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Whitey's  'fwromp fwromp'
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Piston Problems

   Whitey - 1975 Spitfire Specific Tasks and Procedures
Transmission    The vibration    second rebuild    Clutch    O/D    driveshaft 
Special Update Whitey finally gets it's 6 cylinder engine, Fuel injected at that!
Section #2 - Whitey's Spit6 conversion Process                     F.I home page

      

     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.

cyl2.jpg (13940 bytes)


 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.   

cyl3.jpg (19830 bytes)
The top of the block was cleaned up before the pistons were played with. #1 cyl (engine front) is at the right, #4 at the left (rear) That Permatex spray on Gasket remover was a real life saver here. Man, that gasket was on there. This engine only has ~37K miles on it. So I have to believe this is the first time this engine has ever been taken apart. (except when I put in new big end bearing about three months ago)

 

cyl4.jpg (13106 bytes)
 

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.

   

cyl5.jpg (17564 bytes)

 

  

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.

cyl6.jpg (14373 bytes)

 

  

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.

cyl7.jpg (33468 bytes)
testing the cyl for warping with the upper most compression ring
from cyl #3.  What's the ring gap..it looks a little big to me. WOAH!
look how shiny those cylinder walls are. ...not good...  

 

cyl8.jpg (14133 bytes)
#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.

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last edited 
3/15/08

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