jzack

Thanks for all the tips on the input seal, I'll make sure to look for a groove in the shaft.

I might try a novel way to pry out the seal I saw on a video the other day. The guy carefully drilled a small pilot hole in the top of the seal. He then screwed in a tall screw enough to grab the seal. Then grabbed the top of the screw with a pliers and used the top of the input shaft for leverage to pop it right out. No mess, easy peasy. If that fails, I can try the messy way!

Ok, I'll ask about dropping the pan to inspect the cam. The mechanic working on it has been working on Macks for 29 years and really knows his stuff so I trust his opinion.

Even though this engine has 1.3M miles it wasn't showing any signs of being on its last legs. I've maintained it since new with regular filter/fluid changes, did the overhead every 300k or so. In fact, the overhead was just done in Dec. along with new injectors.

Thanks fjh. I'll make sure and ask the mechanic about the lifters. I'm curious now.

Well, Mack says it was the fuel pump, no big surprise. Sending it out to get rebuilt now. The oil looked good, no metal. Valvetrain also looked good, other than a couple of frost plugs leaking. The mechanic said he will put the rebuilt pump on and see how it runs. He did start it briefly already and said there wasn't any bad noises. Thinking about putting it on their dyno to see if it can put power down without any issues after the new pump install and go from there.

Picked up the T880 today. Kind of surreal going from a 28-year-old truck to a 28-day old truck LOL!! I can already tell my Mack has a better ride. The KW ought to really go though with a 510HP/1,850TQ and 12 speed auto. Amazing they can get that from a 12.9L.

Joey Mack, thank you, I appreciate the sentiment. I was literally across the street from our local Mack dealer when this happened, so I thought it was fate to have it towed there. They do have a few old timers left there that really know their stuff and I'm friendly with the service manager there. I wouldn't hesitate to have them do a full re-build but the $$$ would be crazy. 

Hopefully a pump is all it needs to get it running, then I can bring it to our shop for a full re-build some time in the near future.

I'll keep you all posted.

fjh, thanks, maybe I should consider myself lucky here. The tow truck driver said that many times a runaway engine ends with the truck burning to the ground!!

Also, as luck would have it the boss (my sister) is leasing me a brand new 2023 Kenworth to break in while my truck is in the shop. Should be interesting, I haven't driven a new truck since I started driving my Mack in 1995. At that time, it was the best truck I had ever driven. Probably why I kept it so long. 

fjh and LtK, very good info, I'll definitely take into account.

Thank you!

Joey Mack, thanks, I'll make sure to check the top end and pay attention to the oil.

As far as the turbo, I didn't see oily residue in the stack. The accelerator issue (cutting out) and electronic malfunction light don't seem to point to the turbo. The idle had a slight lope to it right before this happened too.....

67RModel, thank you, yes I'm local so I could go in baby steps like you said and see how it responds.

Thinking about at least pulling the valve covers and inspecting, send the oil out for analysis too maybe....I would think the shop would have a check list before starting a runaway engine either way.

My mechanic mentioned rebuilding or replacing the Econovance too, but they are NLA and the pump shop said they don't work on them either. 

Well this was an awful experience. Been driving this truck for 28 years with no major issues. Over 1.3 million miles, 45,000 hours all original engine, even down to the turbo.

I left with my second run for the day and the accelerator started acting funny. When I would let up to grab the next gear the RPMs would immediately drop too fast for me to grab the next gear, then they would come back. Like the accelerator lost signal momentarily. Did this twice, then the electronic malfunction light came on and the engine de-rated. Great I thought. So I started moving to the shoulder, pushed in the clutch to grab a lower gear and, BAM the engine immediately went WOT!!! Of course I panicked for a second, turned the key off, no response from the engine. I got it pulled over, remembered reading about runaway engines and what to do, so I grabbed my jacket and stuffed it in the air cleaner intake. That slowed it down to what sounded like a safe RPM but she kept going! White smoke pouring out the exhaust. Now what? Next, I grabbed a wrench and started to crack loose the fuel line to the filter tree. Two or three turns and it finally shut down. Whew!!

Not sure how long it ran like that but probably a good 2-3 minutes at least. So disappointing, I'm sure anything in or attached to the engine will be suspect for failure now. An old mechanic at Mack suspects something gave way in the injection pump. We'll see I guess. They are a week out on service work. Three weeks to re-build the pump maybe. The worst part is, short of a full overhaul, not sure I can trust this engine again. Am I right? Before this, she was still running strong with no issues or symptoms whatsoever.

On a side note, my Old Man, who I love but enjoys Monday morning quarterbacking, said I should have jammed it in gear and side stepped the clutch? Not sure the drivetrain would have enjoyed that experience though.....

