yyymmm31

Like most Toyota cars, our LS460 uses one radiator to disseminate heat for both engine coolant and transmission fluid. Basically, the top portion of the radiator is used for defusing the heat in the coolant while the bottom of the radiator is used to cool down the transmission fluid. Such a shared radiator, while making economic sense, poses a big risk of having transmission fluid leak into cooling system and vice versa. In fact, it is a frequent occurrence on high mileage Toyota 4Runner trucks. Owners of 4Runner trucks call it strawberry milkshake because when transmission fluid has leaked into the cooking system, the coolant reservoir shows pink chunks of transmission oil, looking exactly like strawberry milkshakes. This strawberry milkshake problem is rare among LS460s. It looks that I am the only one so far on CL LS460 forum to have the bad luck to experience this transmission fluid and coolant crossing into each other’s system. I’d like to share my experience of fixing the problem, so that other LS460 owners will be aware of this potential problem and know how to fix it.

About a month ago, when my LS460 reached 103K miles, I followed the service schedule to replace the coolant. After I took off the plastic engine covers, I found that the transparent plastic coolant reservoir looked blurry and I could hardly make out the coolant level in the reservoir. After I opened coolant reservoir cap, there they were – thick chunks of pink-colored transmission fluid, looking like strawberry milkshakes. After I removed the radiator hoses, they were half-filled with the pink oily chunks of transmission fluid. I took the following steps to clean up this mess.

Materials used:
1) Two 16-oz bottles of L-11 radiator oil degreaser (made by Ve Labs) ($30)
2) One 12-oz bottle of BG Universal Cooling System Cleaner PN540 ($15)
3) Lisle 75500 Combustion Leak Detector ($37)
4) 24 gallons of distilled water ($25)
5) 24 qts of Toyota ATS WS transmission fluid ($240)
6) 6 gallons of Toyota super long life antifreeze ($120)
7) Transmission filter and rubber pan gasket ($35)
8) Transmission pan ($120)
9) A new life-time warranty radiator ($75)
10) Aisin OE thermostat ($35)
11) Dishwashing powder (for automatic dishwasher)
12) Techstream (for checking transmission fluid level)

Steps to clean the cooling system
1) Replace the leaked radiator
2) Clean the “strawberry milkshake” oily chunks from the radiator hoses
3) Clean the coolant reservoir tank with dishwashing powder
4) Installed the cleaned radiator hoses and coolant reservoir tank
5) Fill the cooling system with one bottle of L-11 radiator oil degreaser
6) Fill the cooling system with distilled water (takes approximately 7 qts)
7) Run engine at idling speed for 10 minutes with AC set to heating at the maximum high level
8) Run engine at 1500-2000 RPM for 5 minutes
9) Release the distilled water from the cooling system and repeat Steps 5-8
10) Fill the cooling system with a bottle of BG Universal Cooling System Cleaner PN540
11) Fill the cooling system with distilled water (takes approximately 7 qts)
12) Run engine at idling speed for 10 minutes with AC set to heating at the maximum high level
13) Run engine at 1500-2000 RPM for 5 minutes
14) Release the distilled water from the cooling system
15) Fill the cooling system with distilled water (takes approximately 7 qts)
16) Run engine at idling speed for 10 minutes with AC set to heating at the maximum high level
17) Run engine at 1500-2000 RPM for 5 minutes
18) Release the distilled water from the cooling system
19) Repeat Steps 15-18 until the released water was clear and clean (it took 8 rounds of distilled water cleaning cycles, that was in addition to the 3 rounds of L-11 and BG540 cleaning, to clean the cooling system)
20) Replace the thermostat
21) Fill the cooling system with Toyota super long life antifreeze
22) Test the coolant with Lisle 75500 Combustion Leak Detector to confirm that there was no engine oil in the cooling system (i.e., no blown engine head gasket).
23) Drain and refill transmission fluid 3 times (run the car about 100 miles after each drain and refill to ensure that the old and new transmission fluids mixed well; use Techstream to monitor the transmission temperature for checking transmission fluid level).
24) Replace the transmission filter/strainer, transmission pan gasket, and the transmission pan.
25) Fill the transmission with 4.7 qts of Toyota ATS WS transmission fluid.
26) Check the transmission fluid level with Techstream (Note: the required temperature for checking transmission fluid is 35C-43C and the transmission fluid level should be checked while the engine is running.)

