Ticking Noise When Warm and Other Strange Sounds

[-tWv-]

Hey all, hoping some of you can help me diagnose and address some concerning noises that have started occurring on my '98 base Boxster with ~91K miles.

Issue #1:
- My Boxster has recently developed a ticking/tapping noise on the driver side cylinder bank after the car is fully warm. The engine sounds normal until I have been driving for ~15 mins and then this noise starts. From my reading on other posts, this seems to match the noise caused by a stuck lifter. However, there have been varying reports of different oil addressing the problem or other solutions. I am running LiquiMoly 5W-40 right now. I read about switching to a higher viscosity oil could help older engines like mine, should I switch to something like a 15W-50? (I've also read that a lower viscosity oil could help, so not sure which direction to go here).

Video of issue

Issue #2:
- Another recent development is a loud high pitched squealing noise seemingly coming from the passenger side. This only occurs when I am off-throttle & decelerating after the car is warm. This seems to be the same or similar issue as this thread. I just replaced my AOS a year or so ago due to some smoke issues I was having on start up. Could it really be bad again and causing this noise?

[Beelzy]

Got me on which oil, I'd probably go higher viscosity.
As for the noise, sounds like the water pump might be failing.

[-tWv-]

Providing an update here after a couple weeks of diagnosis. Making some progress but haven't fully resolved these issues.

On Issue #1: I suspected this to be hydraulic lifter noise so I did an engine flush/oil change. No immediate results after this (to be expected). However, I added some Liquid Moly Hydraulic lifter additive after the oil change and the lifter noise almost immediately went away. I'll report back after a few weeks of driving, but turns out this stuff may not be snake oil...

On Issue #2: Even though I had just replaced the AOS about 2 years ago I went ahead and did it again and replace the oil fill cap to try to rule out crankcase ventilation issues. The noise has not changed at all, so I think my next step is to smoke test the intake to see if there are any leaks there. I don't have a smoke machine, so going to have to see if I can find/borrow one.

If anyone has experience with common intake/vacuum leaks and how to diagnose, I'm all ears.

[elgyqc]

I made a couple of DIY smoke machines and was not satisfied with them so bought one... and it turned out to not be much better. There are videos on how to make one, it is simple and cheap.
You can also use a hand vacuum pump to check the vacuum system, it won't tell you where the leak is but if it holds vacuum you know there is not a leak.
From my limited experience I get the impression the vacuum canister, just in front of the AOS, and the lines around it are often the problem. I have tested 3 canisters and all 3 had cracks around the base and leaked. On one engine the vacuum lines near the canister were brittle and broken, while the other lines were OK. Perhaps they get hotter because they are the lines closest to the engine block.
Some good info here
Vaccum Canister replacement and other vacuum stuff

[-tWv-]

Originally Posted by elgyqc

I made a couple of DIY smoke machines and was not satisfied with them so bought one... and it turned out to not be much better. There are videos on how to make one, it is simple and cheap.
You can also use a hand vacuum pump to check the vacuum system, it won't tell you where the leak is but if it holds vacuum you know there is not a leak.
From my limited experience I get the impression the vacuum canister, just in front of the AOS, and the lines around it are often the problem. I have tested 3 canisters and all 3 had cracks around the base and leaked. On one engine the vacuum lines near the canister were brittle and broken, while the other lines were OK. Perhaps they get hotter because they are the lines closest to the engine block.
Some good info here
Vaccum Canister replacement and other vacuum stuff

Thanks so much for this! Still haven't gotten around to doing a deep dive on the issue but I'll start with the canister!