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Dm690 With 300L Engine


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MACK 300L WITH 193,000 MILES , PUMP HAS NEVER BEEN TOUCHED. SEEM TO WANT TO HUNT AND PULSE WHEN RUNNING DOWN THE ROAD UNDER NO LOAD, BUT WHEN PUT UNDER LOAD IT SEEMS TO GO AWAY ONLY TO RETURN WITH NO LOAD AGAIN. WAS WONDERING IF THIS IS A PROBLEM IN THE PUMP OR IS THIS JUST IN THE LINKAGE WITH THE TRUCK BEING OLDER. TRUCK IS A 1989, I HAVE BEEN NOTICING THIS MORE AND MORE OVER RECENT YEARS. DOES ANYONE HAVE ANY IDEAS. THANKS

GG2

We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful.

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Check the return spring and throttle lever first.. if thats ok then it sounds like the pump or gov is getting worn out. time for a check up! some have claimed they may run away if it gets worn out real bad...

Yup like Trent has said check the the throtle lever internal spring if there is any movment between the spring ends this will cause the engine to surge!If its not loose then the govener is at falt!

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Yup like Trent has said check the the throtle lever internal spring if there is any movment between the spring ends this will cause the engine to surge!If its not loose then the govener is at falt!

what kinda money do you think if gov.

gg2

We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful.

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I have a pump guy in Il that turned up / calabrated some of our pulling trucks for $300-400 this is a no parts involved deal. most of it is his time and use of his pump stand. I think $800-$1000 would be the avg standard rebuild of a pump. never had a pump rebuilt so cant be for sure. Price will also depend if its a Robert Bosch or American Boasch pump. one seams to have cheaper parts?

FJH will know more than I on the costs involved....fyi be glad its not a V8 Pump. they cost as much as a E6 300Hp motor...seriously!

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I have a pump guy in Il that turned up / calabrated some of our pulling trucks for $300-400 this is a no parts involved deal. most of it is his time and use of his pump stand. I think $800-$1000 would be the avg standard rebuild of a pump. never had a pump rebuilt so cant be for sure. Price will also depend if its a Robert Bosch or American Boasch pump. one seams to have cheaper parts?

FJH will know more than I on the costs involved....fyi be glad its not a V8 Pump. they cost as much as a E6 300Hp motor...seriously!

The If its an AMBAC pump you can remove just the governer to have the repairs done!

If its a robby bosch the pump has to come off!its been awhile since we had any pump work done but some where in the 1000 buck range sounds correct!Get a quote!

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I have a pump guy in Il that turned up / calabrated some of our pulling trucks for $300-400 this is a no parts involved deal. most of it is his time and use of his pump stand. I think $800-$1000 would be the avg standard rebuild of a pump. never had a pump rebuilt so cant be for sure. Price will also depend if its a Robert Bosch or American Boasch pump. one seams to have cheaper parts?

FJH will know more than I on the costs involved....fyi be glad its not a V8 Pump. they cost as much as a E6 300Hp motor...seriously!

The If its an AMBAC pump you can remove just the governer to have the repairs done!

If its a robby bosch the pump has to come off!its been awhile since we had any pump work done but some where in the 1000 buck range sounds correct! take your pump No#s in and Get a quote!

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A quick way to isolate if the governor is at fault is to elevate the front end on jack stands with front tires about a foot off the ground. If the engine hunts when level, and does not hunt with the front elevated. Have the governor rebuilt.

You can also do this with the front wheels in a ditch or other depression. You need the have the truck out of it's normal orientation of operation.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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I MAY JUST TRY THAT ROB. BUT THE TRUCK DOESNT SEEM TO DO IT WHEN AT AN IDLE. JUST ABLE TO HEAR ONE INJECTOR FIRE ALITTLE HARDER, BEEN LIKE THIS FROM NEW. I WILL CKECK WITH MY PUMP PLACE TO SEE IF THEY CAN FIX AND WHAT THE $$$$$$ WILL BE. THANKS.

P.S. RO , HOW IS YOUR 700 WITH THE 12V-71 DOING.

GG2

We the unwilling, Lead by the unqualified, are doing the impossible, for the ungrateful.

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I MAY JUST TRY THAT ROB. BUT THE TRUCK DOESNT SEEM TO DO IT WHEN AT AN IDLE. JUST ABLE TO HEAR ONE INJECTOR FIRE ALITTLE HARDER, BEEN LIKE THIS FROM NEW. I WILL CKECK WITH MY PUMP PLACE TO SEE IF THEY CAN FIX AND WHAT THE $$$$$$ WILL BE. THANKS.

P.S. RO , HOW IS YOUR 700 WITH THE 12V-71 DOING.

GG2

Hi, it is fine but on hold for now. I've got a lot of ground to make up since wrenching my back and the B-67 is first as I need something to drive. The Project R-12 will move forward shortly after the B-67 is rolling again.

Thanks,

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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GG2 & Rob, I just put my third Ambac inj. pump on my R600 E350 4 valve only over 300,000 i forget exact mi.what's the deal with these ? I pull side cover off and thers brass in pump,asked Mack about changing to a P7100 robert bosch said i'd have change turbo ?any ideas????Ernie

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GG2 & Rob, I just put my third Ambac inj. pump on my R600 E350 4 valve only over 300,000 i forget exact mi.what's the deal with these ? I pull side cover off and thers brass in pump,asked Mack about changing to a P7100 robert bosch said i'd have change turbo ?any ideas????Ernie

I've never been around the four valve engines myself. I know the Stanadyne, (Roosa-Master) pumps could be rebuilt using the original plastic internals but the quality rebuilders would use stainless steel in it's place. They then offered a lifetime warranty on the rebuild. I can only assume the Bosch pumps would be similar in parts availability.

The only time I've seen injection pumps chewed up internally, (sounds like yours is) can be attributed to a high moisture content to the fuel, and filthy abrasive oil. You mention brass and the only places bronze is used is in the supporting ends of the governor shaft, and sometimes the sliding rack assy through the pump body.

Are you sure the brass is originating within the pump itself? There are a couple of other places that could be wearing, or chewing, and the engine oil pump supplies the injection pump with oil without being run through the oil filter first.

You may need to look into the engine further. After the same part fails this many times it would seem time to explore.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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Rob, I had 4 other R models 1986 EM300 4 valve had the same prob.Mack said it was a brass bushing prob. inside the pump?Ernie

I'll have to do a little research as this has me curious. As I mentioned I've never been around the four valve engines as they are too new for my level of experience. For a part to repeatedly fail tells of lubrication problems.

I'm wondering if the lube oil passages are rifle drilled, or just a simple sleeve bearing setup. Be interesting to learn.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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