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EWB555

Porch Pup
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    50
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About EWB555

  • Rank
    Old Iron Expert

Profile Information

  • Gender
    Male
  • Location
    MD

Previous Fields

  • Make
    Mack
  • Model
    RD688S
  • Year
    1995

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  1. My dad and I picked up a 2007 Granite MP7 405 Tri Axle dump from auction this week. Truck only has 112k & 6xxx hours. Cab& chassis are in great shape, ox steel body is beat to hell. Curious on everyone's thoughts about the early MP7 engines? What do we need to be aware of? Truck sounds and runs good. Only issues I can find are a minor air leak under cab, and the small gauges on the dash are broken off from the bezel and have fallen back a little. It has the Mack 10 speed trans. So far pretty happy with it from what we see. We have owned 3 R models over the years 78,86.& 95 (still have the 95) and they have consistently been the most reliable trucks. Hopefully this Granite will live up to the Mack reputation.
  2. Been a while since I posted this. Call me crazy but as soon as temperatures went up during spring & summer this air leak went away. Now here we are in December and it's back again, I replaced the switch today and that was not the problem. I moved the switch on the shifter and that did I not seem to change the air bleed from the dash. The only thing I did realize is that when I switch to low, the leak doesn't go away, it moves to a union in the air line down under the cab. Isnt the inversion valve what steps down the air pressure? Maybe it's letting too much air to my dash switch.
  3. EWB555

    Help! Towed back to shop

    Figured it out. Should have known that when I cracked the fuel line at the pump and some fuel dribbled out that didn't necessary mean it was getting fuel to the pump. First thing I did today was pull the filters, neither one was full. Put 2 new ones on full of fuel, hit the primer on the new transfer pump until it was hard to pump, and it fired up after about 5 seconds. Let idle hoping that maybe it actually was the transfer pump and it just needed a good prime, but I had a feeling that wasn't it. Anyway after a few min I could tell the idle had changed and it was clearly not right, hopped in the cab gave it some fuel to confirm it was missing then shut it off. Disconnected the main line from the primary fuel filter, slid under the truck and stared tracing it, when I got to the back of the trans where it crosses over I discovered that it had a hole in it from rubbing on something. Pulled the line off the truck and will have a new one made tomorrow. Thankful it's not an electrical gremlin however frustrated that I didn't pull the filters when I first checked the truck out last week.
  4. EWB555

    Help! Towed back to shop

    Well, we know it's not the fuel transfer pump. Dad talked to a mechanic who suggested we try that, he picked one up and put it on today, nothing changed. I am going to mess with it Sunday, it's going to rain here all day Saturday. We didn't want to put the truck in our shop since it's loaded. Will definitely crack one of 6 lines on the pump and see what we have. From there I'm going to start checking wires in the harness. Does anyone know how to check the sensor in the side of the pump or the one in the flywheel housing? Will these make it not run if they fail? I have a multimeter and can check voltage, resistance etc. Just not sure what I need to look for. I do appreciate everyone who has chimed in with suggestions!
  5. EWB555

    Help! Towed back to shop

    Ok, so this evening I checked every single fuse, circuit breaker and relay, all good. No malfunction light on. Voltage was 12.5 in the fuse panel. Turned key on and had 12+ on on one pin at the round fuel pump connector, and an even 3 volts on another. Looked in both tanks, pickup tubes seem in tact, cracked fuel line at the pump and there is fuel. Thinking it has to be something with ecm or pump electronics. When cranking it doesn’t even try to start, shoot it with either and it will run a few seconds. Not sure where to go from here, appreciate any suggestions.
  6. 1995 RD688S E7-400. Shut off today, while driving. Seems to be a fuel problem as it will start and run on either. All accessories are coming on when turning key so ecm should be getting power. Thoughts on what to start with to trouble shoot? This engine is computer control but not an etec. Appreciate any suggestions!
  7. Looking at a 2012 Granite Tri Axle Dump MP7 405 10 speed, air ride. Thoughts on this model year? What should I look for? Truck has been fleet maintained 250k miles.
  8. I have a 95 RD688s with the 12 speed air shift. The extended range switch on the dash bleeds air when it's in direct. It's so bad we switch it into low in the am to allow it to air up. Everything works fine, I'm just wondering how to I determine if it's the switch or something causing air to bleed back? It is not leaking from the lines to the switch, its coming from the exhaust ports. I appreciate any suggestions.
  9. On the grant swap out the stock mike if you still have it. There is a pin in the mike plug that has a "receive"wire if that wire is off the terminal or cut somewhere in the mike cord you will get no sound from the speaker.
  10. EWB555

