The V8 Owners Forum -

My 1993 Disco 3.5 is making an infuriating "tick tick tick" under acceleration to about 25mph. Its seems to quiet down but this takes a good 10 mins and doesn't completely go. Otherwise its running very well.

Does this indicate a cracked exhaust manifold or lifters?

Any cheap tricks to quiet either down?

Cheers!


I know this has probably been asked before, I did search!

Hello Grant,

It could be lifter related.....

How many miles has the engine covered? How often do you change the engine oil and filter?

Ron.

Could also indicate head gasket failure.

But most likely exhaust gasket problems or manifold crack.

Chris.

I would opt for exhaust manifold / gasket probs first.

gaskets are normally accompanied with plenty of soot in the related area.

it could very well be PINKING ..??

mine does the same thing , as soona s it warms up a bit it stops ...but thats only on gas , if i switch to petrol it's ok
and it does sound like a ticking noise

Hi again, I've got myself a new exhaust manifold...

if it doesn't solve the ticking, how much should I be looking at for new lifters etc to be fitted? Anyone know of a place in the SE that could make a decent job of it without ripping me off? (pushing it I know!)

Cheers

Grant, I agree with mgbv8, a probable cause is a small exhaust gasket leak thet reduces with heat expansion of the metal thereabouts.

It may not even need a replacement part, just tighten up all the exhaust manifold bolts to their correct torque to see if it can be attenuated.

If it is a leak as suggested, you ought to be able to hear which side of the engine its coming from.

And if it does turn out to be thus, but cant be stopped, fit new gaskets.

Have a good look with a torch for any signs of soot marks around the EX flange gaskets Grant.

As Ramon says, run a socket around them first all to make sure they are nipped up ok.

Hi again, its definitely on the drivers side... the rocker cover has a few slight leaks which has left black stains around the manifold! Will give the bolts a tighten and see what happens, cheers!

Changing the tappets looks pretty simple from the haynes manual (basically remove inlet manifold and pull them out?) but the full whack cam/chain- not sure about doing that myself

Grant
You have to remove the rockers as well. And remove the pushrods to get the lifters out. Then you have to check / set tappet pre loads before rebuilding. Not recommended to fit new lifters to a worn cam though. They may not last too long.

Well, changed all the manifold gaskets- definitely no leak there now. I've taken out the rocker shaft, looks ok to me, no loose cups or pads. I'm guessing the ticking has to be the tappets now?

Cheers

I would still go for head gaskets myself. Tappets won't change their noise depending on engine load. Head Gasket leakage will.

Have you done a compression test?

Chris.

Grant
The rocker shafts tend to wear on the underside. Mind you, if you had a shaft that was worn bad enough to make a noise it would be obvious as there would be a huge recess.

Hiya, the push rods all move up and down smoothly except one which flops around and feel disconnected at the bottom- is this a sign of a bad lifter?


No compression test but no other usual hgf signs (overheating/mayo/coolant loss/steam etc).


Its difficult to describe the ticking, now I've listened more closely its there at idle as well, the tick just isn't as pronounced if that makes any sense!


Cheers