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Lessons in Asian drivability

Thursday, July 20, 2017 - 07:00
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With Asian vehicles being a very large part of the US automotive market, more than likely you are already working on a few of the different brands. This article will describe some of my recent experiences with Asian vehicles, and what I did to diagnosis and repair them. Let’s start out with a 2009 Subaru Forester 2.5 DOHC turbo that came in with a complaint of low power.

A sagging Subaru

Since this vehicle had 171k miles, it just may be in need of some normal service. A vehicle check of this Subaru revealed that the Check Engine light was not illuminated and there were no codes stored in any computer system. The vehicle owner’s complaint was an intermittent noise from the engine as she was driving. Our normal routine when checking out a vehicle is to always check the basics first since any one of these can potentially cause a problem. Prior to the previous checks and test, we had performed a visual inspection, TSB look up, Identifix search and a system scan of the complete vehicle. Our next step on this Subaru was to check the mechanical condition of the engine by performing a relative compression test using one of our labscopes. Believe it or not we still use our old Fluke 98 labscope since it just turns on by pressing a button and goes right into the relative compression test with a few clicks of a button.

The test is easy to perform, since all we have to do is connect the labscope leads with a filter to the positive and negative leads of the vehicle’s battery post. Once the labscope is connected to the vehicle’s battery, the fuel is disabled by either the Clear Flood method or removing the fuel pump relay, followed by cranking the engine over for 30 seconds or so while the test results are being displayed on the screen. We make sure to perform the test two times making sure that the test results are the same whether the results indicate a good or a bad condition. If the test indicates a cylinder problem we then proceed to connect another scope channel so we can sync to the firing order, via number one ignition. The reason to sync the scope is to confirm what cylinder in the firing order (1-3-4-2 in this case) would be identified as the problem cylinder. When we locate the weak cylinder, we request more time from the vehicle owner to perform a dry and wet compression test followed by a cylinder leak down test, so we can pin down the cylinder that has the issue.

Figure 1

Since the Subaru engine’s relative compression test was good we could rule out an engine issue and continue to look elsewhere for the noise. We road tested the vehicle and thought that we heard a noise so we returned to the shop and set the vehicle up on the lift. To pinpoint the exact area of the noise, Franklin drove the vehicle on the lift while Bill and I were underneath the Subaru confirming the area the noise seemed to come from. The noise seemed loudest at the turbo, so Bill unbolted the rusty exhaust and here is what he found (Figure 1). As you can see the turbo was in bad shape (Figure 2) and needed to be replaced. To make sure the new turbo would not fail prematurely the oil lines where checked for proper oil flow along with the banjo bolt that connects the line to the turbo. FYI, the banjo bolt does not come with the turbo, so make sure you order it or the new turbo will fail prematurely. Subaru will not warranty the turbo if you don't install that new bolt! So, on this Subaru, we replaced the oil feed tube along with the banjo bolt that connects to right front of the engine head. Remember that the bolt is crucial for proper lubrication since the small filter that is inside it is prone to clog up. Once the repair was completed and an oil change was performed the Subaru was test driven and ready to be billed out.  

Figure 2

No charge
Our next Asian gem at first seemed like a typical alternator failure that needed replacement. Over the years, we have all replaced our share of alternators without encountering any real problems. Well this 2002 Toyota Camry with 222,861 miles on it with the original alternator may change your mind. It’s not what you’re thinking, it wasn’t difficult to remove because of rust or broken bolts, in fact it was an easy removal and install. The problem was that after the alternator was installed in the vehicle it did not seem to charge and the idle seemed low. The white wire at the sensing terminal on the alternator had 11.6 volts at idle, while all the other wires had battery voltage. This is where you start to question the quality of the replacement alternator and your install. Since the alternator was a quality NAPA alternator (Figure 3), that has never let us down in the past and my top tech Bill was working on it, neither one was likely the problem.

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