Quote:
Originally Posted by Skid Row Joe
Just had two glow plug cavities helicoiled on a '99 W210 turbodiesel. Glow plugs were stuck because of carbon build-up, and were summarily drilled-out......
Is this an acceptable, permanent, long-term, viable fix or repair? The car seems to be running perfectly in the 50 miles or so, being driven daily since the helicoiling installs.
Will it ever compromise the seal of the cavity to the atmosphere, i.e. loss of compression, or shoot the glow plug out / malfunction?
I'm skeptical as to the feasibility aspect of anything approaching long-term (years/10s of thousands of miles) on a helicoil in the glow plug cavity.
Any actual, experience in this arena greatly appreciated!
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I think there is only 2 ways the Original Glow Plug cavity could have gotten Carbon; they were loose; or, they did not seal in the sealing area for some unknown reason.
If the Glow Plug holes/cavity was machined properly and the Glow Plug was not loose I think the Carbon build up inside of the Glow Plug cavity would likely be due to some localized warping of the Aluminum Cylinder Head.
So Helicoils or not if the Head warps and mess with the sealing area of the Glow Plug it could cause a leak.
I think the Helicoils are Stainless steel so I don't believe there is going to be rust between it and the Glow Plugs unless the Glow Plug itself rusted. A Neverseeze type compound on the Glow Plug threads should prevent that Rust.
In your particular case I would likely have coated the whole of the Glow Plug body between the where the Tip/Element comes out of the Plug and the top of the Threads. That way if they for some reason Carbon again filled the cavity they would not get easily trapped.