Help! is this noise my crankshaft bearings? (1 Viewer)

[cruz]

I need to get my 2F running before Thanksgiving and I am hearing a bad noise coming from the engine. This is my first time really driving this FJ60 since I bought it. At first I thought it was the valves but after adjusting those I still hear it. It happens only at RPM's above 1000 when acclerating, decelerating and at idle. It is like a clatter tied directly to the rpm's of the engine. I had someone rev the engine while I was down near the flywheel and it sounds like it is coming from the lower part of the engine. At first I thought it could have been the pilot bearing but now I think it is more forward in the engine.

Any ideas what it would be?
How difficult is it to pull the crankshaft and bearings? I do have another 2F I can pull parts from if needed.

I would welcome any ideas.

 

[60wag]

If it was the pilot bearing, or anything in the clutch, the sound would likely chage when you pressed on the clutch pedal.

It could be a rod knock. At test that was described to me was: Have the engine idling, rev it up slowly so you can hear the knock, then rapidly let it drop back to idle. If the noise goes away while its decelerating then returns at idle, its a good bet that you have a bad bearing. My 2F had a bad bearing at cyl #5. When I got it it had been run long enough to wear through the bearing and damage the crank. The crank had to be reground and oversize replacement bearing were used - part of a complete rebuild. When I took the oil pan off, I was able to grab the each rod where it was connected to the crank and shake it. It was obvious that #5 had way more clearance than the rest. If you're lucky and the truck hasn't been driven too long with the bad bearing, you might luck out and be able to simply replace it. Who kow's maybe they're all shot. You might confirm that its developing good oil pressure and also do a compression test before taking it apart. That might help determine how far you want to go if you do find a bad rod bearing. You might get lucky and find that the previous owner simply forgot the fuel pump spacer and the noise you're hearing is just the fuel pump being beat up. Good luck.

 

[cruz]

I will go ahead and pull the pan and check the bearings. Which bearings can be replaced without removing the crankshaft? How could I tell if the crankshaft needs to be reground? Is it visible after removing the bad bearing or do I mic it?

 

[60wag]

The rod bearings can easily be replaced with the crank in place. The mains would be harder - I'm not sure if you can slip them out or not. I know of some people who have just pollished the crank with sand paper to reduce some scratches then tossed in a new bearing and got many more miles out of the engine without any problem. I think its depends how much of the old bearing is left. The brass shouldn't do much damage to the crank. Its the rod hitting the crank that trashes it. The crank should be smooth and shiny. You could mic it but if its damaged, I think you'll see it. If you do decide to get replacement bearings, definitely measure it to find out if it was reground at some point.

While you're under there, take a good look a the cam and the gear driving the distributor. Look for anything else that might be making noise.

Oh, also when you drain the oil to pull the pan, look for bits of brass or steel in the oil - might be a clue.

 

[lovetoski]

One simple diagnostic would be to send an oil sample to a lab (blackstone is the one I use). Their report will tell you if any bearing materials are in the sample. If you don't have unusual amounts of bearing material in the sample, then it's unlikely that you have worn bearings. $20 bucks + the ride.

 

[ballardcruiser]

Here's where I get admit one of my many car repair mistakes!

I had the almost the exact same symptons happen to me right after replacing the oil pan gasket. I was freaked out that the worst happened and that I'd need an engine rebuild. The reality? I bent the oil pan so bad when I removed it that a rod (I suppose) was hitting the side of the bent pan. Replaced the pan immediately with a new unbent one and all was back to normal.

I guess when you take off that pan, inspect it to make sure it's not bent in, too!

 

[cruz]

Well I have already changed and disposed of the oil so I cannot test the oil. The fuel pump has the appropriate gasket/spacer assy. I just checked the compression and it seems they are all between 160 and 170 psi. I have pulled the pan (easiest one I have ever done) and now I don't know where to go from here. There is movement side to side when I grab the rods. The gap measures 0.4mm on #6 but most are from 0.2-0.3mm.
What is the real way to check? Should I disasemble one? The cam shaft looks good and doesn't have any sign of wear.

 

[cruz]

I cannot believe it! I went back out to check out the oil pan for any scraps and it looked like a metal recycling bin. I found 3 inches of an old dip stick bent into a nice curve sheared off perfectly to a square, a few dark chunks of something that used to be round and made of a hard orangeish brown insullating material (not metallic), and a handfull of tin foil like flakes. Ouch! The vehicle has almost 275K but I am beginning to think that my noise isn't from normal wear but rather from feeding it like it was a garbage disposal.

 

[60wag]

Are the tin foil flakes magnetic? If not then hopefully they are journal bearing shavings. The side to side movement of the rods on the crank is ok. Its radial play that's bad. The book specs 0.02 to 0.10 mm of clearance between the rod bearing and the crank. I think the only accurate way to measure it is with plastigage. I think you're safe to disassemble the rods bearing to inspect them. Just make sure you put them back together EXACTLY the way they came apart and make sure they are torqued properly.

You might try rotating the crank by hand. Pull the plugs first and you might have to pull the rockers. You might be able to feel it binding at some point, maybe not. You might pull the oil pump and confirm that it roates easily and that it hasn't ingested any big chunks. I'm guessing you'll find one rod bearing that looks different from the rest when you take them apart.

 

[cruz]

I finally have the truck running sweet. I was able to grab the bottom of the 6th piston and shake it up and down. When I pulled it apart the bearing was all chewed up. One way to tell what bearing it might be before pulling the pan is to unplug one spark plug at a time while it is running. The noise should significantly reduce if that pistons bearing is shot. The shavings were off the 6th bearing, probably nickle??? These bearings were cake to replace. Thanks for all the help, excellent forum!