joes mack Posted January 5, 2011 Share Posted January 5, 2011 ive been working on the dozer that my friend owns we had the fuel pump rebuilt, new injectors,timing and valves checked,turbo and heads. but we cant get it to run worth a crap. i replaced the line from the intake to the fuel pump, new fuel and air filters today and it still wont rev and it barely will pull up a small hill. my question is what does the high idle screw/bolt do? if i adj it will it make it have any more power? if so how much should i go from what the rebuild shop sent it back with. my dad said its not reving up like it should he says its only got about 1/2 to 3/4 of what it should have. (he has run these old cat dozers a lot more than i ever will) thanks for any help in advance...joe Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/ Share on other sites More sharing options...
randyp Posted January 5, 2011 Share Posted January 5, 2011 ive been working on the dozer that my friend owns we had the fuel pump rebuilt, new injectors,timing and valves checked,turbo and heads. but we cant get it to run worth a crap. i replaced the line from the intake to the fuel pump, new fuel and air filters today and it still wont rev and it barely will pull up a small hill. my question is what does the high idle screw/bolt do? if i adj it will it make it have any more power? if so how much should i go from what the rebuild shop sent it back with. my dad said its not reving up like it should he says its only got about 1/2 to 3/4 of what it should have. (he has run these old cat dozers a lot more than i ever will) thanks for any help in advance...joesounds like some throttle linkages out of wack. have someone work throttle while you watch linkages for slack or out of adjustment or slop. randyp Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69785 Share on other sites More sharing options...
joes mack Posted January 5, 2011 Author Share Posted January 5, 2011 took linkage off and worked arm on the pump by hand and the rpms still wont go up much above 1/2 to 3/4 without a load on the engine. Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69788 Share on other sites More sharing options...
bullhusk Posted January 5, 2011 Share Posted January 5, 2011 Joe, You probabally have the D342 motor in your D8K, and if you had the pump & injectors done and you have a question about it call the shop that did the injector pump before you touch it! Also check the travel on your linkage make sure when you pull the throttle down it doesn't creep, if I remember correctly that machine has a two peice spring loaded throttle rod under the hood,just make sure that it's not slipping back, look at your pump an make sure the throttle stays open. Did the machine have any of these troubles before you did the work? let us know is it smoking? hard starting did you bleed down all your injectors& lines did you check your fuel filter gaskets some times the old gasket sticks to the housing I know some of this sounds @#$%! crazy but this shit does happen hope some of this helpsBULLHUSK Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69790 Share on other sites More sharing options...
theakerstwo Posted January 5, 2011 Share Posted January 5, 2011 Timing. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69792 Share on other sites More sharing options...
bullhusk Posted January 5, 2011 Share Posted January 5, 2011 YEP, your right!! THEAKERSTWO he had the pump off the machine!!! Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69796 Share on other sites More sharing options...
joes mack Posted January 5, 2011 Author Share Posted January 5, 2011 the machine starts like it did before (fairly easy) and before the pump went down it would roll black smoke and push like crazy. but now it wont push a full blade and doesnt smoke at all. the guy that checked the timing said it was right. (retired cat mechanic) he has his own business and cant get back on the job for another month so im trying to find something on this dozer to make it run better. ive done everything that i know to do for it. the only thing thats left is turn the pump up but im not real sure on how to do that. it has 2 screws/bolts under the rear cover. one low idle and one high idle...joe Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69803 Share on other sites More sharing options...
bullhusk Posted January 5, 2011 Share Posted January 5, 2011 Joe, OK if you open throttle wide open does the motor rev an then level off ? Or when you go to push, an the engine calls for power, you should hear the turbo an start to see black smoke. If thats not happening it sounds like your governor is not opening inside of your pump when the engine calls for power. But it does sound like a timing prob. but if you had that checked then maybe the gov. is stuck,an that would cause the engine to run in a no load, but again like I said before call the guy that set your injector pump up because if you do something to burn a piston or something like that those D342 motors are very $$$$$$$$ to fix Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69811 Share on other sites More sharing options...
hillconst1 Posted January 5, 2011 Share Posted January 5, 2011 This sounds like a timing or fuel starved pump problem. If the pump was rebuilt I would not touch it. If the pump is set to factory specs this tractor should push its ass off. Mine would spin the tracks or push in second gear always and the pump was set stock. I did however have a problem just as you describe and checked everthing and it turned out to be a collapsing fuel line. Have you checked to see if it will turn up to 1300 rpm under no load? If it will and has no power it probably is fuel, governor, or timing preventing the machine from producing power. As far as the retired Cat guy, even the best make mistakes I would have the timing checked again. I would check everything before I touched the pump and then I would take back and have it tested at the injection shop. If you have other problems turning up the fuel is only going to wind up cooking a $30,000 engine. Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69825 Share on other sites More sharing options...
fifth wheel Posted January 6, 2011 Share Posted January 6, 2011 Check fuel pressure.I had the same problems a few years ago, not quite full rpm's. It was in the hot side of the turbo, it would be fine idle to about 3/4 throttle, at full throttle it didnt have the power it should, if I loosened the Marmon clamp on the hot side of the turbo it would rev up a little more. The flange on the cartridge was pitted and worn enough to allow the impeller to rub the hot housing at high speed/temp. With a new cartridge I still had to dress up the inside of the hot housing. If they sit for long periods rust builds up, doesn't seem to be the problem here. When its in spec, full throttle,full load, exhaust haze to a trace of smoke.77V14800's FW Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69856 Share on other sites More sharing options...
joes mack Posted January 6, 2011 Author Share Posted January 6, 2011 thanks for all the info. i ran the dozer today and adjusted the high idle to where it puffs just a little smoke under a load when you hit the fuel pedal and let off agin. it has about twice as much power as it did yesterday and it still dont get hot so im going to leave it alone. its still not where it used to be but it will do for now. thank agin joe Quote Link to comment https://www.bigmacktrucks.com/topic/17127-d8k-help/#findComment-69863 Share on other sites More sharing options...
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