okay to remove main/rod bearings then reuse?
04-30-2013, 08:16 PM
#1
okay to remove main/rod bearings then reuse? I have an LS6 engine that had a low oil pressure issue soon after a cam install. I've pulled the oil pan and found tiny metal particles etc. so I know a bearing is screwed somewhere. I want to check the main and rod bearings so I can decide whether to pull the whole engine apart or just pull the cam itself out.
I have ARP rod bolts and stock main fasteners. Is it okay to unbolt each one by one and remove it to check for damage/wear, then reinstall it in the same position? I assume the ARP fasteners are reusable; I suspect the main fasteners are not, can anyone confirm?
TIA
I have ARP rod bolts and stock main fasteners. Is it okay to unbolt each one by one and remove it to check for damage/wear, then reinstall it in the same position? I assume the ARP fasteners are reusable; I suspect the main fasteners are not, can anyone confirm?
TIA
04-30-2013, 09:07 PM
#2
I'm pretty sure the mains are TTY bolts. You should have no problem removing main caps and re-installing them for inspection. Do you have the engine removed? I would swap out all the bearings anyways, get the crank polished etc. If there is trash in the cam bearings, the mains most likely have imbedded crap too.
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Homer_Simpson (11-20-2021)
05-01-2013, 01:13 AM
#4
TECH Senior Member
You guys should not mess with things you do not understand. Gosh I'm tired of seeing inexperienced people butchering these motors.
Bearings are seated and should not be removed and reinstalled. And no even if some apprentice did it and thinks it was fine, it is not proper protocol/procedure.
Bearings are seated and should not be removed and reinstalled. And no even if some apprentice did it and thinks it was fine, it is not proper protocol/procedure.
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lawrenq (01-08-2021)
05-01-2013, 01:50 AM
#5
You guys should not mess with things you do not understand. Gosh I'm tired of seeing inexperienced people butchering these motors.
Bearings are seated and should not be removed and reinstalled. And no even if some apprentice did it and thinks it was fine, it is not proper protocol/procedure.
Bearings are seated and should not be removed and reinstalled. And no even if some apprentice did it and thinks it was fine, it is not proper protocol/procedure.
However, thanks for the information regardless. Perhaps you'd be so "kind" as to inform the rest of us as to why this is a totally improper procedure...for those of us who like to understand the "why" behind the "yes or no". Do the bearing halves/caps change shape or size after tension is taken off the bolts?
05-01-2013, 06:15 AM
#6
TECH Senior Member
Not "hard ***", more like "honest" opinion. See, I used to do the same (with SBC)s. I've ruined more parts than I care to admit, but I was willing to modify my "under the tree mechanic" attitude and actually learn/practice proper ways of fiddling with my motors.
Certain procedures have to be followed in order to properly assemble/disassemble mechanical parts.
Shortcuts only lead to more expense and weak returns.
Yes, bearings "seat" themselves and will change shape if removed. It would be pure luck if you could reinstall them in exactly the same spot as they were before. It just doesn't work that way and can result in premature death of your assembly.
The same applies to "what push-rod should I use". It is not on the net that the answer is found, one has to measure; that is the only way.
2 identical setups but different blocks will not necessarily mean same length push-rods.
Yet this question pops out over and over again.
My apologies if my style is sometimes too forward and direct. I lack diplomacy. We all have weaknesses. That is one of mine.
Certain procedures have to be followed in order to properly assemble/disassemble mechanical parts.
Shortcuts only lead to more expense and weak returns.
Yes, bearings "seat" themselves and will change shape if removed. It would be pure luck if you could reinstall them in exactly the same spot as they were before. It just doesn't work that way and can result in premature death of your assembly.
The same applies to "what push-rod should I use". It is not on the net that the answer is found, one has to measure; that is the only way.
2 identical setups but different blocks will not necessarily mean same length push-rods.
Yet this question pops out over and over again.
My apologies if my style is sometimes too forward and direct. I lack diplomacy. We all have weaknesses. That is one of mine.
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billymgb1000 (11-12-2020)
05-01-2013, 07:15 AM
#7
not "hard ***", more like "honest" opinion. See, i used to do the same (with sbc)s. I've ruined more parts than i care to admit, but i was willing to modify my "under the tree mechanic" attitude and actually learn/practice proper ways of fiddling with my motors.
