Cm871 tune up
02-22-2021, (Subject: Cm871 tune up ) 
Post: #1
Cm871 tune up
Recently I purchased a 09 w900 kenworth with a cm871, the truck has 1,015,000 miles on it and the engine had never been touched, other than the turbo and egr cooler. I’ve watched rawzes videos since he started making them and remember him posting on various forums back in the day. I use to only own caterpillar engines, I went and checked this truck out. The price was worth a look, long story short truck was on consignment I was able to find the owner and got quite the story. It ran ok, very minimal blow by, but it did act as if it just didn’t want to come to life like it should. Well I brought it home, bought some sensors, spent a day cleaning stuff (intake and Venturi wasn’t to bad but Imap was plugged shut) finally was able to take it for a spin and holy s#it what a difference! Power everywhere, instant turbo response, once again I have a truck that’s fun to drive! Thanks to rawze for all the time and effort you put into this! Can’t wait to put it under a load!!

Now I just need a m*m tune


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 Thanks given by: Rawze
02-22-2021, (Subject: Cm871 tune up ) 
Post: #2
RE: Cm871 tune up
I'm not trying to burst your bubble here but with over a million miles on it your on borrowed time. Especially if the rod and main bearings haven't been changed. You should be thinking about an inframe real soon if you plan to keep this truck.. Congrats on getting it to run good though.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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 Thanks given by: Rawze , LTWON
02-22-2021, (Subject: Cm871 tune up ) 
Post: #3
RE: Cm871 tune up
I’ll rebuild it myself when the time comes, it’s not going to work to hard. More of a back up truck or play truck for now. But I agree, although today I was at the local Cummins dealer and they were rebuilding a 871 that had 1.6 million on it that’s never been opened.
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 Thanks given by: tree98
02-23-2021, (Subject: Cm871 tune up ) 
Post: #4
RE: Cm871 tune up
Id inframe that thing before you go tuning it.
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02-23-2021, (Subject: Cm871 tune up ) 
Post: #5
RE: Cm871 tune up
After a million miles and no one did the rod and main bearings back at around the 800k mark (or equivalent engine hours) ... It starts to become a ticking time-bomb for sudden wrist pin failure. It is one of the more well-known things that the ISX will do if someone keeps driving one blindly, expecting it to last forever.

For a CM871, The more miles above about 1 mil or so (this would be 1.2 mil for a CM570 or CM870), the higher the gamble of it throwing a piston straight thru the side of the engine block without any warning whatsoever. Engine = boat anchor if this happens and there is no fixing it.

That is why the comments by others has been said. It has been seen around here before.... so yeah .. its time to take it to pasture and inframe it at that 1 mil miles or so. You'de be doing good to maybe get it to 1.1 or 1.2 mil but would be at a very high risk at that point. Some people get real lucky and get more than that but it is the exception, not the rule, and should not be relied on.

de-manding it will loosen all the carbon packing up and open up the ring clearances, etc.... so the risk is even higher for sudden high blo-by or a wrist pin failure at that age as well.

Like others mentioned ... inframe it first ... do all the stuff talked about to extend its life during the inframe .. and then after that (or during) would be the time proper time to do any mods to it, not before. Just be lucky that you did an EGR tune-up on it and got it running well again in the mean time.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: PuroCumminsPower , LTWON
02-26-2021, (Subject: Cm871 tune up ) 
Post: #6
RE: Cm871 tune up
(02-23-2021 )Rawze Wrote:  After a million miles and no one did the rod and main bearings back at around the 800k mark (or equivalent engine hours) ... It starts to become a ticking time-bomb for sudden wrist pin failure. It is one of the more well-known things that the ISX will do if someone keeps driving one blindly, expecting it to last forever.

For a CM871, The more miles above about 1 mil or so (this would be 1.2 mil for a CM570 or CM870), the higher the gamble of it throwing a piston straight thru the side of the engine block without any warning whatsoever. Engine = boat anchor if this happens and there is no fixing it.

That is why the comments by others has been said. It has been seen around here before.... so yeah .. its time to take it to pasture and inframe it at that 1 mil miles or so. You'de be doing good to maybe get it to 1.1 or 1.2 mil but would be at a very high risk at that point. Some people get real lucky and get more than that but it is the exception, not the rule, and should not be relied on.

de-manding it will loosen all the carbon packing up and open up the ring clearances, etc.... so the risk is even higher for sudden high blo-by or a wrist pin failure at that age as well.

Like others mentioned ... inframe it first ... do all the stuff talked about to extend its life during the inframe .. and then after that (or during) would be the time proper time to do any mods to it, not before. Just be lucky that you did an EGR tune-up on it and got it running well again in the mean time.

I’ll definitely do an inframe on it, not planning to run it like so for long. Although I did dyno the truck and it has rock solid oil pressure and minimal blow by. I’ll drop the pan and check the bearings out, and roll some new ones in at least for now. I’m not working it, well not full time. I’ve never had one of these engines before, so I’d like to learn as much as possible by doing all the work myself.

All that aside, I’m still impressed with this engine, coming from CAT engines.
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