7 minutes ago, Joey Mack said:

a couple of the ones I service had the same issue..    I got pissed and took the little clamp plates out, and the issue stopped.  I think the newer lines arent as good as the original lines.

Interesting, maybe I'll try that when I finally get to the end of my rope on this.

I've got a 1994 CH with the E7350. Back in December I replaced #4,5,6 injector lines. They were leaking at the head. Now 4 months later all three have failed with small hairline cracks behind the nipple at the injector. Mack has been warrantying the lines but I'm really growing tired of replacing them every few months. Yes, I make sure all the line clamps are good and tight. The lines stay dry for weeks, maybe months and then bam, they start dripping on the manifold.

My original lines were 0.25" OD, the new OEM ones from Mack are 0.23 OD I noticed. I let Mack know about this....

Do I have any other options here?

• Follow up question- How many ft/lbs do you torque the "outer" nut to on the budd style wheels? I've seen sources say 600ft/lbs for outer, 450ft/lbs for the inners. But most people seem to say 450ft/lbs for both. I'm asking because i've been having problems with my lugs coming loose.  

Try adding a centrifugal filter system. All Macks have had these for years and they work great.I think Amsoil makes an aftermarket system you can add to almost any motor.

I have a 2000 Vision with a 460 and experienced the same Jake problems. Had Jake rebuild and very little improvement. Added external oil kit and had some improvement but not great. Changed engine oil and added two gallons of Lucas and could not believe the difference. Pennsylvania mountains on I80 I had to brake going down I can now go down without applying brakes.

Also saw a 10 lb increase in oil pressure.

The Jake in my Mack has always worked great. I also use 2 gallons of Lucas at every oil change.

So the president says new trucks have to get better fuel economy, which puts more dollars in your pocket... And you're complaining?

No, I'm complaining that the last 10+ years of R&D have been too focused on decreasing emissions instead of increasing MPG.

I agree, too much focus on cleaner emissions and not enough on improving MPG. A truck that gets good fuel mileage will, by definition, emit less pollutants AND save the operator $$$$$.

I mean c'mon, 20 year old technology is still capable of getting the same if not better than a brand new truck. THATS CRAP!

Check your codes. My truck did the exact same thing and it was throwing a code for the Econovance solenoid (sits in front of the fuel pump). Threw in a new solenoid and problem solved.

The 427 and 454 are both 10.0 BTDC. The only difference between the two is the data file in the V-mac program.

I probably have 250,000mi on my Blixxton in my 94 E-7 350 now and I still just love it.

My guess is the Blixxton keeps the timing advanced throughout the RPM range because I notice a definite lumpy idle when I have the switch set to 30%. Idles like I have a hot cam in it, kinda cool!

While I haven't had your particular issue, I have heard that re-pinning the connector has cured similar issues as yours. I have also heard of wires shorting out on the firewall behind the washer fluid reservoir causing erratic running quality.

Even if Mack were a "stand alone" company, who knows what it would look like today. We only assume it would look like the "old" Mack. Things change, it's a very different and very competative world out there. There were many years Mack owned over 50% of the heavy truck market. Look what happened - who's fault was that? Can't blame that on Volvo.

I agree. You can't blame Volvo for tougher EPA regulations or the more competitive global market either. Both of which played a part IMO. Mack's management probably could have done better.

I love my 94 CH w/E-7. Has 992,000mi and still running with the original motor, including the turbo and injectors. Still gets 6-7 MPG too. The motors built today would have a real hard time matching that kind of reliability/longevity. Where's the progress?

Maybe I'm a glass half full guy, but I think Volvo really does know and respect Mack to a certain extent. I mean here we are some 12 years into this and Mack is still here. A guy can still spec a "Mack" truck that has a Mack hood, cab, interior, transmission, axles, and an engine tuned and programmed by Mack engineers. These aren't just re-badged Volvos as some would say. No one in this global economy can go it alone anymore and this marriage has gone better than many others. In fact, if Volvo owning Mack "is a crime" than what GM did to Saab should be considered man-slaughter! Remember the "Trollblazer"? Simply a re-badged Trailblazer for the SUV shopping Saab faithful. No wonder Saab is dead!

Could Mack have been better without Volvo? Who knows? Maybe, but it could also have been worse than it is now, a lot worse.

Had this problem also with the Holset compressor on my 94 CH. Went through 3 compressors before switching to a Bendix and the problem seems fixed 3 months into it. The Holsets all passed oil almost immediately. BTW, the Holset comp. were Mack grey, while the Bendix is blue/green.