1979 Superliner w/ ENDT676 Maxidyne 300 losing prime

[Truckie Harbison]

Well, I asked someone earlier what a rack was and didn’t get a reply. I do think I have the problem fixed. I really felt it had something to do with the lift pump so I took it off , took it apart, blew it out and made sure everything moved freely. I didn’t have new copper washers for the check valves so I sanded them to make sure they were smooth. Put it all back together, blew air through the return line until fuel was at the injector pump, and it fired up. I’ve gone out a couple more times and it has started each time. I’m guessing there was a little trash in the pump, but I really didn’t notice anything.  As long as it continues to work I guess I don’t care. 

[mechohaulic]

let's all hope for the best. greatly appreciated  if you keep the forum updated. alot of good people here try to help solve others mechanical issues . 

[mechohaulic]

(1) = i would definitely acquire the right and proper copper washers ;sanding ?? . (2) - confused as to blowing air through  return line.  a pound or two of air to the fuel tank sends fuel to the engine -air in return line would send fuel to tank,,

[Truckie Harbison]

I will get new washers, but considering I leave on vacation tomorrow and will only have a couple days when I get back before Walcott, I wanted to see if it would work. For the washers, I laid a piece of sand paper on a flat piece of steel and sanding each side of the washer in a figure 8 pattern to flatten both sides of the washer. Is it ideal, no, but it works in a pinch. As far as the return line, I plugged the vent on the fuel tank and blew air into the tank through the return line to pressurize the tank and force fuel to the injector pump.  Again, probably not how others do it, but worked for me. I didn’t see an issue putting air in the return line since it just goes to the tank anyway. That line is after the filters, lift pump, injector pump and injectors so it shouldn’t force air into them. 
 

After letting the truck run for 30 min, I shut it off, waited 10 seconds, and then tried to restart it. It did restart, but I did have to give it throttle to do so. So I would say that it still isn’t right, but it’s better than it was. 

[JoeH]

Common on these at this age for the plastic fuel return lines that jump from injector to injector to crack and let air in when off. Any dampness up there indicates a problem. 

Strange that it hard starts immediately after shutdown but restarts after it's cooled down.  Worn injector pump barrels?... We have an old Ford diesel pickup that got a "rebuilt" fuel pump that wouldn't start when hot.  If you dumped a cup of cold water on the injector pump it would chill down the pump housing on the injector plungers and then it'd start.  Pump shop gave us another pump free of charge.

 

[fjh]

10 hours ago, Truckie Harbison said:

Well, I asked someone earlier what a rack was and didn’t get a reply. I do think I have the problem fixed. I really felt it had something to do with the lift pump so I took it off , took it apart, blew it out and made sure everything moved freely. I didn’t have new copper washers for the check valves so I sanded them to make sure they were smooth. Put it all back together, blew air through the return line until fuel was at the injector pump, and it fired up. I’ve gone out a couple more times and it has started each time. I’m guessing there was a little trash in the pump, but I really didn’t notice anything.  As long as it continues to work I guess I don’t care. 

RACK is the rod that connects the plunger segments Joe is Talking about they are calibrated together ! If one or more segment gets stiff it can lead to stalling or worse a run away ! That said chances are it could  be a governor issue also how ever ! Sounds like you have solved part of your issue there try a dose of Standyne  Or Howes fuel conditioner in the tank and see if it changes your Drivability issue!

[Truckie Harbison]

Ok, so the problem isn’t fixed. It starts fine in the morning. Yesterday I started it and took it for a short drive into town. Came to a stop sign and it died. Wouldn’t restart without ether. Drove it back home fine. 

right now I have the tank rigged so I can pressurize it. I’ve had pressure on it for a couple hours and I don’t see any leaks yet. I’m wondering if either the hose from the tank to the first filter or the hose from the filter to the lift pump is coming apart inside and the vacuum is collapsing the inside of the hose. Either that or I got a lot worse problems. 

Any thoughts?

