The other day I was replacing all 3 motor mounts on a Mack truck, there is always a lot of drama involved in doing this, no matter the make of the truck. Some worst that others. With this particular model of Mack the only real drama is being able to get to the mounts or getting the old ones out of the truck once you manage to get the bolts removed.
Reinstalling them is hardly any less tedious. Once you have one bolted to the frame it is time to lower the engine back onto the mount then drop the 2 long bolts in an tighten them up. However on this model as well as many others there is usually a spacer block to position the engine at the correct height these are doweled to the mount and sometimes to the matting support on the flywheel housing by a single dowel either on top/ bottom or both, During installation these blocks can rotate slightly or the engine can shift just enough to prevent the bolts from passing through all corresponding components.
To assist in alignment the best thing is to pass a drift through them, the drift needs to have a long enough straight shank near to the hole diameter with a slight short taper to bring everything in alignment, this is especially true when aligning multiple components whether a motor mount or structural steel
here is my alignment drift for this application.
I slightly knurled one end to identify it as a tool and not just some machined piece of stock to be later forgotten what it had been made for
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