2014 XKR convertible 70k miles. I smelled a little coolant over the last few months. Then I brought the car to the dealer for an oil change and mentioned for them to check for a leak. They didn’t mention anything but then 2 weeks later the low coolant light came on for the first time and the overflow tank was very low. I added coolant and the light went off but within 10 minutes of driving the light came back on again and the tank was half full. I didn’t see any leak on the ground or white smoke but I did notice coolant at the rear of the engine on the passenger side near the top. See photo. I circled in yellow the bright spot that is the coolant sitting on a part. Maybe coincidentally but the washer fluid was also low and after filling it also went empty very quickly. That I did see run out on the ground. So where can this rapid loss of coolant be coming from? I watched in the garage with the hood open but couldn’t see anything dripping. I put a towel under the overflow hose and nothing dripped from there. I cant drive the car like this since it runs out too fast. I won’t go to the dealer since they are bad at diagnosing and missed it when it was there for the oil change. I have never had the water pump changed before but I have had the intake manifold replaced twice because of a coolant leak but the light never came on for that.

 

Did you take off the under tray, and see if coolant was puddling on top of it? If so, leave the under tray off while the car is running to check for leaks.

 

Is there any sign of steam in the exhaust? Have you checked the oil level (assuming no dipstick) or removed the filler cap to see if there is coolant in the oil?

If you're losing that much coolant and it's not dripping out under the car it must be going into the cylinders or into the oil. You definitely need to remove the undertray but I'd be very surprised if it could hold that much liquid.

Richard

 

I didn’t remove the tray but I can see coolant collecting on it but I also see coolant up higher at the top of the engine where my yellow circle is so it must be dripping down from there. I was wondering if anyone knew what part of the engine that is if it’s a hose or something else.

 

Unfortunately it can be coming from numerous places. With all the plastics it’s hard to diagnose unless you are the original owner and know all the history. When car cools down check everywhere after pressure testing and using a boriscope helps. If you do find the culprit it’s best to replace as many plastic hoses while in there. Very common and needs to be watched as a maintenance item when replacing plastic hoses.

 

I’m the original owner. Only previous coolant leak came from the intake manifold. That had to be replaced and then it failed again 3 years later. This time it is a rapid loss within 10 minutes but it started as a faint smell for the last 6 months. I won’t be the one fixing it or diagnosing it. I just wanted to rule out water pump or anything else that’s not in that area. I don’t have the equipment to diagnose or fix it. I will probably bring it to the Lexus dealer.

 

After a cold soak, preferably overnight, use a cooling system pressure to pressurise the system to 1 bar. If the gauge on the pressure tester begins to show a pressure loss, check for coolant leaks.

Known common failure points are the water outlet pipes under the supercharger shout, and the heater pipe at the back of the cylinder heads.

 

Also good thing about pressure testers is they often make finding the source of the leak easier on a cold engine as you'll quickly pinpoint the source of the escaping coolant without getting burnt!

 

Me, I don't HAVE pressure in my coolant system. I do sacrifice 3-5 degrees f though.

 

Pressure testers are available for use at no cost through almost all auto parts stores. Also, remove the vanity cover and put some light on the engine for better pics. Your first pic is too dark to see anything.

 

Unless you have modified your cooling system to one with an overflow tank which runs at atmospheric pressure, you definitely will be running at least a couple of psi above atmospheric.

Richard

 

Mine was cracked under the radiator inlet hose... couldn't see it and it definitely found its way to so many different random parts to drip off of. The connector is plastic and gets soft so I think i cracked mine by trying to do too much (tightening and pushing the hose on).
Also i got a new reservoir... the crack in the old one was razor thin and only leaks out when it got hot.. good luck

 

Nope. I can run with the cap off at 200 degrees. It's spill if too full, but that's all.
Course if the pressure is measured right at the outlet of the water pump it'll be a bit, but a very small amount. Gotta have some pressure to move liquid. The system total will still be zero. Maybe that's what you were stating.

 

How did you make out?

 

Exactly so. If you run with the cap off, there will be no pressure other than atmospheric but if you drive the car like that without a proper catch-can system you will lose coolant but due to physical sloshing about rather than boiling. If you run with the cap on, as you do, the expansion of the coolant and any air in the system must cause a pressure increase above atmospheric. It's physics.

Richard

 

Sounds like the valley hose to me.

 

Here are some new photos with the engine cover off and some light you can see pink in a lot of areas. I didn’t find it yet but ordered a new pump just in case old posts indicated that rapid coolant loss has been from a bad pump. I will bring it to the Lexus dealer to repair as they are the only honest shop I can find.

 

Did you get a pressure tester yet? You can usually borrow one for free from auto stores like Advance or AutoZone

 

Get this thing up on Axel stands man and remove all the under trays - get a powerful flashlight in and check everything with the engine running, see where it's leaking.

As per usual safety first, if you aren't comfortable doing such a job leave to a garage

 

I'd say not engine running, but a pressure tester put on the coolant system. Don't need boiling coolant spraying a person's face.