Rated rpm problem ?

   / Rated rpm problem ? #1  
C

CaseIH485

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Apr 21, 2014
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3
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Rossland
Tractor
CaseIH485
Hello all,

long time since I'v been on this forum.I have lately been trying to figure out a problem with a Case IH 485.

The problem is that the engine does not reach the rated rpm, 2200, even if I pull the lever on the injector pump, an Bosch AVxxxxxxxx (do not have the number here), all the way to the mechanical stop. Rpm meter stops at approx 2000.

I have changed the filters and bleed the system, but no improvement. So far I have not adjusted anything on the pump. As far as I known nobody else has adjusted anything before.

So I wonder, do any of you have an idea as where to start fixing this problem ?
 
   / Rated rpm problem ? #3  
Could be air in the system, or an air leak. Did you try bleeding at injectors? If you crack at the injector and the engine sound does not change, the problem is isolated to that cylinder.
 
   / Rated rpm problem ? #4  
Who's to say that on a 50yr old tractor, the tach is correct.??
Go get a 20.00 photo tach from harbor freight..
 
   / Rated rpm problem ? #5  
A 485 is a 90s tractor. A good one at that. I worked on quite a few of them.
 
   / Rated rpm problem ? #6  
Whoops! 485 was 1985-91. I dealt with the 95 series. Still fairly modern.
 
   / Rated rpm problem ?
  • Thread Starter
#7  
Ok, it has crossed my mind that it could be the airfilter. But I haven't got around to check it yet.

Will also check the theory to check at the injectors.

The tachometer could of course be of but it feels/sounds like it is not reaching the rated rpm. Comparing with earlier experience....

The tractor is a 1987 mod.

Thanks all for your input.
 
   / Rated rpm problem ? #8  
When revving your engine look at the inj pump and see if the lever on the pump is at max revs...if not pull it by hand to see if you can reach max rpms...adj on other side at the controle link...or see if that lever on the inj pump is still tighern ? 8mm spanner or 5/16 spanner ...do not brake it !
 
   / Rated rpm problem ? #9  
CaseIH485 said:
Hello all,

long time since I'v been on this forum.I have lately been trying to figure out a problem with a Case IH 485.

The problem is that the engine does not reach the rated rpm, 2200, even if I pull the lever on the injector pump, an Bosch AVxxxxxxxx (do not have the number here), all the way to the mechanical stop. Rpm meter stops at approx 2000.

I have changed the filters and bleed the system, but no improvement. So far I have not adjusted anything on the pump. As far as I known nobody else has adjusted anything before.

So I wonder, do any of you have an idea as where to start fixing this problem ?
Click to expand...

If you can't reach rated rpm with no load and your pump lever is at the high idle stop, you either have restricted fuel flow, restricted airflow, or a problem with the pump.

Does your fuel system have a lift pump to supply the injector pump? Some of these have a screen filter so check that. Make sure the pump is supplying fuel at pressure to the injector pump, generally on the order of 3-5 psi. Check fuel delivery to the filter. There is usually a strainer at the tank bottom that can clog, a hose or line can be kinked, the filter can be installed with the wrong oring, etc. Make sure the vent in the fuel cap I not clogged.
 
   / Rated rpm problem ? #10  
Just back the hi speed screw out 1/2 turn and see what you get.. worse comes to worse, just screw it back in..
 
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