For those who'd rather avoid the rambling backstory, is it normal to see lines on the parts of the camshaft that ride on the bearing surfaces?
While progressing towards my presumably inevitable timing chain tensioner work on my 2000 MGM, I went to work on a 2001 MGM at my favourite U-pull. The intake manifold had a plastic crossover, so I wasn't about to take that home. I made a point of getting the timing cover as a spare (for less than $14 all in) so I don't have to leave my timing stuff exposed when I work on it outdoors.
The passenger side tensioner arm was worn to the point where the chain was just starting to eat into the tensioner. The driver's side arm was obviously worn along most of its length, though the tip had about half of the plastic left.
I got the valve covers off without having to mess around with the engine mounts, though I doubt I could've gotten the one on the passenger side off without removing the intake manifold. (I thought maybe the heater pipe might be worth taking, but it was too corroded.) I got one camshaft out to see if they would be worth swapping. I could see lines on the parts that ride on the bearing surfaces, though there wasn't any obvious roughness when feeling them or dragging a fingernail across them. I didn't have too close of a look at the cam retainers, but I could see at least one line on each of two of the bearing surfaces on one of them.
Are the lines a normal wear pattern? The cam surfaces were nice and smooth, and that's what I was expecting on all contact surfaces. My first guess was that some aluminum from the passenger side tensioner arm had been floating around in the oil. (AFAIK, the oil filter does not provide 100% protection.) Another consideration was that the various timing parts had a dark glaze, so I guess the owner had not been diligent about oil changes. The odometer had only five whole digits, so I don't know if the reading 37k was 137k or 237k (presumably kilometers). Overall, I had no problem holding out for something better, though I'd appreciate some input regarding what to look for. Thanks in advance.
While progressing towards my presumably inevitable timing chain tensioner work on my 2000 MGM, I went to work on a 2001 MGM at my favourite U-pull. The intake manifold had a plastic crossover, so I wasn't about to take that home. I made a point of getting the timing cover as a spare (for less than $14 all in) so I don't have to leave my timing stuff exposed when I work on it outdoors.
The passenger side tensioner arm was worn to the point where the chain was just starting to eat into the tensioner. The driver's side arm was obviously worn along most of its length, though the tip had about half of the plastic left.
I got the valve covers off without having to mess around with the engine mounts, though I doubt I could've gotten the one on the passenger side off without removing the intake manifold. (I thought maybe the heater pipe might be worth taking, but it was too corroded.) I got one camshaft out to see if they would be worth swapping. I could see lines on the parts that ride on the bearing surfaces, though there wasn't any obvious roughness when feeling them or dragging a fingernail across them. I didn't have too close of a look at the cam retainers, but I could see at least one line on each of two of the bearing surfaces on one of them.
Are the lines a normal wear pattern? The cam surfaces were nice and smooth, and that's what I was expecting on all contact surfaces. My first guess was that some aluminum from the passenger side tensioner arm had been floating around in the oil. (AFAIK, the oil filter does not provide 100% protection.) Another consideration was that the various timing parts had a dark glaze, so I guess the owner had not been diligent about oil changes. The odometer had only five whole digits, so I don't know if the reading 37k was 137k or 237k (presumably kilometers). Overall, I had no problem holding out for something better, though I'd appreciate some input regarding what to look for. Thanks in advance.
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