spark plug oil leak...
- Thread starter borntofli
- Start date
How tight is "as much as I dare" ? If you have a torque wrench set it for 80 inch pounds and tighten the plug. Is there a gasket on the plug? (metal, movable ring above the threads) It might be flattened so much that it's not sealing. Some engine builders maintain that a new gasket should be used anytime a plug is removed. That's possibly overkill for our little engines but the gasket should be there and capable of sealing. And the plug must be tight.
Are you sure your leak is at the spark plug and not a cylinder head gasket problem?
Tom
Are you sure your leak is at the spark plug and not a cylinder head gasket problem?
Tom
I crank it as tight as I can with one arm (without putting any body weight into it, so leaning FORWARD and pulling it BACK), but yes, at high RPM I have an oil leak (I'm talkin 6000+), otherwise it's all good. The only thing I can suggest for you is gasket maker (permetex copper, plugs get reeeeaaaaally hot). Unless of course you're running a ton of oil in your fuel, in which case, it'll do that anyway
Sorry, Mew, but excess oil will not make a spark plug leak. The OP possibly has defective threads in the cylinder head, possibly a crack, both have been reported before, or his plug is not torqued sufficiently. A new plug with a new gasket and installed correctly should not leak. There should be no reason for gasket sealer on spark plug threads.
Overtightening a plug can distort and damage the threads in the head also. That's why I recommend using a torque wrench if you don't have a 'feel' for how tight you're making something.
Tom
Overtightening a plug can distort and damage the threads in the head also. That's why I recommend using a torque wrench if you don't have a 'feel' for how tight you're making something.
Tom
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More times than not on most engines I run (especially 4 cyl. Japanese), I like to use anti-seize on the spark plug threads. It also helps the plug seal but don't go overboard with it.
I just put a brand new plug in my HF 212cc before the race last week end and tightened it a bit too much......it almost didn't come back out.....seriously. A dab of anti-seize is in order here. Sure beats a heli-coil.
I just put a brand new plug in my HF 212cc before the race last week end and tightened it a bit too much......it almost didn't come back out.....seriously. A dab of anti-seize is in order here. Sure beats a heli-coil.
I experienced some residue around the plug too. I replaced the original plug with a Denso and no further problems. My guess is that the plug that came with the kit was simply not machined as accurately.
IMO
I use an anti-seize product on sparkplug threads... and was surprised when I read in the NGK literature that they DO NOT advise it.
Oh well, I'm gonna keep doing it!
Very wise to use a torque wrench when installing plugs.
With aluminum heads, it's probably even perilous, at that, after the motor has a buncha miles on it...
The machined suface at the top of the sparkplug hole is probably not cut well.
And it's probably too bothersome to have it milled properly...
I would investigate a replacement head if the leakage bothers you.
Then it would be luck of the draw, if you got a better one! lol
Good luck
rc
I use an anti-seize product on sparkplug threads... and was surprised when I read in the NGK literature that they DO NOT advise it.
Oh well, I'm gonna keep doing it!
Very wise to use a torque wrench when installing plugs.
With aluminum heads, it's probably even perilous, at that, after the motor has a buncha miles on it...
The machined suface at the top of the sparkplug hole is probably not cut well.
And it's probably too bothersome to have it milled properly...
I would investigate a replacement head if the leakage bothers you.
Then it would be luck of the draw, if you got a better one! lol
Good luck
rc
My plug is tight as well, fuel goop runs down the head. Could it be that the crappy stock plug just can't burn all the way? I have an NGK (b6hs) and new boot coming. Will this solve or at least alleviate the problem?
Most it would do is perhaps seal it properly, my B6HS has the same issue. spark plugs have squish gaskets that are good for only one use, removing the plug renders it virtually useless. Only thing I'd suggest is maybe your fuel mix is too rich, or too much oil mixed in with the fuel (I noticed that when my friend decided to put 12:1 in my tank, the motor ran like crap and oil was EVERYWHERE). However I run mine relatively lean and even with a good mix (around 24:1), at 7000 RPM my head leaks a lot too, you can see it leaks from the plug at the very least, unsure of the head gasket
Leaks around the threads or sealing surface have nothing to do with the plug firing nor will changing the plug wire and boot help. If the plug leaks it's due to the reasons suggested in the above posts. Either the gasket surface wasn't machined correctly or the threads are bad, or the head might have a crack in the threads. The plug itself might be the culprit.
Head gasket leaks are much more common that leaking spark plugs and the residue seen on the cooling fins is sometimes mistaken for a leaking plug.
Tom
The short answer?
Replacement may alleviate the problem.
Longer answer.
Welcome to life dating a chinagirl!
Ain't they cute?
I LIKE 'EM!
Yet they do have their faults. Imagine that!
Everything is suspect!
The plug could be on the wrong end of the tolerance scale, the crush washer could be trash, or trashed, or the threaded sparkplug hole could be on the big side of tolerance, or beyond tolerance, OR, the seating surface for the sparkplug could be machined poorly.
Take your pick!
Fuel mix should NOT affect leaks from the top of the cylinder.
..and I say, 'should not' !
( Years back I learned that the graphite oil Arco once marketed WOULD DEFINITELY find EVERY tiny flaw in ANY gasket on an engine.)
....and you can take THAT to the bank! lol
That stuff could make ANY engine look like absolute trash in just a short time!
...and 24;1 is ok for the first tank of break-in mix... slim it to at least thirty to one, and forty to one is probably better for any chinagirl using some sort of modern mix oil designed for two stroke use.
50 for the good oils, and I have not tried Opti2, but I'd like to !!!
and of course, the top of the cylinder to head mating surface could be wonky, or the head gasket, itself.
By golly, I hope that helps!
rc