Certain procedures have to be followed in order to properly assemble/disassemble mechanical parts.
Shortcuts only lead to more expense and weak returns.
Yes, bearings "seat" themselves and will change shape if removed. It would be pure luck if you could reinstall them in exactly the same spot as they were before. It just doesn't work that way and can result in premature death of your assembly.
the same applies to "what push-rod should i use". It is not on the net that the answer is found, one has to measure; that is the only way.
2 identical setups but different blocks will not necessarily mean same length push-rods.
Yet this question pops out over and over again.
my apologies if my style is sometimes too forward and direct. I lack diplomacy. We all have weaknesses. That is one of mine.
Certain procedures have to be followed in order to properly assemble/disassemble mechanical parts.
Shortcuts only lead to more expense and weak returns.
Yes, bearings "seat" themselves and will change shape if removed. It would be pure luck if you could reinstall them in exactly the same spot as they were before. It just doesn't work that way and can result in premature death of your assembly.
the same applies to "what push-rod should i use". It is not on the net that the answer is found, one has to measure; that is the only way.
2 identical setups but different blocks will not necessarily mean same length push-rods.
Yet this question pops out over and over again.
my apologies if my style is sometimes too forward and direct. I lack diplomacy. We all have weaknesses. That is one of mine.
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05-01-2013, 10:58 AM
#13
Not "hard ***", more like "honest" opinion. See, I used to do the same (with SBC)s. I've ruined more parts than I care to admit, but I was willing to modify my "under the tree mechanic" attitude and actually learn/practice proper ways of fiddling with my motors.
Certain procedures have to be followed in order to properly assemble/disassemble mechanical parts.
Shortcuts only lead to more expense and weak returns.
Yes, bearings "seat" themselves and will change shape if removed. It would be pure luck if you could reinstall them in exactly the same spot as they were before. It just doesn't work that way and can result in premature death of your assembly.
The same applies to "what push-rod should I use". It is not on the net that the answer is found, one has to measure; that is the only way.
2 identical setups but different blocks will not necessarily mean same length push-rods.
Yet this question pops out over and over again.
My apologies if my style is sometimes too forward and direct. I lack diplomacy. We all have weaknesses. That is one of mine.
Certain procedures have to be followed in order to properly assemble/disassemble mechanical parts.
Shortcuts only lead to more expense and weak returns.
Yes, bearings "seat" themselves and will change shape if removed. It would be pure luck if you could reinstall them in exactly the same spot as they were before. It just doesn't work that way and can result in premature death of your assembly.
The same applies to "what push-rod should I use". It is not on the net that the answer is found, one has to measure; that is the only way.
2 identical setups but different blocks will not necessarily mean same length push-rods.
Yet this question pops out over and over again.
My apologies if my style is sometimes too forward and direct. I lack diplomacy. We all have weaknesses. That is one of mine.
You do realize that some motors call for removing the rear main bearing cap when replacing the rear main seal? For example, Jeep 4.0L engines require this. In many cases you have to loosen all the main caps to get the seal out so I see no issue in doing what the OP is asking about.
HOWEVER, you must not switch them around. Make sure they go back the exact position they came out and torque them properly.
I did a rear main seal on a Jeep Wrangler following that service information and 30K miles later it still has great oil pressure.
05-01-2013, 11:54 AM
#16
So, I guess the consensus that I'm reading here is that it's not okay to remove a cap here and there and check the bearing and crank condition, so anytime a single bearing anywhere in the engine goes awry to any degree, you are required to assume that every bearing is damaged, do a complete teardown of the engine, and replace them all.
Here is another question for those who "know best". I build rotary engines, and in our world, used bearings are generally superior to new ones when their condition allows reuse, because age and heat cycles strengthen the old bearings and bond them in place so that they are unlikely to spin. Once you replace an older bearing with a new one in those engines, you increase the chances of spinning it in the future, as it is not as well bonded to the parts they are installed with. Is that also the case with these engines? I am guessing based on your responses that it is not the case, and people just throw in new bearings on a whim.
