Archive for February, 2012

Blown out oil seals

This happens when the PCV System gets clogged up. The “check engine light” will be illuminated because the engine can’t breathe. Finally, pressure will  build up in the crankcase and blow out your oil seals, the result is an expensive oil leak.

This sad oil sludge story begins with a poor history of oil changes and ends with blown out oil cam seals. For this leaky story don’t expect to see oil stains on your drive way, but rather bluish smoke — burning oil – coming out the exhaust and from the oil cap or oil-dip stick area. As oil seals age, they harden and start to crack. Blow by fumes build up pressure in the crankcase and blow out the old cracked cam seals. The result is an oil leak problem.

The tell tale sign of a clogged PCV (positive crankcase ventilation) system is a whistling sound coming from the engine. Some customers describe it as whining sound, like a belt in the engine. But this is not the case. A clogged up PCV system is an expensive affair.

The whistling sound is caused by built up pressure — from blow-by combustion fumes — pushing up and looking for an outlet, somewhere around the oil cap and oil dip-stick area. If you do a balloon test, place a balloon on the oil dip hole, you will notice that it will start to inflate with gases. This test confirms that the PCV system is clogged up with soot or oil sludge. The check engine light will also be triggered because the engine will combust a lean mixture (fuel:air ratio) at idle.

What does the PCV System do?

The PCV system lets the combustion blow-by gases escape from the crankcase through a valve.

Picture the piston moving down in the engine cylinder during the intake. The throttle, which is a valve that regulates or restricts the amount of air at atmospheric pressure entering the cylinder at a pre-determined fuel:ratio creates what is known as manifold vacuum. Manifold Vacuumis when the pressure in the intake drops below normal atmospheric pressure (low or negative pressure). The job of the piston rings is to prevent the combustion gases during intake from escaping the tight seal formed between the cylinder wall and the piston. But the reality is that some combustion gases do get past the old piston rings. These combustion gases or fumes are referred to as combustion blow-by. So, the PCV System helps the blow-by escape through the PCV valve and the manifold vacuum speeds up the process.

Volvo’s have a Breather Box

The Breather-Box or oil vapor separator is a box that captures the vapor/fumes and recycles the vapor back into the intake manifold, the excess oil drains down into the oil pan. Late model Volvo’s don’t have a PCV valve, just an outlet with a screen leading to the breather box. The Breather Box is attached to tubes, one which drains into the oil pan and another tube leading back to the intake manifold.

The PCV system was created in 1968 when only a valve served the purpose of expelling these blow-by emission back into the atmosphere, leading to pollution. This emissions device is not only more effective in getting rid of fumes, but it’s also crucial to keeping your motor oil clean.

Poor Maintenance leads to clogged up PCV System

 Sludge will plug up the PCV system and do some serious damage to your engine. Sludge — gel like oil residue — forms when you go too long between oil changes or when you completely ignore oil changes. Just yesterday, a customer called to set up an appointment for service. When I checked his car’s service history on Reynolds, I was shocked to see that he last had an oil change for his Volvo in 2010.

Conclusion

Changing your engine oil frequently will prevent the PCV system from plugging up, The PCV System w ill thus remain clear for the life of the engine.  However, since the PCV Valve works  continuously, it will eventually fail over time. The Volvo Maintenance schedules will ensure that the PCV System is clean and working properly, as it should.