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+--- Thread: Isx cm871 turbo issues (/showthread.php?tid=8859)
Isx cm871 turbo issues - Doodles_mmr - 04-17-2023
I'm having some issues with my cm871. I'm on the second turbo and it is same problem as last time about a month apart. It's leaking oil out from behind the compressor wheel. These are cummins reman chargers. Truck has been demandated for about 3 months now. This truck has had multiple issues since then. The shop that worked on it says only way to fix it is remove vgt turbo and replace with a standard old school turbo. Everyone has told me this was wrong. This is one of my fleet trucks and driver has been off work and I'm at my whits end on what's actually wrong with it. Also getting since demandated are Intermittent code and derate for sensor supply voltage low. Measure around 3 volts on that part of the harness then can disconnect batteries for about 15 mins plug back up measures at 4.85 volts. Any help will be greatly appreciated. I'm about ready to pull my hair out.
RE: Isx cm871 turbo issues - Nilao - 04-17-2023
Demandated trucks need the turbo closing tables adjusted to produce positive pressure at idle otherwise the engine will create a vacuum and suck the oil past the seals.
Mine is not hooked up to the CAC and I started the truck and idled it for around 5 minutes. The passenger side of the engine compartment was sprayed with oil in the short time I ran it that way.
RE: Isx cm871 turbo issues - arazdolgin - 04-17-2023
(04-17-2023 )Nilao Wrote: Demandated trucks need the turbo closing tables adjusted to produce positive pressure at idle otherwise the engine will create a vacuum and suck the oil past the seals.
Mine is not hooked up to the CAC and I started the truck and idled it for around 5 minutes. The passenger side of the engine compartment was sprayed with oil in the short time I ran it that way.
Open imap sensor and look if it vacuum sucking or blow air.
I’m on the same issue. Probably turbo rebuild again.
Also, check oil drain hose, air filters, position turbo at idle, oil you use, crankcase pressure or blowby pressure struggling oil to come out, air compressor.
RE: Isx cm871 turbo issues - Doodles_mmr - 04-17-2023
(04-17-2023 )arazdolgin Wrote:(04-17-2023 )Nilao Wrote: Demandated trucks need the turbo closing tables adjusted to produce positive pressure at idle otherwise the engine will create a vacuum and suck the oil past the seals.
Mine is not hooked up to the CAC and I started the truck and idled it for around 5 minutes. The passenger side of the engine compartment was sprayed with oil in the short time I ran it that way.
Open imap sensor and look if it vacuum sucking or blow air.
I’m on the same issue. Probably turbo rebuild again.
Also, check oil drain hose, air filters, position turbo at idle, oil you use, crankcase pressure or blowby pressure struggling oil to come out, air compressor.
I've checked all that. This is new turbo fresh outta the box thrusday. Fresh service with Rotella. Has the Crankcase filter that never has to be serviced on last turbo. All drains are good and clear. 38lbs of oil pressure at turbo inlet cold. Blowbye is almost none. And new air compressor when work was done a couple months ago. New oil coolers was done at same time. I know boost at idle is dead zero lbs via ecm reading. Starts showing boost parked at around 1100 rpm just idling truck up. Pressure tested CAC found no leaks.
RE: Isx cm871 turbo issues - Doodles_mmr - 04-17-2023
(04-17-2023 )Nilao Wrote: Demandated trucks need the turbo closing tables adjusted to produce positive pressure at idle otherwise the engine will create a vacuum and suck the oil past the seals.
Mine is not hooked up to the CAC and I started the truck and idled it for around 5 minutes. The passenger side of the engine compartment was sprayed with oil in the short time I ran it that way.
How do you change the tables? I know one of my buddies suggested tune is wrong but idk what I'm looking for on calterm to see what's wrong.
RE: Isx cm871 turbo issues - Mrkentee - 04-17-2023
Get your programming checked. That’s probably where you’ll find your problem. The sooner the better.
RE: Isx cm871 turbo issues - Rawze - 04-17-2023
Turbocharger turbine seals are not like a typical o-ring. The turbine spins in excess of 100,000+ rpm's at times. a simple rubber or perfectly sealing o-ring is not possible, as it would burn up or cause the turbine shaft to get galled up. . The face seals are a turcon style ring with a split in it so that it can be installed. They will leak if there is a vacuum on them (not spinning fast enough at idle, etc.).. OR ... .if there is any restriction or back-pressure in the drain line. It is also in fact ... ONLY the drain-line oil pressure at the face seal, and not the 30+ or 40+ psi from the supply line on them.
Like others have said... Remove the IMAP sensor from the manifold without disconnecting the wiring from it. Idle the truck and slide the corner of a sheet of paper over the hole. See if the paper is mostly trying to be sucked into the hole.. or if it is mostly only fluttering up and down.. or if it is being mostly blown away from the hole.
