Hey all-

I've noticed sporadically I have a strange "crunch" sound that happens somewhere right after startup, and I noticed today it happened after it had been idling for 30-45 seconds or so. It sounds quite ugly. Doesn't happen often, maybe once every 10-15 startups.

Any thoughts? Engine/powertrain feels totally normal at all times otherwise.

 

Hi Steve,
Does it sound more like a vibration? How long does it last? I had this sound two years ago that was diagnosed as a vibrating or bad exhaust manifold and replaced under warranty. In the beginning, it happened once in a while, then almost every time I started. The problem has returned but doesn't happen often, so the dealer says they won't diagnose to fix something if they can't replicate the problem. So, I am just having to wait until the problem worsens. It has not affected my car's smooth running.

Here's the link to the thread where I have posted videos of the sounds. Your description doesn't match my vibrating sound, but it is worth taking a listen.
https://www.clublexus.com/forums/ls-...1st-start.html

 

 

 

It could be the A/C compressor "slugging". Refrigerant oil can migrate down to the compressor after sitting a while, and when the HVAC turns the compressor on, it passes this "slug" of oil through it, making a sometimes-startling noise. To see if that's what it is, turn the climate control off before shutting the car off, and see if it makes the noise with the system off on the next start.

 

 

It comes from somewhere around the engine for sure, I can sort of feel it. It definitely doesn't feel right, and my 2015 never made any sort of noise like that.

It was at the dealer today for the 5k service, of course they "could not duplicate it"

 

 

This sounds reasonable to me. May not be the true issue, but plausible. Steve - Is this with the car sitting stationary?

 

Yep, always sitting stationary...