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850 engine pressure build-up

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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efkaba
Posts: 22
Joined: Wed Jun 20, 2012 12:38 pm
Year and Model: 850, 1995
Location: pennsylvania
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850 engine pressure build-up

Post by efkaba »

1995 850 GLT non-turbo, 158,580 miles. Replaced the breather system at 157,036 miles because I noticed oil accumulating on the lower half of the engine when I changed the oil, and the glove test which I saw posted on Robert's DIY video indicated that pressure was building in the engine. Everything was fine after the replacement, did not see any oil leakage, and there was no pressure building in the engine as indicated by the glove test. Within the last couple hundred miles or so, I noticed some oil collecting around the bottom of the engine again, and it seems to be getting worse. I did the glove test, and the engine is building pressure again. I am pretty positive I thoroughly cleaned the port on the side of the engine where the breather box connects, so I am not sure why I am again having this problem. Purchased the OEM breather box kit from FCP Euro. Any help with this problem would be greatly appreciated.
DeathRex
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Joined: Sat May 28, 2016 9:03 pm
Year and Model: 1996 850 Turbo
Location: Cortez, Colorado
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Re: 850 engine pressure build-up

Post by DeathRex »

Did you replace the hoses?
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FLXC90
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Year and Model: 98 V70 T5
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Re: 850 engine pressure build-up

Post by FLXC90 »

Do dry compression test, note results, if there's a large variance between cylinders do a wet test to check condition of rings. You may have blow-by that the breather can't keep up with in its stock configuration. You may need to upgrade to larger hose per the "Ultimate PCV" thread here.
Current Volvos:
1998 V70 T5, 112k sat 5 years, still in mechanical coma (finally at the top of the pile )
2004 XC90 T6 AWD: 186k, 60 on transaxle ( traded in )
1998 POS70 N/A: DD/training aid, 236k but really about 240k, I think...ABS module( passed on to son who sold it)
efkaba
Posts: 22
Joined: Wed Jun 20, 2012 12:38 pm
Year and Model: 850, 1995
Location: pennsylvania
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Re: 850 engine pressure build-up

Post by efkaba »

DeathRex wrote: Sat Jul 21, 2018 2:20 pm Did you replace the hoses?
Yes I did.
efkaba
Posts: 22
Joined: Wed Jun 20, 2012 12:38 pm
Year and Model: 850, 1995
Location: pennsylvania
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Re: 850 engine pressure build-up

Post by efkaba »

FLXC90 wrote: Sat Jul 21, 2018 2:40 pm Do dry compression test, note results, if there's a large variance between cylinders do a wet test to check condition of rings. You may have blow-by that the breather can't keep up with in its stock configuration. You may need to upgrade to larger hose per the "Ultimate PCV" thread here.
Thanks, I will do that. I did notice an occasional odor of blow-by fumes while driving.
dj_v70
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Re: 850 engine pressure build-up

Post by dj_v70 »

Likely that either your pcv vacuum (hose to intake manifold) is clogged or you didn’t clean the bottom pcv port to engine as well as you think you did. This port clogs after 90 degree bend down to oil pan. Many remove oil pan to clean it. I dumped a qt of gunk oil flush down the port to clean it and then changed oil
efkaba
Posts: 22
Joined: Wed Jun 20, 2012 12:38 pm
Year and Model: 850, 1995
Location: pennsylvania
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Re: 850 engine pressure build-up

Post by efkaba »

thanks, I am going to remove everything and recheck the oil return port in the block. Also read about replacing the vacuum line to the intake manifold with a 5/8-inch heater hose. Thinking about doing that.
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