AnthonyMtz

Ok guy's, the past 6 months I started noticing the coolant reservoir creeping it's way down to the low mark. I just grabbed some bottled water and added about half of it (16oz bottle) and left it at that, then maybe 4 months ago it was low again!... so I was concerned but not too much, anyways another 2 months go by and it was almost bone dry... I was like what the hell is going on, I was in a hurry so I added a whole 16oz bottled water and closed the hood, now I went out tonight and low and behold it almost back at the low mark again! It has only been drivin about 5 or 6 times in the past 2 months as it's not a daily anymore, I changed the spark plugs a while back when it was consuming the coolant and checked the piston heads and they had a normal amount of carbon on them, none looked out of the ordinary clean, so the head gasket is fine. It's never dripped a drop of water either, and I have not noticed the heater core leaking. I smelled the coolant and it smells normal, no gas odor to it, also there is no odor present inside the vehicle. I'm stumped here, no major issues other than my battery/alternator and a little smell of burning oil from leaky valve cover, any advice/help would be wonderful, and I appreciate anyone that helps! Happy 2016 everyone!

fastnoypi

Rent a coolant pressure tester to help track leaks. If none are found, consider doing a block test to realy confirm for a possible head gasket failure.

artbuc

I would not rule out leaky HG based on how clean the pistons appeared. I assume your oil looks ok?

salimshah

I loaned out the testing kit with all adapters from PepBoys and AutoZone, but could not get them to fit on to either the RX, SC or GS.

The kit had all kind of adapter but none allowed me to hook on to the radiator. I was able to check the radiator cap.

Assuming there problem is with the radiator, Lexus uses plastic top and overtime they tend to crack open right behind the front edge, which is not visible till the radiator is pulled out.

Salim

fastnoypi

Last i used one on a Lexus i borrowed it from Oreilly Auto. You have to double check with the stores if they have a compatible pressure tester that works on Toyota/Lexus...adapter size is approximately 27mm IIRC..i'd have to measure my cap again to make sure.

If you want to take advantage of Harbor Freights return policy, they have a kit with an adapter that should work for 89.99 minus the 20%-25% coupons you can find.

AnthonyMtz

Yep, oil is perfectly fine, gas millage is about 13-14 city and 17+ highway, it's up to date on oil, I run pennzoil synthetic with a k&n filter (changed every 4,000 miles).

AnthonyMtz

I don't think my block is cracked or anything, I've never seen it drip one drop of water, plus it takes a while like over a month for the water level to start dropping. I'm stumped....

AnthonyMtz

Thanks salim, I recently replaced the radiator with a new one around August of 2014. I've never seen steam or on drop of water, it's parked in my driveway and I would have noticed cause I check and inspect everything since I really noticed it consuming water.

maxSteel

Mine has a slow leak here. I don't see it on the ground, but occasionally I smell coolant.
I just top it off occasionally.

https://www.clublexus.com/forums/rx-...ml#post8849702

fastnoypi

a block test doesnt check if your block is cracked but checks your coolant system for hydrocarbons in the event of a headgasket leak. Based on severity, coolant doesn't necessary noticeably mix with your oil right away. It may just be burning up in the cylinder.

The test fluid will change color immediately if it detects the hydrocarbons.

thomas1

Check the drivers side of the engine by the thermostat housing...Mine had a crust there and it turned out being a leaking intake manifold gasket to the head. Water actually flows thru the intake on the RX300. After I replaced the gasket (intake) my leakage stopped.
see post number six on this thread for my picture....
https://www.clublexus.com/forums/rx-...side-rear.html

sktn77a

iTrader: (2)

Check for the same crusty deposits by the water pump - they can start leaking at this mileage.

(Oh, I'm sure you know that bottled water is not distilled water - it;'s just filtered which doesn't remove any of the dissolved salts.)

AnthonyMtz

Yea, it's all I had at the time, trust me, it's much safer and cleaner than my water hose.

AnthonyMtz

Was it consuming alot of water? I would think if it was leaking the water would disappear alot quicker right?

thomas1

Actually it was a very slow leak, had me going for months...Never ran dry in the reservoir, but definetly was going down.