Rod knock

[Agro]

Can I just change the bearings out. Motor is still in the car . Probaly not the best solution but id rather not do a complete overhual...... Yet. Any input or experience with this would helpful.

[Festy46]

The bearings are the softest part, so there is a good chance your crankshaft may not be worn. Take the spark plugs out and then take the rod cap off and push the connecting rod up off the crankshaft. Get a good caliper or a micrometer and measure the crankshaft at several points where the rod was running. Compare your measurements to the specs for the crankshaft including the allowable tolerances. If your measurements are within the specs put the new bearings in and check the clearance with a piece of plastigage. If the plastigage is good, clean it off the bearing and oil up both halves and assemble the rod cap and torque to specs. If your crankshaft is a little undersize, you may be able to buy .002" undersize bearings that will get your plastigage flattened to the correct size. If your crankshaft measurements are way off from the stock specs, look at the back side of the old bearings. You may see a number like .010 or .020 stamped on the back. It's possible you could have an undersize crankshaft with undersize bearings in which case you would need to buy undersize replacement bearings.

Years ago I bought an old Minneapolis Moline tractor that had a rod knocking really bad. I took the rod cap off and sandpapered the crank journal because it was rough and installed a new bearing. It lasted for years, but the max rpm for the engine was only about 1500.


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[Larry Hampton]

Pull the plugs, drop the pan. Disconnect the tranny and remove the clutch and flywheel. Pull the front cover and remove the timing belt (might not be a bad time to replace) Pull the rod and main caps and drop the crank. Take it to a machine shop to be turned down to the next sized bearings. Get some plastigage and bring the crank back home to be reinstalled (another crank is an option as there won't be as much down time.) Install the crank on the mains and check the thrust so that its in spec. Pull the mains one at a time and plastigage them. Then move onto the rods, you can plastigage as you go. You might also pull the oil pump apart to make sure no trash got in there, clean the pan out and reinstall with a new pan gasket.

Any job worth doing is worth doing right. I tried the memory cloth turning of a rod journal on a Dodge Shadow. Fail.

[Agro]

Thanks festy46. I will give it a whirl. Finding someone with a good longblock seems to be more of a task then anything. Ive built plenty of motors but all with a preformance goal in mind. Which is unnatural for this motor. I guess I'm just trying to get some more miles out of this motor. this is just my get to work with good mpg car. I'll update with my findings and outcome.
Larry.... Unless I have a bad wrist pin on my rings are shot pulling the motor out seems unnecessary. especially for my goals. If it lets go .... Maybe. I want to avoid a motor swap for the sake of fuel mileage. I also have other projects that deserve attention. A bandaid is instore for the festy....lol

[Larry Hampton]

I wasn't talking pulling the motor, just the crank out the bottom.