Little Bubbles!

[jonnyconcrete]

Having finally, after 2 months, manged to stop all of the leaks on my engine and got it running like Japanese sewing machine...I decided to give the engine bay a good scrub and degrease. Having gunked it and swilled it all down there were pools of water surrounding the spark plugs. I started the engine so the heat would dry everything out and noticed a steady stream of bubbles (only very tiny) in the water pools for number 1 & 3.

When it was dry, I whipped out the plugs...it appears that number 1 & 3 have helicoils! I tightened the plugs back down...1 & 3 as tight as I dared, added water and re-tested. Bubbles still there, is this tiny loss of compression normal with helicoils?

I was considering fitting new plugs with new crush washers and re-testing...

[GrUmPyBoDgEr]

Having finally, after 2 months, manged to stop all of the leaks on my engine and got it running like Japanese sewing machine...I decided to give the engine bay a good scrub and degrease. Having gunked it and swilled it all down there were pools of water surrounding the spark plugs. I started the engine so the heat would dry everything out and noticed a steady stream of bubbles (only very tiny) in the water pools for number 1 & 3.

When it was dry, I whipped out the plugs...it appears that number 1 & 3 have helicoils! I tightened the plugs back down...1 & 3 as tight as I dared, added water and re-tested. Bubbles still there, is this tiny loss of compression normal with helicoils?

I was considering fitting new plugs with new crush washers and re-testing...

It is highly likely that gases are escaping around the outside of those Helicoils & that the crush Washers are not large enough to cover the outside diameter of them.
IMHO Helicoils should not be used as a repair for Spark Plug Holes as it is impossible to make them leakproof.
Provided there is enough Material the Plug Hole should be prepared for a solid threaded Insert then the Cylinder Head with fitted Insert should be spotfaced to provide a flat sealing surface for the Crush Washer.
You may get away with fitting new Plugs; certainly worth a try when the rework on the Head will mean a Head off job & a suitable repair in a properly equipped Machine Shop.

Good luck!
John

[rocket]

Hi,

I have used helicoils on many cylinders over the years,mainly jap bike engines.Never found them to be a problem.I expect many engines if tested for air leaks in this way would also be found to leak...dont worry about it.

Ian.