Rapid tapping sound over 4000rpm

sophos9

I noticed yesterday that I've got a rapid metallic tapping sound coming from the engine bay when going over 4000 rpm, its noticeable loud and seems to have become noticeable after blanking off the EGR valve and/or changing the exhaust to something more quiet

Would the EGR make the sound?
Aux belt tensioner?
Exhaust manifold heat shield vibration (bolt has bust in manifold grrrrrr)?

Thanks in advance

vocky

probably the heatshield rattling dunno..

sophos9

I tested it along the dual carriageway, the noise comes in at 3500 rpm however does not increase in frequency with RPM - stays pretty constant to around 5500rpm. It also only happens in 2nd and 3rd gear - my guess is exhaust head shield which is not connected to the exhaust manifold (damn bolt snapped in the manifold)

Parked next to the wall and reved the engine to near 4k, no tapping rattle noise. Think I will remove heat shield and go for a drive around - hopefully will be sorted then can figure the best way to attach the heatshield to manifold

Any suggestions welcome 🙂

sophos9

Question please - went to take the exhaust heat shield off to test car tomorrow and noticed that the earth strap from cylinder head to cam cover had come off and was not attached at all :wtf:

Stupid question - what problems would the earth strap coming off cause??? (the above?)

sophos9

Earth strap made no difference to anything dunno..

The noise is still there however noticed its only prominent in gears 2 and 3 - heatshield off tonight

sophos9

Got to the bottom of this one and fixed it

Last night, fitted new exhaust centre section so now I have complete new exhaust instead of 2inch downpipe, 2.5inch centre into 2inch backbox. Rattle was still there, removed heat shield, rattle still there and disconnected EGR, rattle still there.

Got missus to rev car to 4k at idle, rattle like crazy. Got stethoscope out and tested again, the rattle was coming from the exhaust cam area. Stripped off cam cover and found that 1 and 5 cam end caps were significantly loose with 2 and 4 being a little loose. Remembered that when we swapped heads, I swapped the exhaust cam out of the old head and put it in the new one. Thought I had done these to 10nm as per Vx spec but obviously the gremlins had tried to sabotage my plans for a smooth 2.2

Circle tightened to 10nm, reset everything and took for test drive. The Vectra is super smooth again - result, fixed!