I'm going to be replacing the timing chain guides on a 2007 Nissan Xterra soon and am running into a bit of a hiccup. There's a tool one can buy that bolts onto the flywheel to lock the engine in place once you've rotated it by hand to TDC. However, that tool is fairly expensive considering what it is and how many times I plan on using it. You need the engine locked to make removing and then properly torquing cam and crank bolts manageable.

My tentative plan was to turn the engine to TDC, override the shift interlock with the button next to the shifter, and shift it into drive, reverse, low gear, etc. However, I'm not sure if doing so would result in the engine engaging the transmission, given that it won't be running when I shift it. My hope is that it would engage with the transmission, locking the crankshaft in place.

So, my question is: will shifting an automatic transmission into gear with the engine off result in the engine being engaged with the transmission, or will it still effectively be disconnected?

If you see any other holes in my plan in general, please let me know.

Thanks in advance!

  • Fred is correct in his answer. You might be able to, depending on the vehicle, take the inspection plate off of the transmission where the torque converter/flexplate is at, then have someone wedge a screwdriver in against the starter ring to hold the engine in place. Some vehicles you can take the starter out to find the starter ring and do the same thing. It takes too people, but finding a friend is a lot cheaper than the locking tool. Jul 13, 2018 at 23:44
  • When you torque the cam gear bolts just use a wrench on the cam it self. The crankshaft is torqued to 33 ft lbs with an additional 90° after. You could do this with a rubber strap wrench.
    – Ben
    Jul 14, 2018 at 4:32

2 Answers 2


An automatic transmission will have a torque converter on the output of the engine, typically combined with the flywheel. On more sophisticated or exotic vehicles, you'll find computer controlled clutch systems. A torque converter is a fluid coupling, which can be compared to pointing one desk fan at another, but putting them in an aquarium pushing fluid instead of air. That's a simplification, but one that is commonly used to explain these devices.

Shifting your transmission into gear will not prevent the engine from rotating.


There are other methods that could be considered to lock the engine :

1) use a "sparkplug lock" available to purchase but you could make one : old plug with internals removed tapped to receive a bolt...

2) bar and socket on the crank pulley - does need some precise mark s to make sure it does not slip...

3) sometimes the starter motor fixing holes will allow bolts through to "clamp" the flywheel...

As Frd says, the auto transmission will not lock the engine.

  • Interesting about the starter motor holes. I've also heard about cramming one or two cylinders at the bottom of their stroke with rope. I've got some things to ponder now. Thanks for the ideas!
    – atraudes
    Jul 15, 2018 at 0:44

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