Compression variation
Moderator: martauto
Just had my 320i tuned before going on the rolling road and the compression test after adjusting the valve clearances was a bit odd. Running from 1 - 6 the readings were 155, 140, 150, 141, 129 and 150. These are all a bit lower than expected, especially number 5. Anyone got any ideas as what might be causing this? The engine's in top nick, I'm only the 3rd owner and the previous chap only put 5000 miles on it in the 12 years he owned it, as well as servicing it fully every 6 months.
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StuBeeDoo
- Engaged to the E30 Zone
- Posts: 6756
- Joined: Sat Feb 05, 2005 11:00 pm
- Location: Up My Own Arse
I'm not sure what the compression figure's supposed to be, but IIRC they should all be within 10% tolerance max. So you're right to be concerned about no.5.
As to what could be causing it, could be a number of things. It's always possible that it's something to do with the 5k miles in 12 years. I'd have thought that even if the servicing was done regularly, it won't have been very good for the engine. 35 miles a month is going to equal short journeys.
If it was mine, I'd have the 'head off, check the bores and rings, skim the head and grind-in the valves.
HTH
Stuart.
As to what could be causing it, could be a number of things. It's always possible that it's something to do with the 5k miles in 12 years. I'd have thought that even if the servicing was done regularly, it won't have been very good for the engine. 35 miles a month is going to equal short journeys.
If it was mine, I'd have the 'head off, check the bores and rings, skim the head and grind-in the valves.
HTH
Stuart.
This is why I no longer drive an E30......
Bud FYI when i had a compression test done a while back it came up with a cyl being underpar bit like yours,but it got better once engine warmed up..did you keep an eye on em or just a one off reading
HT lead,plugs etc too
HT lead,plugs etc too