SeriesEwan Posted May 23, 2011 Share Posted May 23, 2011 Hi all, I fear I may be looking at the death of either a piston ring set or a head gasket. Essentially cyl number 3 is not firing at all & it definitely does have a spark. I am going to exchange my compression tester this evening ( dont ever buy a hilka one this is my second new unit & its simply useless ) to see what the extent of the problem is. Anyway, the point of my post is... do I need to buy a complete set of cylinder head bolts if change the gasket? Equally if its rings that have gone ( which I may change anyway as its smoking a fair bit ) do I need to replace any fittings on the big ends if i were to go opening them up? Quote Link to comment Share on other sites More sharing options...
rtbarton Posted May 23, 2011 Share Posted May 23, 2011 Most people don't change the head studs and nuts, but if they show any signs of damage or stretching it would be as well to for what they cost. I suppose it's a case of avoiding the risk of damaging the threads in the block if the studs don't want to come out. Whilst the sump is off I'd measure the big end journals for wear and if they're in spec change all the big end shells. I'd fit new big-end bolts and nuts as a matter of course. If the bore is damaged and the engine has come out for a re-bore then check the main journals and replace main shells and thrust washers. (You can do this in situ on some engines, not sure about the Landrover engine though). With the head off obviously do a decoke and valve grind, maybe check for flatness and fit new guides, seals and springs - it all depends on how far you want to go. On the one hand if it aint broke don't fix it, on the other a stitch in time saves nine. Quote Link to comment Share on other sites More sharing options...
Greg S Posted May 23, 2011 Share Posted May 23, 2011 ... it definitely does have a spark. ... I have to ask. How do you know it has a spark? Do you mean it has a spark to the end of the high tension lead going to the plug? Okay, that's possible. But you still might not be getting a spark in the combustion chamber. I've found it common to have a spark plug that is dead. Before you do any of this other expensive, dirty, frustrating work, buy one NEW spark plug, a regular, inexpensive, plain old ordinary copper core spark plug (not Champion) and then try running your motor again. If the piston is going up and down, and there isn't a rag stuffed in the intake manifold, that cylinder is going to fire no matter the shape of the rings as long as the spark is getting there at the right time. Distributor cap is in good shape and clean inside isn't it? No cross firing? Then worry about things like compression checks. Even knackered engines with half or less of the compression they are supposed to have, still run. So there's no excuse yours won't fire on that one cylinder just because the compression is low, unless you have a great bl**dy big hole in the piston. Quote Link to comment Share on other sites More sharing options...
SeriesEwan Posted May 23, 2011 Author Share Posted May 23, 2011 aha well Greg S your theory is correct, well it could be anyway I have equal compression on all cylinders (9.5 bar) Sparkplugs are all new items & i have swapped them around too to make sure I had no duff units, the next item I have checked is the leads / cap this has been done by swapping around the (new) leads & even rotating the cap half a turn. I am now strongly inclined to agree that it may be an ignition problem but I will be dammed if I can figure it out. A new dizzy cap & rotor arm may be on the cards to rule those out. Quote Link to comment Share on other sites More sharing options...
rtbarton Posted May 23, 2011 Share Posted May 23, 2011 Check tappet clearances and that the valves open OK - if the cam has worn on No3 inlet you won't get any fuel in, but compressions will still be OK. Quote Link to comment Share on other sites More sharing options...
SeriesEwan Posted May 25, 2011 Author Share Posted May 25, 2011 well I have checked the valve clearances & all are now set correctly, interestingly enough the exhaust valves on 2 & 3 had closed up somewhat (so much for the unleaded head it was sold with) no real difference to performance on number 3 though. Even did a rough check to make sure that airflow to that cyl was not impeded by removing the plug, rotating until cyl 3 was IO then blowing an airline through the carb to see if the draft makes it out the spark hole ( which it did easily ). while fettling about I did notice a bit of a funny.... my exhaust feels like sucks!! I would say regularly on each engine cycle! I am assuming this would probably be a big contributor to my problem but with correct valve clearances i really don't know how this can happen?!? Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 25, 2011 Share Posted May 25, 2011 Check the lobes on the dizzy cam, and look for play in the dizzy shaft, reset the points gap at the same time -if they are at all pitted, change them for quality items (not from local motor factor!) as well as the condenser. Quote Link to comment Share on other sites More sharing options...
rtbarton Posted May 25, 2011 Share Posted May 25, 2011 ...... while fettling about I did notice a bit of a funny.... my exhaust feels like sucks!! I would say regularly on each engine cycle! I am assuming this would probably be a big contributor to my problem but with correct valve clearances i really don't know how this can happen?!? A burnt exhaust valve or broken gasket between 2&3 could cause that, but that would show up in a compression test. Did you notice the sucking with the engine running? If so it may be that because #3 isn't firing you're not getting pressure in the exhaust once a cycle, and this feels like a suck? Quote Link to comment Share on other sites More sharing options...
SeriesEwan Posted May 25, 2011 Author Share Posted May 25, 2011 yes the engine was running, & it felt regular almost as it was 3 out & 1 in with a change in tone to go with it. Reading around other forums/ websites on the net agree with your theory that the missed combustion would feel like or cause a suck back as it disturbs the gas-flow down the exhaust Quote Link to comment Share on other sites More sharing options...
SeriesEwan Posted June 1, 2011 Author Share Posted June 1, 2011 huzzarr,, well it got me to the lakes & back this weekend, the problem seemed to improve but not go away. Anyhooo got her back & whipped off the rocker cover & started pressing the valves with a bit of wood to act as a lever.... inlet valve on the offending cylinder was sticking a bit & not allways coming home each time thanks for all your help guys Quote Link to comment Share on other sites More sharing options...
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