Member Since: 14 Aug 2022
Location: Osnabrück
Posts: 27
Piston Ring orientation - tricky question
Hey Guys,
the next problem on my 2016 XF Jaguary GEN2 Engine ... after the previous owner interchanged the main bearing blocks (1-2-3-4 / 4-3-2-1) and interchanged the rod bearings (top/down) i got the next problem/question refering the Pistons.
Pistons are 84.5mm Sonne Pistons (2nd oversize), they look mint, even the cylinders. But the piston rings seem to be installed wrong in my oppinion. I attached a picture how they are acutually installed, and how they should be in my oppinion.
What to you think?
Click image to enlarge
20th Oct 2022 7:25 am
Dondiddy
Member Since: 26 Dec 2019
Location: Hamilton
Posts: 307
Yes, I think you are correct as they are installed incorrectly in your upper diagram. They need to be installed as per your lower picture and your suggestion. There should hopefully be a part number on the ring itself which would help identify it correctly as they look similar . Take care as the rings are very brittle and can snap quite easily whilst trying to take them off and on again! Good luck!
20th Oct 2022 8:40 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8110
Usually rings are marked, the mark is usually on the top end of the ring, it can be anything from a name to a "x " or "." , you may need a magnifying glass to see it, the mark should be fitted facing up.It can when others can't,
It will when others won't,
It goes where others don't.
20th Oct 2022 9:29 am
Fischirian
Member Since: 14 Aug 2022
Location: Osnabrück
Posts: 27
Yeah, i got a "0.5" on both rings.
But i can`t identify which ring belongs TOP and which ring belongs BOTTOM.
Furthermore they got the 0.5 both on the side with the bevel. But i can`t imagine, that the bevel on both rings pointing upwards...
20th Oct 2022 9:34 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8110
I would say the bottom diagram is correct, the bevel is for lubrication, the bottom ring for instance when going down is scraping oil off the cylinder walls and a small amount of oil is getting into the cavity to provide lubrication, the same applies to the top ring when going up but there is less oil on the cylinder walls.
I have come across a step on the outside of compression rings but not on the inside except oil control rings which is common.It can when others can't,
It will when others won't,
It goes where others don't.
20th Oct 2022 10:09 am
Fischirian
Member Since: 14 Aug 2022
Location: Osnabrück
Posts: 27
On a stock 306 DT Piston i see a piston ring with no bevels on top, and a bevel on bottom. Furthermore the gap of the upper ring is smaller then the gap of the bottom ring.
Equivalent to this i thought it could be the bottom combination.
Small bevel on top with low gap.
Bigger bevel on bottom with bigger gap.
I talked to Sonne Pistons and they wanted part numbers, i will check today evening for further stamps on the rings. I HOPE TO FIND A S02 or S03.
But i think the piston rings are installed in any case wrong, because both bevels pointing upwards. Even in the Sonne Pistons picture i attached the belvel of the bottom ring pointing downwards.
20th Oct 2022 10:46 am
Breg90
Member Since: 04 Feb 2017
Location: Falkirk
Posts: 348
This is what I found on a 2.7:
Series one 1949 - in bits, chassis is strapped to the ceiling in my garage (beside the canoe)
LR 90 - In bits
Disco 3 - currently in bits
20th Oct 2022 9:47 pm
Breg90
Member Since: 04 Feb 2017
Location: Falkirk
Posts: 348
Fischirian,
Just bought some Goetze piston rings for my TDV6 2.7 - Part 08-432400-00. Scan the code on the box and it takes you to the data page on the Goetze web. You get the data below that has ring arrangement on the 2nd page.
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