Tech

The Inch-Pound Torque Wrench: An Unsung Hero Tool for Leak-Free Valve & Differential Cover Gaskets

While the inch-pound torque wrench is less famous than its bigger brother, it still handles really important jobs. (Image/OnAllCylinders – Paul Sakalas)

Like so many of our other automotive maintenance adventures, this one started with a few drips of oil on our garage floor. A quick inspection of our engine bay revealed a leaky valve cover gasket on our inline six engine.

No surprise there—any gearhead who’s worked around inline sixes (Ford, Chevy, AMC, Pontiac, or whatever), knows that I6 valve covers can leak like crazy. That’s because the valve covers and gaskets are usually pretty long, making them more susceptible to warping and flexing. And those leaks can be exacerbated by the valve cover material, particularly some later-model I-sixes that feature plastic valve covers.

And, you guessed it, these leaks can often be traced back to valve cover fasteners that are either too tight or too loose.

Though replacing a valve cover gasket is a relatively simple job here, it’s not something we enjoy doing. And considering how many I6 valve cover gaskets we’ve replaced over the years, we set out to finally do it right.

Though it’s a bit blurry, you can see that the dial indicator on the inch-pound torque wrench is pretty much the same as its foot-pound counterpart. It works the same way too, just set it to the desired torque, and it’ll click when you hit it. (Image/OnAllCylinders – Paul Sakalas)

After chatting with some engineers and mechanics, our quest led us to an oft-forgotten branch of the torque wrench family: the inch-pound torque wrench.

Understanding the Inch-Pound Torque Rating

Yep, inch-pounds. It’s similar to the familiar foot-pound torque rating, but obviously just requires a little less oomph. And if you look at a lot of factory service manuals, you’ll see inch-pounds spec’d-out for things like valve covers, differential covers, heat shields, spark plugs, and intakes—anywhere that demands a less-snug, yet still incredibly precise, fit.

We had to use an extension bar to clear the tall valve cover, which can lead to inaccurate torque readings (edit, we clarify in a comment below). We’re not too worried about it here as the worse case is just another drippy gasket, but it’s something to be mindful of in more critical applications. (Image/OnAllCylinders – Paul Sakalas)

Why In.-Lb. Torque Wrenches are So Handy

A lot of us are guilty of tightening down valve covers by feel, simply sensing for a bit of compression in a cork or paper gasket; many of us also use sight, by watching for a bit of RTV to ooze out of the sides as we tighten our bolts.

But as many inline-six owners (and their oil-covered floors) will tell you, being precise counts.

While our particular wrench was a 3/8-inch drive model, you can find inch-pound torque wrenches in 1/4-inch drive configurations too. (Image/OnAllCylinders – Paul Sakalas)

So we cracked open the service manual for our particular engine, set our inch-pound torque wrench to spec, and got to work.

After a summer of driving, we’re happy to report no new oil spots on the driveway.

Turns out, all we needed to save years of gasket installation hassle was a trusty, tiny torque wrench—an unsung hero tool for a drip-free valve cover.

An inch-pound torque wrench isn’t just helpful in valve cover installations either; we used one to snug-up our rear differential cover with drip-free success as well. (Image/OnAllCylinders – Paul Sakalas)

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2 Comments

  1. Perhaps you could dive a little deeper into the overall torque accuracy of the wrench when using extension.

    Thanks
    B. Woods

    • Used properly in a perfect world, extensions shouldn’t affect the accuracy. The general consensus seems to be that any effect is negligible provided that you use the shortest extension possible (to mitigate angles/flex), use high-quality tools, properly support the head, and keep the socket/extension perfectly seated in-line with the fastener. In everyday practice though, you may have to deal with angles, obstructions, or worn (or bent) tools that can have an effect on the result, so it’s something to be aware of.

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