...and its so easy to diagnose belt tensioner or belt driven accessory issues. Just temporarily remove belt, or even just loosen it off of the tensioner pully, so its just laying there not doing anything, then see if noise is gone.

Its ok to run motor like this for a few min or even drive it. You will not have water pump cooling motor so you only have limited time before you will overheat, but plenty of time to see if noise is gone.

This is easy, and free to try. So do this first. Then report back.


...and noise is likely one of these things:

- rod knock, aka rod bearings (can possibly save motor if you don't drive it, polish crank and replace bearings. Can be done with motor in car, head still on. But requires S2K experience. There are multiple size bearings used in this car, and mechanic will need to use the correct size. Factory would select the correct size as they built each motor, based on clearances of the parts being used. This is very unique and even very experienced engine builder won't know about this if they havent worked on S2k before)

- piston slap - common to S2k. Not harmful. Not anything that can be done about it.

- TCT - commonly fail. New Honda replacements will also soon fail. Use a Billman modified TCT instead for bulletproof service. He is a vendor onbthis site, order from him.

- Valve adjustment - a shop that works on sportbikes would have way more relevant experience with this service than any car mechanic will (who probably has none).

- tensioner or other belt driven accessory



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I did a cold start this morning to get some better footage.

The knocking is now obvious at idle. I'll upload the video later on.

I can't belive it's gone from seemingly working well with a little rattle to an audible knock when stationary as the revs drop down from a blip. Its gotten far worse immediatly after the oil had been changed.

 

Here is the video from this morning. Today it sounds significantly worse. It looks like my hopes of dropping the sump and replacing the rod bearings if the crank looks OK are probably now over.

Sitting in the car and displaying the knock (about 5 mins after start): https://youtu.be/33-JHUNGDvo

Fairly long cold start video: https://youtu.be/ROuCwIQdTTQ

 

You can try this. Pull each spark plug cap, one-at-a-time, and listen to the engine idle. If pulling a particular cap changes the engine noise --- lessens the knocking sound --- then you prolly have rod knock associated with that cylinder. If pulling each coil pack does not change the noise, you have other issues to rule-out.

Good luck!

 

Thanks windhund. I haven't tried taking the coils off when the engine is running yet. I have used a mechanics stethoscope to try and locate the source of the noise. The engine is too loud and i cant hear anything through the ear pieces over the ambient noise though.

Since I said the noise has got worse I have been out driving it. The very faint knock like sound can only be heard with a cold engine. Otherwise the only symptom is the nasty rattle at around 2500-3500 rpm especially when using the clutch setting off in 1st or reversing. I believe this is because using the clutch holds the revs a little longer at the rpm point where the rattle occurs.

I'm still tempted to get the sump pulled and the bearings looked at and likely replaced. The other part of me thinks I should carry on driving and accept this is a noise it makes.

 

"Symptom is the nasty rattle at around 2500-3500 rpm, especially when using the clutch setting off in 1st or reversing.."

Could this be a lugging noise? Is the rattle more apparent under load (like backing up on a grade)? Or not pressing the accelerator pedal enough, when moving from a stand still? Lugging will be most apparent when there is too much load on engine for the RPMs. If you are a bit more aggressive with the RPMs, at slow speeds, does the noise go away? If this is the case... stay away from those conditions that gives you the most bottom end noise.

 

It isn't lugging. I think you can pull away in 1st with just over 2k rpm without straining the engine on a flat surface. I have to as more than 2500rpm causes the nasty rattle to appear.

 

I guess you could try slightly heavier weight oil (say 10W-40) and see if that quiets the engine, a bit.

 

Wait, nasty rattle, setting off in 1st, that almost sounds like wheel bearings to me.

 

I had another go with the stethoscope. It definitely sounds like the clattery sound is present most at around 3000 rpm and sounds strongest with the stethoscope pressed against the front of the cylinder head rather than the block. Perhaps this is something to do with the timing chain the previous owner had installed, maybe an improper install. Not sure how to investigate further.