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        General >> Give/Need advice to/from others >> Spark plug colour after rebuild!
        
(Message started by: ro284 on Nov 12^th, 2013, 4:27pm)

Title: Spark plug colour after rebuild!
Post by ro284 on Nov 12^th, 2013, 4:27pm

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

Title: Re: Spark plug colour after rebuild!
Post by Mike H on Nov 13^th, 2013, 6:18pm

Only leaded petrol produced the brown colour, unleaded makes grey/white. However yes, if very white then is not good .. ;D

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. ;D

HTH

Title: Re: Spark plug colour after rebuild!
Post by PJDavis on Nov 13^th, 2013, 6:29pm

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!

Title: Re: Spark plug colour after rebuild!
Post by Mike H on Nov 13^th, 2013, 6:37pm

I concur ;D

But as you'll also lose power steering and braking efficiency, do you fancy it ;D

Title: Re: Spark plug colour after rebuild!
Post by amigafan2003 on Nov 14^th, 2013, 4:22pm

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).