Bowie69 Posted August 13, 2009 Share Posted August 13, 2009 A short video of the issue: *CLICKY FOR A GIGGLE* I've rebuilt engines before, so it holds no real fear for me, but I would be interested in anyones likely diagnoses before I start ripping it apart too much.... the timing of the smoke is interesting to me, for instance, as it takes quite a while to build up. I pulled the plugs, and they looked like this on the left bank: and this on the right: Compression test when hot showed this: 1. 168 3. 158 5. 195 7. 158 1. 175 3. 180 5. 178 7. 158 195 is the badly oiled plug, so pretty self explanatory, I think... I was going to do the cam fairly soon, just wasn't quite planning on it being now! Packet of Jaffa Cakes to the winner Thanks in advance P.s. If anyone can explain the science of a smoke ring it would be hugely appreciated P.p.s. Jaffa cakes may or may not exist, either in RL or virtual. Quote Link to comment Share on other sites More sharing options...
errol209 Posted August 13, 2009 Share Posted August 13, 2009 Packet of Jaffa Cakes to the winner P.s. If anyone can explain the science of a smoke ring it would be hugely appreciated P.p.s. Jaffa cakes may or may not exist, either in RL or virtual. When any object moves through the air, it must push the air out of the way. As the air in front of the object makes way for it, the object moves forward, and an empty space is left behind. If the air is frictionless, then the "chunk" of air moves foward, and a very thin layer of air moves backwards over it. Air is pushed away from the front of the chunk, and it fills the space behind. If the air is frictionless, a "chunk" of air can keep moving forever without losing its shape. But real air has friction, and the chunk of moving air will be stirred as in the figure below. figure In the figure, as the air ahead of the red chunk is spread apart, it makes the air inside the red chunk spread apart too. As the red chunk moves forwards, its outer layer is dragged backwards. A central stream of air starts moving forward through the red chunk, and the chunk swirls inside. I claim my prize Quote Link to comment Share on other sites More sharing options...
disco_al Posted August 13, 2009 Share Posted August 13, 2009 don't stare at that image for too long - it does funny things to the eyes.... Quote Link to comment Share on other sites More sharing options...
Coastcard Posted August 14, 2009 Share Posted August 14, 2009 I'm struggling to see the link between Time Attack and your 8 plugs. Oh... The Gobstopper all the way! No prizes for me then. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 14, 2009 Author Share Posted August 14, 2009 Thanks for the most helpful replies so far Well I pulled the heads off, 3 cylinders from the right bank were blowing badly into the valley, 1 blowing badly into the valley from the left bank, and another one looking like it was starting to blow. None look like they were blowing into an oil way, so still a little stumped as to where that amount of oil was entering the combustion chambers, when these V8s blow, do they suck oil in from the valley, or is it just a one-way process? I'll post some pics if it helps anyone... Thanks Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted August 14, 2009 Share Posted August 14, 2009 Generally when RV8s burn oil it can be one of three reasons ………. and usually a combination of all 3. 1. After some decent mileage the bores will show some ovaity ……… ………… if its 5 thou or so then you tend to get crankcase pressure build up which forces oil mist into the induction system through the closed circuit breathing (through the flame trap) ……………… any more then 3 thou will require a rebore. The crank case pressure is caused by the compression leaking past the rings on the oval part of the bore (the thrust side). 2. If the head gaskets are blowing into the valley (common fault – especially if the outer row of head bolts have been used) …….. then again this will cause an increase in crankcase pressure and oil mist into the intake system. 3. The other area is worn valve guides ………… this generally causes oil burn on a continual basis and if its bad the exhaust gases will stink and you will see a blue haze at idle. Ian Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 14, 2009 Author Share Posted August 14, 2009 Cheers Ian, I got to play a bit more today, pistons out, front cover off etc, and cracked a crank main bearing cap, reckon it is time to unbolt what remains of the engine from the gearbox and start the full rebuild process All big end shells are shot (I have seen worse mind...), the main bearing cap I cracked off was starting to show the copper (not as bad as the big ends), on closer inspection the head gaskets are blowing very badly. Stripped the oil pump off and found it quite badly scored (worse than in your rebuild thread, Ian) And then fished around in the sump to find what I can only really call 'sandy clay' settled in the bottom -arse! I'll mic up the bores, I suppose this will determine what I end up doing, either a rebuild (which I would enjoy doing), or a good low mileage engine to drop in and get me going sooner, not to mention a small capacity increase Assessing the engine leads me to think it is just a fairly worn unit, which may have suffered from irregular oil changes, or maybe just the sandy gloop and 100mile journey home... the head gasket issue is probably secondary to the gloop/wear issues, just coincidental it happened at a similar time... I think your #2 is about bang on the money, I am still very surprised by the sheer volume of smoke though Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted August 27, 2009 Author Share Posted August 27, 2009 Well..... I got hold of a dial bore gauge and mic'd up the cylinders(eventually), worst case is 2.4 thou out of round, on cylinder #1, top and mid measurement, all the others are between 0.4 and 1.6 out of round -seems like the block at least is worth saving. Still undecided on rebuild/replacement route, though of course I would get exactly what I want if I rebuild, and enjoy it, even if it takes longer Thanks for help Quote Link to comment Share on other sites More sharing options...
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