    12 speed

    I have a 95 rd with a 12 spd. The outside inversion valve is constantly leaking air from the botom of the valve, not from an air line or fitting(two bolted together on side of tranny, one closest to frame leaks)I replaced it and still acts the same. The only way to make it stop is if I flip the switch on the dash for low low, then i flip the switch back and the air leak is gone but will come back after driving.The transmission works fine, anyone have any ideas what's causing the air leak?
  11. My truck leaks air when its not in the off position, and I cannot get air to blow out of my defrost when selected, however the Compressor does come on. If I change the "Mulit Position Air Switch" will my defrosters work? I do snow removal with this truck and it sucks to have no defrost!
  12. EWB555

    Fan clutch stays on.

    On the VMAC 1 what would be the proper diagnostic prcedure? I feel I have eliminated the fan clutch, actuator on the side of the rad, and the ECM has been replaced (for another issue, however fan stayed on before & after)
  13. EWB555

    Fan clutch stays on.

    I'm having a similar issue with my 95 E7 VMAC 1, I found this post useful however I still havent solved my issue. Bench tested the solonoid that stops the air to the fan and it works (Clicks when 12 volts applied). Fan clutch disengages when I disconnect the air line so I know it works. I tried the following procedure today to attempt to rule out ac high pressure switch: With the air pressure up and the engine cold, I turned the key on, unplugged the high pressure switch and jumped connector with paper clip, nothing happened. I think the solonoid on the side of the radiator should have clicked if the high pressure switch is the problem? also tried the same method with the coolant temp senor,and nothing happened either. The ECM on the truck has been replaced and the fan was staying on prior to replacing. I looked for the fuse however my truck only goes to number 24, I guess since its older then the one in this thread. I believe my coolant level sensor is in the water manifold towards the front of the truck, as there doesnt appear to be any wires going to the top tank (However I didnt climb up there and look at the back). Appreciate anyones suggestions on how to diagnose, fan belts keep stretching and squealing as a result of fan running all the time. I know I could easily install a manual switch on the fan, however the truck is in really good shape and I hate to bypass a factory system.
  14. I noticed the Turbo on my 95 E7 400 is leaking oil in the center. Its a pretty decent oil leak, dripping down on the injection pump. Is this a sign of potential Turbo Failure? The leak is around where the oil fill tube connects to the Turbo below is I picture I pulled off the net to show where the leak is (its not my truck but the same setup). Truck has almost 450K on it, the turbo seems to have markings on it like it was engraved from a junkyard, I've owned the truck for about 18 months so I dont know the history. Last time I drove it it was putting out 30lbs of boost under load, I seem to recall it used to go up to 35. (I dont drive it that often) Appreciate anyones thoughts!
  15. I feel your pain on this-I have a 95 e7 400 that I was getting the same codes & engine derate. I was able to make the 3-4 go away by changing the sensor in the side of the pump, the 3-5 ended up being the ECM. If I had it to do all over again I would just bite the bullet and take it to Mack. I blew $500 on a new econovance solonoid trying to fix it myself, then the shop I took it to charged me their labor rate to throw parts at it themselves, they changed the timing sensor in the flywheel housing, rebuilt the actual econovance unit, and ultimately the ECM was the problem. Runs great now, but it was a complete nightmare! I wish you luck whatever you decide to do. ---Also I made the same mistake of thinking the 3-5 code was Jake Brake Solonoid instead of Timing Acutator, guess you cant believe everything you read on the internet.

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