ticking noise and exhaust manifold

[Stag-Victor]

Over the last few weeks my stag has developed a tappety ticking sound, something akin to an old talbot avenger, from the nearside bank that can be heard mainly on light throttle.

So far i have checked the condition of the plugs, all ok, so moved on to checking the exhaust manifold is not blowing before I then go on to check the timing chain and tappet clearances.

The exhaust was found to have two loose bolts; lower front and upper centre. The front one tightened up ok. The centre one has been helicoiled and the helicoil has failed. So my first question, how best to replace a failed helicoil and what are the chances of doing it in situ? I really dont want to take the head off if poss.

I have also had a check of the timing chains and I am minded to replace it as I dont know its age - there is a about 1cm of deflection after the chain passes the cam sprocket and back into the head on the lhs. The rhs is taut both sides of the cam sprocket. I've looked through whatever I can find in previous forum posts and tech section but still not sure if that is normal or a sign the chain is worn out?

Finally I suspect the worst case is a loose valve guide? Is there a way of diagnosing this easily without removing the valve gear? The car still pulls well and doesn't burn oil.

Thanks in advance
Kevin

[jbuckl]

Helicoil… yes can be pulled out with skill and patience, manifold will have to be off.
If the same size can be used again depends on how much of the aluminium is left.

Does sound like the chain is loose.

Remove the rhs cam cover (oil filler) & check the tensioner extension. Iirc 1/2” is about max.

no way to tell about the guide Afaiaa, without inspecting.

Photos & audio can help with these queries.

Exhaust blows can sound metallic.

[Jeff]

Hi Kevin,

Does the 'ticking' sound go after engine has warmed up? Mine has done it since a rebuild by a Stag expert and seems to be quite common.

Jeff.

[Stag-Victor]

Thanks, in answer to the questions the tensioner that can just about be seen on the rhs is about 15mm extended. So sounds like it is due to be replaced regardless of whether it is the source of noise or not.

Sound comes regardless of engine temp.

I did take some video of it which I will try and add later, I cant seem to upload it from my phone..

[jbuckl]

15 mm tensioner extension is a sign it’s beyond service.

[Stag-Victor]

Ok I have now had time to look a bit further into this.

Tightening up the exhaust manifold seemed to reduce the noise quite markedly, but I decided to plough on with replacing the chains and tackling a few other jobs while things are apart.

On setting the engine to tdc, I find the left hand cam is out of alignment. Without a boroscope I cant tell if this is far enough out to cause valve to piston contact😳 see photo- what do others think? it would explain the rattling if so... I wonder if its slipped a tooth? Or just previous owner error?

Knowing how sensitive engines are to cam timing I am surprised it was running as well as it did, I'm a bit nervous of resetting it and finding it runs badly once all reassembled.

Thanks
Kevin

[Stag-Victor]

photo hasn't uploaded I'll try again shortly

[jbuckl]

If it’s 1 tooth & was only ever 1 tooth, the piston should not have touched a valve.

[richardthestag]

I found that setting the RH drivers side chain it is possible to get it one tooth out unless you rotate the cam slightly when fitting the chain.

This I found over 20 years ago, cranked the engine over by hand after fitting new chains and came upon a tight spot. I backed out and checked the tdc to find the rh cam marks didn't line up. Adjusted the RH chain again and sure it was one tooth out. Cranked over by hand twice and the cam marks lined up beautifully.

no idea if my engine is tighter than others on heads, the block is standard i.e. not decked. The heads were standard and unskimmed until they were skimmed mercilessly by a local machineshop trying to get rid of the corrosion from the block coolant blanked passages. Machine shop in question is a lot wiser now. I didn't pay for that job and although the heads are within tolerance I use a thicker headgasket.

On stripping the engine down 30k later because "cheapo crap not fit for purpose parts" some pistons had a little crescent nip on the top

Might have been past the old red line while overtaking another stag full of ladies

IMAG1114.jpg