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While waiting for the camera to arrive I have been working on the interior. Here is a 3D printed cover when doing the centre console delete: https://www.thingiverse.com/thing:4018981
While waiting for the camera to arrive I have been working on the interior. Here is a 3D printed cover when doing the centre console delete: https://www.thingiverse.com/thing:4018981
Camera finally arrived today, below are the bore scoping results(lots of pictures).
Shortly: No evidence of excessive scoring but points of concern.
So, can I see any cause for the ticking? Yes, check the bottom of piston 5 and 6, they are shiny. Why? I guess the injectors are leaking (as mentioned before, my fuel pressure goes to zero within 24h) and it ends up at the bottom of the cylinders/piston, effectively cleaning off the sot there. It will also clean off the oil from the cylinder causing different coefficient of friction from top and bottom of the cylinder. I guess this will cause the piston rings to move and maybe also the piston to tilt back and forth at a cold start, causing the ticking sound. As soon as the cylinder is oiled properly the sound goes away: the piston is moving as normal.
There is one thing of concern that I need the forums help for. Check the top of piston 5. There is a spot there which is clean from sot. Are the clearance so tight that just a few mm of tilt will cause the piston to hit the head?
What to do:
It could be possible to take the injectors out and clean them one by one, identify which once are bad or not. I would do that if it was my daily. On the Porsche, I will just buy all new. At around 85$ each it's quite expensive but so, it is an expensive car and a hobby.
First: Cylinder 1 bottom/top as reference
cylinder 6: bottom/top, bottom, top
cylinder 5: bottom/top, bottom, top. The small black streak on the bottom here is most likely only a smear of sot. It appeared while I was turning the engine to position the piston at the bottom.
Edit: What a proper scoring looks like(32min20sec)). Many thanks JR!.
Looks like something has been bounding around in the cylinder. Are you sure there isn't a washer or something foreign in there. The top of the piston looks really beat up.
Imo000: The camera is rather **** ( as expected at 26 USD delivered) so the picture is a bit so-so. But, when looking at the video and moving around it does give a good picture of what your are looking at. I spent a lot of time looking at the pistons and they have no markings from any collision what I could find. The thing on the nr5 piston top side is just the sot which is gone, the surface seams untouched.
Thanks for the injector buying tip! I've fired off an email to check the shipping.
So, I'm in the middle of replacing the injectors and noticed something odd.
When taking off the intake manifold I could see the oil sludge build up on the mating part on the engine(the aluminium part which also the injectors are attached to).
cylinder 1-5 showed equal sludge build up while 6 was almost clean, big difference!
There could be two things happening:
1. More/Less air getting to the cylinder and hence less oil sludge build-up.
2. Part of the intake works like the original AOS and separates out the oil from the air before it reaches 6.
First scenario it would get more/less air than 4&5 and would be running rich/lean. This was my first thought when seeing this.
Second scenario, the air which reaches 6 is actually cleaner with less oil in it. How would this affect the running? Well, 4&5 have an oil mix in the air which means they need less fuel. The closed loop fuel trim will adjust so that the sum of all three (4,5,6) will produce a good combustion. This means that 4&5 will run slightly rich while 6 runs rather lean. Since the intake to 6 is cleaner it also have less resistance leading to even more air going in and leaner running.
With what others have reported, that bank 2 runs hot ,I would guess scenario two as the most likely.
Remember where you heard this first.
I will clean up everything and then hopefully my AOS solution will prevent this in the future.
On a side note: it would be nice to see someone build a proper CFD optimised aftermarket intake manifold.
Everything is back togheter and working. Since last post I have:
All new injectors
Replaced AOS including the two purge hoses (all original)
New radiators, all aluminium
New coolant
New thermostat, 71 degrees.
New fan resistors (put normal resistors for now)
New wheel bolts, the old was a missmatch of different types which caused vibrations. All adjusted to within +- 0.2g per wheel.
Removed rear 15mm wheel spacers which previous owner had put on.
Replaced all idler pulleys and belt
Et voila, the ticking at cold start is gone! It previously ticked at cold start (loud and clear) for around 1-2min while fading away.
The sound from the engine is now a pleasant noise of mechanics doing their job.
The idler pulleys was also rather worn so i replaced them, reducing the engine noise even more. I went for the newer 997 plastic once and they are noticeably lighter also. Well worth the money and time spent.
It took a long time since I replaced the AOS twice. First with my own system which turned out to be a larger project than intended, vacuum regulation was not directly plug-n-play. After a week of trying to get something close to standard I had enough and put back to original. It will be for next winter.
12-03-2019, 02:11 PM
