Engine/Transmission (1994 - 1998) Ticking noise

[Texis]

I have a ticking noise that I am unable to locate? It appears to be on the drivers side, is somewhat random and only ticks between idle and maybe around 1100 rpm. After 1100 it is gone. It does not do it when you first fire the engine up, but rather after it is warm.



Also, it is not "exactly" in sync with the engine rpms? It is fairly rymthmic at idle and becomes less rymthmic as the engine speed increases.



The only things on the drivers side are the P-pump, fuel transfer pump and power steering pump. Truck runs great. It has been doing this for about the last 1,500 miles.



Any ideas would be nice.



Thanks

 

[hsmith]

Most likely the lift pump, especially if it is original.

 

[Texis]

Yes it is the original, and my first hunch as well. Do they fail slowly, or just stop working in the middle of nowhere? I put around 700 miles p/week on this vehicle and don't won't to be left on the side of the road.

 

[GAmes]

They fail slowly, the tick is the spring gets weak and the rod does not maintain contact with the cam lobe. I would venture that eventually the cam could be damaged, plus you probably have less than normal fuel pressure. 300k is about the life cycle of the ones I have replaced. While you are getting parts spend a few extra bucks on studs and nuts to replace the mounting bolts. Makes installation of the new one a lot easier. IIRC I used a pr that are 55mm long. Sorry, don't remember the thread size.

 

[FDavid]

I wouldn't worry about it. I had a brand new lift pump installed that made the ticking noise. When I contacted Cummins they said it was totally normal.

 

[Texis]

I have a very bad habit of not worring about it. It seems this old truck is always making some type of noise, from somewhere. If I worried about them all I would have to sell the old girl. I have found that if you enore it for a few days it typically goes away.



But this little tick has been around awhile and I feel "almost" compelled to fix it. Afterall, it is embarrassing at stop lights and in parking lots.

 

[HLEschenko]

What is the fuel pressure at idle?

Maybe the overflow valve needs a tweaking? More back pressure may help keep the fuel pump plunger in closer contact and reduce the clicking sound that you have?

 

[hsmith]

Would be nice to know the pressure at idle. If it were mine I would replace the pump and OFV at the same time. You mention leaky valve cover gaskets. Man, that is so simple, you must be getting real lax or lazy. LOL

 

[Vaughn MacKenzie]

A weak overflow valve can cause ticking. But my lift pump was replaced 40K ago and it is really ticking bad off and on recently, despite good fuel pressure of low 20s at idle and close to 40 by 2300 RPM. The original LP was pretty dead at 160K, low fuel pressure.

 

[Texis]

Well mine stopped ticking for a couple of weeks and now has started again. I like old trucks, you just can't pay too close attention to them... until they stop, then you gotta fix something.