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pauly_adams

mystery loss of comprssion

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hey all, about a month ago i was driving the zed and herd a bang and there was a loss of oil pressure, i got the car home thinking it was a blown head gasket so i rand a compression test and sure enough the 6th cylinder was down 30psi to the other cylinders (150psi) so i went ahead and went to machine my head only to find it had severely twisted i have no idea how. so anyway the old head was pulled out new valve stem seals etc where put on, so then on went a new head gasket permatex etc only to find when i cracked it over it was running like a dog still, yet again i ran a compression test on all cylinders and funny enough the 6th cylinder was still down 30psi. since then i have pulled the engine out and stripped it down thinking it was the rings and guess what there appeared to be no damage to the piston or bore and the rings looked OK, the only other thing i could find is the compression rings where lined up which i have herd can cause it to loose comp. so is it possible for them to move and line up also before this problem occurred the comp was all 150psi and i mean perfectly 150psi, any one got any ideas.

 

 

cheers Pauly

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thats what i thort it may have a hairline fracture it also did blow my head gasket when it happend the bang that is i was told this afternoon it could be caused by this, does anyone know if it may be valves at all as i did use the valves from the old head as they better condition then the ones in the other head the ones i put on after

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i dont know how i missed this but i dont think this is normal it looks like the valves have crowned my pistons im not sure when it happened but it looks that way heres a pic. its not very good but you should be able to see it.

 

cheers pauly

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i did think of that but both heads i have are the same size i used my verniers but then again they both could have been shaved, well it looks like time for a new engine

 

 

cheers pauly

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Did you get the specs of the OEM head......

 

If it has been shaved, have you thought of shimming the head back to tolerance and see how you go before getting a new block

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To check how much the head has been shaved, compare the little indentations on the head surface; I think from memory there are 3. One at each end and in the middle. They are about the size of a 1 cent piece maybe smaller, if you can remember them! Don't have a pic sorry..

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