Using compressed air to blow out carbon from glow plug holes
 

The FSM procedure for replacing the CDI glow plugs specifies using a pair of cylindrical brushes, 6mm and 10mm. So I got a set of brushes. What about also using compressed air to dislodge the carbon? Any downside to that?

Why would you want to blow dislodged bits of carbon deeper into your engine?

Use a shop vac to remove the bits instead.

I don't have a suitable vacuum.

Won't dislodged carbon fall into the engine when using the brushes? Why would that matter...won't it just get blown out the exhaust?

You can use compressed air to pull a vacuum, just blow air through a tee with both ends open. The tee side will pull a vacuum:
https://i.pinimg.com/236x/2e/1a/20/2...made-tools.jpg

Bucket Head 5 gal. 1.75-Peak HP Wet Dry Vac-BH0100 - The Home Depot

For $20 plus tax, you can't go wrong.

Thanks for the tips/recommendations. But as to the fate of carbon that drops down into engine....it just gets blown out the exhaust, right?

AFTER it gets dragged up and down the cylinder walls. Usually causes no problem when it's loose but using compressed air can force it into any gaps of the rings, valve seats, etc.

Your car, your money.

Thanks for the clarification....makes sense just to stick with the brushes like MB recommends.

Put this on your Xmas/wish list.

https://www.shopvac.com/product/shop-vac-5-gallon-4-0-peak-hp-hardware-wet-dry-wall-mount-vac-catnum:3942300

Handy to have and it's one of those things you wonder how you did without. Keep an eye out for specials. I picked mine up for $39.95 at Ace Hardware during one of their spring special savings deals.

I actually have a shop vac...what I wasn't clear on was to how to rig attachments in such a way as to get down in the hole.

Excellent....thanks, Mike!

That Amazon kit may not be small enough to get in the hole. I use a hose or tubing small enough in diameter and duct tape it to the large vacuum hose. Works every time.

Where did you purchase your brushes?

I use a series of rubber hoses with duct tape wrapped around the end as a seal ring. Wrapping a few rounds of tape on a 5/8" hose makes it fit tight into the vac hose. The tape forms a really good seal which isn't necessary but it is quite efficient.

I never blow anything into a cylinder on purpose. I use heavy grease on the reamer when I do glowplugs. Most of the carbon comes out then.

Turning the engine over after reaming glow plug hole blows most of what the greasy reamer misses.