View single post by Sylva
 Posted: 04-21-2009 04:40 am
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Sylva

 

Joined: 09-14-2006
Location: Malaysia
Posts: 54
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 Some more Info, up until 2007 I had a problem with con rod stretch and the pistons hitting the head at high revs, (JE+ 30 piston). Did a lot of work decking the pistons etc, and it looks like this is sorted.

But at end 2007 I lost compression in No4 cyl, and of course assumed again that I had broke a piston, head off but nothing wrong, head back on cam gaps set right and no problem, (although the car did only run 100km in 2008 due to my ill health, it was started every 2 weeks and brought up to operating temp)

Ran the car over the weekend, free practice 10 laps no problem (50KM), went out for qualifying engine stopped after 1 lap (5Km), towed the car to the pits, no compression in No 2. (engine had cooled in this time).

Towed the car home, and next day still no compression in No 2. Head off last night, very slight mark on the piston in the vicinity of the rear most exhaust valve, (in the 3 ocklock position looking from the front of the car) no mark on the valve, but a small mark on the head corresponding to the piston mark. Valves are all sealing fine.

I do not see how it can be a valve touching the piston as no marks, and nothing like enough damage for the piston to have touched the head, I cannot see how it is a sticking valve as there was no compression when the engine was cold the next day.

My best bet is that I was real stupid and got a stone into the piston when I changed plugs, I try to watch this and blow the plugs with an air line, but maybe not careful enough.

Appreciate any comments or experience.

 

Kelvin