Compression test results
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Category: Technical & Model Specific Forums
Forum Name: General Motors
Forum Discription: This forum will deal with technical issues for the cars not dealt with in the other forums. These don't need to be BMWs!
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=9019
Printed Date: 06-May-2024 at 12:02
Topic: Compression test results
Posted By: kbannon
Subject: Compression test results
Date Posted: 10-July-2004 at 18:10
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I had mine tested today on the 523i. Anyone care to comment on these results [dealer says they way above average]:-
------------- Current: 2009 E60 520d "Sport" tractor Previous: 1989 E30 320i SE 1997 E39 523i 2003 E39 525i Sport Individual |
Replies:
Posted By: Brucey
Date Posted: 10-July-2004 at 18:19
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-I assume the pressures (in BARs) were obtained by cranking with the starter motor (~x10), with the throttle butterfly wide open. -if so, the dry pressures seem fine. -the 'wet' pressures do seem high- I would suspect that a little too much oil was added to each combustion chamber for these tests. -if so I bet it smoked like blazes when they started it up again, throwing all sorts of crud down your exhaust pipes. -why not ask them if they are TRYING to destroy your cats...???? cheers
------------- ~~~~~~~ Brucey ~~~~~~ |
Posted By: BM Fan
Date Posted: 12-July-2004 at 09:40
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Killian If its bar then they are not to different from my own results. The main difference when compared with mine is that I have a larger differnce between cylinders approx 20psi (1.5bar). If I remeber right my lowest was 170psi. 11.25 - 163psi 12.00 - 174ps Does anyone know what a new engine spec is and what is the story with differences between cylinders, is that significant aside from the fact that some cylinders are more worn than others. Which is to be expected given that my block is original and its cylinders 1 and 6. My block is supposed to be OK also but what are the actual figures that distate when the block needs to be replaced? ------------- Martin In BMW exile at the moment (Shame on me for lurking!!!) Previous Models 2001 E39 520i Auto 1996 E36 M3 Evo Individual 1996 E36 328i Coupe 1997 E36 318i Conv 1992 E36 316i Sln 
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Posted By: dave 328
Date Posted: 12-July-2004 at 10:46
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some where in between 10 and 12 psi is OK. A difference of 1 or 2 PSI per cylinder is also within limits, but idealy it should be very close. New engines won't be different really - could be less until the bores are run in, or more, depends. Most engines will vary between cylinders. ------------- 
328 Coupe Sport, Digital climate, full leather, OBD computer, De-restricted with M50 manifold, big bore throttle, chippeduk remap, custom cold cone intake and X-brace |
Posted By: kbannon
Date Posted: 12-July-2004 at 10:54
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I had my NCT (MoT) yesterday & the emissions were excellent which is another good sign for the car! ------------- Current: 2009 E60 520d "Sport" tractor Previous: 1989 E30 320i SE 1997 E39 523i 2003 E39 525i Sport Individual |
Posted By: ian M635UK
Date Posted: 13-July-2004 at 22:47
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New engine i.e. rebuilt M635 with rebore new pistons and total seal rings. Tested warm, throttle wide open, fuel pump disabled, 6 cranks only needed. 220 psi on each cylinder. Prior to rebuild 180 psi
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Posted By: Jumbo
Date Posted: 26-July-2004 at 17:01
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Killian
Can I ask what your emmission results where so as I can compare to mine..I'll get mine and let you know I did my NCT in May and had no problems either ------------- Brian... |
Posted By: kbannon
Date Posted: 26-July-2004 at 17:26
------------- Current: 2009 E60 520d "Sport" tractor Previous: 1989 E30 320i SE 1997 E39 523i 2003 E39 525i Sport Individual |
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Posted By: Jumbo
Date Posted: 27-July-2004 at 14:35
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Killian mine are:
Anything I should be looking at i.e CO seems a lot higher than yours As you can guess I know nothing about engines ------------- Brian... |
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Posted By: kbannon
Date Posted: 27-July-2004 at 14:40
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look at the allowed levels written beside these values on your test report. Your engine seems perfect! I should have added that these results are 'correct' at the time of testing. If you repeated the test an hour later it is possible to get different results. ------------- Current: 2009 E60 520d "Sport" tractor Previous: 1989 E30 320i SE 1997 E39 523i 2003 E39 525i Sport Individual |
Posted By: Jumbo
Date Posted: 27-July-2004 at 14:49
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Thanks...I thought it must have been to pass but wasn't sure how close to failing I was.. Is the engine oil temp not a bit high? ------------- Brian... |
Posted By: kbannon
Date Posted: 27-July-2004 at 14:55
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Not sure about the temp but don't assume their equipment is working 100% either! ------------- Current: 2009 E60 520d "Sport" tractor Previous: 1989 E30 320i SE 1997 E39 523i 2003 E39 525i Sport Individual |
Posted By: dave 328
Date Posted: 02-August-2004 at 11:17
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Oil temp will be around 95 on a fully warm car. Drive it hard and you'll see 120+ -------------
328 Coupe Sport, Digital climate, full leather, OBD computer, De-restricted with M50 manifold, big bore throttle, chippeduk remap, custom cold cone intake and X-brace |
Posted By: Pozzer6
Date Posted: 03-August-2004 at 22:57
| My '97 323i cab shows 180/190 on all six cylinders. Seems good to me as this is probably a Nikosil(?) engine |