If you have positive crankcase ventilation (PCV) bogging down your ride indicated by oil blow-by on your oil filler hose or smoke coming from your dipstick tube, now is the time to replace or at least clean your PCV system. Without proper maintenance, you could be damaging your engine seals without knowing it.
Here is a write-up from another site, but really excellent with pictures!
PCV cleaning & replacement
Volvo 850 R PCV cleaning & replacement
As your engine runs, gases from the cylinders leak past the piston’s sealing rings into the crankcase. This leaked gas is sometimes referred to as “blow by” because the pressure within the cylinders “blows” them “by” the piston rings. These gases include compounds harmful to an engine, particularly hydrocarbons (unburned fuel), as well as carbon dioxide and water vapor. If allowed to remain in the crankcase, or become too concentrated, the harmful compounds will condense out of the air within the crankcase and form corrosive acids and sludge on the engine’s interior surfaces. This can harm the engine as it tends to clog small inner passages, causing overheating, poor lubrication, and high emissions levels. Additionally high pressure in the crankcase can build to a point that leads to a rear main seal failure, an expensive repair. To keep the crankcase air as clean as possible, some sort of ventilation system must be present.
There are different types of PCV systems depending on your car. Some systems use a PCV valve – a one-way valve that ensures continual evacuation of gases from inside a gasoline internal combustion engine’s crankcase. Other systems use an oil trap or separator to do the job.
Over time PCV systems and associated tubing can become clogged and fail to vent the buildup of pressure.
How can you tell if you need to replace your PCV system? One test is with a warm running engine pull your dipstick. Does smoke billow out of the dipstick tube? If so a faulty PCV system could be the cause.
The following write up describes my approach for the PCV system replacement on my 1997 850r turbo which uses an oil trap to do the job.
A couple of notes:
- You may want to try cleaning your PTC before tackling the PCV replacement. This is an important step when you replace your PCV system as PCV tubes attach to the PTC on the air intake hose. A blockage there may be the source of the increased manifold pressure and a smoking dipstick. If this is indeed the source of your problem this is a quick, inexpensive fix compared to replacing the entire PCV system.
If the PTC is clean and you still have a smoking dipstick proceed with the PCV replacement.
- While researching how to do this I found there were those in favor of removing the fuel rail & injectors from the intake manifold. The same thing for the throttle body. It’s a good time to remove these things if you want to do a thorough cleaning of the throttle body or if you want to service the injectors.
Others preferred to keep both in place on the intake manifold.
Because of my relative inexperience I wanted to minimize the number of parts I removed so I choose to leave them in place.
- Another good recommendation I read was to remove the fan shroud to give you more access room to work. You may choose to do that, It’s fairly easy to remove.
More useful suggestions:
Try a little ‘O’ ring grease to make hoses slip onto the nipples a little easier.
Use blue tack or magnetic socket inserts to keep from dropping bolts.
Bonus! 10 Interesting Volvo Facts
- In Latin, the word Volvo means: I spin. Today however the nearest meaning is “I roll”.
- Volvo was founded in 1924. The two founders were Gustav Larsson and Assar Gabrielsson.
- The ÖV 4 is the first Volvo car. The first car was sell-ready in 1927. The 2-Liter, 4-cilinder car got the nickname: Jakob.
- Volvo’s very first commercial vehicle was the Type-1 truck. The release year was 1928. In the same year, Volvo released the second car, the Volvo PV 651. Volvo manufactured a total of 1383 of both vehicles in the first year; of which automaker exported 27.
- This trend saw a sharp rise in 1932 when Volvo released a good amount of 10,000 vehicles, both trucks and cars.
- The company, however, started making a large-scale profit from the year 1935. The first luxurious car by Volvo was the PV36, which could carry six passengers at a time. The design of this iconic car paved the path for future Volvo cars to come. I came in the market with a price tag of 8,500 Swedish kronor.
- Volvo touched a landmark in 1941, with the sale of its 50,000th vehicle; this is a unique achievement considering the time when WWII was in full swing.
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