This is a followup, telling the outcome, to my posting last week about a timing belt that might have been installed out of synch. That posting was titled, "New Timing Belt, How To Test Correct Synch? ".
My thanks to those who wrote in.
Mazda MPV, minivan, 1989, V6, 3.0L, 2wheeldrive, 133,000Mi, autotrans
It was really two questions: 1?) If there is suspicion a new timing belt is out of sync, off by a tooth or more, is there a way to test it without disassembly? Everyone answered that there is not. You must remove the cover and look at the alignment of all the marks. 2?) Do the symptoms of my car sound like a timing belt is misaligned, and can a car even run if off by one tooth? The symptoms were that, while the engine with belt replaced actually seemed to run smoothly but it did this: When starting off, it had low power and I had to keep putting my foot deeper into the accelerator, with little increase in speed. Then when it finally built up to a certain RPM, it would wind up to a much higher RPM instantly, faster than you could let off the gas it would be at 4500+RPM and then the auto.trans would do a radically hard upshift. (I don’t know, sounds like the way you might want a racing cam to work.) Everyone’s answer was that it sounded as if, yes, the camshaft was out of sync. One person had personally experienced similar symptoms when mistakenly misaligning the timing belt in their own car. So that was a big lesson learned for me.
RESULTS AND RESOLUTION: It was a tough situation for both me, the customer, and the auto shop. Since my car had been towed in, not running, and an older car, they could not know if it was running poorly before it ever arrived there. And they had absolute confidence in their technician. Upon test drive (after first installing the new timing belt) the technician had noted a hard upshift not knowing the car, he could not really know if the engine felt different (as I certainly did). But the shop could find no other problem with the car, nor could a transmission shop explain the hard upshift. So the shop acknowledged this was a very odd case and agreed to dismantle the front of the engine and look into it. Result: They found the timing was off by one tooth. However, the apparent reason was a failure of the timing belt tensioner. Of course, they had examined that tensioner during the initial job and determined it to be not leaking (hydraulic) and did not replace it (only the tensioner pully was replaced). But on this second disassembly they found the tensioner device was broken. There is a little shaft about a quarter inch in diameter and it had completley broken off. (They gave me that old tensioner.) The failed tensioner allowed the belt to jump off by a tooth (on one of the two cam shafts). We can only assume that the tensioner broke immediately after the timing belt job was complete, because the car’s bad performance was noticed as soon as I received the car and even noted by the mechanic’s test drive. The shop did this second disassembly at no charge, and even did not charge me for the new tensioner ($180 retail!), for which I am grateful. Before doing this second tear-down, it was a difficult discussion for me and the shop owner. We both knew it was a very unusual situation, impossible to say confidently what might be going on. The owner knew he might have his employee dismantle the engine and find nothing wrong, but they went for the option of trying their best to make it right for the customer. They succeeded and I am grateful. The car runs beautifully now. Thanks again to all who wrote in.