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Topic: Spark plug colour after rebuild! (Read 976 times) |
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ro284
Full Member
I'm a YaBB newbie!
 
Posts: 508
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Spark plug colour after rebuild!
« on: Nov 12th, 2013, 4:27pm » |
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I always thought most engines plugs would have a light brown electrode, my new ones after just a few days running are white/grey electrode, (surely lean!) white insulator, black body! (surely rich!) cyl-no 6 as above but more sooty black body! The engine has settled after rebuild, steady tickover, performance is good, the heater fantastic! i feel something is still not quite right, so next step to make a code reader, see if that puts me in the right direction, but any thoughts on the plug colours, please share  Bob
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Bob Dorset
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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: Spark plug colour after rebuild!
« Reply #1 on: Nov 13th, 2013, 6:18pm » |
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Only leaded petrol produced the brown colour, unleaded makes grey/white. However yes, if very white then is not good .. 
If black soot is very light and will brush off easily, it's not a problem, probably just due to standing idling for a few minutes, or you had just started it and not driven it any distance yet to burn the soot off. If however it needs scraping off then yes it's too rich.
If "performance is good" can't be much wrong with it though.
HTH
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Mike H
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PJDavis
Senior Member
2 x 1995 Jag X300 3.2 / 4.0 (Henley) 1957 XK140
Posts: 1474
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Re: Spark plug colour after rebuild!
« Reply #2 on: Nov 13th, 2013, 6:29pm » |
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There is only One-Way to 'chop' a plug properly. Make sure the car has run for 20 miles or more at normal temperature, find an open road and get the car really warmed-up using all the gears at maximum revs, then bring the car down to 'cruising-speed' (about 70 + mph), then instantly put your boot on the floor and just as it gets to the red-line, foot-off, and cut the ignition! (whilst pulling into the side like the hard-shoulder, obviously out of gear for both auto and manual) Now 'chop' the plug) This is all very old fashioned and maybe extreme, but it still works - believe me!
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I love 'Movvy'
1995 Jaguar XJ6 X300 3.2 (Henley)
1995 Jaguar XJ6 X330 4.0 (Dopey)
1957 Jaguar XK140 USA (converted to RHD, and to have fitted Mk10 420G Engine with BW 65 Auto Trans)
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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: Spark plug colour after rebuild!
« Reply #3 on: Nov 13th, 2013, 6:37pm » |
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I concur
But as you'll also lose power steering and braking efficiency, do you fancy it
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Mike H
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amigafan2003
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I'm a YaBB newbie!
Posts: 972
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Re: Spark plug colour after rebuild!
« Reply #4 on: Nov 14th, 2013, 4:22pm » |
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Don't bother checking plugs if the recon engine has less that 1k miles on it. @ 1k, replace the plaugs and check 100 miles after that. How was the engine run in after the recon?
If you've got bad combustion etc then it'll show up in codes in the ecu. Get an emissions test on it to be as well (but again after 1k miles).
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