Northstar Engines and System Technical Discussion Discussion, Northstar headgasket job did I f up? in Cadillac Engine Technical Discussion; I wire brushed the head for like a good 2 minutes to get some gasket material off did I mess ...
Automobile(s): 2002.5 F55 STS/64500mi, 2004 Ford F150 SuperCab4x4
MD Eastern Shore - Kent Island
Re: Northstar headgasket job did I f up?
NEVER wire brush an aluminum head. If you can see any pattern or scratching on the head surface you now need to take them to an automotive machine shop and get an educated statement on whether you need a slight cut taken on the head. The spark plug hole threads need to be carefully cleaned with mineral spirits, a twisted brush, and shop air. The head bolt holes need to be brushed out.
If you wire brushed the block deck, then unless every coolant hole was plugged with rags, the block needs to be flushed out and cleaned. Any gasket material in the cooling system, cylinders or chaincase will play hell with the rest of the engine. Assuming that you're either inserting or studding the block, that job needs to be surgically clean also.
Aluminum is a problem. It's soft and easily damaged. If you use a wire brush, special technique has to be used- like Sub said - any dust created is that of the aluminum itself and will damage the rest of the engine. Surgically clean is the correct term to use.
Personally - I do use a wire brush in a high speed die grinder. One day I'll take a video of how I do it. A drill is too low of a speed and it will dig in and gouge the surface. Gasket scrapers are a no-no because they will also nick/gouge the block / heads no matter how careful you are. The trick is to BARELY touch the surface and keep that brush moving at all times. This is an aluminum block / aluminum head combination (not a bi-metal engine) so surface smoothness is not AS picky. Once you have different expansion rates, like that of the 4.x series engines with aluminum/iron combination components, you have to have the correct RA on the surface so the gasket won't wear out too quickly from the constant scrubbing.
One note about a wire brush spinning at above 20,000 rpms - unless you're tough and can handle it when one of those wires shoots up one of your nostrils (safety glasses or face shield an absolute MUST!!) don't even attempt this. And a drill IS too slow. A new wire wheel will be too rough on the surface- it needs to be broken in first on other parts.
No Scotchbrite - as Ranger said.
Surface conditioning discs may be OK but no matter what you use, but 3 keys are:
1) EVEN cleaning and no gouging
2) Be careful with that aluminum dust- where it goes- it can destroy your engine
If you're nervous about this take it to a machine shop and have the heads milled. Very little material can be removed.
Here's how I cleaned the gasket material off my heads and block when I installed the stud kit: with Ford/Motorcraft Metal Surface Cleaner and a PLASTIC scraper. Worked like a charm and no risk to the head/block surfaces.
Here is Ford's statement on cleaning gasket material off aluminum blocks and heads on ANY Ford engine (from Ford TSB):
WARNING UNDER NO CIRCUMSTANCES ARE ANY ALUMINUM GASKET SURFACES TO BE CLEANED USING RAZOR BLADES, ROTARY ABRASIVE DEVICES INCLUDING ROLOC AND 3M BRANDED SCOTCHBRITE PRODUCTS, ROTARY WIRE BRUSHES, SINGLE HANDLED WIRE BRUSHES, HAND ABRASIVE SUCH AS SANDPAPER OR EMERY CLOTH, OR ANY CARBON STEEL BLADE. THESE TOOLS ARE PROVEN TO CUT AND DAMAGE ALUMINUM AND WILL DISRUPT THE POLISHED FINISH. ABRASIVE PARTICLES ARE ALSO SUSCEPTIBLE TO ENTERING THE ENGINE CAVITIES AND MAY CAUSE INTERNAL ENGINE DAMAGE. THE ONLY TOOLS ACCEPTABLE ARE PLASTIC AND WOOD SCRAPERS COMBINED WITH USE OF MOTORCRAFT METAL SURFACE CLEANER, F4AZ-19A536-RA, OR EQUIVALENT SOLVENT.
If it's good enough for Ford (who arguably had the better DOHC V8 design), it's good enough for a Northstar.