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Blue smoke at idle

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
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Canadian850
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Canadian850

Blue smoke at idle

Post by Canadian850 » Sat Mar 05, 2016 11:49 pm

Hi everyone.
I'm a new member, seeking your opinions about the next step I should take.

I have a 1996 Volvo 850 GLT (manual, NON Turbo), it had 190,000 kilometers (118,000 miles) when I got it June 2014. The car had a issue with oil burning during start up and idle periods, I had a feeling the valve seals were in need of replacement, but after some online research, I decided to change the PCV valve as a first step. A genuine Volvo piece was installed and those ports in the cylinder were all clear.This did not help.

I continued to drive the car, never letting it run low of oil until May 2015, when I got a misfire on cylinder #4. Compression: 0 psi.
An exhaust valve was burnt.

I pulled the cylinder head, ordered a valve and head gasket kit (included head gasket, exhaust, intake, thermostat housing gaskets, valve seals... Elwis brand made in Denmark). All the seals were badly worn, those on the exhaust side were worse. Some exhaust valves were also coated with a hard crusty layer ( at the bottom half, due to oil burning) they were are cleaned.
So after new valve seals and a new exhaust valve, the cylinder head was put back on. Everything was perfect. There was no more smoke after the car had been sitting for a long time, mo more smoke at idle, all was fine.

In fact, after 4000 kilometers, the oil level was at maximum, never moved. I was happy.

This lasted about 12,000 kilometers (7400 miles), 5 months. The car never used any oil during this time. Currently it has 214,000 kilometers/ 133000 miles.

Then all of a sudden, back in October, I checked the oil (I do every 1000 kms) and realized it was half liter/quart low. I added oil, and kept and eye on the rear view mirror and realized the dreaded puff of blue smoke is back...

1. There is NO blue smoke if the car is parked after sitting for a long time.
2. The smoke appears only when the car has been idling while fully warmed up.
3. From what I can tell, there is no smoke when the car is cold. Even if idling while engine is cold, it appears there is no smoke (just my observation)
4. While stopped, if I keep the RPM around 1500/2000 there is no smoke. It only appears on a warm engine @ idle speed.

I checked the oil filler cap, its hard (I plan to change it soon). I also pulled out the intake boot: inside is coated with oil (normal?). Also the flametrap is clean.
In your opinion, what is the most likely issue? I've seen the posts regarding PCV hose modifications with 5/8 hose, but I'm not certain if this will help.


I apologize for the rather long thread, I thought I would try and give all the details and history of the repairs/maintenance to give a better idea of what was done to this car.

Thanks for your help.

Ozark Lee
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Ozark Lee

Re: Blue smoke at idle

Post by Ozark Lee » Sun Mar 06, 2016 7:30 am

When you serviced the PCV you referred to it as "replacing the PCV Valve". What exactly did you change?

There is no PCV valve per se on a Volvo whiteblock but rather a PCV system. The heater hose modification is just one part of it and a proper PCV servicing includes cleaning or replacing the oil trap along with the hoses as well has cleaning out the passage from the oil trap to the sump and cleaning (of just throwing away) the flame trap. If any part of that system is faulty, the entire system is faulty.

Your symptoms are consistent with either a plugged up PCV system or bad rings.

After you did the valve job did you make any compression measurements? If so, what kind of numbers did you come up with? Bad rings will show up as low compression as well as causing the blue smoke.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

Canadian850
Posts: 3
Joined: Sat Mar 05, 2016 11:00 pm
Year and Model: 1996 850 GLT
Location: Canada
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Canadian850

Re: Blue smoke at idle

Post by Canadian850 » Sun Mar 06, 2016 8:42 am

Lee, thanks for reply.

It was rather late at night here when I was posting this thread.
You are right, I meant the oil trap. I changed the oil trap itself and the small hose that connects it to cylinder block (both genuine Volvo).
The hoses going to upper cylinder head (valve cover) and intake were in good shape, flexible and they were not clogged. Flame trap is also clear.
Before removing the head, all cylinders except for #4 were in 200~220 psi range. I Have not checked compression since but the car is running fine, engine pulls strong and no idling issues.

Ozark Lee
MVS Moderator
Posts: 14798
Joined: Thu Sep 07, 2006 8:24 am
Year and Model: Many Volvos
Location: USA Midwest
Has thanked: 4 times
Been thanked: 50 times
United States of America
Ozark Lee

Re: Blue smoke at idle

Post by Ozark Lee » Sun Mar 06, 2016 6:59 pm

Did you clean the hole in the block where the elbow from the oil trap attaches? That area is tough to clean but it is essential that the hole be open. The rubber glove test should tell you if the PCV is clear though.

How many miles has it been since you did all of the service? it is possible that in its previous state that the exhaust system got badly oiled up and it can take several hundred miles of sustained driving to burn the residual off.

The compression numbers would tend to rule out rings.

...Lee
'94 850 N/A 5 speed
'96 Platinum Edition Turbo
Previous:
1999 V70XC - Nautic Blue - Totaled while parked.
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

Canadian850
Posts: 3
Joined: Sat Mar 05, 2016 11:00 pm
Year and Model: 1996 850 GLT
Location: Canada
Has thanked: 0
Been thanked: 0
Canada
Canadian850

Re: Blue smoke at idle

Post by Canadian850 » Sun Mar 06, 2016 8:38 pm

Hi Lee.
Yes, the port/hole in the block was clean. I have seen pictures online of the clogged/partially clogged holes, but it was clear.

I replaced the oil trap back in June 2014 when the car had around 190 kms/ 118K miles. Now it has 133K miles.

I will check the compression. After the valve and valve seal replacement (which was done almost a year after oil trap replacement), there was no blue smoke and the car did not use a drop of oil. However this lasted 5 months/7400 miles.

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