Coolant in my transmission oil?

[Kurtatron]

2004 Lexus rx330. These are susceptible to coolant mixing with the transmission fluid via the radiator, which cools them both. I bought ethylene glycol test strips for transmission fluid. I only tested this because this car has high miles 195k and the transmission is very slightly jerky on shifts. The strip is quite dark compared to a strip dipped into fresh automatic fluid from the bottle.

Is the dark color due to the dye of the fluid in the transmission or maybe its age? Anyone used these before?

There is NO oil pooling in the radiator or reservoir tank. No strawberry shake consistency in the transmission.
I plan on getting a Blackstone fluid test, but I need to know if I should stop driving this car in the meantime.

 

[D60]

Old tx fluid is often dark.

Water will show itself as milkshake, visible separation etc

I would not rely on color alone to indicate cross-contamination

 

[ctechbob]

Water/coolant is one of the worst things to get in a trans. It tends to delaminate the friction material from the clutch discs.

 

[eljefino]

If the radiator is known to fail, why not prophylactically install a new one? Then you won't worry when going on a road trip or whatever.

 

[Trav]

I would eliminate the radiator cooler part of it and use an aftermarket one with a thermostat if the transmission doesnt use one already.
There is a good chance the trans will make like skippy shortly.

 

[JavierH19]

If the radiator is known to do that I'd just use a separate cooler as trav suggests.

 

[Cujet]

If the radiator is known to do that I'd just use a separate cooler as trav suggests.

And change transmission fluid fully.

 

[Kurtatron]

New radiator from Lexus is $400. Can I just use an aftermarket one? That’s why I’m waiting before replacing it.

 

[eljefino]

New radiator from Lexus is $400. Can I just use an aftermarket one? That’s why I’m waiting before replacing it.

Absolutely! Yesterday! I've had great luck with generic rads from ebay or wherever.

 

[AZjeff]

New radiator from Lexus is $400. Can I just use an aftermarket one? That’s why I’m waiting before replacing it.

They're talking about isolating the trans cooler and plumbing in an aftermarket one. Not a new rad.

 

[supton]

Dumb question: if the rad is suspect, would it be worthwhile to find some cooler line and plumb in & out together on the now unused trans cooler portion? That way, if it leaks, maybe it'll hold long enough to give heads-up or otherwise prevent it from losing too much coolant.

 

[benjy]

earlier frontiers with the auto had that issue, but being a shifty guy my 2011 is a 6 spd manual which was hard to find ASAP after my 2008 colly got totaled!!

 

[joegreen]

I have had good luck with two denso radiators i bought. One for a lexus and one for a honda. They have been working great for at least 5 years

 

[Exhaustgases]

Water/coolant is one of the worst things to get in a trans. It tends to delaminate the friction material from the clutch discs.

Very correct.
If there is any water in it, the damage is done, no draining and refilling fixes it. Its rebuilt trans time.

 

[Donald]

2004 Lexus rx330. These are susceptible to coolant mixing with the transmission fluid via the radiator, which cools them both. I bought ethylene glycol test strips for transmission fluid. I only tested this because this car has high miles 195k and the transmission is very slightly jerky on shifts. The strip is quite dark compared to a strip dipped into fresh automatic fluid from the bottle.

Is the dark color due to the dye of the fluid in the transmission or maybe its age? Anyone used these before?

There is NO oil pooling in the radiator or reservoir tank. No strawberry shake consistency in the transmission.
I plan on getting a Blackstone fluid test, but I need to know if I should stop driving this car in the meantime.

View attachment 239999

Send it out for a UOA. They can certainly test transmission fluid for contaminants including coolant.

If there is coolant in the transmission then time for a new transmission cooler.

 

[zzyzzx]

Isn't that one of the Toyotas famous for having cracks in the radiator top plastic piece? If it's the original radiator I would be inclined to replace it as a fix for the mixing issue and as PM on the plastic tank crack. Aftermarket radiators work fine, I used a Spectra Premium on a 2000 Camry and it worked great.

 

[Kurtatron]

Bought a Denso from rock auto for $150. I’ll change it proactively and still get a UOA.

 

[wgtoys]

New radiator from Lexus is $400. Can I just use an aftermarket one? That’s why I’m waiting before replacing it.

I have had great luck with Denso branded aftermarket radiators on my Honda and Subaru vehicles. See if one is offered for your Lexus. The last two I purchased where made in China, but otherwise looked identical to the original radiators right down to plastic mold lines. Denso is a major supplier to the Japanese auto industry. I bet that if I had gone to the dealer I would have gotten the same part at three or more times the price. RockAuto is an easy place to order Denso from.

 

[supton]

I got a Denso replacement for my Camry due to the tanks cracking (plastic), but wound up replacing it after 4 or 5 years. The transmission cooler lines started looking funky, like dissimilar metal corrosion. Try as I might, I could not source fittings and I replaced the radiator for that. Granted, it was only like $100 each time.

Tossing that out there, even though it's Denso it might not last as long as you'd think.

 

[Kurtatron]

I got a Denso replacement for my Camry due to the tanks cracking (plastic), but wound up replacing it after 4 or 5 years. The transmission cooler lines started looking funky, like dissimilar metal corrosion. Try as I might, I could not source fittings and I replaced the radiator for that. Granted, it was only like $100 each time.

Tossing that out there, even though it's Denso it might not last as long as you'd think.

I like Trav’s idea of a separate aftermarket cooler for the transmission, but I can’t fabricate something like that until I am liberated from apartment living.