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A lesson in the need for routine maintenance

Wednesday, September 16, 2015 - 06:00
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We had a 2006 Volvo XC 90, 2.5 L 5 cylinder with 128,852 miles on the odometer come in with a complaint of low power, stalling and excessive oil consumption. The Volvo owner brought the vehicle in for a timing belt replacement thinking that this would solve the problem. I explained to him that the timing belt had nothing to do with the stalling or oil consumption problem. After conversing with him further, I uncovered that the vehicle had close to no maintenance performed other than routine oil changes about every 6,000 to 7,000 miles, using non-synthetic oil. In addition to the work he requested on the vehicle, I suggested that we perform a thorough vehicle inspection.

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Upon inspection of the vehicle, we noticed that the serpentine belts and timing belt were all overdue for replacement. We also noticed that the Positive Crankcase Ventilation (PCV), or oil trap system, was in real bad shape. The PCV system consists of the flame trap, small and large vacuum hoses, along with an oil cap. A telltale sign of a problem was that there was a cracked PCV breather hose located on the upper part of the engine next to the fuel injectors. The odd thing about this hose being broken (Figure 1) was that there was not much oil in the surrounding area, leading me to believe that the breather system had to be clogged. A quick test of the system for proper operation is to remove the dipstick and place a rubber glove or balloon over the dipstick tube. If the balloon or rubber glove starts to blow up, it indicates crankcase pressure is present and not vacuum. Since one of the customer’s complaints was excessive oil consumption (using 3 or more quarts of oil within 5,000 miles without any visible signs of a leakage) it was a good indication that the flame trap and hoses were clogged. To perform the PCV flame trap replacement, the intake manifold would have to be removed to uncover all the hoses and components. One of the PCV hoses is connected to the fuel line that goes from the front of the engine to the rear. Since this vehicle had more than 128,000 miles on it, it was in desperate need of every PCV line. Obviously since the engine had so many miles on it and all the plastic components had hardened with age, everything we touched broke, forcing us to replace more than the normal PCV breather replacement parts.

Once the manifold was removed, we were able to see just how clogged this engine’s PCV system really was. Take a look at one of the main breather ports (Figure 2) for the system that is located on the lower front engine block. As you can see, it was totally clogged and needed to be drilled, scraped and picked clean. My tech Franklin had to spend a good two or more hours just cleaning all the passages, as well as cleaning carbon deposits from the valves and intake manifold. If the vehicle would have had proper maintenance, the replacement of the flame trap (Figure 3) would have been much easier. If we would have just done what the customer originally requested, he would have still had the same problem of oil consumption and stalling. It’s always a good idea to make a thorough inspection and make sure to address the vehicle owner’s concerns so they leave the shop satisfied with a vehicle that is running well.

Figure 1 Figure 2 Figure 3






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