Thread: 3.9 V8 engine knock

Originally Posted by chazza

Double Row.

I think we found your problem .....


Click on the link ... 3rd answer on page 1 by It'sNotWorthComplaining ...

new noise after V8 cam install

Thanks Mike - I had been following that post but for some reasons the pics don't enlarge and I can't see any detail in it.

I wonder why the knock only appears after the engine is warm; and why it knocks at all, given that it was the same dimensions as the old one, as far as I could tell?

Cheers Charlie

Originally Posted by chazza

I can't see any detail in it.

I lifted the post across ....

Originally Posted by It'sNotWorthComplaining!

If they installed a dual rollmaster chain , then have a look at these pics, there are rub points in the timing case, one at dizzy input there is a lug in the casting that will interfer, and the oil pump cover gets a scrape from the link pins.

The pictures are of the Timing case .... Serpentine belt V8


You can see the shiny scrape line around the oil pump gear





Shows the Dizzy lug

Originally Posted by chazza

I wonder why the knock only appears after the engine is warm; and why it knocks at all,

If you follow the other post, you would have read my input .... Cam knock .... Your cam & chain most likely has the timing case jammed hard up on it

Thanks Mike. So is there an easy fix, or should I contact my supplier if this proves to be the problem?

Cheers Charlie

Originally Posted by chazza

. So is there an easy fix,

Depends what you call easy ....

First thing to do is to think about your problem .... Then look at those pictures ... then ask yourself if this is the probable cause

If yes ... Then

Off with viscous fan
Off with the fan cowling
Remove the serp belt
Remove the Coolant Drain plug located behind and under the exhaust manifold of *7 piston
Remove the top and bottom coolant hose
Remove the coil lead
Pull the coil positive power line
Put a socket with small extension and solid strong bar on the Harmonic crank bolt
Place the bar handle side on the passenger chassis rail
Place a 2x1 between the radiator and the socket to jamb and hold the socket in a stable location
Crank the motor quickly to crack the crank bolt
Take out the crank bolt
Remove the harmonic balancer
Remove the Timing case bolts (Leave the water pump bolts in place)
Take off the timing case

Inspect the cover
Use a dial gauge to check cam play tolerance
Remover the cam retainer plate
Inspect the retainer plate

Phew ....

Well I have changed the big-end bearings and most of the alarming noises have disappeared - yippee!

However; the knock in the top end of the engine, which I could hear before, is still coming back when the engine gets warm
The oil pressure is up to specification; I have looked inside the timing case with a camera and it is as clean as whistle, so it is not the trouble ItsNotWorth Complaining had with his; the engine runs superbly at idle and at higher revs, so it can't be any of the camshaft lobes.

I suspect it might be camshaft end-float but it is an intermittent knock and it goes away with an increase in revs. I can't tell if it is a half-engine-speed knock but it seems to be. Given that I found aluminium in the oil, could it be the camshaft knocking occasionally into the block somewhere?

I suppose my next step is to remove the inlet manifold and gasket and have a look at the cam itself; before I do that can anyone give me some idea of what else it could be?

Finally; are the tinplate gaskets re-useable, or should I buy a new one?

Cheers Charlie

G'day Chazza

New is best, the amount of work to fix a pesky leak isn't worth the dollars.

But before you embark on this can you lay your hands on a mechanics stethoscope, with this you will be able to locate the (almost precise) point of the troublesome noise, fingers crossed that it is not a liner.

Cheers John

Thanks Johno; I don't think it is a liner, I have had that trouble on my P6 and this seems quite different.

Since posting earlier I drove out to my cobber's place so he could listen to it and for 5 minutes at idle and at higher revs we couldn't get a peep out of it!

I think I will take the serpentine belt off when the knock comes back, to see if it might be the water pump.

Another mate of mine has a stethoscope so I will bear that in mind,

Cheers Charlie