Need help with my big end.... Ooooo errrr

[Cro]

Ok so i'm getting a loud knocking which from having watched videos from others on here I know could all too well be the big end.

Heres the background as to what happened.
The car was off getting mapped for the new cams and injectors, the cams were running fine installed and I drove to the dyno no bother. I changed the injectors up there for megane r26 ones as they were running very high duty on the last mapping session on just itbs.

All was going fine through the mapping session and on the power runs, the figures all looked grand so off it came for me to take it home.
As soon as I took off I heard a slight knock but put it down to a cv joint or something as it went away with some revs, but before I even got out of the yard I heard the knock again so shut the engine off and pushed it back inside.

I had the plugs out and put a bore scope down and the pistons looked fine, did the same down the trumpets and the valves looked fine which was something good I guess.

The ht leads were taken off running to rule out spark knock, which I presume would show that but I could well be wrong.

So I need to find out what might have been the cause and what damage might have been done.

Could ignition be a cause , I know the mapper was changing the spark a the top end to see if there was any more power to be squeezed out but its not something I know much about.

Jonny and laine suggested checking the oil pressure and the oil pump but I dont fancy starting the car without knowing that it'll not cause any more damage.
Just on the oil pressure suggestion my oil breather is currently in a bottle and was touching the bottom in the vapour. During starting there were some bubbles so theres obviously air or whatever coming from the breather to cause that, is that normal?or could be a symptom of the above? It didnt trigger anything with us at the time purely because the pipe should just come in from the side and not be touching the bottom


Any suggestions on what to check/ look for first to confirm things, hoping that its something simple or should I just start getting the engine out so things can be taken apart to be looked at?

 

[jinjur]

Aww fug man......hope its a "non-big-end" issue



J

 

[Cro]

Cheers Andy, never a good time for it! :S

 

[MaintenanceMan]

Im no expert, but I had 2 big ends go on my Charade turbo. You normally notice knocking at the top end of the rev range at first, but as time goes on the knock will get louder and will will happen at lower revs, so you should of heard it on the run. Check the oil for any metal shavings from a worn bearing.

 

[Cro]

Will do mate cheers. There was no noise on any of the runs, it literally just appeared as I took it off the dyno and went to drive off.

 

[Cro]

What do people think of this video?

Didn't want to be running it too long but the knocking is certainly only audible at certain parts of the rev range

 

[Adey.]

put a screwdriver on the rocker cover and see if the sound is top end. to me it sounds too high pitched to be bottom end noise tho the camera could be making it sound different. dephaser poss?

 

[Cro]

Tried it Adey and couldn't pinpoint to be honest, dephaser was changed for a brand new one a couple of weeks ago so wouldn't have thought that

I'll see if I can get a better video perhaps, that was a bit rushed

 

[incy-spider]

Sounds big end to me, whip the sump off. At least drain the oil and look for swarf, bronze colour material! What a nightmare. Hope I'm wrong but defo worth checking the oil first!

 

[Riley!]

who did the dephaser? Any chance something could be loose from changing belts

 

[Cro]

I did the belts and the dephaser riley, done loads and never had a problem. Its also been on a few weeks running grand with no noises, but I can't even think what might even have come loose so sound that way

 

[jinjur]

My old Civic lost No:5 main........




Sounded like that

Again, sump aff......that was what led me to diagnose the civic prior to strip down.

J