Hi everyone,

I was running the engine to check the source of a noise and saw the coolant was moving a little in the expansion tank. Is this normal?
Here's the vid. The engine was cold, had been running for maybe two minutes after being stopped for 48 hours. Outside temp was around 12C. It may not be obvious in the video, but the coolant's surface in the tank wasn't moving or bubbling :


Cheers,
Alex

 

I'd be more concerned with the loud ticking noise over the coolant flow!

 

The video was recorded without the engine lid, with the phone a few inches over the fuel rail / injectors. So that would explain the ticking.

 

If the ticking noise goes when the engine has warmed up, it's just the high pressure fuel pump. Perfectly normal and nothing to worry about, my 2017 V6S did exactly the same.

 

Coolant will move due to convection. (When engine is off)

 

It definitely runs quieter when warm. But the HPFPs rattle when cold so I think I'll swap'em out anyway. About 500 bucks for a pair (Bosch) with tappets and seals and it seems reasonably DIY-able. I may eat these words later.

Engine was on in the video. Someone on Reddit pointed out this is probably just coolant from one of the return lines.

 

Engine on, it moves mostly due to the water pump.

 

I would not swap then out, if everything is fine ,not necessary to introduce another problem that may appear

 

You are most likely hearing injectors and the hi pressure fuel pumps are a ROYAL PAIN, you have to unbolt the engine mounts and lift the right side of the engine and the fuel lines are a pain also.
Coolant moving is normal, as the thermostat has small holes to let water through.

 

Also, how many km's on the car?

 

About 80 000k / a tad under 50k miles.
My car is actually an XE. RWD LHD which should make things easier as far as FP removal. Some people say it's a 1h job, others say it's a complete nightmare. I guess I'll just have to see

I've read a couple of threads where people had the same noise irregular rattle as I did and both changed the HPFPs which solved the issue. My rattle is definitely coming from there, it actually made my ears hurts when listening to it with the stethoscope on the fuel lines .

 

With what you said, I would replace the HPFP's and I would do it sooner, rather than later. When mine went out, I was 30 miles from home and that tow bill was over $250, but the worse part was waiting for the tow for 2.5 hrs and getting home at 2am.