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- - Crankshaft grooves? (https://blazerforum.com/forum/engine-transmission-35/crankshaft-grooves-93220/)

Crankshaft grooves?

So, dropped the oil pan to replace a leaky gasket and to my surprise, found this (see pic). This is a 305 engine. Um, the crank should be smooth, yes? It runs fine (no smoking, no crazy vibrations, no metal in pan or oil). This is my other truck. I have a 73 K5 (an on-going project so it seems). The 305 engine in question is in a 84' GMC pickup.

Side note info: The flexplate rubs on the trans/starter cover so I took it off. It became worse after I put new motor mounts in. I raised the truck a few inches to install the mounts, nothing crazy, done it before and all went in smoothly. The flexplate 'wobbles' rubs more after securing everything.

When I bought the truck, I noticed the oil leak from the pan caused the trans bolts to come out. I replaced the trans mount and thought perhaps the flexplate bent (turbo350c), but after seeing the crank, not so sure.

My concern is perhaps I walked into a mess. Bad crank leads to bad flexplate wobble equals rubbing I get with the trans flexplate cover on?

Thoughts?

Thanks guys.

I had to replace an engine because the thrust bearings went bad and the crank would actually move forward when I disengaged the clutch. The flywheel dug grooves into the back of the block.

Quote:

Originally Posted by 73K5 (Post 668829)

Remove the rear main cap for thrust bearing inspection. Looks like the crank is so far forward that it is rubbing on the block near the bottom of the cylinder. If you do fix this vehicle, monitor trans cooler line pressure and make sure it is not excessive. That can cause bad thrust bearing problems.

Thanks for the input guys.

Les, I appreciate the explanation. Although I am very new to engine internals, what you stated makes sense. I have a local shop that rebuilds these engines at a reasonable price so I may opt to go that route for peace of mind. Not what I wanted, but that's what you get sometimes.