Part numbers:
1) Transmission pan drain plug gasket/washer: 35178-30010
2) Transmission drain plug: 9031110011 or 9034110011
3) Transmission pan overflow plug gasket/washer: 35178-30010 (same as drain plug gasket)
4) Transmission WS fill 24mm plug o-ring (gasket): 90301-15004
5) Transmission WS fill plug: 90341-18059
6) Transmission filter/strainer part number: 35330-50030
7) Transmission pan part number: 35106-50050
8) Radiator petcock drain plug: 16417-21280
9) Radiator petcock drain plug o-ring seal: 16492-21050
10) Radiator assembly: 16400-38170

Torques:
1) Overflow check plug (5mm hex): 15 ft lbf
2) Refill plug (24mm): 29 ft lbf
3) Drain plug (14mm): 15 ft lbf
4) Transmission pan bolts (9 10mm bolts): 66 inch (Note that is inch, not foot)
5) Transmission filter/strainer (4 10mm bolts): 8 ft lbf
6) Thermostat (3 10mm screws): 7 ft lbf

Transmission check level temperature range : 95-108F or 35-42C (In Techstream, go to “Engine & ECT” screen, then go “Data List” on the left panel, and view “A/T Oil Temperature 1” to watch the transmission fluid temperature). Then engine must be running at idling when checking transmission fluid level (i.e., unplug the overflow plug to wait for the transmission fluid to flow down in “a thin stream”.)

Observation:
1) It is very time-consuming to clean up the coolant system. Each cycle of rinsing coolant system took about an hour to complete. The 11 cycles of cleaning coolant system took me more than 11 hours. The 4 drain-and-refill transmission fluid process took 4 weeks to complete. (With so many transmission drains and refills (I also did 5 transmission fluid drains and refills last year), I feel that I have unwillingly become an expert DIYer on replacing LS460 transmission fluid.)
2) Be careful with the toques of transmission drain plug and the overfill plug. Although Lexus service manual says that the torque for both plugs is 15 ft lbf, I found that 15 ft lbf was too much torque for both drain and overflow plugs. Using 15 ft lbf, I easily stripped the thread on the oil pan for the drain plug, resulting in having to replace the transmission pan (a $120 lesson). Instead, use hand wrench with enough turn to just tighten the drain and overflow plugs to crush the aluminum gasket (about 10-12 ft lbf).
3) The thread in the transmission plan for the drain plug is very shallow, just about 4-5 threads, and therefor can be easily stripped or damaged.
4) Make sure the transmission plan surface and transmission unit contact surface are clean of oil and dry. This is a required condition to properly seal the transmission. (Some postings in Toyota 4Runner forum suggested using oil to make the rubber seal stick to the transmission pan. Don’t do it because the oil will cause a leak).
5) Use a new crush washer for the drain plug and overflow plug every time. New washers will ensure no leaks.

Recommendation: To avoid having this messy problem of transmission fluid mixing with coolant, replace your radiator if your LS460 is getting close to 100K miles, or install a dedicated transmission fluid cooling device, so that the transmission fluid doesn’t need to flow through the radiator. That’ll be a small cost compared with the cost and time to clean the strawberry milkshake mess.

jaishanker

Hi ..thanks for your review. I own a 2007 LS 460 L american Spec car in Dubai...the Car has currently clocked 128000 Miles with its original Radiator and transmission Fluid. I have never touched the transmission fluid , radiator and its hoses. Everything is still on the original. Recently i just topped the collant very little.

How will we know if the transmisssion fkuid is mixed in the radiator? Did u see any overheating issues in your car? I have not faced any issues till now. How can we identiy or recognize this? How will this problem come up normally?

did you change the transmission fluid anytime? What was the condition of the fluid when you changed it...because inhave read a lott of reviews on transmission saying thag...it must be changed and some feedback sahing that transmission should not be touched at all..

jdanielca

roadfrog

LOL..... From the OP:

TDC1

There is a significant difference in price between the dealership radiator and Denso radiator. I believe Denso is the original manufacturer. Do you think it's the same quality? I have a 2005 LX470 which I believe has the same radiator as the 4Runner.

yyymmm31

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Denso is an OE supplier for many Lexus/Toyota parts. If you can find a Denso radiator at a lower price than the dealer's OE price, go for it. As I said in my posting above, I used one of those "life-long" warranty no-name radiators for approximately $75 from eBay. So far, the radiator is holding without issues. A Denso radiator should have much better quality than my no-name radiator. I wouldn't hesitate to use a Denso part over the dealer's OE. For mission-critical parts, I always use Denso parts if I can get them at a lower price than Lexus OE parts from the dealer.
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