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Thread: Engine on the stand with spun bearing...what should I look for?

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Posts: 1-6 of 6
2010-03-15 17:36:37
#1
Engine on the stand with spun bearing...what should I look for?
So I picked up a lowport from my friend who gave it to me for free...he said he spun a bearing but as soon as he heard the noise he had the car towed home, and only had it started for about a minute after to get it into his garage. I haven't been able to get in touch with him in a while to find out if it was a crank or rod bearing...and I've never disassembled an engine before. What am I looking for? How bad do you guys think the damage may be?
2010-03-15 20:12:49
#2
Originally Posted by noob13
So I picked up a lowport from my friend who gave it to me for free...he said he spun a bearing but as soon as he heard the noise he had the car towed home, and only had it started for about a minute after to get it into his garage. I haven't been able to get in touch with him in a while to find out if it was a crank or rod bearing...and I've never disassembled an engine before. What am I looking for? How bad do you guys think the damage may be?


I would check the rods first. remove the upper and lower pans. then crank the motor over and check each rod and bearing. to check the mains you will need to remove the girdle. then you can check each main(at least one side of them) bearing and journal. this will help some and fsm will be better.

http://www.sr20-forum.com/general-maintenance/5570-how-change-rod-bearings.html
2010-03-15 20:33:20
#3
Yah it's 99% of the time going to be a rod bearing failure not a main bearing failure. Also I think 90% of the time the trouble is rod bearing #3.
What you're looking for when you take the rod caps off are bearings that are completely missing (shreds of them will be everywhere in the oil pan and the oil will sparkle with copper flakes in it), or bearings that have "spun" which means they lost their seating and the tab that holds them still has failed and the bearing spun around inside there.
Regardless fo what has happened, you'll be able to tell by looking at the rod bearing what kind of shape they are in. They should be lead in color and sheen. There should be little to no gouges in the bearing material. You should see no copper. (When you see copper it means the lead got hot enough to melt away from the lead/copper bearing compound leaving only copper behind.)
2010-03-15 20:49:08
#4
You don't even need to pull the rod caps off. Look at them for discoloration due to heat. You'll see almost 99.9% of the time that #3 will have discoloration vs. all other rod caps. Another easy way to tell? Just push on the rods back and forth and the bearing that has failed will allow you to move the rod against the crank journal pretty easily. There should be VERY little movement.
2010-03-16 01:11:02
#5
Well after checking it out it looks like I'm actually missing the rod caps alltogether...when I picked up the motor the oil pan was already off but I thought that was all that was missing. I guess I was wrong...so now I'm not sure what to do. It looks like the bearings are missing too...but keep in mind I am a total noob (hence the username lol). Anyone have a pic of a complete bottom end with just the oil pans taken off so I can compare? I really do appreciate all the help guys
2010-03-16 11:40:46
#6
If the rod caps are missing, that's no good. You're going to need to replace the rods completely, since the caps and rods are matched. You MAY be able to get away with just replacing the caps, but I would risk it personally.
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