Knocking after new rod bearings?
10-07-12, 06:23 PM
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Knocking after new rod bearings?
I have a '93 lexus gs300 with aristo 2jzgte swap, converted single turbo. Stock head and block. I bought it in july it developed a knock. Found out it was in cylinder 4 and pulled motor and it ended up being the rod bearing. I put a new set of rod bearings in. Just got it back together thursday and drove it a little friday and Tonight. Well tonight i noticed the same type of knock that i had before around 2k rpms. Could this be my bearings again? It Knocks on start up, until i get oil pressure which is like 2 seconds. I have good oil pressure on start up and while driving but while idling its between 0-1 Bar ("Defi" oil pressure gauge measured at oil filter housing). Could this knock be bearings again?
10-08-12, 06:14 PM
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Possible knock
It sounds as if it might be your bearings again. Without knowing exactly what you meant by "replaced the bearings" I would not know for sure if it is bearings. Did you have your crank measured and polished or turned if necessary? Did you check the main journal for out-of-round? and have it line bored if necessary? Did you replace your main cap studs/bolts? Did you replace your Rod bolts/studs? Did you replace every bearing? Did you check ever journal? Did you check the bearing clearances on every main journal? There is quite a lot of measuring and checking when you spin a bearing. Just some things to think about.
1. Possible Crank Bearing Surface damage
2. Possible Main Journal damage/out of round
3. possible Rod bearing Surface damage/out of round
4. possible bad rod cap bolt damage/failure
5. possible Main cap bolt/ stud failure.
Just slamming in a new set of bearings by itself almost never solves the reason for the bearings initial failure. At a minimum I recommend having your crank polished and micrometer-ed to ensure your crank is true, then have your block Line bore-checked to ensure that is true as well. After that is completed have your rod caps checked for round, and then install new bearings if everything is in tolerance. You can accomplish most of these measurements at home with a good set of gauges. (Inside outside Micrometer, bore micrometer, plunge micrometer) Always ensure all your rotating assemblies are "true" before setting up new bearings, and check your readings with plasti-gauge as an added indicator of proper clearance. Do NOT use plastigauge to measure trueness... big mistake many have made. Just my two cents...and one more thing of you were skimpy on the assembly lube you might have burned a bearing as well. Hope this helps.
1. Possible Crank Bearing Surface damage
2. Possible Main Journal damage/out of round
3. possible Rod bearing Surface damage/out of round
4. possible bad rod cap bolt damage/failure
5. possible Main cap bolt/ stud failure.
Just slamming in a new set of bearings by itself almost never solves the reason for the bearings initial failure. At a minimum I recommend having your crank polished and micrometer-ed to ensure your crank is true, then have your block Line bore-checked to ensure that is true as well. After that is completed have your rod caps checked for round, and then install new bearings if everything is in tolerance. You can accomplish most of these measurements at home with a good set of gauges. (Inside outside Micrometer, bore micrometer, plunge micrometer) Always ensure all your rotating assemblies are "true" before setting up new bearings, and check your readings with plasti-gauge as an added indicator of proper clearance. Do NOT use plastigauge to measure trueness... big mistake many have made. Just my two cents...and one more thing of you were skimpy on the assembly lube you might have burned a bearing as well. Hope this helps.
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