oldtuckunder Posted December 5, 2017 Report Share Posted December 5, 2017 Thought a few techies might be interested in the following pictures to have a guess at cause. As you can see all the exhaust valves stems have a very light white coating. A few clues to help you on your way. All 6 are identical, the plug colours (as much as you can tell with modern fuel) are in the nice mid brown shade. I run permanent AFR logging on both banks of cylinders, they never go lean, apart from at gentle cruise (no load) say 2-2.5K when I allow the AFR's to hover in the 15-16 band. About 1300 miles since last winters light rebuild, new shells, new rings, cleaned and relapped valves, they are stainless. Slight damp black oil on back of inlet valve heads (so a tiny bit of stem leak even with stem seals fitted. Compression test a few weeks ago all were just about even, but about 15psi down on what I expected, Leak down test gave very good results for road engine, but a tad lower than I would have liked hence head coming off for a check and relap. I have never seen valve stems & heads quite that white, normally at season rebuild they have a similar but tan coloured deposit. The only difference being that this engine last ran fast idling for an hour or two a couple of weeks ago whilst taking manifold temperatures. Alan Quote Link to post Share on other sites
Peter Cobbold Posted December 5, 2017 Report Share Posted December 5, 2017 (edited) Burned glycol smoke - from leaking into carb inlet manifold from rusted and leaking water-heating pipe ? Peter Edited December 5, 2017 by Peter Cobbold Quote Link to post Share on other sites
Drewmotty Posted December 5, 2017 Report Share Posted December 5, 2017 Oil from inlet valve guides burning? Quote Link to post Share on other sites
Alec Pringle Posted December 5, 2017 Report Share Posted December 5, 2017 Lean running at high revs is a possible candidate . . . . . . . Cheers Alec Quote Link to post Share on other sites
GT6M Posted December 5, 2017 Report Share Posted December 5, 2017 (edited) nowt t,worry aboot good clean combustionee, and a wee bit of ash frae the oil ye use welcome to the club M Edited December 5, 2017 by GT6M Quote Link to post Share on other sites
Nick Jones Posted December 5, 2017 Report Share Posted December 5, 2017 Should be running pretty lean at fast idle......... Looks like it is. Nick Quote Link to post Share on other sites
oldtuckunder Posted December 5, 2017 Author Report Share Posted December 5, 2017 Lean running at high revs is a possible candidate . . . . . . . H'm was vaguely wandering in that direction, last event was Prescott and I did have it stretched to the max for a few seconds a couple of times, and whilst the AFR's are always logged, at the end of the run I flipped the power off without saving the log (heat of the moment) so its just possible I have missed an event. Will have head off shortly and look for other traces. Also wondered about stuff in this crap fuel we have to use? Alan Quote Link to post Share on other sites
Guest ntc Posted December 5, 2017 Report Share Posted December 5, 2017 Valve bounce at high rpm. Quote Link to post Share on other sites
GT6M Posted December 5, 2017 Report Share Posted December 5, 2017 (edited) Its nowt t,dee with any thing but temps int chamber. yer inlets are black, as they are cooler, think coal ona fire then look at the coal as its finitoed burning, is it black, nope its what shade of colour !!! its same for yer exhusts, Oil / ash ev been subjected t,extreeeeem heat, simples Mine are that shade, and it aint running weak want,rm t,go red, then bung in some octain booster, or redex it,ll change because of the heat, sparky plugs , and chambers. its a metalik left owa residue M Edited December 5, 2017 by GT6M Quote Link to post Share on other sites
Lebro Posted December 5, 2017 Report Share Posted December 5, 2017 Just looks like a slightly lean mixture to me Bob. Quote Link to post Share on other sites
oldtuckunder Posted December 5, 2017 Author Report Share Posted December 5, 2017 Its nowt t,dee with any thing but temps int chamber. Mine are that shade, and it aint running weak As I said I'm fairly certain from all data logging that I don't run weak either, and to be honest If their the same colour as Marcus's then that's probably good enough for me! It may be as Nick suggested that the leaner no load fast idle period before shut down coloured them a bit. I'll have them out in a few days for close inspection. Alan Neil could you explain why you think valve bounce at high rpm could be a cause I'm interested to learn. Quote Link to post Share on other sites
Waldi Posted December 6, 2017 Report Share Posted December 6, 2017 Alan, Some metals (oxides) or low melting point eutectoids deposit like this. Think like "lead" in the old days. No idea where these originate from. Did you use a duel additive? Regards, Waldi Quote Link to post Share on other sites
oldtuckunder Posted December 20, 2017 Author Report Share Posted December 20, 2017 Hi No fuel additives used, apart from what they bung in at manufacture, which just out of interest since rebuild in march this engine has only been run on BP Ultimate and not a drop of anything else. Finally got head off (world kept interrupting me) and below is a chamber shot, which seems to be just about exactly as expected. Alan Quote Link to post Share on other sites
