Dan107

Okay, I got the combustion gas test done and it was positive. Also, for whatever reason, now I have oil literally running a steady stream out of the crank case vent tube from the ventilation cannister. I think I'm just going to set this thing on fire!!!

So, is there any definitive test I can do to determine if it's a cup, or bad cylinder? First, I really appreciate all the help from everyone here. You guys have helped me get through issues on many occasions, but this cup thing seems, at least in my mind, crappy! I guess I'm just being lazy, but the steps needed to pull the cover, pull the rocker assembly, the injector, then the cup and replace without knowing for sure seems labor intensive. Don't get me wrong, I'm not questioning anyone here. I'm just trying to get to the answer the simplest way possible...😎

No issues with questions here, it's how we get better. As far as the cleaning process, I believe I have the correct tools. I'm kinda OCD when it comes to prep work, so I'm comfortable that it was clean and ready. The seating tool I have has only been used once before when I changed the original cups out along with a new injector set. Purchased the truck and less than 90 days later the bull gear failed...The engine warranty I purchased when I financed the truck had a neat little clause in it that allowed them to get out of paying for the repair. I call it the "nut clause". If a part was attached by a torqued nut, and the nut failed, the insurance would not pay...That was an expensive fix. I said all of that because two months later injector and cup failure began. It was a tough first year with the truck.

I'm going to get a combustion leak detector kit today and check my coolant for exhaust gasses. Would a bad injector cup let exhaust gas get into the coolant reservoir?

LOL...you are right!! When I originally put the new harness on I got the oil pressure and crankcase plugs crossed, as well as the cam and crank sensor. When I tried to start the engine it would make a quarter turn, like one cylinder at a time would come up. I was wondering why I was getting the improper voltage codes to those sensors then it dawned on me....(hey stupid, those plugs are crossed!!!!) I switched everything and she fired right up. Didn't make sense to me why the plugs would be the same with sensors that close together, but I'm just a lowly owner not a high powered engineer.....

I guess, I'm pulling the valve cover in the morning and seeing what I can see and go from there...I'll update when I figure something out.

Truck runs rough, when it will continue to run. That was my issue last night, it would run for a mile or two, then derate. Then the next restart, run for 15 or 20 miles. Also, on the radiator fill side of the reservoir, there is a small hose that connects to the bottom of the tank. When the engine is idling, there are bubbles coming up through that tube into the coolant. When the engine is at 1000 rpm's or better, the bubbles disappear. It's crazy!

I did a follow-up test and six was green instead of a red bar! Not sure what would cause the mistake in the reading though. I've done the injector cut-out test, and the cylinder balance as well. The cut-out produced the expected results and the balance test was in the green. As to improper cup install, could be. I definitely don't do this on a daily basis like some of ya'll out there, but have done it a couple of times on this truck. I may not have mentioned there is significant pressure on the oil fill cap, and the crank-case vent cylinder on the block feels like a fan blowing out of the down tube. I'm going to pull the valve cover and check what I can. Question though; if it were a cup failure would I have coolant running by and out of the cup into the oil pan?

This was done today, three weeks after I did the work. Injector trim codes can’t be programmed on this year model from what I’ve been told. 2012 CXU613 MACK PINNACLE.

Need help again! So I replaced the cups on these two cylinders along with the wiring harness due to cracked wires and shorts. Loaded yesterday and the truck would randomly derate and quit. Codes are all over the place with crankcase pressure and injector 1 errors. Cylinder balance test was within tolerance, but this compression test is nasty looking. I’m lost with what to do next….

New injector cups installed on #1 and #6. Cleaned and serviced the plungers. Put it back together and the injector harness cracked and frayed to the point it is beyond repair. The connectors on some are coming apart! $1484.82 for a new harness because Mack/Volvo doesn't think it practical for a connection and separate injector harness! Turbo in December, now this!

Okay, good deal...I'm just showing my ignorance!

Okay, so I'm also replacing the two injector cups while I'm here. I pulled the #1 cup and the injector hole filled with coolant. I don't recall this happening when I originally replaced the sleeves and injectors. Do I have something else going on? Head gasket???

Thanks for the help everyone! To answer this, yes 1 and 6 were tight and there is also cracked wire shielding as well. I'm going to address these two issues and try again.

I forgot to add, the head was rebuilt last year at this time with all the seats, guides and valves replaced. #2 liner cracked and I had to replace it. Also, there is no smoke, or oil consumption from the engine. I did check the springs yesterday, and they all look good.

950000. Replaced injectors and cups about 500000 miles back.

Evening everyone. I have a 2012 Pinnacle CXU613, MP8. I was unloading my pneumatic trailer yesterday and noticed the engine began making excessive noise. I initially thought something internal was about to fail. The noise quieted down somewhat, and on the way back home, I only noticed it when the truck was at idle. I put the computer on it today and there was an inactive injector code related to a bad signal. Through diagnostics, (cylinder balance reset, and compression test) I found that #1 and #6 cylinders are outside of normal (big red bars on the graph) with #1 being the worse of the two. I ran an overhead on it, and did another compression test with the same results. My question is; does this mean I need to do an in-frame? Is there any other tests that I could run to help me determine if this is needed? Any help would be greatly appreciated.

Quick question about piston design. The truck dropped an exhaust valve and cracked a cylinder. I couldn’t afford a Mack cylinder kit, so I purchased an aftermarket one. Not mentioning the brand, but on the original piston there are two small reliefs molded in alignment with the exhaust valves. The new piston is flat with no reliefs. Every other dimension on the new piston is the same. My question is will it work, or will the exhaust valves strike the new piston?

Okay, I've spent the past few hours searching the site with no luck. So if this has been asked and answered in the past, I apologize! I have a 2012 Pinnacle and am looking for compatible engine's that will fit this frame. I pull overweight, nothing extreme, 84K. The MP8 just doesn't have the muscle most of the time but the weight of the tractor is perfect for what I pull. Is there any pre-emission engines that would be a fit for this frame that wouldn't take an engineer to retrofit? Again, I apologize if this has been asked, but any help is appreciated.

Thank you for the reply and the assistance.

So after a $20K bull gear replacement expense I now have an issue with power. I'm leaning toward an injector and cup problem, but I'm not sure. The truck is a 2012 Mack Pinnacle MP8 with 560K miles. I have to hand prime the truck every morning to avoid the long cranking start times. Once it is started, it runs well at idle, but between 12 and 1400 rpm it feels like the truck is running over rumble strips and looses power. Once it's past 1400 RPM it smooths out and all is good. I pull 84K pound loads if that helps. I also get a "check fuel filter" warning on the display at times. It has also said there was a fuel restriction. I have gone through three different sets of fuel filters, finally purchasing Mack filters trying to fix this. I'm not sure where to look next, but from reading the posts here am leaning toward possible injector cup and injector issues. Might this be correct, or is there something I'm missing? Any help is greatly appreciated.

It looks to me that this is a catch all clause to exempt them from ever paying a claim.

The nut backed out from what I'm being told.

The insurance company is Chicago based, so..... I feel like I'm getting screwed without the courtesy of a reach around!

Warranty that was purchased is useless! Because the gears are held in place by a "fastener" they have denied coverage! Now the repair shop has given me an estimate of 20K+ for the repair. From the estimate it looks like all I would need is sleeves and pistons and I would have an in-frame overhaul. What is going on?