NEXT: -== like mentioned, if there is any restriction in the drain line it will bleed oil. this can be from too much blo-by in the engine (piston rings are worn out) or from the crank case filter being restricted due to not changing it often enough.. or some other reason that causes crank case fumes to build up in the engine that cannot escape well enough.
Besides making a turbo bleed some oil.. Crank case fumes buildup inside an ISX is very harmful to the engine too. It is one of the biggest reasons that cause them to wipe out the overhead cams... starving the top-end of oil internally. It is nothing to take lightly.
A maintenance free crank case filter solves most of this.. but if the engine is worn out enough, then not even the maintenance-free crank case filter can keep up.
maintenance-free crank case filter, etc..:
http://rawze.com/forums/showthread.php?tid=65&pid=376#pid376
===================
NEXT: is the de$lete itself. Assume it is and, as more than 90% of all of them seen are. It can contribute greatly towards turbocharger and engine issues and for a shop- not to address this as first priority, // or to even suggest at all.. to remove the VGT .. is a shop who clearly does not know that they are doing. That turbocharger is the very device that the red engines use to properly control fuel-air-mix and all of that is lost when you remove it. Is it very harmful to the engine over time + causes a lot of secondary issues like significantly lower fuel mileage (thousands of dollars a year lower for most highway trucks) + loss/significant weakening of engine brakes, turbo lag, and other diriveability issues. It also significantly shortens engine life because the ecm can no longer maintain its reduced internal friction control.. causing dropped liners and other severe engine problems in much shorter time spans than normal (shortened engine life results).
I.E.>/../ YES.. it is very bad to butcher the h$ell out of a $40,000 commercial engine with red-neck style of garbage mods.. and costs the truck owner a whole lot in lost fuel mileage and major engine issues over its lifetime.
So ... that shop... I would run like a ll he$ll away form them for even suggesting such trash be done to it.
The solution is to #1.. ensure there is no way the engine can build excessive crank case fumes up within it due to blow-by or crank case filter, or anything else. The reason the turbo leaks is that ...
A. you got it from a non-oem place and they did not re-machine the intake housing + install better seals.
or B. it is oem, and it is not spinning fast enough at idle to maintain a postive pressure (above the drain line pressure) so that the oil does not seep out.
or C> there is just enough crank case fumes buildup in the engine to be higher than the face pressure due to the gasses not being able to escape well enough.
Ensure a maintenence free filter is used.
Ensure the engine does not have excessive blo-by by actually having it properly tested on a dyno if necessary.
Ensure the piping for the crank case relief circuit is not blocked up with crud at the bottom where the hose ends.
Ensure also that the cover-plate mesh screen in the upper gear housing is not packed up with soot. There is a metal mesh on the back side of the upper gear housing cover that can get packed with soot over time that can restrict crank case fumes. Many people overlook this thing and never bother to even clean it properly during a rebuild, etc.
Ensure there is no exhaust restrictions at all. Those cans (DOC,DPF, and SCR for those trucks that have them) under the truck a\have to be 100% hollow to the bare metal. No restriction whatsoever!. And a lot of places that de-mandate these engines to stupid things like only drilling a few holes in the elements or other garbage things that cause problems like this.
Ensure that an after-garbage CAC unit has not been installed like a dur-ralite CAC cooler (they are the worst) as most brands of after-market CAC coolers on the intake are very restrictive and cause vacuum. flow restriction, and other problems.
== -- ensure the program is not total garbage by copying it out of the ecm ( using the Cal$term software) and e-mailing it to me for a proper review. It can also be checked to se if it is a heavy contributor of the turbo slobber issue too.
-0= I.E.> Otherwise, unless they got damaged by some means.. the turbine shaft seals simply do not leak unless there is some other issue causing it. This means that putting a different turbo on does not fix it, because the issues is rarely ever actually the turbo itself, but instead, one of the reasons I mentioned above. This also again, points to the repair shop that is telling you that mis-informed garbage, obviously not knowing what they are doing with regards to this issue.
RE: Isx cm871 turbo issues - Doodles_mmr - 04-17-2023
(04-17-2023 )Mrkentee Wrote: Get your programming checked. That’s probably where you’ll find your problem. The sooner the better.
I figure as much. I've done all kinds of hard parts and nothing is helping. It's been down 3 weeks now....
RE: Isx cm871 turbo issues - Doodles_mmr - 04-17-2023
I'd gladly send the file. I pulled it today just in case someone needed it. I'll pull imap sensor in morning and check that. All ready running maintenance free filter. Hopefully it ain got excessive blow bye. It's got about 200k on inframe. I really appreciate the information and help