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2004 3400. Spun rod bearing on slug #4. Rod bearing number GM A500. I measured good rod cap vs. failed rod cap, ID on failed was .084" smaller. Measure OD of crank rod journal good journal vs #4, failed side is .014" smaller. I have not tried to micropolish the bad journal yet, it measures out for roundness. Can I hand polish the journal and then is there a bearing that is over sized for that? Will it hold? Or should I just pull the crank and send it out to be cut? I'm borke trying for a cheap fix. thx
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sigpicHow to make High performance Emissions:
A "true" High flow converter, straight pipe.
Low/No flow EGR valve, block off plate.
Carbon canister and purge valve mod, place in large 30 Gallon can, cover, and place curbside, the city will do the rest.
PCV valve and vent tube, reroute to exhaust to dump where it belongs, on the ground. Or add breathers and let it all free. -
HMMM, my #4 bearing just spun not long ago also, but there was no knock and only found it because I checked pulled the caps while the pan was off.
I just finished throwing a new bearing at it and am hoping it will hold a few hundred miles until I get my 3.4 here. Fortunately this is one of five vehicles so if it goes again I'm not that concerned.
If this is your daily driver, I suggest pulling the crank.
Did the bearings spin together, or did they overlap? .014" and .084" is a lot, you would be talking minimum .1" oversized bearings and I don't even know if you can get them that big. I'm sure someone else will chime in.
How long did you run it while it was knocking (if it did knock)?Last edited by ForcedFirebird; 06-14-2007, 04:10 PM. -
Firebird- don't post and lead folks astray if you have no idea what you're posting about. Read and learn. Contribute IF you know that of which you speak.
Cranks are generally turned in increments of .010", .020", and .030"... or .25mm, .50mm, and .75mm, respectively. A few engines use different increments... maybe .016" and .032". Undersized bearings are available accordingly. If the damaged journal is .014" smaller than the rest, then you MIGHT be able to have it turned. A reman crank (a.k.a. "crank kit") might be a cheaper (definitely quicker) option.
About that rod. There are no "oversize" bearings designed to compensate for a damaged rod- it's simply not done that way. .084" is quite a bit of metal... that rod is not salvageable. Your only options would be a junkyard or reconditioned rod.
There's no cheap fix here. Unless you have quite a bit of experience at engine rebuilding... and the time, tools, and facilities to do it... you'll be LOTS of time and money ahead to find a good junkyard engine and throw it in there.Last edited by tractorman; 06-14-2007, 08:14 PM.Comment
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Not trying to be misleading, but he was talking about polishing them up and re-using them. I suggested he pull the crank.Firebird- don't post and lead folks astray if you have no idea what you're posting about. Read and learn. Contribute IF you know that of which you speak.
95 sleeper:Can I hand polish the journal and then is there a bearing that is over sized for that?
I've got a rod I can sell you if you want, but ARI engines sells them for $18 plus shipping.Comment
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Thats just it, the damaged rod is smaller. Usually a damaged rod from a spun bearing is spread out, larger ID. This makes me wonder if the rod had a problem from factory. All this damage was caused by a failed oil pressure sending unit, I didn't know it was pumping oil out of the motor till me 50 mile haul was done and i left the freeway to a tapping motor. I drove on it for about 6 weeks 'cause I thought the tapping was a collapsed lifter, thats what it sounded like, it was very tinny sounding, I too used to listening to big iron V-8's. Then one day I dropped her to 2nd to pass by a guy and boy that tapping got real bad, it sounded like I a shot a lifter out of the valley. I still thought it was a valve-train problem. I tore her down and it wasn't in the valve train. So today, after being broke for so long, I popped the oil pan off to find #4 shot. Normally I would just pull the motor, and buy another one or rebuild her right. I ain't got the funds too. So far even trying to get a stock bearing for this motor has been a chore. So now that I have a good bearing to get part #'s off of.....
I guess what I'll do is, is hand polish the crank, emery cloth and a shoe string, and install a stock replacement bearing with that dental floss looking clearance string and see what I got. BTW, anyone got the torque specs the connecting rod cap? She's too new, beyond all my books and software.sigpicHow to make High performance Emissions:
A "true" High flow converter, straight pipe.
Low/No flow EGR valve, block off plate.
Carbon canister and purge valve mod, place in large 30 Gallon can, cover, and place curbside, the city will do the rest.
PCV valve and vent tube, reroute to exhaust to dump where it belongs, on the ground. Or add breathers and let it all free.Comment
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Rod caps are 39ftlbs. This is odd,after re-reading your post, I guess in my head I was thinking the rod was oversized. I will measure a set of stock rods when I have time and see how close they are (possibly today), and get back to you.
EDIT: I don't know if it is a bad rod from the factory, mine was also #4. As I inspected the other rod bearings, there seemed to be more wear at the center of the crank. With your 3400, you have main priority oiling where I don't so this could be coincidence.Last edited by ForcedFirebird; 06-15-2007, 08:20 AM.Comment
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LOL I'm procrastinating! I haven't gotten to it yet. I got a oil pan to replace on my probe, a tranny to pull on my dad's sho, a monte to retime, and then I can try and fix my olds. I'll let you know.sigpicHow to make High performance Emissions:
A "true" High flow converter, straight pipe.
Low/No flow EGR valve, block off plate.
Carbon canister and purge valve mod, place in large 30 Gallon can, cover, and place curbside, the city will do the rest.
PCV valve and vent tube, reroute to exhaust to dump where it belongs, on the ground. Or add breathers and let it all free.Comment
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