Extremely odd occasional sound on cold start 🤯 (1 Viewer)

[creakycruiser]

Hi all,

I need some help hunting this grind/groaning sound down.

It only occurs when the car has been sitting for 24 hour and during a cold start.

I've recently replaced the starter, alternator, PS pump, tensioner pulley and fan pulley bracket.

What else could it be? The AC compressor?!



It's the "chu-chunk" roughly 1.5 seconds after turning the engine over.

Thank you so much!

 

[Zuberg]

When did this sound start?

Before or after starter install? Is the starter gear slow to retract from the flex plate....?

Are all fluids at proper level, including transmission?

My mind goes to starter, transmission, etc. When it's started and makes the clunk does the driveshaft move at all (might be subtle)?

 

[creakycruiser]

When did this sound start?

Before or after starter install? Is the starter gear slow to retract from the flex plate....?

Are all fluids at proper level, including transmission?

My mind goes to transmission, etc. When it's started and makes the clunk does the driveshaft move at all (might be subtle)?

Sound started after replacing my AC evaporator and recharging about 1.5 months ago. I’m unsure if it’s related.

I replaced the starter roughly 2 years ago and it’s been trouble free. I don’t believe it’s the starter, I’ve heard my starter not retract before and it was a very different sound.

Trans fluid level is good but I’m about to double check all the fluids so may find something there.

I don’t believe the driveshaft is moving at all when the clunk/grind happens. It feels like it’s in the front end, I can feel it near my feet and the steering wheel. My fear is that it’s the transfer case, if that’s even possible. I have a part-time 4WD kit spool installed in it.

 

[Zuberg]

If it started after the AC repair, I'd chase that lead. I listened again with better headphones and it does sound a bit like compressor, always hard to tell on video.

 

[creakycruiser]

If it started after the AC repair, I'd chase that lead. I listened again with better headphones and it does sound a bit like compressor, always hard to tell on video.

Compressor is my gut reaction. I was able to find videos of commercial AC compressors that (sort of) sound like this when they start up. But the fact that I can’t find a single 2UZ report of this makes me self-gaslight.

 

[Mike NXP]

Compressor is my gut reaction. I was able to find videos of commercial AC compressors that (sort of) sound like this when they start up. But the fact that I can’t find a single 2UZ report of this makes me self-gaslight.

Someone else posted recently about a loud clunk on startup and it was due to the AC compressor as well. Although yours sounds a lot louder.

First step I would take, remove the accessory belt, make sure all components are installed properly / no wiggle, and then start the engine and see if the noise goes away. At least that will narrow it down to something pulley driven, not a starter or anything else

 

[creakycruiser]

Someone else posted recently about a loud clunk on startup and it was due to the AC compressor as well. Although yours sounds a lot louder.

First step I would take, remove the accessory belt, make sure all components are installed properly / no wiggle, and then start the engine and see if the noise goes away. At least that will narrow it down to something pulley driven, not a starter or anything else

The issue is that once the sound occurs, it doesn't occur again until at least 24-48 hours later, when the truck has been sitting in the heat. So it's difficult, hair-pulling even, to diagnose. Any other diagnostic tricks you can think of?

 

[TLCPNW]

I've got the same sound which started after I installed a new condenser. I attribute it to adding too much Pag oil. My plan is to bring it into a shop to have them evacuate the refrigerant and add new stuff to see if they can fix the issue (correct amount of Pag oil). Hopefully this works as I've already swapped the clutch assembly and set the air gap and that didn't fix it.

 

[Jack90210]

User name checks out

 

[creakycruiser]

I've got the same sound which started after I installed a new condenser. I attribute it to adding too much Pag oil. My plan is to bring it into a shop to have them evacuate the refrigerant and add new stuff to see if they can fix the issue (correct amount of Pag oil). Hopefully this works as I've already swapped the clutch assembly and set the air gap and that didn't fix it.

Well shucks, that's a darn good lead. Thank you.

 

[Mike NXP]

The issue is that once the sound occurs, it doesn't occur again until at least 24-48 hours later, when the truck has been sitting in the heat. So it's difficult, hair-pulling even, to diagnose. Any other diagnostic tricks you can think of?

I hear ya, but at least it seems consistent given those guidelines and its free / easy thing to check.... Pull your belt, and let it sit for 2 days and fire it up to help narrow it down. If the noise goes away you can hone in on belt driven components. I also assume its AC related based on the repair history and info you mentioned, but no idea how to fix and totally just guessing

Belt have good tension?
Tensioner feel good n springy no binding? I forget all the details here but there was a revision to the original tensioner at some point so if you replace to the newer pulley the tensioner needs replacing too.

 

[nissanh]

window locks?

 

[MS100]

My 2000 does the same thing, though not as loud. It’s the AC compressor on mine. Simple test is to crank with AC off and see if noise goes away. After much research on the problem, I decided to quit worrying about. Apparently, the freon inside hoses and compressor condenses overnight as things cool off and the shot of liquid into the compressor at starting causes the noise.