Just an update from my original post which was about 6 weeks ago. I checked my coolant level and it is down about .25 inch. I have driven the car about 350 miles. I always check it when the engine is cold. The level should not be down so there is a very slow leak somewhere. Too small to find I suppose or too small to be concerned about? I will check it again next month. My last car was a Nissan Altima and I checked the coolant level every 3 months. It never budged. So, 1 or 2 times a year I add a few ounces of coolant? No big deal? I would feel a little uneasy going to the stealership complaining that my coolant level is down .25 inch.
Any engineers out there with brilliant ideas? My biggest fear is that the head gasket might be leaking.

 

I always check it cold.

 

0.25 inch, in that small reservoir, is not much fluid. But it seems significant when lost driving only 350 miles. If you can do a careful inspection, especially around the water pump, and you can't find the pink stain, then I too would start worrying about an internal head gasket leak. Look at your oil and make sure there's no strange foamy stuff in it. Look at your coolant and make sure there's no oil floating on it. Maybe start taking photos of the full reservoir and odometer at the same time, to start building your case for a chat with the dealer.

 

dibl, you have some good thoughts but, I don't even know where the water pump is on this car. I checked the oil dip stick and it looks like brand new.

 

There's a photo of a coolant leak from the water pump on post #5 on this thread:

https://www.clublexus.com/forums/rx-...tires-too.html

The water pump assembly is on the passenger side of the engine, where you can see the pulleys and serpentine belt that drive it. So along the edge of that assembly, particularly the lower edge, is where you need to look for any sign of pink fluid.

If you're not comfortable with your own ability to do that type of inspection, it's worth paying a mechanic to check it.

 

Headgasket issues are not unheard of on the 3.5 gr but they seem to show up when the engine gets older rather than a defect out of the gate. If there actually is a leak odds are it will be the water pump as that has always been a fairly common issue on these engines. Likely though you are fine, just monitor it and see if it drops.

 

Just an update on an old issue. It has been 10 months and about 3600 miles of driving. The coolant level was down about one inch. I added about 12 ounces of 50/50.
I don't see any leaks and would challenge anyone to find one. There is one somewhere but so small. Since I am retired and drive so few miles I will not be concerned about it. I love this car and will keep it until I die.

 

We did have to replace the radiator in our RX350 once for a slow leak. Eventually I could see some drips on the garage floor. The local Toyota dealer amazingly asked if he could just use a inexpensive non-OEM radiator to save me money. The replacement ended up costing just a few hundred dollars. I doubt the Lexus dealer would have done that.

 

Here is what is interesting. I bought this beautiful 2017 RX 350 in February of 2021. I was checking all the fluids and noticed the coolant reservoir was dry. So, I assumed the previous owner never checked it. I bought the car from Carmax who changed the oil. Now I assume that they did not look at the coolant reservoir. I bought the car in NJ but I live in PA. I took the car in for a PA state inspection to a local mechanic. They said nothing about the low coolant level. There is a lesson to be learned here and you know what it is. Let me add one more LOL. I brought it in for the fuel pump recall to the Lexus dealership in NJ. They said nothing about the low coolant either. That's 4 institutions that never looked at the coolant level. Does it get any worse?

 

Not surprising at all. One time when I had my wife's 17 RX in for an oil change atbthe dealer, I asked them to check the brake pads. They returned the car and said you have plenty fat left in the pads. I was actually surprised as it was 40k+ miles and I saw the fluid in the reservor was down a bit which is normal as the pads wear down. Two months later I hear metal on metal 😣 I called them, raised heck and after an arm wrestle with the GM, they agreed to give me new rotors on them but I still had to pay for the pads of course. Complete incompetence.

 

Well, did you ever fill the coolant reservoir?

 

See post #22