Sunday, October 28, 2012
I recently was at a shop that just did a timing belt replacement on a 2004 Hyundai XG350 3.5 liter v6 with 75,136 miles as part of routine maintenance. The vehicle ran well into the bay. Unfortunately, it ran quite poorly after the service. It was setting misfire codes and had a terrible lack of power and a rough idle. These cars normally idle like glass and perform quite well.
The tech that did this job was sickened. He is a very thorough tech and I have been there a couple of times in my life where the vehicle ran worse after I serviced it. It is a bad feeling. I really felt for him. I went over the timing belt procedure with the tech and on the car several times. I often find that more can be found out asking questions than looking at the car. After some head scratching the tech said something that stuck with me. He said he had a hard time seperating the crank pulley from the crank sprocket. With this I broke out the scope and decided to check CKP/CMP correalation. I had a hunch.
Here is how it fits together. What happened here is when the tech was seperating the crank pulley from the sprocket it pulled the crank sprocket forward and disengaged the CKP interruptor ring from the crank sprocket. When the tech reinstalled everything it moved and therefore corrupted CKP/CMP timing. This caused the vehicle to run like the timing was retarded drastically. This was very easy to do. Hyundai does not extend the crankshaft woodruff key all the way in and relies on these two small tabs that are easily broken to index everything. One new crank sprocket and interruptor ring and away it went.