Chain slip each piston has 2 dent marks replace 8 valves????

john2666

Hi Guys,
doing another one, took the head off, all 4 pistons have two marks where the inlet valves have hit them, looking at the valves it only looks like one valve on each pot is bent, i have replaced these, it all looks well but with the marks on the pistons has concerned me a bit, if the valve has hit the psiton even slightly would i need to change all 8 ??? the exhaust valeves are fine

sdbutler10

i would have thought so if its had enough force to mark the pistions its bound to have bent the valve even if its so minamal u cant see it

MikeS

worth getting pics up 🙂

i have seen piston faces with serious det marks and they still run oki

john2666

hi mike i have attached some pics of the pistons and the head, i have replaced 3 of the inlet valve as they were obviously bent, im thinking replace them all whilst the head is off but wondering if i would get away without doing the rest

vocky

are the valve guides cracked dunno..

those pistons look quite bad, it might be worth pulling the pistons out and see if the piston rings still move freely

john2666

Hi vocky, no the valve guides were fine, what makes you think the rings wont move freely mate?

MikeS

does she crank over with no tightness ?

vectra2k9

how bad do the indentations have to for the engine to be knackerd

john2666

Hi Mike, yeh the engine cranks manually with no tightness all nice and even

vocky

at the moment, with the head off, it's easy to check the rings are still ok, but once rebuilt the engine can smoke heavily if the rings have been squashed by the valve piston indentations :thumbdown:

john2666

is there anyway of checking the rings without dropping the sump to undo the conrod and drawing the pistons out ?

MikeS

nope 🙂

see if u can move the pistons around by putting pressure on the faces

also another trick is to put petrol on the top of the pistons to see whether it just falls straight through into the crank, it should eventually drop into the crank but we are talking hours here, good indication of how good the seal is on the rings

john2666

Hi Mike
pistons dont really have any play in them if you press on them and try moving side to side, i will try the petrol thing and i have replaced all 8 inlet valves, probably best

vocky

Mike's petrol tip is a great idea :thumbup: