LS430 2001: Radiator - oil cooler inputs for newbie

[The-Acre]

13 hours ago, ThePerfectionOfLexus said:

Thanks, I'll go with replacing the radiator with another stock part.
According to Lexus in my department, the issue should have been fixed by now, and the stock radiator has a different part number.
Regardless, I'll stick with replacing the coolant every 5 years, and hope to keep a good preventive maintenance this way. 

I would also think about replacing the two rubber trans fluid hoses at the same time which is what I did. I found mine on a previous LS to be cracked, again, peace of mind. You'll probably find the foam between the radiator and AC condenser falls apart, just leave it off if it does.

[John N]

A lot of Toyota and Lexus modals use the arrangement of a transmission fluid cooling pipe in the bottom of the radiator.

We run a LS430 and a RAV4 and they both have the same arrangement.

The main cause of the cooling pipe connections corroding and water getting in the transmission fluid is not changing the cars antifreeze every 3 years. All good antifreeze contains a corrosion inhibitor that stops this problem.  But the effectiveness of the corrosion inhibitor fades with time, and this is why antifreeze should be replaced every few years.  

Worse still is filling the engine cooling system with plain water when it has been drained down, or topping it up with plain water when you have a leak. That can be a very expensive penny pinching move.

Change your antifreeze every few years and stop worrying. Both our cars are over 20 years old and have not had a problem.

[ColinBarber]

42 minutes ago, John N said:

Change your antifreeze every few years and stop worrying. Both our cars are over 20 years old and have not had a problem.

There is more to it than that. The conceptual design is the same as for the GS430 or SC430 of the same era but these don't suffer this failure problem. There is something unique to the LS (and some Toyota trucks in the US) that causes this issue to be a weakness rather than the odd freak occurrence. Pipework design putting stress on the joint, vibration, different radiator supplier, bad manufacturing batch of radiators etc.

The vehicle uses Toyota SLLC which initially only need changing after 10 years, then every 5 years. The service interval isn't the problem - any GS or SC that is being serviced by a Lexus dealership is using the same schedule and isn't suffering the same issue. LS owners have suffered failures when only authorised Lexus dealers have touched the vehicle and no plain water has been added to the cooling system.