Re: Spark Plug Photos.....Lean Condition?
Bill, There were no water beads on the plugs... Which eases my mind... You're seeing in the pics exactly what I saw when they were pulled from the engine... What I wonder about is why half of them have a small droplet of oil on them and the other's don't... Why?<br /><br />As I posted earlier, the water pressures are good. So I'm sure the pump is fine.. Impeller was changed late last year... All the cylinders have compression in the 115-120 psi range...<br /><br />However, the plugs have a lot of hours on them... <br /><br />And remember, I'm running premix...<br /><br />I'm not, and never have had an overheat condition, but when the guage reads almost at the max (and I mean almost!), it makes me wonder... This however has always been the case when at WOT... The problem is, my guage doesn't show numbers, so I don't know exactly what the head temps are... Just yesterday, I did hold my hand under the tell-tail just after a wide open run while at no-wake rpms and the water was hot, I could hold my hand there for about four seconds. I also did this on the head just after pulling out of the lake.. And I could hold it on there for about 5-6 seconds before I had to say "that's hot enough". So things were diffinitely warm but not scalding... This was just as or after the guage read about 3/4 up before I pulled it out of the water.. <br /><br />I need to mention that since I changed the head gaskets this spring it seems that at no-wake/cruising speeds have resulted in much higher temps than before.. Before the change, the guage read right at the middle or below at those speeds. Now however, it gradually climbs way up there.. The head gaskets I installed had smaller water passage holes than the originals... I was assured by Mercury that this was a design change made in the late 1980's... Maybe they wanted this motor to run hotter at lower rpms? Since my stats are new, I've eliminated those as the culprit, as well as the water pump, and poppet valve.
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<br /><br />It looks like I have a lean condition, at the top cylinders and maybe on #4 also... 2 & 4 have a little darker color to them, especially #4.. It has what looks like carbon deposits which can be scraped off with a little work...<br />These photos were taken the next morning after running the motor on the muffs, so they sat in the block for about 15 hours (if that matters). <br />Thought I'd ask for your input, since I'm trying to isolate a possible hotter than normal WOT temp issue.<br /><br />Compression was checked just prior to running the motor yesterday. and all checked at 115-120psi...