[mrsmackpaul]

Well that rules out the rack been stuck

Maybe move things about a bit while the tank is pressurized and see if you can find a leak, shake twist fiddle etc 

Maybe try cracking the return to tank part of the fuel system at the injector pump, check the flow there 

Is something is floating about in the tank ? I don't think this will be likely from what you have described 

This has happened when it is running so I  believe that it must be in the supply side of the fuel system 

 

Paul

 

[terry]

10 hours ago, Truckie Harbison said:

Ok, so the problem isn’t fixed. It starts fine in the morning. Yesterday I started it and took it for a short drive into town. Came to a stop sign and it died. Wouldn’t restart without ether. Drove it back home fine. 

right now I have the tank rigged so I can pressurize it. I’ve had pressure on it for a couple hours and I don’t see any leaks yet. I’m wondering if either the hose from the tank to the first filter or the hose from the filter to the lift pump is coming apart inside and the vacuum is collapsing the inside of the hose. Either that or I got a lot worse problems. 

Any thoughts?

If them hoses are real old they definitly can come apart on the inside.   terry 

[Joey Mack]

I dont understand how it can be running and warmed up,  shut down and not start right back up without ether.. to me if is warmed up, then the compression should be at it's best.  so yes, fuel supply may be the issue here.  Do you have a small tank you can mount above the level of the injection pump, that you can connect to the inlet of the primary filter, and run a return line back to it so you can run it for a while til it warms up, and try to restart it in an attempt to duplicate the problem..  I know I may sound like a nut,  but sometimes I do these things just to see.... especially if I dont have new parts on hand.  ok,  I will set back and watch now..  jojo

[terry]

45 minutes ago, Joey Mack said:

I dont understand how it can be running and warmed up,  shut down and not start right back up without ether.. to me if is warmed up, then the compression should be at it's best.  so yes, fuel supply may be the issue here.  Do you have a small tank you can mount above the level of the injection pump, that you can connect to the inlet of the primary filter, and run a return line back to it so you can run it for a while til it warms up, and try to restart it in an attempt to duplicate the problem..  I know I may sound like a nut,  but sometimes I do these things just to see.... especially if I dont have new parts on hand.  ok,  I will set back and watch now..  jojo

I'll bet it is something so simple, just being overlooked!   terry maybe this has been mentioned, something in the tank plugging pickup at different times?

 

Edited July 10, 2022 by terry

[Joey Mack]

I actually posted this before..  I was trouble shooting a similar problem in an RD many years ago,  after a day of going nowhere, when I pulled fuel line inlet to the primary fuel filter, I found electrical tape in the line, I was able to gently pull the tape out of the line.  and just like that, problem solved. My bossman said that is was sabotage, because if you drop a roll of electrical tape into the tank, the diesel will dissolve the glue and the tape gets sucked up the line...   The most recent one was about 4 years ago, on a CXN..  similar issue, plus the fuel tanks wouldnt balance out, (no crossover hose)..  I found slivers of Bamboo swing around in the tank..   my guess was that they were using the bamboo to check the fuel level.  there was a stick of it laying in the headache rack.  the slivers got sucked into that supply line..   anyway,   I hope his truck isnt addicted to ether at this point..   jojo

[Truckie Harbison]

So I gotta ask, how does a truck get addicted to ether?

[Joey Mack]

compression becomes too low, in order to burn diesel.  since ether will burn at much lower temperature, it lights very easily.  the wear is already in the engine to start with, the ether just allows you to start it up, and when the engine is running at around 650 RPM's, it has enough rotational force to maintain itself. and compression is higher due to the speed of the running engine compared to the typical 250 RPM's that the starter provides..  this next part is just my opinion...  Because a diesel is a compression ignition engine, introducing fuel at the right time is crucial. The issue I have with 'sprays' into the intake is that,  as the piston comes up on the compression stroke, to compress the air. the temp of the air is hot enough to light the ether early..  "Pre-ignition"  Not a Good thing...  this can and will weaken the engine, and if abused can bend rods and such..  I welcome any and all opinion's on this, and even those that dissagree with me.. I always learn from the many comments here..    jojo

[Truckie Harbison]

That makes sense. I wouldn’t think it is addicted since it starts fine on its own each morning, or maybe that would be typical of an addicted engine. When I do have to give it ether to start, it is only a very short spray. 

