Diagnosing Engine Rattling/Tapping Noise

[mmranch]

OK, I got my hydraulic gear pump problems solved.

But before I installed the new pumps... I had been running the old pumps for about a month with a new drive gear while I waited for the new pumps. The new splines of the new drive gear were able to spin the pumps and provide hydraulic pressure. But I knew that it could fail at any time and that the setup was not good. When the engine would run, I could hear a bad sound and I attributed it to the worn splines of the gear pump being spun. When I opened it all up to replace the pumps, I was pleased to find that there was no metal debris in the drive gear zone and the drive gear splines still looked new. I installed the new pumps and all is working fine so far.

But when I started the tractor after the install, the bad sound continues so it was not related to the gear pump setup. The engine runs fine and works fine and sounds fine. But there is a sound which is overlayed over the normal engine running sound. It is more pronounced when the engine is cold. As the engine warms, the sound becomes quieter but it is still there. It sounds like a broken bit of metal or a bolt that is being thrown around and when the metal bit hits the metal of a housing, it gives that sharp tick or tap (imagine holding a small bolt and tapping it against a metal casing).

It seems to be coming from the front of the engine and the upper part of the engine. The water pump lives in that zone.

My question is, do water pumps exhibit this type of sound as they are failing? I'm sure this is the original water pump that is 16 years old. A couple of months ago, as I was driving the tractor back to the shop up our steep driveway at full revs, the engine started overheating and steaming badly and I stopped the machine half-way up. Opened the hood and the main fan belt had shredded. I replaced the belt and all was good. In the process, I moved the fan a bit (with no belt on) and there was some creaking as the bearing moved.

Just wondering if the water pump is the cause of this rattling/tapping sound?

Thanks for any ideas!

 

[mike0000]

I can’t really offer much help. Sounds like a tough one to diagnose without some parts removal. I think I’d start with getting the belt off, and spin the water pump and feel for play/noise, may have to drain fluid. I’ve only experienced a leak, bearing noise, or overheating from any water pump failures, all were on cars. I haven’t dealt with a tractor water pump failure.

Mike

 

[LS Tractor Owner]

Yes, without isolating where the sound is coming from specifically, there are multiple things that could be making the sound. Usually water pumps will squeal or squeak. Tapping could be a lifter or a valve. Could be an injector or a piston slap. Too many possibilities......

 

[mmranch]

Thanks for the ideas!

I will try to do some strategic listening with a shaft and some headphones to see if I can isolate where it's coming from.

Thanks again.

 

[BravoXray]

Get or rig up a stethoscope and see if you can localize the noise.

 

[ptsg]

I think I would just take the belt off and spin the water pump by hand. Granted if it's bearings, it would make a lot more noise under the tension of the belt but just spinning it by hand should give a good feel too.

 

[Rod in Forfar]

Does pressing the clutch have any effect upon the sound? Does it matter what gear it is in? Is is related to engine revolutions?

 

[Richard]

Is is related to engine revolutions?

(I know you're not the OP)

Does noise rise/fall in direct correlation to engine RPM's?

I once had an odd tapping noise in my car (1969 Mercedes 280 SL) but the timing was odd. Long story short, one of the lobs on the camshaft had worn down so when the cam lobe came around, it would (I suppose) smack the valve and make my ticking noise.

Never got it fixed, car ran fine (or fine enough) and ended up selling car.

 

[mmranch]

Thanks for the ideas!

Yesterday, I got my listening setup ready and pulled the side panel off the engine before starting the engine up. When I did start... the engine did not make the bad rattling sound. It sounded smooth and normal. It warmed up and sounded normal all day. So I didn't get to listen for the rattling sound because it was gone or greatly diminished.

When the rattling sound was happening... it didn't sound like it was repeating perfectly with the revs of the engine. More like something (broken bolt/metal chunk?) that was randomly hit by the revs and thrown into the wall of a casing making the metallic hit sound a bit random.

Back when I had the fan belt off and spun the fan... it felt like only a very slight resistance when turned and there was a slight creak sound to the spin. Nothing that seemed like a major problem.

I will keep listening for the sound.

Thanks again.

 

[seville009]

Could it have been the side panel making the noise?

Put the panel back on and see if the noise returns.