Radiator Flush (Valuable Info!)

Mar 30, 2003
A big THANKS to ParadiseCruiser!

A followup to a thread I posted a while back. To refresh your memories:

"When I bought my 80, it had 35k on it. According to the service history, the PO performed all recommended scheduled maintanence at the dealer up to 35k.
I had the coolant flushed when I got it, then I drove approx. 10k miles on the new coolant (green). I then had a coolant flush to switch to the red stuff. At that time, the coolant in the reservoir bottle was also emptied and refilled with fresh coolant mixture. In only 1k miles or so, the mixture in the coolant reservoir bottle has changed from fresh red to dirty black. Is this normal? Should I be concerned?
(Wary of head gasket failure)"

Well, I decided to take it to the dealer (truck is still under warranty) to get it checked out. I told them the color of the coolant had changed from red to brown in less than a month. The dealer checked with the mechanic. He tested the coolant and said it tested fine and the brown color was nothing to worry about- just the mixture of the new red and old green coolant. Doubtful, I asked if they had done a coolant FLUSH like I had asked them to. Although he told me he had, he went back and checked with the mechanic and it turns out they only did a DRAIN AND REFILL. The dealer and mechanic assured me it was okay to keep this mixture and to just change it out and the next scheduled coolant flush.

I thought about it for a while, and finally decided to get a REAL coolant flush. The dealer called me at work to tell me that, while performing the flush, the mechanic noticed that he couldn't get any flow out of the radiator. It turns out it was badly CLOGGED! The dealer will now replace the radiator under warranty. But I am very curious how this could have happened considering this truck has had every 5-15k interval dealer service since new. The green coolant I had in it was only 8 months old when I decided to switch to red. The red coolant (that quickly turned brown) was in for less than 2 months.

Although I'm glad I'm getting a new radiator under warranty, I asked the dealer if I could get the older, 3-row, brass-core radiator instead of the newer, 2-row design. Unfrotunately this is a disadvantage of owning a Lexus- they can only replace it with a Lexus part so I can't do it.

This board is invaluable- thanks for your help, ParadiseCruiser! Let this serve as a WARNING to others out there mixing coolant types- the results can be disastrous if you're not careful!

(Beo- head gasket, head gasket, head gasket)


I originally put 500ml of Nulon Corrosion Inhibitor then later topped up with 1l of Castrol Anti-Freez/Anti-Boil Conentrate in to my BJ40 and have no problem for the last 8 months.
Apr 28, 2003
Turquoise Trail, N NM
I basically had the same thing happened to me, only I forgot to flush the heater core of the old green (flushed the block/radiator), refilled w/ red. A few months later, I'd hear these weird sounds like what you hear when someone upstairs flushes the toilet and water runs down the pipes. Low and behold, radiator was 60% clogged and the coolant looked like mud.
Mar 27, 2003
Alaska -

As many times as some issues arise - in this case coolant contamination - we often forget that there is always someone who is new to Cruisers, or who have not been over the same ground. So I am quite glad to have helped out.

I cannot count how much advice I have also gleaned from others on this list. It's value cannot be measured in $$$ alone. My thanks to all of them as well.


R -

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