2007 Lexus IS 350 RWD
Yesterday night after driving hard for a little I noticed 2 things.
While driving and accelerating a bit hard I hear a loud clunk for a second then don’t hear it if I smoothly accelerate, I then stopped driving held the brake down and hit the gas and I can replicate the sound 100% of the time.

When driving last night I smelled antifreeze so I parked and noticed that the small hose connected from the coolant reservoir to the engine block was disconnect with a slight leak im guessing from the hose disconnecting from the reservoir cap. I checked the antifreeze level and it was on full, car didn’t overheat or anything at all. (Replaced radiator last month due to major crack on the top hose location of the radiator)

Now, I go to my car today at night and see that the coolant on the reservoir is completely empty. Nothing inside. First thing that came to my mind since I couldn’t throughly inspect for leaks was a bad head gasket cause I couldn’t see any leaks from the rad cap or the hoses/ radiator.
Now I have a few thoughts of what this can be
1. The clunk sound is a bad engine Mount that can possibly tug the hose out the cap causing it to loose coolant?
2. Bad head gasket..

I want to lean more towards a water pump or thermostat considering my car is at 150k miles but when my radiator went out my car did overheat.

My car still have solid power and runs well.
let me know what you guys think. Will be taking it in tomorrow for a inspection.

 

Video of clunk sound while holding down brake and hitting the gas

 

So the hose blew off even clamped? That's a lot of pressure to force that off.

 

No the hose from the reservoir cap came off not the one that connects to the engine block is The holes on the reservoir cap supposed to have a clamp?

 

No only the one from engine thermostat area is clamped. the one on the cap are just push on.

Right now since the hose came off. You have introduced air into the system. You'll have to bleed the coolant somehow with out introducing more air in. Oriley's may have the Lisle funnel in stock. This will help bleeding the coolant tremendously. As for the motor mounts check both, and the rear trans mount. Also the oil on dip stick looks a bit oxidized. Not sure if it's the pic or what.

 

Hmm interesting so in my case the one that’s not clamped and pushed into the reservoir tank came off. Maybe the endgame did pop it off with that bad mount I’m assuming?

 

I edited my comment above. Sorry I been fighting auto correct since I joined the forums. Android and this chat box don't play well

 

Well took it to my pops shop tested the mount by brake and gas popped the coolant line right off. Explains a lot!

 

Good to know you found your issue. Still bleed the coolant system it may have air bubbles.

 

How do I bleed properly? Can you link me somewhere I can get a step by step tutorial or anything. Thanks in advance!!

 

 

If the engine moves that much and pops the hose and/or pulls on the radiator top hose, that's no good. Cost me a radiator in the old Camry years ago for the same reason, a bad mount. Of course those are transverse mounted and really pull away compared to these.

My thought is that you are fine. Fix the mount as the system did what its supposed to do, it refilled itself on cool down. You connected the hose and it pulled a vacuum on the tank filling the block back up during cool down. That's how it's supposed to work. You mention just a small amount of fluid spilled, that is the only odd part but who knows how long the tube was off? It could have lost fluid at other times.

Good luck.