Chugging Sound Tied to Engine RPM

[willincalgary]

I've got a new sound to diagnose. I would describe from the driver's seat as chugging when driving at speed. Clearly tied to engine speed and gets louder with increasing RPM. Throttle position has no effect on volume or frequency. Under the hood if you rev the engine it starts around 2000 RPMs and is clearly coming from the top-front of the engine in the vicinity of the water pump.
I've never had a water pump die so I'm not sure what they sound like. I've also had issues with overheating under extreme loads offroad but it is generally well behaved. The rad and thermostat are new and both hoses on the rad are warm when running. Perhaps it is a low flow problem due to a dying water pump. Maybe I'm being optimistic that I might kill two problems with one solution.
Any thoughts?

[SafeAirOne]

Are you sure it's not coming from the timing case?

[Nium]

If it's tied to the engine couldn't you just untie it?

Water pumps typically fail by pissing fluid out the bearing of the pump shaft. If the pump belt isn't slipping and the coolant fluid isn't dropping probably soemthing else.

Examine the exhaust manifold for leaks. More likely to be a problem there that could sound like it's coming from somewhere else. Especially since it increases with speed.

[willincalgary]

Are you sure it's not coming from the timing case?

It may very well be. It's in the right place. If it were in the timing case what might be the cause?

[Nium]

With your overheating issue a compression test would probably be a good idea to make sure there isn't a problem with the pistons or valves. A burnt exhaust valve could lead to overheating issues.

Use a broomstick, a short one or shorten one, in lieu of an automotive stethoscope to try and isolate where the chugging noise is coming from. Hold one end close to ear and place the other end on the engine where you think the sounds coming from.

A last test for the water pump is to take hold of the pulley and try to shift it left or right or up and down. There should be very minimal movement. It may move a tiny bit, 1/16" or round about.

Cheers!

[SafeAirOne]

It may very well be. It's in the right place. If it were in the timing case what might be the cause?

Well, I'm not really suggesting any specific cause--I was just thinking that it doesn't sound symptomatic of a failing water pump. A water pump can squeak, but I've never heard of one chugging.

Not having a 2.25 installed, I wouldn't really know what the symptoms a slack timing chain or a failed timing chain tensioner are, but others on this list would, I'm sure.

You could probably eliminate the belt-driven accessories by removing the fan belt and running the engine for a brief period, before it heats up (overheats from no water fllow) to see if the chugging is still there.

Be extremely careful if you use any stethascope or similar item in the area where you suspect the noise is coming from--One good whack from a spinning fan blade could send a wooden dowel through your skull.

[kevkon]

I have heard something similar when a thermostat was not operating correctly. You might try temporarily removing it and seeing if the sound goes away.

[Hawaii_SIII]

I'll preface this response with I have a 2.25 diesel so it might not apply. I hd a chugging/clicking sound coming from that same area. After spraying the area with engine/brake cleaner, I was able to determine the sound was from a blown head gasket. I confirmed the location of the leak using a sheet of paper. It would blow in the wrong direction (against the wind from the fan) and got some black soot on it after a few minutes. It turns out the gasket had failed from old age (the motor is a '74) since the head and block were straight and smooth while the gasket was just aged.

[kevkon]

Maybe we should create a standardized list of sounds to be used in these diagnostic threads!
Chug, click, clack,.....

[willincalgary]

Maybe we should create a standardized list of sounds to be used in these diagnostic threads!
Chug, click, clack,.....

This would result in a long list! "Normal" sounds versus "Anomalous" sounds would have to be included.

[willincalgary]

Okay, I'm an idiot!

Noise was the alternator. I admit that's a pretty big difference from the water pump (which appears to be very healthy). The trick with the piece of wood near your ear works well.
As to the overheating I had a Kenlowe electric cooling fan thermostat die recently (subject of a separate thread) and switched the truck back to the belt driven fan and shroud today. I can't get it to overheat and it is rock solid at ~85F. I haven't tried climbing a hill offroad, which was the source of my overheating woes, but is it possible the Kenlowe fan just wasn't providing enough air flow? Seems unlikely as many people have had a lot of luck with them.

[SafeAirOne]

I wish I could use an engine-driven fan and shroud system on my 109. They are usually much more efficient at RPM than an electric fan because they draw air through the entire area of the radiator, not just the footprint area of the fan.

[Nium]

I wish I could use an engine-driven fan and shroud system on my 109.

Excuse my ignorance, but why can't you use an engine driven fan? I'm sure the answer will be obvious when you reply and I'll end up slapping myself on the forehead.

[SafeAirOne]

Excuse my ignorance, but why can't you use an engine driven fan? I'm sure the answer will be obvious when you reply and I'll end up slapping myself on the forehead.

No---it's not so obvious and I probably should have explained...The transplanted 2.5 Diesel's water pump sits too close to the original SIII radiator to attach an engine-driven fan. I'd have to "defenderize" the nose to get it to work.

[rwollschlager]

I had a Kenlowe electric cooling fan thermostat die recently (subject of a separate thread) and switched the truck back to the belt driven fan and shroud today. I can't get it to overheat and it is rock solid at ~85F. I haven't tried climbing a hill offroad, which was the source of my overheating woes, but is it possible the Kenlowe fan just wasn't providing enough air flow? Seems unlikely as many people have had a lot of luck with them.

My sIIA 109 had a kenlowe fan fitted, after over heating several times (2 head gaskets over the course of 4 years), I finally pulled it off and put the mechanical fan back on. No problems yet...

-Rob