Clunking sound on very cold start

[Untyped]

Previous issue posted here regarding the choppy idle/rpms got fixed with an upstream O2 sensor replacement but I am puzzled about this one....

When it is extremely cold(bellow -15C) car starts fine but there is this rhythmic clunk sound coming from front of the engine... of course the first thought it is timing chain issues but I feel like that is not the case. It stays for 2-3 mins and fades fast. It sounds like it's coming from the fan/radiator area.

I removed the oil cap and put my ear there to see if it is inside the engine but no... it sounds very external.

I am attaching a video that captures the sound very well and how it fades off.

 

[scapistron]

Might be motor mounts. With the hood open how much do you see the engine move when you rev it up? You can also check the clearance between the intake pipe and the fan shroud.

 

[Untyped]

Might be motor mounts. With the hood open how much do you see the engine move when you rev it up? You can also check the clearance between the intake pipe and the fan shroud.

Will do those checks later. But I am pretty sure the engine does not move much under rev.

For the second option.. why would it disappear when slightly warm?

 

[JDiehl]

Watching this thread. Had the same issue last winter on some very cold morning starts but forgot about it until now. FYI my timing chains have been updated.

JD

 

[alldazed]

I have the same noise .on a 2011 RRS . It’s something to do with the fan clutch and I don’t worry about it . Been doing it every cold day in the winter at initial start up since I bought it 5 years ago.

 

[txfromwi]

Interesting...

 

[Untyped]

I have the same noise .on a 2011 RRS . It’s something to do with the fan clutch and I don’t worry about it . Been doing it every cold day in the winter at initial start up since I bought it 5 years ago.

Nice! That's reassuring. Did not know there is a clutch there but I can totally "picture" the sound now.... there was a moment where I told myself that is the AC compressor clutch but obviously wasn't....

Thanks for your comment!

 

[Untyped]

Watching this thread. Had the same issue last winter on some very cold morning starts but forgot about it until now. FYI my timing chains have been updated.

JD

Glad to hear that this is happening to someone with for sure updated timing chains, since I don't have history on my recently purchased LR4. I was 99% sure that's not this sound.

One of the posts here suggests some kind of clutch in the fan... and I totally buy it!!