jzack

Ya know I think the cable show "Myth Busters" tested that theory out in one of their episodes. They found that at freeway speeds they actually got better mileage with the windows up and the A/C on than with the windows all down. Of course in a big truck the variables would change a bit.......

Exactly.

I guess for the kind of work I do I can honestly say that yes I DO need AC up here in Minnesota. I drive a black day-cab -think "greenhouse". Most of my deliveries are local, I probably only average 35mph some days, not enough breeze to get the heat out. When I do get out of the truck I get to stand on a shiney aluminum flat-bed chaining and unchaining sheet metal -think "tanning bed". When I get back in my cab after a delivery I sometimes have 5-10 minutes of paperwork. So its just nice to have a place to work thats a few degrees cooler.

I also agree with you on the plastic leveler valve parts. Seems to me that parts on a truck that are moving all day long should be made out of metal and not plastic. I usually replace mine with stainless steel heim-joints found at the local hardware store. I for one though couldn't drive w/o AC. I have mine running from May through September! My older CH does have the vent in the door which I do use from time to time. Keeps the feet and legs nice and cool.

Well she fired right up Sunday night so I'm fairly certain the new return line was the fix. Thanks to all who contributed, it was greatly appreciated. Jeff

Reminds me of a quote I often heard from one of our O/O who's Mack lacked all the chrome "trinkets" always found on the Paccar's- "chrome don't get you home".

Well, I THINK I found my leak. I'll know for sure next time I let it sit for over 24hrs. I pressure washed the motor the other day to start out fresh and the next day I noticed a tiny bit of wetness around a fitting at the front of the head behind the waterpump (tough bugger to spot). It was the 3/16" fuel return line from the injectors back to the pump. The line looked to be all dry-rotted and practically desintegrated when I removed it. Went to Mack and got a new line and clamps and all was dry today. Fingers are crossed............

Thanks for your input HK. I'll check all my lines and filters to make sure they are tight this afternoon. The reason I've been focused on internal parts (check valve, seals) is because I've yet to see any wetness on lines or fittings. I figured if air is getting in that fuel would make its way out, but this is just my backyard mechanic logic. I've never worked on trucks for a living. Curiously, after replacing the plunger and check valve the problem did get better. Back to happening once a week rather than every day. So after replacing a part I would think its fixed until the next Monday morning rolls around and no fuel....argghhh!! I'm starting to think I should have just taken it to Mack in the first place rather than trouble shoot it on my own.....we'll see. Jeff

Well I've replaced the hand-pump and it still leaks down. Then I noticed when I prime with the hand pump I can hear fuel splashing back into the fuel tank. So I replaced the check-valve in the return line, but I am still getting leak down over a weekend. So Rob, now I'm thinking the next step would be the supply pump which I believe is what you were referring to in your last post, correct? If so, my dealer here told me there isn't a rebuild kit for my E-7 and a new one is about $200-300. Oh well.... Thanks, Jeff

I've seen a couple here in Minnesota. One looking pretty at the dealership in Roseville and another in the yard at Lefebvre in Elk River. The one at Lefebvre is interesting because they've run Petes and Kenworths for as long as I can remember. I couldn't help but think Mack would sell more of these if they would square off the hood in a retro/modern sort of way ala Mustang/Challenger, put a sleeper on it and rename it Superliner........lower price probably wouldn't hurt either. Haaaaah to dream.

What you described above sounds real similar to how my '94 CH 350 runs. The boost builds fast and peeks around 30lbs. while going through the gears (accelerating), but when I dip into the throttle at cruising speeds I can barely get 25lbs sometimes. Not sure why this is so. Maybe it is in the programming like fjh said. I am currently running the Blixxton box which has increased my peek boost (22lbs. to 32lbs.) but I still notice the variance. One other noticeable improvement with the Blixxton is better throttle response and lugging power in the lower RPMs. I believe the box fools the electronic nannies into providing full fuel in the lower RPM range. My pedal used to be dead between 1200 to 1400, now it feels like the pedal is connected directly to the pump if that makes sense. I know Blixxton only mentions E-7 300-400HP but the 427s and 460s all had the same pump so it may be worth a shot to give you a better torque rise in the lower RPMs. I've been running mine now everyday for a year and a half with no problems. There is a guy on BMT here who runs one on his 454HP and knows quite a bit about them........

Thanks much Rob. You may have just saved me a good chunk of change. I'll ask my dealer about a rebuild kit for my E-7.

I grew up in my Dad's '79 Superliner. It was a beautiful truck with a show-truck paint job that would turn heads everywhere we went.....life was good. So it really pains me to see the Bulldog disrespected, and slowly bled dry by an arrogant foreign company. To all the Mack employees, hold your heads high! You have built THE BEST, LONGEST LASTING trucks the industry has ever seen. My family owns a small trucking company that has relied on Macks for over three decades. My current truck is a 94 CH (the one in the avatar) that has worked almost every weekday since it left the factory and has NEVER left me on the side of the road once. Quite a feat considering it has seen 15 Minnesota winters! Think Ice-Road Truckers. Our company had a couple of Volvo's in the mid-nineties around the same time my truck was new. Guess what? They are long, long gone. The drivers didn't like them, and they were hard to keep on the road. They have probably been scrapped or made into soup cans. Who knows? Maybe I even hauled some of their recycled remains on my flat-bed. So, to all of the Volvo Truck employees, no disrespect, but don't think for a second your company is in its current position because it builds a better truck than Mack because YOU DON'T. Yes, maybe you have a better business model, impressing shareholders by selling thousands of 5 year throw-away trucks that drive like campers to dumbfounded fleet-managers nationwide. I can here the Volvo execs now, "how could Mack be so stupid building trucks that stand the test of time, can't make money doing that!" They have forgotten what trucking is all about for a small company like ours. Only a company that has been building trucks since trucking began remembers. That company is MACK TRUCKS! For me, my fondest memories are of waking up, peeking out the sleeper of that old '79 Superliner and looking out, wondering where we were. The scenery always changed but one thing stayed the same. I remember seeing the Bulldog, sun sparkling on its back, always confident, leading the way.

Funny thing, I'm having almost the same problem with my 94 E-7 350 right now. Every morning my truck needs to be re-primed. Called the local Mack service manager and he said probably take 2-3hrs to diagnos....ouch @ $108 per hour. So before I bring it in to let a mechanic hook up a pressure guage and eat a sandwich while he watches for the needle to drop (at least thats what I picture him doing) thought I'd try for advice from the Mack savvy folks here on the forum. Here are some clues- 1) Gradual Worsening: this problem would pop up once a month, then once a week, now every morning. 2) Manuel priming has limited results: first 2-3 pumps are air, then I can feel the fuel in the plunger, but I can never get it to feel rock hard no matter how long I pump it (I know that sounds bad). I've run this truck out of fuel before when I was younger and dumber and I remember it popping right off after pumping the primer until it hardened up. Now it can take 10 seconds of cranking to start even after the manuel priming. 3) No Visual Leaks: similar to the earlier fellows problem, I don't notice an outside leak or smell any fuel in the garage. If anyone with knowledge and/or experience with the electronic Bosch V-mac I system, and recalls a common problem or two that fits the above symptons, I would greatly appreciate the advice. Thanks, Jeff

If you lose your jake again, check the wires to make sure one isn't worn through and shorting against the motor. This was the problem when I lost my jake.