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Interesting Compression Test Experience

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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warmblood58
Posts: 141
Joined: Wed Feb 24, 2016 9:42 am
Year and Model: 1995 850 T5-r
Location: SF Bay Area
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Interesting Compression Test Experience

Post by warmblood58 »

So I thought I still had a gas compression gauge but no, just a diesel comp gauge so I borrowed a loaner from my flaps and had engine warm ('95 850 T5-r). First cylinder -0, second - 0 . . . . I was getting worried but knew something had to be wrong with gauge as car just passed smog. Cylinder 3 also 0 so I returned faulty gauge and went to Harbor Freight and picked up one of their gauges. This time, I was getting readings Cold of 110 across the board and again, I knew something had to be wrong with gauge - throttle body valve was open during all testing. Fortunately, the HF kit came with an old school compression style adaptor so I had my gf crank while I pushed compression fitting tight against spark plug ports and finally got these readings of 155, 155,150,155, 160 . . . pretty even! I was relieved to say the least! I will most likely take warm readings next week but curious if anyone knows (in general) the variance between hot and cold compression test readings? Perhaps 10% higher? Thanks!
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rspi
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Joined: Sat Nov 05, 2011 10:40 am
Year and Model: 850 T-5R Wagon
Location: Albuquerque, NM
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Re: Interesting Compression Test Experience

Post by rspi »

No set percentage. Sometimes there is very little. Make sure you have a real strong battery or use some sort of jump box.
'95 855 T-5R M, Panther - 22/28 mpg
'98 S70 GLT, Lil' Red 25/32 mpg
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Volvo's of past: '87 740 GLE, '79 262C Bertone, '78 264, 960's, '98 S70 GLT, '95 850 T-5R YellowVolvo Repair Videos
j-dawg
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Year and Model: 1999 V70 T5
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Re: Interesting Compression Test Experience

Post by j-dawg »

The most important thing is really consistent compression across all cylinders.
1999 V70 T5 5-SPD | ~270k mi | burns more oil than gasoline
warmblood58
Posts: 141
Joined: Wed Feb 24, 2016 9:42 am
Year and Model: 1995 850 T5-r
Location: SF Bay Area
Has thanked: 4 times

Re: Interesting Compression Test Experience

Post by warmblood58 »

yea, I must say it was nice to see the final numbers with little variation
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