CM871 - camshaft bearing issue

[PekySVK]

hello, i have 2011 CM871 i replaced cylinder head on 1M mi . around 1.2M mi i start having issues with crankcase pressure so i saved some money and did inframe (cost of crankcase pressure were broken piston rings ). let the machine shop inspect cylinder head sense was of even it had less than 200k on it. they convinced me that i had to upgrade all my valves, springs, cups, bearings and seals. everything was great and put to gather and truck run great with no issues. put 2000 mi and i spun injector cam bearing #1. ... i brought it back to the shop take it a part and i found no explanation why it happened. machine shop repaired cylinder head. everything was fine for 6-7 hours of truck running with no load on parking lot on idle . with oil pressure 32psi spun bearing #3 on injector cam . i don't know where to start looking . what could be my problem of spinning injector cam bearings .

[SemiSweet]

Bad or clogged oil supply to the cam oil ports ? The shop damaged the bearings while installing the cam in the head? That cam is very heavy and it would not take much to compromise the bearings while removing or installing.

[PekySVK]

Oil supply was inspect and cleaned before installing the head. also cam was installed properly with first cylinder head replacement on 1M and than after inframe. i know that for sure because i did it my self. just can get my head around the fact that firs time it baked only one bearing and nothing else and now it did the same thing on new bearings same camshaft but different location. with good oil pressure.

[Bengy88]

Ummm just wondering how you used the same camshaft if it spun a bearing? Did you have the machine shop turn the cam and put oversized bearing in the head? When a bearing turns 90% of the time it fu**s the cam... Or crank. Not being a smartass im literally curious.

But oil supply isnt the only thing that will cause a bearing to turn... Oil temp and engine temp play a large role as well. Just an idea

[Signature620]

Did they fit aftermarket bearings? They are a lot easier to source and machine shops seem to love non-genuine Cummins parts if you don't specifically request otherwise.

Also, as Bengy says.....The cam and cylinder head casting will both he trash if a cam bearing has spun.

[Rawze]

Sounds a lot to me like people trying to take shortcuts or cutting corners .. and then wondering why things went sideways.

Not replacing everything with new, all OEM-ONLY parts, including the head itself the first time it spun a bearing sounds like a big mistake to me. and now your paying the price for half-baked decisions that tried to save you moneys.

and like mentioned .. yeah... a lot of shops are not nearly careful enough not to ding cam bearings when installing the cam...

Also.. what is the oil pressure at idle?... and has anything been done to ensure crank case fumes cannot build up in the engine.. like bypassing the CC filter or installing a maintenance free one?... any crank case fume back-pressure or restriction will wipe out cam lobes.. but will not cause spun bearings. SPun bearings either come from carelessness during cam install OR someone trying to re-use a head.. Don't matter that it only had 200k miles on it.. it should NOT have been re-used!..

Just my thoughts... so if things are done 100% right... then unexpected results like that simply do not happen. Makes me question the entire rest of the inframe too. Here is what should have happened. Anything less and your just wasting your time and moneys ...
ref: http://rawze.com/forums/showthread.php?t...6#pid70606

[PekySVK]

i replaced camshaft after bearing spun. first time and now i will replace it again ... also camshaft was installed properly. entire engine was put together by the book.

crankase filter is maintenance free. oil pressure is 40 on cold start and 28 - 30 on operating temperature .

i don't know what brand of bearing was used. head was in machine shop while inframe and was completely rebuild. didn't have issue with had before i let machine shop rebuild it after 200k .

[PekySVK]

i'm here ask for your opinions to try to fix issue and have diffrent angle of view on issue i have so i can move forward. oil pressure is good. want to see if there is any test that i didnt think of or there is a possibility of machine shop using cheap bearings and that could be the cost of spinning them.

[Rawze]

(10-14-2022 )PekySVK Wrote:  i'm here ask for your opinions to try to fix issue and have diffrent angle of view on issue i have so i can move forward. oil pressure is good. want to see if there is any test that i didnt think of or there is a possibility of machine shop using cheap bearings and that could be the cost of spinning them.

replace the head.. like said.. with A BRAND NEW ONE.. OEM FROM CUMMINS .. NOT A REMAN!.. AND NOT SOME GARBAGE A MACHINE SHOP BUGGERED UP!.