Checking rid and main bearings

[icanfixall]

Replace the mains or end up with a problem later... A pic would really help too. If its worn thru the babbit your method of measurement is off. The bearing caps will line up properly but... The thrust bearing needs to be centered properly. The crank needs to be pushed both backwards and forwards while centering the thrust cap. I don't have my manual so someone is going to have to fill in the procedure for this.

 

[cowman79]

Here the two pictures of the bearings with the brass showing. As for the bearing blocks not lining up properly I was looking at the back of the block. When I looked at the front of the #5 bearing block it looks pretty close.

 

[flareside_thun]

That is interesting bearing wear. I agree with Gary, replace all the mains.

 

[OLDBULL8]

Those bearings got, "WIPED" they need replaced. Amen.

That will fix your knock.

 

[icanfixall]

The first pic shows what a main bearing bore wear looks like when its in need of line boreing or line honing to straighten the bore in the crank webs. You see the small area where its worn thru... That bearing is higher in that area. Now if this engine was rebuilt by someone it could be they got some dirt under the bearing and it road up higher in that area but... Usually this is the factory maching not really being straight thru the webs in the block... Its an engineered "thats close enough to work well" kinda additude for something thats not going to live forever.. Like my engine is.... I also would post some pics of the rod bearings. If the crank bearings look like this the rods can't be any better. Mains wear more on the bottom half and the rods wear more on the top half.

 

[cowman79]

None of the rods had brass showing and they were all to spec with the plastiguage.

 

[cowman79]

I would like to thank all of you for the help with my problem even though it is not what I wanted to hear.

 

[icanfixall]

When you say its not what you wanted to hear I completely understand.. But you have to know nobody here will tel you "thats fine.. Just run it"... Thats about the worst thing a forum can do to a member. So... You leave the bearing alone. Put it back togehter and my gosh.. Its still knocks.. Now what. Your mains are shot.. We agree on that... But they will continue to work in your engine but for how long.... Maybe 6 months... Maybe 6 weeks.. No matter... They are shot. Did you actually see the top half of the rod bearings. Thats the side that wears most. Remember the rod bearings are getting pushed down for a long time by the piston weight and the compression. Then the rod is driven down by the combustion... Still its wearing down on the top half of the rod bearing....
Now the mains are always being pushed out of the block so the bottom half is the bearing that shows wear first. I just don't want to tell you the rods are fine just because you said they measured out fine with plasticgage. Actually seeing ALL of them is important. Your this deep into the bottom end its best to have all the inspections prove you are correct. Its never fun to do a job twice because you skipped one step. Look at the back side of the rods and mains. See if they have the nembers 010 on them... That means the crank was turned 10 thousands undersize so the bearings are that much thicker to fit the smaller diameter crank journels.

 

[cowman79]

I do thank you icanfixall for the information. With the data I have collected today I feel that this engine is in need of a complete rebuild. I will probably be sitting this motor in the corner for a while due to the cost and focus on the motor that is in the truck currently. I do not have the time or the money at this time to do this motor properly. I was hoping this was a quick fix and I could stick this engine back in the truck because the engine I bought and put in the truck has used two gallons of antifreeze in the first 100 miles along with occasional white smoke at start-up and water coming out of the exhaust.

 

[Ethan Smith]

Dang man im sorry to hear that. Im tearing down an engine myself and hoping to see hood news rather than bad. Its never easy to find out youve got to spend money.