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This was on my '91 4BTA.
I noticed a lot of play of the crank shaft when you pushed the clutch (maybe a 1/4"?). Turns out it is a common problem that Cummins came up with a replacement part/cure for...
If you leave the stock part in there, as long as it is in tact, it will probably be fine but keep in mind that it can come apart. If you notice a lot of crankshaft play then this is the case. You can either preventatively fix the problem or do it under your truck. Not a big deal but it involves removing the oil pan. If you have the problem (lots of crankshaft play) and leave the problem unresolved for too long, especially with a standard trans, it can cause your crank to wear into your block and possibly majorly F things up for you...
Unfortunately I forgot to take a pic of the new replacement bearing before I installed it, but there is a pic of it installed. The old bearing, the #4 counting from front to back, is a three piece, with the washers on the side (that prevent lateral movement of the crank) which are pressed into the main bearing. The replacement is a single one piece so it cannot seperate and have the same issue happen again... With the old piece, the side washers ("thrust washers") become unpressed from the main bearing, and this allows for the excess play. If your engine has never been rebuilt, it probably has the older style bearing. This is the only bearing of this style in the whole engine and the only place where this issue can ocur.
It is also good preventable maintenance IMO, the bearing I think is less than $30 from Cummins. You can get from either Cummins or Case or a slew of other places. Most cummins dealers know the problem well. I imagine it is also a common problem for earlier 6BTs as well. Not sure when Cummins redesigned the part...
I also have still to this day never rebuilt an engine and this was my first time replacing a bearing, if it matters. Super, super, easy...
Directions:
Pull oil pan. In bottom of oil pan, you should find the thrust washer if you had excess crank shaft play... Undo cap the cap of bearing number 4 [number #3 in photo below, secured by #4 in photo ]. Remove old bearing, both the top and bottom half of the bearing.
Your new bearing will be both top and bottom pieces. I personally dunked the new bearing in oil for a couple minutes hoping that it might somehow absorb oil but doubt it actually did. Most importantly is making sure that you **DONT INSTALL BEARING DRY. Make sure there is oil there and on the bearing.**
Then I replaced top and bottom pieces. Top pieces (the troublesome one) needs very gentle persuasion with something thin like a flathead screwdriver. Be **VERY CAREFUL** not to score anything, particularly the crank shaft. Using something dull could be very helpful as well, rather than a flathead screw driver.
Place new bearing in that is pre lubed. Replace cap, use red loctite and torque to 130ft/lbs, replace oil pan gasket, button up, good to go...
Parts Needed:
- Oil Pan Gasket
- #4 bearing. As I get the actual cummins part numbers, I will post...
EDIT: 3927772 "Bearing, Crankshaft Thrust"
Description of photos:
First photo: 1) Bottom half of old bearing. New bearing will look identical.
2) The trouble bearing, you can see the thrust washer that came off the bearing. Normally the half circle piece is pressed into the rest of #2 to make a single piece.
3) The bearing cap that you have to remove to replace the bearings.
4) The bolts that keep the cap on. According to page V-19 or 566 of 588, of the big 4BT manual, torque to 130ft/lbs.
(See this thread for info on downloading the manuals: http://www.4btswaps.com/forum/showthread.php?t=32 )
Second Photo
Picture of the new bearing (notice how it is one piece) installed...
Third Photo
The oil pan all cleaned up. Notice the marking at the bottom from the thrust washer sitting there for ages.. I bought the motor with a bad thrust washer. But it was no big deal, ran fine...
:beer:
I noticed a lot of play of the crank shaft when you pushed the clutch (maybe a 1/4"?). Turns out it is a common problem that Cummins came up with a replacement part/cure for...
If you leave the stock part in there, as long as it is in tact, it will probably be fine but keep in mind that it can come apart. If you notice a lot of crankshaft play then this is the case. You can either preventatively fix the problem or do it under your truck. Not a big deal but it involves removing the oil pan. If you have the problem (lots of crankshaft play) and leave the problem unresolved for too long, especially with a standard trans, it can cause your crank to wear into your block and possibly majorly F things up for you...
Unfortunately I forgot to take a pic of the new replacement bearing before I installed it, but there is a pic of it installed. The old bearing, the #4 counting from front to back, is a three piece, with the washers on the side (that prevent lateral movement of the crank) which are pressed into the main bearing. The replacement is a single one piece so it cannot seperate and have the same issue happen again... With the old piece, the side washers ("thrust washers") become unpressed from the main bearing, and this allows for the excess play. If your engine has never been rebuilt, it probably has the older style bearing. This is the only bearing of this style in the whole engine and the only place where this issue can ocur.
It is also good preventable maintenance IMO, the bearing I think is less than $30 from Cummins. You can get from either Cummins or Case or a slew of other places. Most cummins dealers know the problem well. I imagine it is also a common problem for earlier 6BTs as well. Not sure when Cummins redesigned the part...
I also have still to this day never rebuilt an engine and this was my first time replacing a bearing, if it matters. Super, super, easy...
Directions:
Pull oil pan. In bottom of oil pan, you should find the thrust washer if you had excess crank shaft play... Undo cap the cap of bearing number 4 [number #3 in photo below, secured by #4 in photo ]. Remove old bearing, both the top and bottom half of the bearing.
Your new bearing will be both top and bottom pieces. I personally dunked the new bearing in oil for a couple minutes hoping that it might somehow absorb oil but doubt it actually did. Most importantly is making sure that you **DONT INSTALL BEARING DRY. Make sure there is oil there and on the bearing.**
Then I replaced top and bottom pieces. Top pieces (the troublesome one) needs very gentle persuasion with something thin like a flathead screwdriver. Be **VERY CAREFUL** not to score anything, particularly the crank shaft. Using something dull could be very helpful as well, rather than a flathead screw driver.
Place new bearing in that is pre lubed. Replace cap, use red loctite and torque to 130ft/lbs, replace oil pan gasket, button up, good to go...
Parts Needed:
- Oil Pan Gasket
- #4 bearing. As I get the actual cummins part numbers, I will post...
EDIT: 3927772 "Bearing, Crankshaft Thrust"
Description of photos:
First photo: 1) Bottom half of old bearing. New bearing will look identical.
2) The trouble bearing, you can see the thrust washer that came off the bearing. Normally the half circle piece is pressed into the rest of #2 to make a single piece.
3) The bearing cap that you have to remove to replace the bearings.
4) The bolts that keep the cap on. According to page V-19 or 566 of 588, of the big 4BT manual, torque to 130ft/lbs.
(See this thread for info on downloading the manuals: http://www.4btswaps.com/forum/showthread.php?t=32 )
Second Photo
Picture of the new bearing (notice how it is one piece) installed...
Third Photo
The oil pan all cleaned up. Notice the marking at the bottom from the thrust washer sitting there for ages.. I bought the motor with a bad thrust washer. But it was no big deal, ran fine...
:beer:
