what effect does a leaking air comp. have on the engines RPM

[dakotafear3088]

If anyone can give a good answer to this thought id be thrilled! I own a deuce and ever since i had it the RPMS at idle were 850.... it was 750, but it was adjusted and idled smoother since. I noticed that i have oil seaping from the air compressor unit and its getting progressivly worse, i.e running the lenght of the engine to the bell housing. As i was saying, the other morning after installing new walmart batteries, I tried to start the truck, and after a few cranks it fires up, but only idles at 750 rpms.... after the truck warmed up and I stopped, the RPMS would read 900. now today, I went for a 40 min ride at 50 mphs, and when i returned home it was now idling at 850/ or 875 . so my question is, Is the compressor causing the R's to jump around like that? or what would be a cause to look into, if its not the compressor.

Thanks for any and all input
jon

 

[FreightTrain]

RE: what effect does a leaking air comp. have on the engines

These trucks are purely mechanical so they will wonder slightly depending on a lot of variables.Fuel quality,Fuel temperature,Air temperature,Air pressure,Altitude,luck.Since there is no computer constantly adjusting things the way the truck runs will change from day to day or minute to minute.

 

[mangus580]

RE: what effect does a leaking air comp. have on the engines

I can say... that mine idles alot lower when cold, and as it warms up, it idles higher.

 

[OPCOM]

RE: what effect does a leaking air comp. have on the engines

I notice less than 100RPM difference between the time the compressor is 'on' and 'off'.

No way to tell hot/cold, since the thing idles quite different when cold started and after coming to temperature. One thing I have noticed, mayby just psychological.. when I let it warm up to 160 or better before moving out, it seems alot happier than when I move out at 120!

 

[DDoyle]

RE: what effect does a leaking air comp. have on the engines

Compressor won't effect RPM except under really bizarre circumstances. Current variation in RPM is more likely related to engine temperature, and maybe fuel temperature.

On REALLY cold days we had a few years back, on start up the starter was barely swinging mine through - and when it finally hit the engine would turning VERY slow - far slower than I've been able to set the idle on one - but once the engine, and lube was warm - the RPMs came up to normal.

From your description - I wouldn't be concerned about it.

Regards,
David