Last Friday, I dropped my kids off to pre school and jumped in the dak…. Stumbled to life and started making this tapping sound and running a bit rough.

I use the word slapping because it sounded like it was hitting something else. It matched rpm but seemed to go away as soon as I was cruising. I had to get to work so I parked it and towed it home.

I took the timing cover off and replaced the chain tensioners… cheapest fix first. No slip in the chains, no visible cracks or chips or pieces missing in the chain guides… took the valve covers off… all the rockers were in place, no valve keepers or guides missing. All the valves and lifters operated when I turned the engine over slowly with a wrench…

I don’t know if this is rod knock or something else… when I rev it… it sounds like a two stroke dirt bike. Struggles to accelerate when I give it the onions Sounds very much like it’s concertating around the air intake plenum underneath the throttle body. Maintains oil pressure…

engine only has 40000kms on it, synthetic oil changes religiously, good filters, keep up with all of my maintenance… ran fine until starting it up randomly 😭so I don’t know who hates me lol

https://youtube.com/shorts/C4gZesBDB_o?feature=share

 

Collapsed lifter? Did any of the rockers feel loose?

Not a rod knock, that's valve train noise.

 

Thanks for the response, I’m scratching my head on this one.

so with the valve covers off, I felt every rocker… they were tight and the ones where the cam lobe was pointing away… were still tight (with maybe) a millimetre of play. When we turned it over, the valves returned from their rotation…

truth be told, I don’t know how to test for collapsed lifters, when I cranked the engine with a wrench, nothing seemed out of place? What should I look for?

 

Press down on the lifter end of the rocker. You should NOT be able to move them, at all.

 

Thanks so much. Just to confirm, I was wiggling the rockets back and forth and they were all tight.

but how do I push down on the lifters with the rockers on? Do I make sure the cam lobe is furthest away so the valve spring isn’t compressed?

 

Yep, make sure the valve is completely closed, and just use your thumb on the lifter end of the rocker.

 

In your experience… is this a “replace em all at once” situation?

 

If just one is bad, maybe just replace one. If two or more are bad, replace 'em all.

 

There are 16 of them and where one fails, the others are probably not far behind. How many times would you like to pull the valve covers? The driver's side is a b*tch. Which one will eject a rocker and cause carnage? You got sixteen chances to find out.

One of mine failed at over 300K, I sure wasn't going with just one. I replaced springs and valve stem seals as well.

 

Update