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Keffer inc

MP8 still sucks at life

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I just called to see what's new. They replaced that injector, still had misfire problems, so they are replacing the full set that they just put in earlier this week. I hope it gets running soon. 

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How did this end?

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injector cups. if you do a cylinder balance test you'll see a couple injectors out of wack. I've had a few no code injector probs. It will clog the dpf quick or be doing regens (or at least trying) often.

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Can anyone say pre emissions E-6, E7 E9. Volvo and their injector cups are pathetic. Best of luck.

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The first set of injectors were bad, they put a third set of injectors in and the truck ran like it should. It was a $21,000 bill. Not buying Mack anymore.

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The first set of injectors were bad, they put a third set of injectors in and the truck ran like it should. It was a $21,000 bill. Not buying Mack anymore.

What’s the mpg u getting with new injectors


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Not very impressive. 5.5 to 6.0 MPG. Today empty container through the mountains, I'm only getting 6.2. 

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Today I clean my 7 inyector this morning seen I bought the truck I was making no more than 6 mpg right now it’s showing 6.7


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But I keep muy speed at 65 on 9th gear when it drops to 13 rpm the truck start to shake


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Mine would shake and rattle like a train at anything above 45mph, and if I wasn't floored. The 7th injector only has to do with the DPF cleaning and shouldn't hurt the MPG should it?

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Posted (edited)

Of course it hurts mpg. It's injecting diesel fuel right into the exhaust pipe. Unless the truck uses Diesel Exhaust Fluid (DEF) instead.

Edited by JoeH

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On 6/5/2017 at 3:23 PM, Keffer inc said:

I'm still in Amarillo Tx, Friday they completed the cam, injectors, and dpf. We went for a test drive and it was still missing badly, maybe even worse. At first they were thinking maybe a valve was damaged inside the head. But Saturday a tech decided that it may have been a fault injector that they got. Haven't heard anything yet but I hope that's it. I've been at a hotel for a solid week now.

Glad it was only the injectors!

A couple months ago I did a cam on an mp8 with only 200k. 

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14 hours ago, Keffer inc said:

Mine would shake and rattle like a train at anything above 45mph, and if I wasn't floored. The 7th injector only has to do with the DPF cleaning and shouldn't hurt the MPG should it?

Doubt it calcs to MPG. Did a lifetime check on one of our Cat C9 (9.3 Liter) interim 4 engines. Just before trade-in. Had burned about 1,600 gallons out the 7th injector. 

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Posted (edited)
10 hours ago, turckster said:

Most cam issues for a mp8 are most likely from either poor maintenance (no valve adjustment) or improper valve adjustment. Mack/Volvo had some issues with the rocker arms but by your year model that should have been fixed. Seen some issues with the reman injectors, hopefully Mack is on their ass about improving the quality. 

I'm currently overhauling a 1996 e7 engine (level 3 overhaul) in a R model (cotton module hauler). Everyone in the shop was saying the truck wasn't worth it and the owner was crazy to spend that kind of money. The truck is in awesome shape, they take great care of their equipment. It is a mechanical engine (non V-Mac) with no emissions other than a LDA (puff limiter), it's a no-brainer in my book. I'm not a fan of modern emissions but it is what it is and that's what I get paid to fix. 

The above comment is so true Agree totally! The smart money is being spent on your current project Bro ! How ever if they don't sell the new stuff you may not be busy! 🙄 However!  Fear Not thou !We have had a rash of EGR cooler Failures  as of late ,they must have found a new Dollar store to shop at for these!😥  And You will always have work doing injector cups as well !😂

Edited by fjh
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I’m seeing a break point on the off-road side. Liehberr gave up on ever perfecting emissions. 

 Liehberr flopped the Interim 4 so bad they had to punt. We stopped buying them and replaced them with Volvo in two positions with waaaaaaay better cost per hour......so that may well describe the desperation?

Liehberr had pulled their normal “Vee ahhhh Germans, Vee invent’id Deeesell” routine. They set the Tier 4 up with logical regeneration. The system doesn’t monitor delta at the DPF. System calculated a thousand operational parameters and not DPF plugging. So in other words it counted cylinder injections and qty and had the regeneration frequency set up according to the logical regen time, with no regard to actual DPF ash load. If an injector started underperforming the computer couldn’t increase frequency of the DPF regenerations to compensate. We were getting to the point of 12 hour reliability. They (Liehberr) didn’t let us force regen..... stripped our customer software. Service calls weekly and dealer couldn’t find source of base engine ash generation issues. 

Liehberr came back by eliminating virtually all external emissions on the motor. No EGR, no DPF, no EGR cooler, no dual turbo, and possibly no VGT (gotta check that). They got the burn so hot it Nuke’s the particulate and creates mega-NOX. Hot burn vs. normal cooled egr burn. The exhaust pipe is a def injection system dumping 8-10% into the exhaust stream via an electric compressor. They stretched the oil change to 2,000 hours... with filters and test at 500 hours.....if you use their synthetic. Engine is so hot and tight the blowby is clean and doesn’t contaminate the motor oil, supposedly. Some local facilities did the 2,000 plan and so far it’s working. We are getting one before the first of the year. Factory rep told me some time after 2020 (estimate) they are bringing back the DPF and junk to comply. So a brief research and development window.

I chum with the mechanics from Louisiana-Pacific. Kept their tier 3 machines, took a depreciation hit, and traded the junk interims in for the newer generation 4.

Verso Corporation out of Wisconsin Rapids has been doing the same. They called the dealership in Wausau last fall and said “get us a Liehberr 934B to replace our current 934B with 40K hours”. The 40K machine’s superstructure (base platform) was breaking. 

Corporations are keeping a small fleet of reliable, outdated, machines so they can maintain minimum material ton-age productivity.

Lot of the log haulers are doing the same. Guys I’m side working for keep a western star with a tier 3 Detroit parked in back and co-share it between two familes as the back-up for the Macks. 

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