Hi,
'89 Escort 1.4 (CVH), 107k miles, well serviced throughout its life.
I've been feeling that it has been lacking power recently (they don't make 15 year old cars like they used to!) so I checked compressions on the weekend, and had a look at the plugs:
#1 11.1 Grey (normal) colour
#2 12.5 Grey (normal) colour
#3 12.5 Grey (normal) colour
#4 12.0 Sooty black colour
First, is this difference in compressions (which I rechecked to be sure) OK, or too high?
Second, any ideas why #4 plug is black (indicating rich running?) but the other three are OK? It's definitely sooty black and not oil-covered black.
Thanks very much!
Mark
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poss valve stem seals on that valve???
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The difference in compression is within 15% which
is tolerable.
I seem to remember vauxhall viva 1800's suffering
from single plug fouling..the cure was to reduce
the size of the carb main jet.
check the carb for dirt/float level.. choke
operation etc. and the thermostat as cool running
can make the problem worse.
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Thanks dieselhead. I'll give the carb a clean and may also reduce the main jet - it's been suggested as a fix for the slightly rich running anyway.
(I know it's running slightly rich - old carb - but confused as to why only one plug shows the symptom...)
Thanks,
Mark
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most conv engine cars ie engine front to rear will alwaysfoul up number 4 due to heat build up at back of engine even more so on straight six's
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Hi,
This car is front wheel drive - engine is transverse. :-)
Cheers,
Mark
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My 1977 Mk1 Cavalier 1600 always had a number 4 plug which was sooty when the others were the perfect colour.
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This seems to be quite common on older engines, I suspect that imperfect inlet manifold design/manufacture gives an uneven distribution of fuel-air mixture between cylinders.
Another possible explanation is no. 4 cylinder running slightly cooler because it's best able to radiate heat.
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Hello
May sound silly and may not work.
try using the next heat range plug up from the one you are using on the engine.
it would be interesting if it clears up.
(iam not a mechanic)
Martin Winters
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Hi
I mean put a plug that is 1 notch higher in that cylinder and see if it clears up.
A silly idea i know but it may work
(iam not a mechanic)
Martin Winters
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MGK may be right as 3 are ok would point to valve stem seal/s
it is also possible the plug lead has a possible slight short
ie not supplying correct current to plug.causing the spark to be less than it should be.as all other three plugs are ok would be inclined to look at plug/lead and distributer cap.could be wrong but just a thought?
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