Compression test results

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norried

Active Member
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210
Location
Stow
Compression test results.
Ok I've got a bit of a misfire and done a.compression test it's a 2.25 petrol. I'm getting 130,100,120,130. Now I'm hoping it's just a burnt valve that's causing my low.compresion on No2 cylinder. Apart from an endoscope or taking the head off is there any way of telling if it's a head or piston problem?
Also I've had a quote to get the head refurbed so new guides and seats plus a skim and been quoted £300. Does that sound Ok? That was only new exhaust seats as they reckon the inlets don't normally need done.
Thanks.
Norrie
 
Teaspoon of oil down the plug hole, comp improves? Piston,bore,rings.
No change? Valve, head gasket.
They all seem a little low to me but it's been yonks since I messed with petrol engines so I could be wrong.
 
iirc anything less than 120 is supposed to be bad.

guess it depends how good your tester is i.e. how close the readings are to what the pressure is. I just have a cheapo tester so I don't pay too much mind to the actual values but look for one that is significantly different from the others so in your case two and possibly three.
 
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