Top end noise as light tapping

[robertofollia]

Hi all,
after chasing one by one the different noises now another one has appeared:
D2 bosch engine 5 speed, 100K miles, original tappets and camshaft, oil changed every 4,5K miles, using Mobil1 5w50.

The noise appeared last october.
-I cleaned (totally gummed) ICV valve. Noise went away. Did not feel any difference in performance and/or idle speed after the clean.
-Noise has come back again.
-Idle engine is perfectly smooth. No codes thrown.
-Noise (as light tapping united with turbulence) begins at 1750 rpm and is much more noticeable at 3,000 rpm
-With the hood/bonnet open it is very difficult to notice, even putting your ear on the intake manifold.
-The noise is much more noticeable from inside the cockpit (back of engine)
-There is no water sloshing sound, levels are spot on
-Should it be the tappets I assume it would go away when increasing engine rpms due to the oil pressure rise.

Could anyone shed some light here please?
Will clean again ICV to see what happens
Best regards
Robert

 

[KyleT]

switch 5/40 rotella T6. more detergents to help with cleaning.

put a qt or more of ATF in with the oil (subtract amount of engine oil added) and run it as long as you feel comfortable. (around the block or for a week) drain and refill with 5/40 and see. I have done this to several discos and it has worked well.

BUt, some just have tappets that are noisey. or like one I found a bent pushrod in. no reason for it from what I could tell...

and you can try adding a oil separator to the PCV system.

 

[singingcamel]

May want to look for exhaust leaks. manifold to down pipes are common.

 

[robertofollia]

Kyle,
I can't get hold of Rotella 5W40 T6 where I live.
The oil separator was nice and clean one year ago.
Will try to record the sound and put it here.

And will check the manifold to block bolts for tightness. GAskets were renewed 4 years ago when doing a HG job.
Thanks for the suggestions and best regards from the other side of the pond. Will report any news
Robert

 

[KyleT]

did you put an oil separator on?

 

[Corprin]

Kyle,
I can't get hold of Rotella 5W40 T6 where I live.
The oil separator was nice and clean one year ago.
Will try to record the sound and put it here.

And will check the manifold to block bolts for tightness. GAskets were renewed 4 years ago when doing a HG job.
Thanks for the suggestions and best regards from the other side of the pond. Will report any news
Robert

Where do you live?

 

[kennith]

May want to look for exhaust leaks. manifold to down pipes are common.

These leaks sound precisely like a valve tap.

Cheers,

Kennith

 

[discostew]

The inserts in the rocker arms used to get loose. You should have new rockers that dont loosen up but I guess its possible you have something like that going on . That noise would be heard from inside the cab at idle . The little cup that the pushrod settles into. We used to find the loose ones by sticking a pocket screw driver into the oil hole and turning the insert , if you could turn it in the rocker arm it would tick when the engine was running.

 

[robertofollia]

Hi all,
I am based in southern Europe (Spain... yes... with regular unleaded at almost 1.50 euro per qt, that is almost 2USD per qt...yes...I know, please don't ask...)
Kyle, the oil separator looks really awesome, it's a piece of engineering. Where can I get hold of one with these dimensions?

Will be taking the manifold off to see the gasket status during the weekend (it's impossible on labour days, don't have enough time), and will check as well the rocker arm inserts that discostew says.
Anyway, I find surprising that a precision machined part as a rocker arm can develop play in the insert (but we are talking Rover, you know...).

It's really odd but the engine is perfectly silent at idle speed.

THANKS so much for the suggestions! Will update results ASAP.
Best regards
Robert

 

[KyleT]

its just a oil air separator for an air compressor.

 

[robertofollia]

Thanks Kyle, Just ordered it on saturday and will have it for wednesday.
-Stew, took both rocker covers off and checked rockers. No play in the small cup where the pushrod locates.
-Checked exhaust manifold for leaks: no one to be found, and bolts are nice and tight.
-And then did the definitive test:
An engineer with a degree in engines told me "To check if it's the tappets, when the engine is at operating temperature -coolant and oil- select neutral and rev the engine continuously for 5-6 minutes at 3,000 rpm. That way the tappets prime perfectly. If the noise vanishes, it's the tappets".
Guess what? It almost vanished completely.
But on normal driving, it was back again. So tappets (and camshaft) renewal time.
The noise is very faint (it does not allow to be recorded by a vcr, go pro or whatever hand held item and can't be noticed with the hood open, only from inside the cockpit). So will wait till it gets worse and will strip engine, doing camshaft bearings, piston rings and crank and big ends bearings as well (hope I don't get a cracked block or slipped liner then...).

Best regards and thanks for your input

Robert

 

[robertofollia]

Weel, some more updates.
I sprayed the manifold to Y pipes liberally with WD40, left it soak for 2 days, and the right bank, screwed down almost one turn.
So noise gone and camshaft, tappets and rest of engine renewal time will be postponed to much higher mileage.

Thank you so much for your suggestions
Robert