Hello to all members and readers.
This will be a rather long post, but it shall provide clarity in the matter of the startup noise.
I wish it was a happy ending post, but it is not the case.
Some pictures attached also.
All info and findings relate to the B16DTH 1.6 liter Ecoflex 100kw diesel engine.
In Jan 2018, I bought for personal use a second hand Astra J from Germany, first registration Sept 2014.
Being an end of series J, right before the new K, it is equipped with the new engine - B16DTH.
The seller was a good reputation second hand dealer, with a 2500+ car park.
Kilometers 123k (miles 77k) certified from 2 sources, service book (all service Opel dealership only),
and Opel dealership (checked myself with their database).
While driving it to my home country, approx. 2000km on highways and the final 300 on normal roads,
there was noise at startup but not so often.
Once switching to low speed frequent city driving, the startup noise appeared frequently.
Not with every engine start, but with most.
Since I had previously owned timing chained cars, it sounded like the chain needed changing.
But at km 126k (as I said certified) it seemed strange that a timing chain would be so loose/warn
so that it would cause timing chain noise.
I went to a local Opel dealership, they said it was a normal noise.
No clarity why it was intermittent, and not constant.
I therefore decided to procure all timing chain kit OEM, and change it, to put my mind at ease.
The mechanic (non dealership) who cared for of all my cars for the last 18 years took on the challenge,
it was a premier for him with this engine. He gathered all info available, and started the works.
The operation was a difficult one, since now the timing chain was at the back of the engine,
compared to previous engine models, which had the timing at the front.
So the gearbox, drive shafts, everything on top of the valve cover and
under the engine and behind the engine had to come off.
And only when we dismantled the timing chain housing, we confirmed
the reason and the source of the startup noise.
- the B16DTH engine has the timing chain at the back of the engine
- the timing chain spins counterclockwise
- the timing chain hydraulic tensioner is placed on the tensioned side of the chain,
very strange, the tensioner sholud be normally placed on the untensioned side
- the untensioned side of the chain has fixed guides
- the timing chain is rattling against the fixed guides
- after startup, in a few seconds, the oil pressure builds up and the hydraulic tensioner
is able to apply such pressure that the untensioned side is also pulled in place.
So now I have a brand new timing chain and accessories, but the noise is still there.
Being a new chain, not as loose as the old one, the noise is shorter, but still there.
In conclusion, there is no remedy, unfortunately, it is a "normal" noise.
Great engine timing design, thank you Opel.
You can find attached some pictures, for graphic illustration.
Drive safe everyone!