doomshake". Thoughts?

kball

I think the milkshake happens pretty quickly. It's not a slow process. I think the cooler keeps working normally right up to the point that it fails.

BigBallsMcFalls

1) the milkshake can happen slowly or rapidly, usually slowly
as pressure from hot coolant works it's way into the tranny,
and this all depends on if you are doing long trips short trips

there is no real 'formula' or statement you can make, other than
'it varies'

the connections do not 'blow open' they tend to start losing the
seal connection a bit at a time...then as time goes on and it opens
up more, final and sudden failure of the rest of the seal

2) milkshake does not make ATF fluid darker, it makes it foam
and have water in it. it will make it lighter if anything

3) if you drain the tranny pan and there is zero
water drops in your clean bucket with those 3 quarts of used ATF
chances are it did not milkshake

4) first symptoms of milkshake are usually an odd clunk
or pop or some other 'thing' when you start out in the
morning and the tranny shifts for the first time. like
putting into reverse is no longer as smooth as it could be,
and you know you have been greasing the u-joints and
slip yoke properly

5) if the milkshake happens quickly, your temp will skyrocket and
your radiator will steam.

item 4 will always go to item 5 if not taken care of
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fix for all this milkshake business:

NO matter WHAT: if your 3rd gen is 10 years old+ (it is)
replace radiator or install tranny external cooler and bypass the integrated one. period.

by the time even a little peep of water hits that transmission, brakes (clutches) inside
will start to erode, bands erode, seals swell up...then it is a crapshoot whether it
will stay working as long as you want it to
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for any vehicle, any make or model, IF it has an integrated tranny cooler in the radiator, 10 years
is really pushing the envelope on reliability. replace that radiator ahead of time. they are not that
expensive, in the 150-250 dollar range mostly

afartinthewind

I don't think I explained my hypothesis very clearly. so I'm thinking the stock trans cooler becomes corroded on its outer surface(inside the rad) and it begins to loose cooling efficiency and as a result the trans runs hot. The extra heat breaks down the trans fluid faster causing a dirty appearance and poor operation. Your saying its a seal design and not internal corrosion?

BigBallsMcFalls

you need to examine pictures, or in your hand, what a cut-open-milkshake-radiator looks like

afartinthewind

I agree,i do. Ya got one? I bypassed so it may be some time until I hack mine open.

ZUK

iTrader: (1)

One of these would allow you to monitor tranny output temps and you would know before the fluid changed color....not every year of Runner/Tacoma has the "TFT" tranny fluid temperature. I had to search the boards to find the code to enter. The water temp and tranny temp are the most valuable to me. If you know anything about your oem water temp "gauge" then you know it's anything but a gauge.