Lash adjusters / Lifters?

[laidbacksnake]

I have a vibration that last about 3-4 seconds on startups and you can hear it again as the RPMS increase 3K-4K, car still has power but I'm definitely keeping my foot off the gas until I can pinpoint this noise and have it fixed. Any tips / experiences?

 

[01yellercobra]

When was the last time a tune up was done? I've never had a lash adjuster cause a vibration. They can make a tapping noise though.

 

[laidbacksnake]

Here's the startup video

 

[laidbacksnake]

It's that 3-4 seconds of tapping / vibration

 

[RX1Cobra]

Car ever been run low on oil and how many miles? It's hard to tell but it sounds like it may be the timing chains. Sure someone with better ears can chime in.

Hopefully not a rod knock but that doesn't sound like a lash adjuster in the video. Think you need to better narrow down where the sound is coming from. Get a stethoscope or a long screwdriver. Coming from a valve cover, timing cover or bottom end.

 

[laidbacksnake]

Car ever been run low on oil and how many miles? It's hard to tell but it sounds like it may be the timing chains. Sure someone with better ears can chime in.

Hopefully not a rod knock but that doesn't sound like a lash adjuster in the video. Think you need to better narrow down where the sound is coming from. Get a stethoscope or a long screwdriver. Coming from a valve cover, timing cover or bottom end.

We found that the oil filter housing was stripped out and I'm not sure. It's been fixed and I run Royal Purple + Lucas. I've checked the fluids since the fix and they're perfect. Someone else said timing chains also. Hopefully my mechanic can look at it today.

 

[Snk-Byet01]

We found that the oil filter housing was stripped out and I'm not sure. It's been fixed and I run Royal Purple + Lucas. I've checked the fluids since the fix and they're perfect. Someone else said timing chains also. Hopefully my mechanic can look at it today.

To me, it sounds like a slightly de-laminated or slightly crushed rod bearing. It's making the noise until the oil pressure is up. Hopefully for you, i'm wrong.

 

[laidbacksnake]

Got this so you guys could hear it better, just need to diagnose it so I can fix it.

Sound at 13 seconds

 

[laidbacksnake]

To me, it sounds like a slightly de-laminated or slightly crushed rod bearing. It's making the noise until the oil pressure is up. Hopefully for you, i'm wrong.

We're 95% sure it's a rod bearing.

 

[01yellercobra]

Sounds like a rod bearing to me as well. Have you opened the filter?

 

[laidbacksnake]

We've confirmed it's a rod bearing. Shit. What to do now...

 

[Snk-Byet01]

You could just have your bottom end redone but as long as the engine is out of the Cobra, you might as well go for forged internals. I have never worked with MMR so I don't have any opinions on them, but they do sell rotating assemblies. You probably won't need a crank, just maybe some cleanup.

If you can find a good machinist who has successfully worked on aluminum 4.6Ls, you might be able to get by for $5000 or less which should include remove and replace the engine block, forged internals, ARP fasteners, machine work, balancing, and the other sundry gaskets and etc.

The only reason that I am recommending forged internals is in the event you ever want to go with forced induction. Otherwise you could stick with OEM rods, pistons and TTY fasteners and save yourself a little cabbage.

My estimate is a pure SWAG and I'll probably get flamed, but this is my $.02.

Good luck.