Will also post in LS forum but want input from broader audience.

- Took LS into Lexus for interior parts replacement 4 weeks ago and they noticed low coolant. Used a boroscope to supposedly identify a leak - they took a pic of something resembling a brain which they said was the red/pink coolant. They gave me a quote for 8 hours labor at a grand total of $1,400 to "re-seal engine block coolant valley". Don't have good experience with Lexus so told them I wanted a 2nd opinion before authorizing work.
- Took it to my Toyota dealership - they supposedly used a boroscope to also identify the area. They were less confident in their ability to do the work due to it being a Lexus V8 engine and suggested I take it back to Lexus to be safe. No charge for assessment.
- Due to my apprehension to my local Lexus dealer, decided to take it to a high end import mechanic who has been in the same location 35 years - used to take my Audi to him and very reputable shop. It is only him and another ASE certified tech and they do tons of work on BMW, MB, Range Rover, Audi, Rolls, etc. He had the car for 2 hours today and said he doesn't see a leak anywhere. He mentioned that coolant leaks leave a chalky white residue and he saw no evidence of that. He also saw no other parts that were wet or had the residue - said he checked all belts, hoses, and water pump as well. He said I could drive the car with confidence that there is no leak. He said the LS460 is a relatively basic engine compared to some of the more complex cars they service and was confident in his diagnosis. I showed him the pic that the Lexus tech sent and he just smiled and said "Not sure what they're doing, but I'm confident you don't have a leak." No charge. *Note - the car had been sitting for 7 days without being driven - I had the car running for a total of an hour and drove it about 6 miles today to get it to the mechanic. Not sure if that impacts if/how coolant would flow - the car was running for a solid hour though.

I don't want to pay for un-needed service (why I ditched my Lexus dealer 10 years ago), but I also feel apprehensive about 2 places telling me they see something and the indy saying he sees nothing. Need some advice.. I'm not a DIY type so please keep that in mind.

Thanks,

 

There is a bypass pipe is that in the valley of the engine? I think so and I believe it is metal with an O-ring that goes into the water pump the other end (firewall side) goes to a rubber line. So I don't think there is a reason to remove the intake to deal with the bypass pipe maybe I'm wrong.

 

Top it off cold. Check it cold every morning and see how much it is going down. Keep a log and get back with us. Some of these so called coolant leaks are so slow topping off periodically could be fine for years.

 

I think you got your answer.

 

Maybe... What I'm most confused about is my Toyota dealer claiming they saw it with the boroscope but passing on doing the job... they get no benefit out of that.

 

OK good idea - thanks

 

Perhaps you need a fourth opinion? (without telling them anything this time) If your coolant is leaking, you will know.

 

Do you happen to have a copy of the image they gave you?

 

 

^^^ the brain, haha.

more seriously, what year is your ls460?

if there’s a leak, has the coolant ended up on your garage (or outside) floor? If not, how is there a leak if it doesn’t make it to the ground?

 

2010 with 99k miles. There's another member in the 4th Gen LS forum with a 2013 who had the same thing - there's a plate that was catching his leak. A quote from him - #17 in this thread: https://www.clublexus.com/forums/ls-...k-miles-2.html
"As far as my mechanic can tell, it was leaking at the entry pipe O-ring towards the front of the engine (likeDoublebase suspected), where the yellow arrow points to, and also at the rear of the valley plate seal (yellow circle).

It was leaking pretty good and coolant in the reservoir tank went from full to below Low line in four days, yet engine temps never rose, no smoking nor smells, and no drips or puddles underneath the car. There was no way to see the leak from above the engine until the late stages and only if you knew exactly where to look. I can see it now through a crevice from the top but could not see it at all a week ago, even with an endoscope camera. It was still Summer temperatures outside so I didn't use the heater yet but apparently that is a telltale sign of a leak if you don't get enough heat. Sometimes the AC blew too cold but I just proudly thought the system was working too well. I am just glad it wasn't a head gasket leak."

 

That definitely looks like a leak, looks like it exposed. I have seen that happen in same area on Toyota 5.7. I think you need to watch that fluid level.

 

I agree - I just checked the fluid level and it's low. Will have to head back up to the indy shop and see what he says. From the pic it looks like a pretty decent leak, so I'm confused as to why he didn't see it...? Wonder if it is only visible with the scope?

 

How low is the coolant? This is quite frustrating for you. I feel for you. Looks like a gasket leak. I saw this on a 5.7 and it was hidden from view for quite a while.

 

Thanks - it is frustrating mainly because I don't want to do damage to the engine or have something happen where I'm stranded - but I also don't want to pay for some non-existent problem..! And now if there is an issue I'm kinda questioning my ability to take it to the indy to repair/re-seal it since he didn't notice a leak. I feel like I'm stuck in taking it to Lexus.

Coolant level is currently showing at the "low" line. I'll have to go buy some coolant and fill it up a bit later this evening once the engine is cool and see what happens.