It seems from my research on this forum that it is not uncommon to spin or walk cam bearings for no apparent reason, and that is most likely what has happened to me. I just changed the cam in this engine before swapping it in and putting 50 miles on it when oil pressure dropped by half. In my mind, it seems like, if it is so easy for original bearings to walk or spin, it would be even more likely for replacements to do so.
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billymgb1000 (11-12-2020)
05-01-2013, 11:56 AM
#17
Now whether or not you SHOULD do it is another story. If the bearing material and/or the crankshaft is grooved (slight surface damage from dirt and contamination), the crankshaft should be polished at a machine shop or resized and new bearings installed.
As for R&I of existing bearings, keep in mind that the bearing shells fit into the journals with a bit of preload. So, removing them requires some touch. If you bend the bearing shell slightly during removal and destroy this preload, the bearing is junk and should not be re-used. Bearings are very delicate and precision pieces and great care needs to be taken not to distort the shell, burr the edge or damage the soft surface materials. Make sure the bearing shell goes back in the same journal that it was removed from. Do not swap them around. If you lose track of what journal they were in, replace them.
In addition, this operation must be absolutely contaminant free. This goes for installing new bearings too. The journals, caps, bearings and crank must be absolutely spotless. One tiny piece of sand between the bearing and it's journal will stop the bearing from fully seating in the journal. This will reduce the crank to bearing clearance and hinder heat transfer. So think clean, clean, clean. Once the bearing is installed back in the journal, lubricate the bearing and the crank surface with assembly lube. Do not lubricate the backs of the bearings where they mate with the rod and block journal surfaces.
Check any bearing you remove for size. Unless you built the engine yourself, there is always a chance that the crank has been turned. If you replace the bearings, you must determine if they are standard or and under sized bearing like .010, .020 etc.
If you are a noob, find somebody with experience and have them inspect the bearings before you re-use them.
05-01-2013, 12:10 PM
#18
I'm not arguing that it can't be done, but it is certainly the more conservative approach to start fresh with new bearings especially if you're not sure of what you have.
As far as cam bearings spinning, check out Loctite 640 sleeve retaining compound. It's a high temp, high strength adhesive that is resistant to engine oil. Could help to add some insurance onto that press fit.
http://www.all-spec.com/downloads/lo...31_120209s.pdf
As far as cam bearings spinning, check out Loctite 640 sleeve retaining compound. It's a high temp, high strength adhesive that is resistant to engine oil. Could help to add some insurance onto that press fit.
http://www.all-spec.com/downloads/lo...31_120209s.pdf
Last edited by ckpitt55; 05-01-2013 at 12:15 PM.
05-01-2013, 12:10 PM
#19
What was the question again?
why would you not spend an additional $150 bucks and replace the rod and main bearings while you have it apart? $150 now for peice of mind vs the labor to pull it back out, tear it down, machine what needs to be machined then buy new bearing and put it back together and re install. No way man
why would you not spend an additional $150 bucks and replace the rod and main bearings while you have it apart? $150 now for peice of mind vs the labor to pull it back out, tear it down, machine what needs to be machined then buy new bearing and put it back together and re install. No way man
05-01-2013, 12:54 PM
#20
What was the question again?
why would you not spend an additional $150 bucks and replace the rod and main bearings while you have it apart? $150 now for peice of mind vs the labor to pull it back out, tear it down, machine what needs to be machined then buy new bearing and put it back together and re install. No way man
why would you not spend an additional $150 bucks and replace the rod and main bearings while you have it apart? $150 now for peice of mind vs the labor to pull it back out, tear it down, machine what needs to be machined then buy new bearing and put it back together and re install. No way man
I suspect I've spun a cam bearing since that's the only thing that was recently changed on the motor and now I have reduced oil pressure and fine metal particles in the oil pan, but I'm not sure yet.
Assuming that I pull the cam, find a bad bearing, and replace one or all the cam bearings, I would want to leave the heads and rotating assembly together. Put cam bearings and cam back in and run it.
I only wanted to check a couple of mains and rods to be sure they weren't damaged.
The one rod cap I've pulled off looks great to me.
What you're suggesting is a full teardown and rebuild, as far as I can tell. The motor only has 33k on a rebuild, so I don't really want to do that.