That sounds like camshaft or follower. Get a big screwdriver and put one end on metal (not plastic) parts of engine in various places, put the other end against your ear. You will be able to hear the noise as it travels through the screwdriver. As you get nearer the noise it will get louder. If its very loud nearer the camshafts then suspect them.

 

Bought some Wynn's Hydraulic Valve Lifter treatment and added about 200ml (half of the bottle). Took out for a short drive in high revs and nothing, still clapping/tapping. Might take it for a motorway blast and do hot oil change.

Thanks for the advice smokie1010, will need to get a long screwdriver .

Is it easy to test for sticking/broken tappets when the cam cover is off?

 

I'm not surprised it made no difference, that engine does not have hydraulic valves you are wasting your time putting that in. Take it for a blast and you are likely to do serious damage. It might be obvious when you take off cam cover. If you are unsure I would take it to a garage for diagnosis as its hard to say without having the car in front of us.

 

Hang on, what? So what are these ?
http://www.partsbase.org/opel/astra-h-2004--5-3-22-valve-lifter/

and

http://workshop-manuals.com/vauxhal...ol_engine/cylinder_head/valves/repair_instructions/check_and_adjust_valve_play/

and

http://www.vauxhall-car-parts.co.uk/acatalog/VAUXHALL_VALVE_LIFTER_-_93174076N.html

 

As said before, that engine (Z16XEP Twinport) does not have hydraulic valves. What you have in the first 2 links is reference to the caps/shims that sit on top of the valve assembly, as the camshaft lobe comes round it pushes them down. They are not lifted etc by any hydraulic action. What does happen is they wear and every 100,000 miles the gap needs checking and the part in your first link is replaced with the correct thickness to correct the gap.

If you read everything in the second link and look at the diagrams you will see what I mean. See #32 in the second link.

Your third link has nothing to do with the Z16XEP Twinport engine. Yes that is a hydraulic lifter but its for the previous Z16XE engine which was the engine prior to yours so has nothing to do with your engine.

Hydraulic Valve Lifter treatment in your engine will do absolutely nothing.

Your local Vauxhall Dealers will confirm all this. Plus I know this as its the engine I have in my Astra.
.

 

Feel so stupid now! I think Z16XE and Z16XEP got me confused. I have been searching all over the Internet trying to find the source of this tapping noise and hydraulic tappets issue kept coming up so I assumed I had them in my engine too.

Anyway, thanks to you I gave up on the hydraulic tappets and started looking into intake manifold issue again. Came across this thread http://www.vauxhallownersnetwork.co.uk/index.php?threads/separating-the-inlet-manifold-z16xe.271209/ which describes the problem in detail.
Went out and bought some carb cleaner and copper sealant after work, took the inlet manifold off again, split it in half this time. Pressing the edges of the baffle in the top half of the manifold I could feel some play I had to apply some force to feel this though. Took the baffle off and cleaned both parts with carb cleaner. Didnt bother taking the baffle off the bottom part as it was solid. Cleaned all parts with carb cleaner, dried it, applied copper sealant, put it back onto the engines and et voila! No more rattling!

Think it's worth draining the oil now that it has that treatment in it?

Thanks smokie1010!

 

Sounds Identical to the issue I had with mine.

Did you split your manifold?

I got mine swapped out for another one and it instantly cured the problem.

Replacement one is now starting to tick 4000 miles later

 

Yes, have a look at http://www.vauxhallownersnetwork.co.uk/index.php?threads/separating-the-inlet-manifold-z16xe.271209/
I just followed his instructions.

good luck.