I had heard that question in the past and as I remember it has always turned out to be not so funny - expensive, bothersome, challenging, but never funny. This time would be no different.
"If this Buick had a generator I would swear it was the brushes. You know like the 57 Chevy?" Arleen has a good way of describing noises coming from under the hood of her pride and joy. "It sounds like it's coming from the alternator. Do they have brushes? Oh, and by the way, it's not doing it now so don't bother to go out and look at it now."
That was a relief since it was about ten above and the wind was blowing the foot or so of snow sideways. Of course I could have put the car in the garage but I hadn't cleaned it out since I put the snowblower on the John Deere and I didn't feel like doing it right then.
Weeks went by and I didn't hear anything about the noise so I figured it had fixed itself. Then came the call. "I think I am out of gas, but not to worry I ran out at the pumps in Ontario. I filled it up but it won't start. Is there some secret to priming a fuel injected engine? There is a truck driver here and he is trying to get it started but it won't even cough."
Now truck drivers are normally pretty savvy about cars and Arleen is no slouch when it comes to understanding what's wrong so I figured that they had the situation pretty much under control. I had told her to listen for the electric fuel pump as she first switched on the ignition switch. It should run for a couple of seconds and then shut off as the pressure builds in the fuel rail. Perhaps she should do it several times to sort of get the air out of the system. After all, she did say she ran it out of gas, didn't she??
I settled down to watch the rest of a football game on TV when the phone rang again. "I guess you better come down here - and bring a tow chain." Now that worried me. So I hopped in the old Ford pickup with 20 feet of tow chain in the back, a can of gas, and a squirt bottle to do some priming if it needed it.
First thing I noticed was the smell of gas at the tail pipe, not a good sign for a car that was supposed to have run out of gas. Next I checked for spark at one of the spark plugs - no spark. It was cold and I wanted to get back home so I closed the hood and went for the tow chain when it suddenly dawned on me. "Arleen, didn't you just tell me we signed up for Triple A last month - a special deal for joining - didn't ya?"
The AAA tow truck arrived within fifteen minutes and we were off to the driveway. I went ahead and cleaned out the garage enough so the wrecker could get the Buick inside. I knew I had to work on it NOW and I wasn't about to freeze my knickers off standing in the driveway.
Now you remember I started this story with an episode about a funny noise? Well there was a reason for that. As I went through the diagnostics flow chart for a "no start - normal crank" analysis I kept remembering way back in my mind about the funny noise, only it didn't sink in until later. The diagnostics pointed to a faulty computer. I have a feeling that all of the diagnostics finally end up there since it is probably one of the highest profit margin items in the whole car! I didn't believe it, having worked around computers for most of my recent life and knowing that there are symptoms other than what Arleen had experienced. The other alternative was the crankshaft position sensor, but I had checked that out electrically and it was right on - right to spec. I called around to the various jun . . . er, automotive recycling yards and found a computer for it for only fifty bucks. Fifty bucks well spent if it solved the problem, but I was told that it was not returnable. They check them out at their shop and they are in working condition - only thing that could go wrong with them is if I put it in a car that had a shorted sensor or some other fault that would trash a computer.
I was still not convinced. I decided to take a better look at the other possibility, the crankshaft position sensor. It is located almost as deeply inside the engine as the crankshaft! After removing the serpentine belt, the water pump pulley and some other hoses and paraphernalia, I could barely see it. I got a really bright flood light and pointed it at the area of the sensor. As I probed the area with a screwdriver to try to get some of the road dirt out of the area I noticed something peculiar. The "road dirt" stuck to the screw driver! I looked closer. There was "road dirt" all over the crankshaft damper pulley! Only some of the "dirt" was stuck like glue to the surface of the steel pulley. Now I know it looks stupid, but when I reeealy want to get a good look at something close up I put on two pair of glasses. It really magnifies the area of view. Then I could see it. There were little fine pieces of magnet covering every steel part in the area! Magnet? Magnet? Where the hell did pieces of magnet come from??
I removed the two bolts that held the crankshaft position sensor to the timing gear case and noticed that the sensor had a slot in it. There was a steel "blade" attached to the crankshaft pulley that fit in the slot. As a matter of fact there were three steel blades on the pulley. Back to the books.
It turns out that the crankshaft position sensor works on a principle call the "Hall Effect". The blades on the crankshaft pulley rotate through the slot on the sensor breaking the magnetic field between a pick-up coil and a permanent magnet. THAT'S IT - A PERMANENT MAGNET! A quick inspection of the sensor showed that there was a nice shiny area in the epoxy where there USED to be a magnet. But no more. That funny noise that Arleen heard? That was the magnet becoming loose in its mounting and rubbing on the blades on the crank pulley. It took a few weeks of rubbing but the magnet finally fell out of its mounting, was demolished by the blades on the crank pulley and killed the engine - just as Arleen was pulling in for gas knowing that she was very close to empty.
It took about a twenty dollar bill to get a new sensor. It was mounted in ten minutes. The car started and ran like a kitten, and I sat down if front of the TV just in time to see the final play of the football game.
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