exhaust doser

[Rawze]

(12-06-2020 )JasonH Wrote:  Not sure why it went bad but it seems to have bent the shaft no oil or coolant restrictions . As far as the boost its never gotten over 30psi boost in the two years I've owned it. I was told that these motors don't build over 30psi as they wont take it so I figured it to be normal. Same with The oil pressure being low at 25-28 psi at highway speeds. The oil pressure is the same as it was prior to rebuild and yes I put a new oil pump on it. All work was done by a local shop that several local friends/owner/ops sent me to. Every time I mention oil pressure to anyone I get the same answers (its a cummins they run low oil pressure). I run Mobile Delvac 15w40 and Fleet guard filters NO Lucas but I do add motorkote every other oil change.

I'm a detroit 12.7 guy this is the first ISX I've owned. I've always owned older trucks and done my own work but these things scare me to death.

I don't know what kind of gaggle of complete idiots and morons you have been hanging around but they seem to be completely clueless towards the ISX 871 engine... I would have run like hel#ll away from those people if they had said those things to me.


- The ISX should have in the range of about 33 - 38 psi oil pressures at highway speeds when going down the road (most fall into the 34-36 range) and the engine fully warmed up with an unmodified oil pump. If your only getting 25-28 psi something is very wrong with that engine somewhere. Even under a hard pull and oil is running 230+ because of tortuous conditions, it should still be up at 33+ psi unless your idling. - only 30 psi when going down the roads is starting to starve the top-end of oil... i can only imagine how bad it would be at 25 psi and trying to climb a hill.


- The proper boost pressure at 500 HP should be every bit of 37,38 psi ... 39 is the high end and 40+ will kill the engine. Anything less than 37 or so at 550hp output is going to result in cooking that turbo and have excessive egt's.

As far as lower than normal boost goes, it could be any given number of reasons. Bad delete programming where the engine is permanently stuck in a silent derate because no one bothered to re-program the engine mode control or other short-comings that god knows what someone did or did not do properly... That type of crap programming is a plague and is everywhere...no more check engine lights any more, but the ecm is screaming its arsse off internally and derating because all the fault codes are blocked form being able to show up in the dash instead of someone doing a proper job in it.

Could also be CAC leaky, when is the last time you pressure tested the entire engine?.. Pressurized the entire intake with 30 psi air and checked everything for boost leaks?.. NOT just the CAC unit, but the entire intake?

- Next, now this brings up,... what someone did to the hardware... Did they drill a few holes in the DPF and not hollow it out completely?- this causes exhaust restrictions and the turbo suffers greatly because of it... Did they use any block plates anywhere? -=- and where did they do this? --- did they remove the EGR cooler?-- or block coolant flow thru it?-- This is a big no-no for that model engine... Like i said.. bad delete everywhere for these ISX's ... brain and engine butchers around every street corner who want to rip you off in return for something you could have done yourself for free.. and properly.

-- Sounds to me like you have had some serious morons telling you what to do with that engine and how it should be run.. Around here, I don't tolerate bad or mis-leading information and it sounds exactly like you have been caught up into just that .. a bunch of garbage info.


As far as the lower than normal oil pressure goes ... Make sure your pressure gauge is accurate. If it is genuinely only making 28 or so psi going down the roads after it is fully warmed up, you have some very serious issues that need to be addressed right away. Your oil temps should be about 218~ish when normally going down the roads F to 230 on the high end when pulling hard. 240+ is too high and something is wrong... either with the programming (bad deletes will often make oil temps run higher than normal) or you have issues internally. Here is some related discussions on lower than normal oil pressures after some shop inframes the engine and don't know what the he#ll they are doing: http://rawze.com/forums/showthread.php?t...5#pid32065


what is the oil pressure when it first cranks on a cold morning? what is the oil pressures at idle?

how many miles are on it? - has it been inframed? -- some more history would help.

That SIX ain't no 12.7 Detroit... learn how to care for it properly, learn how to drive it properly, and learn to regularly wrench and maintain it properly ... it will be good to you in return. Anything less and your just wasiting your time and mine by me trying to help you.