Transmission Milkshake 2002 Sequoia (1 Viewer)

[proteolytic]

Just wanted to document what happened and what I am doing to hopefully remedy it.

Noticed the Sequoia was shifting a little hard for all gears the last two times I was driving it (~ 50 miles). It was just slightly noticeable - when previously transmission shifts were completely unoticeable. Otherwise the truck drove fine. Checked fluids - engine oil looked good and was at a normal level; transmission oil looked okay on dipstick but was really high; coolant in radiator was half a gallon low.

Without thinking much I filled up radiator coolant and noticed oily residue.

Symptoms seemed consistent with a leaking transmission cooler in the radiator. Decided to diagnose issue by draining radiator - definitely something oily in there, wouldn't quite call it the pink milkshake. Next drained the transmission and got the milkshake. Collect 5 to 6 quarts when I would normally get 4 quarts from a transmission drain.

The radiator was relatively new (Denso, 221-0518, replaced on 2/2023 when I was doing the timing belt, purchased from Amazon). Not sure if this was a 1 in a million flaw for Denso radiator, or if it was a knock-off sold through amazon (visual inspection when installing - it looked pretty decent), or really hot weather (southwest Arizona) was a factor, or all of the above or none of the above.

My plan is to replace the radiator (purchased Toyota radiator from local dealership for $170, 16410-AZ012, surprisingly inexpensive), flush the coolant system and transmission, bypass internal transmission cooler, and replace the external transmission cooler with a Hayden 698 transmission cooler.

I will update as I progress through the work.

 

[joseywales]

I put that same Denso rad in my 2003 a couple of years ago, and it’s been great. I trust Denso and living rural (this was during the tail end of “the troubles”), I got it delivered by Amazon as there were literally ZERO of these rads in Canada. None in Toyota inventory and none in any of the parts store chains. I’m not sure if it’s a knockoff or a genuine Denso, but it’s been great.

Fingers crossed for an easy repair for you.

 

[proteolytic]

For the most part the radiators look alike. Differences are that the Denso 5 digit code is different. My amazon one was a Denso 42206 (221-0518) and the Toyota Denso was Denso 42311. Also of note the brack tab (mid-way down the radiator that supports the radiator on the truck) on my amazon one were not originally bent in - I had to bend them myself. The Toyota one was set right. Both needed my to bend the top tabs that you would use to lift up the radiator.

Now I am just waiting on the hayden transmission cooler to be delivered.

 

[proteolytic]

Sequoia is running and driving fine.
Here is what was done so far:
Drained the cooling system (and refilled with distilled water), replaced the radiator with a new toyota one, and drained the transmission pan (refilled with 4 quarts of new transmission fluid). Setup the transmission lines so that they bypass the radiator and go to the transmission cooler only.
I "flushed" about 10 gallons of Valvoline Dex/Merc ($20/gallon at walmart). This was accomplished by disconnecting the transmission fluid return line from the transmission cooler, turn engine on, and collect about 2 quarts of fluid, then turn off. Refill with 2 quarts of new transmission fluid. Repeat this process until the fluid coming out looks like new transmission fluid.
The Sequoia shifts fine (barely perceptible just like it did before the leak).

Now I am going through the process of flushing the cooling system. There looks to be a little oily residue coming out. I will drain and fill with distilled water for about 4 or 5 times (about 2 gallons each time).

Transmission temp is about 140 degrees F in 100+ degree weather. Coolant temperature gets no higher than 190.4 degrees F.

I will install the Hayden 698 Transmission Cooler soon.