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Whitey - 1975 Spitfire Specific Tasks and Procedures |
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Well as usual, I couldn't leave well enough alone. I decided to fix the sticking oil press gauge, and re-calibrate the temp gauge. About a week later, I noticed a weird vibration at speed. I thought the rebuild I just did on my tranny was about to show me I might not have known what I was doing. I was wrong!
Apparently the slight over heating of the engine during the temp gauge calibration managed to jam/freeze the #3 cylinders rings in the piston groove. The strange sound effects and vibration were from the low compression in that cylinder. #1,#2, and #4 cylinders were all at 150 +/- 2 psi. #3 was at 70. A squirt of oil in the cylinders and another compression test only brought #3 up to 125 psi. Oh well. Off with the head. What did I screw up this time!
The rest of this page is/was currently a slight re-hash of my initial picture publication for people to look at while I was trying to determine the real extent of any damage I might have caused.
*******
QUESTION.... Could the piston
ring get 'stuck', which drops the compression? It sure can with all the crap additives in
gasoline these days. That combined with the improper heat range plugs, can clog up your
ring grooves pretty quickly . Just look at the tops of the pistons in the next couple of
photos. This is with only 37K original miles on the odometer. |
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Nice shiny cyl. walls in #3 after the piston was removed. The first compression ring is sitting down in the cyl for warpage testing. A bright light from underneath shows no light up between the ring and cylinder walls. |
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You can see just a bit of wear on the side of the piston (silver color) but there is no scoring. The oval is not a broken hole, but it is a hole cast into the piston. There is a matching one on the other side as well. The oil ring s a little snug but can be easily rotated.
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Top of the piston is pretty carbon covered with a bit on the edges as well above the first compression ring. The first ring is already off in this photo. It was used to test the cyl. for warping. This is after a bit of crud was cleaned of the piston. The rest seems to be baked on. |
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The bottom end...already had new bearings installed about 400 miles ago. So these look like they can stay. Well...if I have to reassemble everything again, I'll probably go ahead and install new bearings here while I'm at it. |
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#3 cylinder walls are WAY too shiny ... looks like I have some glaze busting to do Luckily there is very little bore wear, identifiable by a minimal ridge at the top of the cylinder. |
©1987-2010
All material copyright© Teglerizer 1996-2008last edited
3/15/08
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