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'96 850 T5 no vacuum at oil filler cap

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

nferi93
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Year and Model: 1996 850
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nferi93

'96 850 T5 no vacuum at oil filler cap

Post by nferi93 » Tue Sep 06, 2016 11:58 am

Hello All,

My problem starts to be a little confusing, and I don't really know where to proceed. At idle when I checked Crankcase ventilation, I noticed that smoke is coming out of the oil filler cap. I removed the clamp holding the black hose (that goes to the PCV breather box from the top of the engine) to the top of the engine and I felt that there is no vacuum at the hose, the pcv is not sucking. The PCV is cleaned, I can blow through it and feel the air coming up on the opening on the engine. The PTC nipple is also clean.

An other symptom is that when I drive about 60 miles on highway (so at a constant speed) I get fault code 231. After I clear it I can go another 150 miles on highway, and it wont return later that day. It will return instead when I will go again on highway a few days later. This occurs only on highway, and never in the every day, city traffic. One time I get also code 232 along 231 in the same circumstances.

Other symptom is that when I accelerate so that the turbo is boosting, and press the clutch and release accelerator to change gear, I can hear a whistling sound, like when the pressure is released, just like a blow off valve. I'm not sure if it is normal or not, but I don't remember I heard that in the past.

The last thing is an occasional hard start, usually when the engine is hot. Sometimes it starts really easy, then I shut off, and after 30 minutes I try to start, and it cranks and cranks, and after like 20 seconds it starts. The next time it will fire up after 2 cranks. I didn't manage to find any logic in when it starts hard.
Overall the car accelerates good, and drives fine, the only thing I noticed is, that when I release the accelerator and let it slow down in the gear, it is not so smooth, it will suddenly tuggle, but RPM wont rise or fall below normal.

What I done previously in the last 2 months:
-cleaned whole PCV system, engine ports too
-new rotor, cap, plugs
-replaced air filter
-replaced vacuum lines
-replaced fuel pump, and tried another fuel rail with regulator too
-tried alternate camshaft position sensor

I suspect a vacuum leak somewhere, but I have no idea where it can be, cause I checked all vacuum and boost lines and I couldn't see anything. (Although it could be a leak when there is pressure in the boost lines, but that wouldn't solve the no vacuum at idle on the PCV)

Sorry for the long post, but I tried to add as much details as possible. I read like all of the previous threads with these symptoms, but I find no similar to this, as I can not feel any performance issues.

Could someone help me investigate this issue? Do you have any ideas?

Thank You in advance

tryingbe
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tryingbe

Re: '96 850 T5 no vacuum at oil filler cap

Post by tryingbe » Tue Sep 06, 2016 12:09 pm

nferi93 wrote:Other symptom is that when I accelerate so that the turbo is boosting, and press the clutch and release accelerator to change gear, I can hear a whistling sound, like when the pressure is released, just like a blow off valve. I'm not sure if it is normal or not, but I don't remember I heard that in the past.

Your CBV could be torn. You'll have to take it off to check it.

Image
85 GLH, 367 whp
00 Insight, 72 mpg

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