2008 Toyota Crown Athlete 2GR FSE (Lexus IS350/GS350) Milky Coolant?

[opal oriole]

Basically like the title says I have a JDM Crown Athlete with the 2GR FSE, same as a IS/GS350, and my coolant reservoir has milky coolant it looks like, see attached image.

Based on my research this colour results when transmission fluid and coolant mix, which then I researched how that transmission oil cooler is setup and the other attached image looks similar to what I see, could a leak between the two interior lines in the heat sink cause this?

How can I test to determine the source of the problem? Also could this just be contaminated coolant? Would draining some of the transmission fluid help by seeing if that is also cloudy?

[jade dome]

Check the condition of your oil and your atf. You’re looking for coolant mixed with one of them.

[opal oriole]

Oil looks fine based on the dipstick, but ATF does not have a dipstick due to “sealed” system, but I guess I’ll just have to drain a bit to check

[hot swallow]

Oil looking good in your engine is a good thing. Your problem is probably with your cooler. Do you know if your transmission lines go into your radiator as well?

Some vehicles will have both an external cooler and a transmission lines that go into the radiator.

Hopefully your trans fluid comes out good and it is just your coolant that is contaminated. If your trans is contaminated, your most likely going to need at the very minimum,

[opal oriole]

Yeah, but I’ve also heard that it could be like a leak that goes one way so oil into coolant but not the other way around?

[opal oriole]

I don’t deliver it does into the rad since there is only the 1 upper and 1 lower coolant hoses

[opal oriole]

Yeah I’ll have to drain a bit and see or otherwise get a combustion chamber leak tester for the coolant to see if it’s a headgasket potentially?

[hot swallow]

A soft rebuild. Hit send before I finished.

[hot swallow]

Well if your oil is fine it’s less likely to be that. You will know what to do next once you look at your trans oil.

It can only “mix one way” but it’s unlikely

[opal oriole]

I drained a bit of the coolant from the bottom of the radiator, it was fine, verified with a mechanic as well that the coolant looks normal

He thinks maybe just a dirty reservoir

[hot swallow]

That looks like strawberry milk lol

I would drain the trans a little bit before confirming that

[opal oriole]

Yeah I might to verify

Might just drain and fill both trans and coolant