Mintyhit

Morning all, I had a thread going here for a knocking noise I was investigating but I figured it was worth starting a new one for this.

https://www.s2ki.com/s2000/topic/855...d-at-idle-vid/

So long story short, I had a slight knocking coming from the bottom end of the engine, it wasn't very loud but it sounded like it needed addressing immediately.

I pulled the sump yesterday and was astonished to find it was full of little bits of plastic/rubber from what looked like an oil seal of some sort - my guess is something must have fallen into the valve train and been obliterated. I checked the bores for scoring and was relieved to find they look clean however, whilst checking the bores I noticed some bits stuck in the oil pickup of the oil pump wedged against the strainer.

This is what I pulled out:



... they fit together


...closer




I'm completely baffled - I have no idea what this is or where it came from but it is pretty heavy so I assume it is major.

I'm going to cut open the oil filter later and perhaps take the rod bearing caps to inspect for damage to the crank but I am fearing the worst now...

Mintyhit

... just had a horrible thought.

Could it be a piston wrist pin?

Are they tapered on the inside does anyone know, anyone have a photo of a non-mangled one?

buaan

Would the wrist pin be able to slide down the side of the piston without scoring the bore? hmmm.

It could be part of the wrist pin, regardless I think finding that in the oil pick up justifies pulling the engine and pulling it apart

If it was part of the pin I'm surprised it hasn't gone pop!?

If I lived closer I'd be happy to come help.

yourboysoap

Regardless of what that is, you will definitely have to pull the motor and figure that out. That's insane.

best of luck to you

Mintyhit

Cheers for the offer, yorkshire is quite a way to go to get covered in oil.

It is utterly bizarre isn't it? I've just been out there again with an inspection mirror and a high powered torch and again I can't see any scoring on the bores.

I just pulled a big end bearing cap as well to see if that crap had gone through the oil and killed the crank:





I'd love to just pull the motor but unfortunately I haven't got a garage to work in or an engine crane here, I'm working on the street in the middle of London. Also with the cost and availability of parts over here if I do lift the engine I doubt I would be rebuilding it as would be cheaper just to get another one.

Like I say though - despite how bad this all looks, the engine was running fine with just a subtitle knocking sound audible at idle - if you stood away from the car with the bonnet closed you couldn't even hear it.

... hmmm its right old puzzle,

Mintyhit

Standard Pin Diameter
Standard (New): 22.961 - 22.965mm



... alright, i'm convinced it is a bit of a piston pin now.

The question is, how does one break this savagely yet not send a rod through the block... how does one of these break at all?

Well I am going to pull the head tomorrow and the pistons for a good look - I am in for a pound now anyway.

zeroptzero

I think it is the wrist pin, they tend to have a shiny chrome look to them , everything else under there is more of a sandy cast look/feel to them. Just my best guess.

SpitfireS

As far as I know, wrist pins do not have a "stepped" outer diameter, as you can see in picture #1 and #3 (first post)
They are held in place by a snap ring on both sides of the piston - in a recessed groove.
The service manual doesn't specify where to measure the 22,961/965 mm and IMO they would if the wrist pin had more than 1 outer diameter.

A stepped wrist pin would only fit in the piston in 1 way.
Also, that is not mentioned in the service manaual.

I don't think its a wrist pin.

Mintyhit

It's the inner diameter that is tapered

I found this picture of a wrist pin from a v8 Camaro - perhaps the F20C ones are similar?

SpitfireS

Is the diameter A different from diameter B?
What is the black line seperating part A from B?
If part B has a smaller diameter and it doesn't look it was causd by wear then I think its is not a wrist pin.
If it IS wear.. then it could be a mangled-up wrist pin but how would the engine have been running at all with one piston not connected to the piston rod?