This is an issue with ISFs and UR engines (Lexus LS models have this issue as well). I don’t think there are any reports on the RCF and GSF but this is a video of the work involved if this ever happens to you.

An early symptom is finding lower coolant levels when the car has not been started. You can check for early warning signs by sticking a $20 borescope down the driver side front intake runner. You will be able to see where the coolant puddles. I made a video of this last year.


Worse symptoms are finding leaks and coolant at the back of the firewall or leaking down the cats or transmission bell housing.

This has affected ISFs from 2008 to 2013. It does not happen to all as some have reported it was never an issue. Leaks may start as early as 60k, 80k, to 100k miles. Mine started at around 85k miles. Some have speculated that the failure part is a sealant used that may have been improperly applied.

Now this may not be an issue with RCFs / GSFs as they use a revised sealant but wanted to give you all a heads up as these cars come up in age. Repairs at dealerships range around $2,000 - $3,000.

Hopefully after multiple iterations of the UR they got it right with the current 2URGSE.

 

Great post. Thanks for sharing.

 

When I had my 2013, I'd smell coolant after pulling into my garage. Coolant level would go down abnormally too, I might have topped it off 3 times within the first 15K miles. I've taken it to the dealer to check if the valley plate issue was happening with it and they confirmed that it wasn't after checking with a borescope. I traded the car in @ 23K miles.

 

I had to fill my coolant every 4 months. I would check it every morning before I made the first start of the day. I would have it at the Hi line then after 4 months it’s at the Lo line. After 3 years of this happening (and getting my water pump replaced) I finally bought my own borescope and recorded my finding so that I could get it done under my extended warranty. The sad thing is that after the repair I noticed that after 8mos...it was at the Lo line again. Annoying for sure.

 

IS-F or RC-F?

 

That's the ticket - Pass on your problem to someone else

Lou

 

ISF...no reports yet on any RCF or GSF that has this issue but wanted to post this in case it might happen and no one gets blindsided. It’s such an easy thing to check too if you have your borescope.

 

Any valley plate instances on the LC500s Lou?

 

I have a borescope. Do you check right down the driver’s side, just behind/below the throttle body? Where there’s a foam insulator? Thanks!

 

umm no, I traded the car in when I saw a white RCF in my dealer’s showroom while buying an oil filter for my is-f. It wasn’t because I thought there was a problem with the car. I actually planned on doing the work myself if it did. Happy?

 

Check out my video. It’s in between the front first intake runner on the driver side. Take the engine cover out first and you’ll be able to stick the borescope down similar to my vid. If it helps watch it frame by frame.

 

Not to side track the discussion about the very real issue of the valley plate leaks on ISF models... But from my understanding
and observation on my ISF the coolant level SHOULD be at the low line when the engine is cool and only increase to the high
line once the engine is warmed up due to the expansion of the coolant. So being at the low line is normal. Some cars will even
label the high line as HOT and the low line as COLD.

 

check your owners manual. This is not correct. That’s the same bogus story the dealer tried to sell me until I showed him on the cars manual that the coolant level should be at the hi line when it is cold. If it is on low then it should be filled to hi.

I thought the same way you did and even made a post about it. Lobuxracer who is one of the more knowledgeable posters here corrected me. I didn’t want to believe it at first but surprise surprise I had the valley plate leak per my video above. Check out the thread below...post #20

https://www.clublexus.com/forums/is-...-question.html

if you have an ISF and you are on the lo line when cold fill it to hi. If it starts to go down within a year...you have a leak. Either it’s the water pump or a valley plate..AMHIK.

 

Valley plate is sneaky too...had 2 engine pressure tests done and both passed. Dealer could not find any leaks. What sold them was the video. Never thought a $20 borescope was such a good investment.

 

Thank you for correcting me...
Do you think you have a valley plate leak again now that coolant level has returned to the low line?