Peter Cobbold Posted December 20, 2017 Report Share Posted December 20, 2017 (edited) BP are coy about the new Ultimate ingredients: http://www.telegraph.co.uk/cars/news/bp-claims-new-super-fuel-adds-21-miles-per-tank/ 'patents pending'. They play big on cleaning 'dirt' from the engine to increase mpg. This Oz article reveals more: https://practicalmotoring.com.au/car-advice/dirt-busting-fuel-fact-or-fiction/ If BP are using a extra-high dose of organic cleaner then the valve deposits might be from ZDDP stripped off the cylinder walls, as 'dirt'. So my best guess is the white deposits are zinc phosphate. And, yes, it is white: https://en.wikipedia.org/wiki/Zinc_phosphate Youtube has several tests for zinc. If Ultimate is stripping the glassy film of deposited ZDDP off rings and bores.... it might not be a good idea...... Peter Edit. Bingo ! - my guess was close ! http://prntscr.com/hq719i Source: https://books.google.co.uk/books?id=C5nfBwAAQBAJ&printsec=frontcover#v=onepage&q&f=false - On March 30, 1981, a symposium entitled "Chemistry of Engine Combustion Deposits" was held at the 181st American Chemical Society National Meeting in Atlanta, Georgia, under the sponsorship of the Petroleum Division. This book is an out growth of that symposium, Edited December 20, 2017 by Peter Cobbold Quote Link to post Share on other sites
GT6M Posted December 20, 2017 Report Share Posted December 20, 2017 Still say that the ash content of the oil is responsible for some As I was having white valves, long long befoer Unleaded was aboot infact, they wer white wid good ole leaded Alan, that inlet valve looks to be far to deep in the heed valve seat been re cut too many times or inlet re cut !! there some pile of sheite inthem chambers for just a seasons blasting up a hill, or are ye running it ont road as weel,!! Best way t,clean yer cyl chambers oot, is t,bung water in inlet mani the water turns t,steam, an blast the deposits away an water costs nowt,!!! M M Quote Link to post Share on other sites
Peter Cobbold Posted December 20, 2017 Report Share Posted December 20, 2017 Still say that the ash content of the oil is responsible for some As I was having white valves, long long befoer Unleaded was aboot infact, they wer white wid good ole leaded Alan, that inlet valve looks to be far to deep in the heed valve seat been re cut too many times or inlet re cut !! there some pile of sheite inthem chambers for just a seasons blasting up a hill, or are ye running it ont road as weel,!! Best way t,clean yer cyl chambers oot, is t,bung water in inlet mani the water turns t,steam, an blast the deposits away an water costs nowt,!!! M M Markus, Agree with water injection. It can also deliver an extra 10 RON points onto 97, if the regs allow it. ZDDP has been in oil for many decades , and looong before unleaded. My expectation is that fuels with greater surface cleaning agents will give more of the the white deposits derived from cleaning-off ZDDP films .Cleaning agents have also long been added to fuel, but more so recently to keep high-tech injectors in good nick. So your white deposits may also be from ZDDP. But Ultimate might have pushed the cleaning tooo far and might render ZDDP ineffective as an anti-scuff. It is possible that BP have not designed Ultimate to be compatible with our obsolete high-ZDDP classic oils. Am hoping Alan will analyse the white powder and tackle BP... I'm going for cheapo jungle-juice 95RON ....and water injection under boost ! Peter Peter Quote Link to post Share on other sites
oldtuckunder Posted December 21, 2017 Author Report Share Posted December 21, 2017 Alan, that inlet valve looks to be far to deep in the heed valve seat been re cut too many times or inlet re cut !! there some pile of sheite inthem chambers for just a seasons blasting up a hill, or are ye running it ont road as weel,!! Best way t,clean yer cyl chambers oot, is t,bung water in inlet mani the water turns t,steam, an blast the deposits away an water costs nowt,!!! Yes not much metal left, standard steel valves sit a bit higher, but the rim flow stainless sit low, still manage to get a neat thin seal when lapping in, but if it goes bad its metal spraying time, as there is not enough metal to even attempt inserts (which I don't like anyway). The MK1 head isn't supposed to be able to take the 36.5mm Inlets so its a bit of a miracle anyway! Yes it did some road mileage last season, as I did a number of events in the road going class, so driving to/from is mandated. Next season back to modified as the rule changes mean I'm excluded in more ways than one from road going. Might try the water injection clean up during next season! Am hoping Alan will analyse the white powder and tackle BP... Well I'm happy to scrape some off, if someone can tell me what to do with it! Alan Quote Link to post Share on other sites
Peter Cobbold Posted December 21, 2017 Report Share Posted December 21, 2017 Yes not much metal left, standard steel valves sit a bit higher, but the rim flow stainless sit low, still manage to get a neat thin seal when lapping in, but if it goes bad its metal spraying time, as there is not enough metal to even attempt inserts (which I don't like anyway). The MK1 head isn't supposed to be able to take the 36.5mm Inlets so its a bit of a miracle anyway! Yes it did some road mileage last season, as I did a number of events in the road going class, so driving to/from is mandated. Next season back to modified as the rule changes mean I'm excluded in more ways than one from road going. Might try the water injection clean up during next season! Well I'm happy to scrape some off, if someone can tell me what to do with it! Alan TRy chemistry teachers at local 6 form college. They will have the test solutions for Zn and phosphate. Peter Quote Link to post Share on other sites
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