Diesel specialist

Forum Members,
The past few days I have running the '65 HD3 Allis dozer. After about three hours of running the diesel increased in rpm without moving the throttle. After the increase in rpm it sputters a short while and runs as it should. Why? I know the filters have not been changed for years,but that does not make sense because it runs well after each episode. If there is a shortage of fuel do diesels rev up? Plan to change filter and add an additive to clean up the system. Any and all thoughts are welcome.

Mr. T. Minnesota
 
If the engine is starving for fuel the governor senses it and opens up the throttle,filters need regular changing and that counts for machine that are both used regular and not at all,nearly all fuel related problems start in the tank,turn the fuel off at the sediment bowl,take the glass bowl and filter gauze off and clean them,before you put them back momentarily turn on the fuel to check the flow from the tank,if its restricted sort it,put the bowl back and remove the two filter elements,clean the canisters,note the primary and secondary locations,fit the two new elements and bleed the system.if it is still playing up take the return line off from the adapter on the top cover of the pump,remove the adapter,inside is a valve that can block causing increase pump pressure and irregular running,if its blocked clear it and try again,if you got a Napa store near you the filter elements are Fil 3101 and Fil 3102.
Good luck
AJ
 
AJ,
Thanks for the reply. Your explanation was very understandable for the diesel novice. Will order the filters today and do as you said and check fuel flow in about two weeks when I head up north again. Are there any short cuts or hints to make the priming/bleeding of the system easier. Any and all thoughts are welcome. Thanks again!
Mr. T. Minnesota
 
There should be bleed screws on the top of the filter,open the bleeders and operate the priming pump till bubble free fuel comes from the primary filter (the primary filter is the first filter on the line coming from the tank) and close it prime on till the secondary is air free and close it,keep priming and pressurize the system,the outlet valve on the pump cover I mentioned before also acts as a self bleed for the injector pump,some of those machines did not have a priming pump as the tank is higher than the injector pump and gravity does the job.
AJ
 
cut an old inner tube and clamp it around the fuel tank filler with the valve up--then pressurize to about 5 psi and it will push fuel thru the system
also make sure the fuel cap is venting properly and not causing a vacuum
 
When my HD4 did the exact same thing - the problem was a failed plastic ring inside the Stanadyne-Roosamaster fuel injection pump. Not sure if the HD3 uses the same pump, but I suspect it does.
 
I think going along with the first suggestion of servicing the fuel system is the way to go,the old trick of using compressed air to push the fuel through is not the best idea as it tends to push the dirt and sediment through the filters as well with bad results for the pump,no reason why the fuel not run down under gravity unless there is a restriction,it would be a bit early to tear into the pump to change the POS plastic ring until it is established it has failed,you do that by removing the adaptor on the top cover for the return line,if the ring has failed there will be signs of it there like mouse droppings.
Ed
 

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