Holes in your head ... Or the fine art of crack detection

By Jim Tapp,
Goodson Tech Services Manager & ASE Certified Master Machinist

In the tech training classes we hold here at Goodson, we were talking recently about crack detection and I thought, "Hey, that'd be a good topic for Talkin' Tech." Of course, I could probably write a book about crack detection, but an overview is all we have room for here.

First, let's talk about why we check for cracks in heads and blocks. The obvious reason is that you can't fix what you don't know is there. Cracks and pinholes in heads and blocks can lead to a loss of power in the engine, resulting in poor performance.  That, unfortunately, is the best-case scenario. Cracks or pinholes can also lead to overheating and complete engine failure, not to mention dissatisfied customers returning again and again in search of that elusive leak.

My recommendation is when a customer brings in a head or a block for you to work on, before you even take the piece, ask him a few questions. Ask if he's had any coolant leaks. If he has, and the deck checks flat you're probably going to be dealing with cracks and/or pinholes. Ask him where he got the head. If it came from a "core specialist" (a.k.a. the junkyard), you have to think the worst. You have no history so you'll need to check every inch of the core. Okay, you get my drift. If your customer wants you to diagnose a problem with the head or block, you'll probably want to use one or more methods of crack detection to determine where the problems are.

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Quick Tips from the Techxperts™

Increase the life of your crankshaft polisher with routine maintenance

Stop premature motor failure by spending a short time every day to perform routine maintenance on your polisher.

• Use regulated compressed air or a vacuum to remove abrasive and metal particles that have accumulated in the electric motor during normal operation.
• Remove frayed belt threads that collect on roller bearings.
• Spin rollers and check for smooth, quiet operation. Replace them as necessary.
• Avoid belt run-off. Correct this by checking frame alignment and the condition of the roller crown. (A crown of at least .030" is required for correct tracking.)
• Use a sensible amount of down pressure while operating the unit. If an undesirable finish is produced and you think that using more down pressure is the answer... chances are, it won't improve the finish. We recommend using an alternative belt or our Crankshaft Polishing Rouge (Order No. CPR-16). The polishing rouge will enhance this process and give a superior finish.
• Remember... the crankshaft polisher has a fractional horsepower motor that is designed for high RPM, not heavy loads. When using wide belts, lift the unit to help limit unnecessary load. Avoiding excessive down-pressure also minimizes belt distortion that causes deformation around oil passages and hourglass-shaped journals.

Techxperts™ Top Picks

The Powered Ring Filer is a must have tool for your shop

Erik Shepard, Goodson Tech Services Department

I've always been a firm believer in using the right tool for the job. Before Goodson developed the Powered Ring Filer (PRF-812DW), when I needed to file rings for an engine, I used the manual ring filer, just like a lot of you. You probably agree that filing piston rings manually is a time consuming, tedious task.

Well, let me tell you. I recently filed a complete set of rings for my drag racing engine using the Powered Ring Filer and it took me all of 30 minutes. You read that right. 30 minutes to file a complete set of rings. And the best part, each one was to the exact clearance every time. Can you believe it? Filing piston rings is actually fun!

And one more thing. The deburring wheel that is available standard on most models, is so handy. I didn't have to look for a deburring tool to remove any sharp edges, it was right there. No scratches or hanging up when installing the rings. It's great!

If you have any ring filing to do, the Powered Ring Filer
(PRF-812DW) is a must have for your shop.