Thrust bearing fail
#1
Thrust bearing fail
Only 600 miles on motor. End play when we put it together was .005 endplay now is at .057 and crank pulley moves visibly. What could have caused this? We found small metal strips in oil this morning, cams were ok, and then observed the movement.
The driveshaft ujoints were loose but I don't see that vibration going all the way through to the thrust bearings.
HELP!
The driveshaft ujoints were loose but I don't see that vibration going all the way through to the thrust bearings.
HELP!
#5
Cpt. Slow
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That's part of your problem. I'd have to read my manual, but I think that's backwards. The crank is the surface spinning, so I think the oil grooves face the crank. It's been a few weeks since I've read and installed a thrust bearing though.
If you used the one pictured above, that's your very obvious reason for failure.
If you used the one pictured above, that's your very obvious reason for failure.
#9
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Its not until .250" that it's seriously bad, and most likely completely missing a thrust bearing. At .057", you can probably replace the thrust bearing and be ok, but that's about .05" out of spec. Which is still a lot.
#13
That's basically what we did last time and pushed them around till they were flush with a screwdriver.
What kinds of things can cause a thrust bearing(s) to fail?
Prolonged cranking? we had some because of a tune problem where the car just would only start after 20 secs or so of crank
Driveshaft inbalance? had a u-joint with about 5mm of play in it that I replaced, don't know if this can cause problems like this though.
Clutch inbalance? we didn't have an alignment fork for my disk so we installed it and measured around the disk at 4 points the overlap of the pressure plate vs the disk and it was even, but perhaps not even enough?
"Pop-starting?" at times my car would die when I put it into neutral so if I was still moving I would put it in gear and slowly release the clutch to get it to fire up again.
Low idle Oil Pressure? I don't know what the deal is, but I switched to Rotella T6 the day we found crap on my drain plug and measured endplay, but my idle oil pressure with T6 was significantly higher than with other oils used up to this point. With Amsoil Signature Syn 10W-30, and the way I have my gauge set, the needle would sit right on the "low" line. When the fan would kick on, the needle would sit right below that line. This doesn't mean pressure was "low" but just how I set my gauge to read. With the T6, and the fan on, the needle sits right above the low line, and with the fan off, even higher than that. Cruising oil pressures seemed the same with both, but at that point I was limping home a car with a known thrust bearing issue, so I wasn't really trying to drive any kind of fast.
I am hoping that at my wristpins I have at least .057 of clearance side to side otherwise my rods will surely start pushing my pistons side to side in the bore. IIRC there was a fair amount of room there, certainly nothing to measure in the thousands. The motor runs very quiet, no knocks or anything, so I am a bit hopeful, but I think it's gonna come out through the top and block will once again get a teardown, but quicker this time. Last thing I want is to assume all else is OK and then have it fail again.
Would compression or leakdown tests indicate anything at this point?
What kinds of things can cause a thrust bearing(s) to fail?
Prolonged cranking? we had some because of a tune problem where the car just would only start after 20 secs or so of crank
Driveshaft inbalance? had a u-joint with about 5mm of play in it that I replaced, don't know if this can cause problems like this though.
Clutch inbalance? we didn't have an alignment fork for my disk so we installed it and measured around the disk at 4 points the overlap of the pressure plate vs the disk and it was even, but perhaps not even enough?
"Pop-starting?" at times my car would die when I put it into neutral so if I was still moving I would put it in gear and slowly release the clutch to get it to fire up again.
Low idle Oil Pressure? I don't know what the deal is, but I switched to Rotella T6 the day we found crap on my drain plug and measured endplay, but my idle oil pressure with T6 was significantly higher than with other oils used up to this point. With Amsoil Signature Syn 10W-30, and the way I have my gauge set, the needle would sit right on the "low" line. When the fan would kick on, the needle would sit right below that line. This doesn't mean pressure was "low" but just how I set my gauge to read. With the T6, and the fan on, the needle sits right above the low line, and with the fan off, even higher than that. Cruising oil pressures seemed the same with both, but at that point I was limping home a car with a known thrust bearing issue, so I wasn't really trying to drive any kind of fast.
I am hoping that at my wristpins I have at least .057 of clearance side to side otherwise my rods will surely start pushing my pistons side to side in the bore. IIRC there was a fair amount of room there, certainly nothing to measure in the thousands. The motor runs very quiet, no knocks or anything, so I am a bit hopeful, but I think it's gonna come out through the top and block will once again get a teardown, but quicker this time. Last thing I want is to assume all else is OK and then have it fail again.
Would compression or leakdown tests indicate anything at this point?
#14
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All those things should be fine. I've taken thrust bearings out of 70,000-100,000 mile engines, they all have very little wear, and measure right at the factory rating of .100 (I think), and the cranks have .005-.007" end play. Something serious happened for one to fail by .050" within a few hundred miles.
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Sorry to interrupt, but are the thrust bearings block dependant or crank dependant?
Example: I have a BP from a 2000 that I will be rebuilding, can I use the obviously superior 01+ thrust bearings?
Example: I have a BP from a 2000 that I will be rebuilding, can I use the obviously superior 01+ thrust bearings?
#19
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ACL lists one thrust bearing for Miatas: 1T8353H
According to 949 that PN covers: Mazda B6, B6-T, BP, BP-T, ZL-VE, ZM-DE & 90-05 Miata MX5, all
ACL Thrust Washer Miata
#20
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No, they were thinking about all the failures of the smaller thrust bearings with pathetically weak Miata clutches.
They were half wearing, half just plain falling out. They were poorly held in place, and once worn would rotate 180* with the crank and fall into the pan. Occasionally catching the crank on the way out, ending like this:
They were half wearing, half just plain falling out. They were poorly held in place, and once worn would rotate 180* with the crank and fall into the pan. Occasionally catching the crank on the way out, ending like this: