Last night i drove about 50 miles, then i put emergency brake on, went out to listen to the engine good. then i heard something weard i think i never heard before, or it never cught me attention, the engine was cycling, like rinning at 800 rpm then 700 rpm then back to 800 rpm. cycle is like every 2 to 3 seconds and last forever. Is this normal or is something going bad, anyone else hear this, it idles like an old greyhound buss.

 

I see you live in N. Maine. Was it really cold out? I am thinking that it's just your fast idle cycling on and off slightly. I live in Seattle where a freeze is very rare, but the engine will fast idle with differing degrees of intensity depending on temperature. Colder=faster. Warmer=slower.

 

no it was 56 degrees yesturday when it was doing it. and the engine was up to temp after 50 miles.

 

it was cycling everytwo second maybe 1 second had to listen good th hear it.

 

Well then we are back to looking at things like time for an oil change, fuel filter, possibly a failing temp senser.

 

where is the temp sensor? everything else is new

 

every time it cycles i hear a click like a lifter just before it changes cycling, like the cam is hitting the fuel pump, and the click is cear the fuel pume, the click has heen their ever since i had the truck 2 years, just thought it was fuel pump and normal?
click-cycle click cycle click-cycle click cycle click-cycle click cycle click-cycle click cycle every 1 or 2 seconds, maybe they all do that?? about 50 rpm diferent, what do you think??? only after it it warmed up totaly, if cold it don't do that.

 

I am not sure. I was thinking that your intake air temperature sensor might be giving you trouble, sending a IAT signal that was far colder than reality.
Anyone care to chime in here? I am mainly guessing at this point.

 

I have a tymar intake, the temp sensor is just tied up in mid air. did not know what else to do with it. it don't move it is secure

 

is a psd suppose to idle at a steady rpm not even 20 rpm different, like a finely tuned gasser???after warmed up/ next time you drive yours,after totaly warmed up open hood and listen to you engine, real good and please tell me if you hear a fine tick and cycle, listen good it hard to hear.

 

I have been a auto mechanic all my life, i am now 63 and retiered, just learning about diesels,

 

Just for thought, look at the a/c compressor. Sounds like the engine is uping the idle to compensate for the compressor kicking on and idles down when the compressor disengages.

DEAN

 

no ac not comming on the click is not that loud

 

just to make you feel better mine does the exact same thing except I've noticed no click-will listen next time i think about it, mine only does it when its warm too, idles beautifuly cold. I have lots of miles so I am just assuming that its a normal wear and tear problem. I've seen a post about cleaning the screen in the fuel filter housing and that cleared up the problem, next time I change my filter I will give that a shot, I'm not too worried though.

 

Do you have a fuel pressure guage left over from pre-retirement? It might be helpful to see what's going on there with that click noise coming from the pump. Possibly the fuel pressure is spiking or something.