Noise at 3000rpm

[punkrockscreech]

Hello. I have a 91 na T bar with a 3sge Engine. I recently had it serviced, about 500 miles ago. since then it has developed a rattling / tappet type noise at 3000 rpm, paricularly in 3rd gear (which i found strange??)

Any ideas on what this could be or if anyone else has experienced this?

Also what sort of cheapish mods would people recommend to get a bit of extra ummph from the old girl.

Also the tyres will need replacing soon.....any recommendations?

Cheers.

[RobCrezz]

does it do it when your not moving and you let it rev up to 3000 and then go back down to idle? If so, check the oil!

If not, then could just be the exhaust heat sheild?

Not much modding to get any more power from the 3sge without spending lots of £££ for not much bhp. Best thing to do is change all service bits that were not done in the last service (plugs? leads? Dizzy cap and rotor arm?).

Induction kits can make a nice sound behind your head to make it feel faster, same with an exhaust system.

[punkrockscreech]

The oil is fine, correct level. does it when stationery both when the engine is warm or cold!
Its not the heat shield either, have tightened all screws that could give rise to a rattle!

[RobCrezz]

The oil is fine, correct level. does it when stationery both when the engine is warm or cold!
Its not the heat shield either, have tightened all screws that could give rise to a rattle!

erm, does sound a bit like big end knock. If you can record the sound and post a video then we should be able to tell.

[punkrockscreech]

Ahh....."big end" didn't want to hear that...I'll try my best to get the noise recorded.....if it is the big end....any idea of cost of repair and what it entails etc?

cheers

[RobCrezz]

Ahh....."big end" didn't want to hear that...I'll try my best to get the noise recorded.....if it is the big end....any idea of cost of repair and what it entails etc?

cheers

Sometimes its cheaper to just get a replacement engine, but if you have a friendly garage that can do this kind of thing or a mate then it just means you gotta drop the bottom end and replace the big end and main bearings and shells.

[cathalferris]

It's also possible that a heatshield has had a break or crack in it, such that the shield resonates though all of the attachment bolts are tight. Once this kind of failure happens, the crack will elongate until either it no longer resonates or it falls off.

I've seen this on a Passat diesel turbo/exhaust heat barrier, with crack propogation caused by fatigue and noise at very particular resonant frequencies until it cracked completely and wedged elsewhere.

If it's a deeper sounding 'knock' or 'thump' that's a more expensive sound.

Try to rev the engine with the engine bay open and listening for the source of the sound, and putting e.g. a brush handle on the shields one by one to see if this affects the resonant frequency or the volume of the sound.