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What liquid to test for valve leakage


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Help please


I've had to replace two valves in the engine and hoped that I had cut them in sufficiently with coarse then fine paste. I've managed to get a even gray colour but if I drag my nail over the surface I can still feel some surface roughness - it's as if I have concentric rings. Not sure this is right nor how to remove them because we've been going with the fine for ages


I've reassembled the head and have tested with petrol to see if it's leaking and kinda think it is. Is petrol too tough a test or should I use a more viscous liquid?


Suggestions please on removing the concentric rings if this is the cause?





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The only way would seem to be have the valves ground and seat recut to the correct angles


maybe time to fit exhaust inserts as cutting will remove some lead memory


Reckon once the rings have formed paste will only keep them generated


re facing the seats is looking a possible solution


I often regring with paste using a reversing battery drill on the stem and you have to watch out for

making rings ,


Petrol maybe a bit thin, and would creep through a reasonable seating , parrafin was an old gag

oil is a bit thick ,

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Pete. The inserts were new a year ago and the valve was new from moss. I managed to get a reasonable gray line about 2 mm wide all around the valve so it must have been pretty close to the seat to get the wear mark .....but I've got groves


The worry is that if I carry on with grinding paste do I just perpetuate the groves now that they have started ?



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I feel the answer to that is ....yes


out the box idea, you dont have a seat cutter but could you erase the rings if you cut a disc of

wet and dry it would not follow the developed rings being on a stiff backing ???? To sit in the seat and rotate with the valve

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If you are getting concerned about the grooving have you a local machine shop that could cut the seats and face the valves for you its normally quite a cheap job


if you have hard seats and two exhaust have burnt then theres a problem somewhere

soft valves , retarded, tight tappets etc. come to mind



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