[D-Day]

38 minutes ago, Joey Mack said:

compression becomes too low, in order to burn diesel.  since ether will burn at much lower temperature, it lights very easily.  the wear is already in the engine to start with, the ether just allows you to start it up, and when the engine is running at around 650 RPM's, it has enough rotational force to maintain itself. and compression is higher due to the speed of the running engine compared to the typical 250 RPM's that the starter provides..  this next part is just my opinion...  Because a diesel is a compression ignition engine, introducing fuel at the right time is crucial. The issue I have with 'sprays' into the intake is that,  as the piston comes up on the compression stroke, to compress the air. the temp of the air is hot enough to light the ether early..  "Pre-ignition"  Not a Good thing...  this can and will weaken the engine, and if abused can bend rods and such..  I welcome any and all opinion's on this, and even those that dissagree with me.. I always learn from the many comments here..    jojo

I second that, I have seen to many people spray to much ether in an engine to get it started usually in cold weather, and afterwards it needs ether to start it even though its not very cold when I tear down to rebuild ill find broken rings the smaller the pistons the smaller the rings they wont handle it as well as a large bore with bigger piston rings we have 2 pieces of equipment down right now that had a lot of hours on them one with a cat 3056 and the other with a cat 3126 both were ether addicts when the cold weather came

[Joey Mack]

Truckie,  my post isnt directed at you, as much as I hope it is info for anyone who needs it.  You may be very cautious about how you use ether, but I have seen heavy doses being sprayed, and its not good..   we had an MP-8 in the shop a few years ago, and a so-called master tech, loaded the CAC so full of ether, rather than taking the intake boot off he just filled it from the turbo side..  anyway, it ran away...  it didnt break...  I put the laptop on it to read the last event, and it hit 3250 RPM's..    the reason the truck would not stay running.....  another guy put the wrong compressor gear on the new compressor, and the gears didnt mesh,  so there was no fuel being pumped..  jojo

[mrsmackpaul]

Dunno the science about ether addiction, I  will say it is with out a doubt in my mind a genuine thing

I dunno if it damages stuff insude the motor but at the very least something changes, I  thought maybe washes carbon out of the ring and piston gap but if Jo says its causes more damage than that I would believe him

To me it is much easier to just fix the problem than it is to muck about spraying crap in there 

This is also not directed at you Truckie but at the question on ether 

 

Paul

[Mark T]

Ether is a tricky thing. if metered in properly it can be a cold weather starting aid.  Just sprayed in recklessly ???  the engine can easily be running out of time and to uncontrolable RPMs  if anywhere in the intake is loaded up with it.  So yeah, it can get out of hand if not used sparingly .  Some old Cummins engines, when they became worn and hard starting in lower temperatures it would seem as if they wouldn't start without it (addicted) most likely the engine was a combination of worn out and cold.  Most guys would sooner forget about how things were years back compared to starting diesels now.

[Joey Mack]

ether is highly volatile. and has no lubrication in it..  I certainly dont know all the aspects, but I have worked on many worn out diesels that were fed ether until they died,,,  (Diesel Morphine) if you will.  or (Diesel Hospice)... anyway... this is one of those topics that I tread lightly on in my world, because..... far be-it for me to tell someone how to operate their machines that they have operated for years...  know what I mean??    jojo

[Onyx610]

Worked well for Bill Cosby, so much that starting fluid is now called “Cosby in a can”.  

[Mark T]

Wasn't there some legal issues with Cosby in someone's can ?

[Joey Mack]

first time I heard that one Onyx...   

[Joey Mack]

yes Mark, forceable entry...   jojo

[Mark T]

I think there was a special ether called Roofy brand he used.  Must have been one of those old ones that you could seat a bead with .