Loud cracking Noise??? Help needed....Again!!!

[jester7]

At high revs ive got a loud cracking/banging noise coming from the right side of the engine(left if your looking under the bonnet) Has any one got any ideas??It certainly affecting performance at the top end of the revs. it sounds almost like an electrical break down ie rev limiter???? Ive changed the leads to 8m Magnacor and the coil is a new Mallory one. My only other thought is a blocked pre cat????????? Help....................Anyone..................

[v8 racing]

out of interest was it there before you put the new leads on?

[jester7]

yes it was.As it sounds electrical i thought it was a lead or the coil breaking down. Now i dont know!!

[v8 racing]

can you definetly identify it is coming from one bank?

[jester7]

I think so, it most certainly Sounds like its coming from the right, ive taken some else out in the car and they agreed??

[steve-v8s]

This may sound odd but don’t suppose it is the bearing in the belt tensioner breaking down ?

[jester7]

Not sure ill have anothar check with a mate of mine tonight, must admit still thinking its a blocked cat???

[Seasider]

Can you try isolating the source with a listening device ??

i.e. 3 foot lenth of wood wedged against your ear and other end pressed against different areas where you think the noise might be coming from

[nicbowman]

Exhaust manifold?

Nic

[bluebottle]

Had a similar fault on mine a while back, but unfortunately had too many issues to single out which was the primary cause of the symptons, but it could have been the manifold cracked (they tend to go at the junction where four pipes become one) or a gasket leak.
On my car which had leaking exhaust valves as well, it restricted the engine to 4.5k rpm with misfire and very loud detination

Edited by bluebottle on Friday 4th August 00:32

[jester7]

Thanks for all the advice got the day off to try and sort it, if not ill be limping to the Growl tommorrow!!!

[v8 racing]

have you checked the engine mounts havent broken, and the headers are hitting the chassis?

[dnb]

I'll have quite a lot of spares at the Growl (everything but manifolds) If you need anything, let me know (somehow... Leave a note on the scruffy Griff that has a Porsche number plate on it if all else fails!)

[jester7]

Ok, checked engine mounts, and manifolds all seem ok, replaced the dizzy cap and rotor arm cleaned the stepper (again) slight improvement. It will make it to the growl so have booked a rolling road session at power engineering for next friday to FINALLY find out whats wrong (hopefully!!) Thanks again for all the help, see you all tommorrow!!!!!!

[jester7]

just in AGAIN from the garage!!! Gonna have to speak to a few of you gents tommorrow, took the plugs out of my car to see what was going on, all the plugs were white (very lean) except one, number 7 cylinder is sooty black !!!! now iam really really really confused!!!! Dnb ill find you tommorow to see if maybe you have a few bits that can help, might try another set of leads, (or just one at least)

[Seasider]

jester7 said:

(or just one at least)

I have put a spare in the car

[Ballistic Banana]

Seasider said:

jester7 said:

(or just one at least)

I have put a spare in the car

What injector!!!!

See ya in the morn Del

[Seasider]

Ballistic Banana said:

See ya in the morn Del