Non Merc V-belt question.

[brucemillar]

Folks. I have a moaning sound when I lift of the throttle or slightly feather the throttle on my Pajero. It sounds like somebody groaning and stops immediately I touch the throttle again.

I was/am convinced it is belt related. Tonight I replaced the idler pulleys with new ones. The old ones were noisy and worn on the bearings.

1 on the power steering belt
1 on the alt/ac belt.

The noise is less pronounced now (quieter) but still there in the background.

Could it be the belt(s)?

They are newish belts and look fine with good tension.

My AC needs a re gas. Could it be the AC compressor?

It is 100% load related as it only happens on the overrun (lifting for traffic lights etc)

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[John Jones Jr]

What I would do is remove the belts and check the PAS, Alt, A/C and water pump for any excess play or roughness. Have a look at the tensioner also. Then refit the belts but in the opposite way they came off an go from there. Also use a long screwdriver or similar as a stethoscope.

There's a guy in Tring...

 

[Codger49]

I think I've just resolved never to let Bruce even look at my cars.

 

[John Jones Jr]

I think I've just resolved never to let Bruce even look at my cars.

Ha, ha.

 

[texterted]

If you look down at the main crank pulley, does it seem to wobble at all?

They are a bugger for delaminating.

 

[brucemillar]

If you look down at the main crank pulley, does it seem to wobble at all?

They are a bugger for delaminating.

Ted.

I am guessing you have experienced the wonderful world of Pajero ownership?

You are 100% correct with the pulley. It had already been replaced along with most of the front end - Last year.

It had:

New Cam belt & Pulley(s)
New Water Pump
New Head Gaskets
Crank & Cam Sensors
New Starter
New Exhaust
New Belts
New Idlers/tensioners

It is (as is usual) difficult to get the truck to do it when it is parked.

It only does it when it hot and occasionally on startup. Always on the overrun - when hot and will stop as soon as you blip the throttle.

This morning I had another go and think it may be the power steering pulley that bolts onto the pump? This sits right on top of the engine on the drivers side. The noise does seem to be from the drivers side (when you are sat inside).

It looks like this is a sealed pulley with grease points. Spraying with WD40 is no good as it blows the spray away before it can get near the shaft.

I think I will try a new pulley.

 

[Bellow]

Bruce, have a look around the inlet manifolding and throttle area.
Throttling is a noisy affair. It could be something in the area loose and resonating with the throttling induced (air) turbulence.

 

[brucemillar]

Bruce, have a look around the inlet manifolding and throttle area.
Throttling is a noisy affair. It could be something in the area loose and resonating with the throttling induced (air) turbulence.

Bellow. Thank you. We took the inlet manifold and cleaned it. This was to fix a small water leak from the engine to the heater matrix (another new pipe required) There was no obvious issues.

It is quite literally like somebody is sitting there making a Whoooooooooooooooooooooooooooooo sound. As the revs settle it will stop suddenly or if you touch the throttle it will also stop (even the slightest touch) My thinking was the Viscous fan but this is free to turn with no wobble or dry bearing feel. It operates as designed (passed the carrot test)

 

[Bellow]

Try and separate if the noise occurs on merely releasing the throttle or with rpm reduction.
The latter points to something moving that can overrun (but overrunning the crank's inertia requires some mass). If the former - induction system resonance. An overthrottled (for the rpm) engine groans like a corpse.

 

[l5foye]

I am also a Pajero owner. If I hear noises, I turn the volume of the radio/stereo up -cheapest solution !!

 

[brucemillar]

Hmmmm.

In going to fit new belts first. I have a niggling doubt that the existing belts (aftermarket) may be groaning and setting up a resonance.

Watch this space.

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[texterted]

Aye Bruce I owned one for many years, a diesel one though. Before you start pulling it to bits. Just check that your viscous fan spins freely. You can CAREFULLY stop the fan, on tick over wearing thick leather gloves or better still a rolled up newspaper. They can make some surprisingly weird noises! They have a replaceable centre viscous unit or you can refill your existing one with silicon oil.

 

[brucemillar]

The fan spins freely when cold and with the engine off !

When I try the carrot or newspaper test it has a lot of resistance. It will shred a rolled up newspaper. I think it would stop but would require some big gloves to avoid shredded fingers.

I am thinking that this maybe too much resistance?

Should I not just be able to place a gloved hand into the spinning blades and stop it without it attempting to drag me into the engine bay and spit me out looking like the Hulk?

How does one re-fill the viscous. I have previously removed it but didn't notice any oil holes?

 

[Bellow]

Bellow. Thank you. We took the inlet manifold and cleaned it. This was to fix a small water leak from the engine to the heater matrix (another new pipe required) There was no obvious issues.

That I take it, was after the noise had appeared?

 

[brucemillar]

That I take it, was after the noise had appeared?

Yes it was after ;ˆ) and it is also another "common" Pajero leak. Unfortunately on the V6 nothing is easy access and this hose is down the back of the engine and between it and the firewall. So manifold off and you still need alien like fingers and a stool to stand on to get above the engine.

FYI: To change plugs on these the manifold has to come off. Joy.


Just had the AC re-gassed. It was empty and I wanted to be sure it was not the compressor complaining that it had no gas. It wasn't. Its nice and cold now but still noisy.

 

[texterted]

Yep, the fan should be stoppable with a newspaper. You have to split the casing to refill it. It has a few very tight screws keeping the halves together, there's a thread about it over on POCUK. I opted to get a replacement unit from Blu-print but it was £150 or so.
The fan can make some serious noises but at least it's working! I prefer a serious fan anyway as the cooling system needs to be tip top on these motors.

Try it with new belts then but use genuine or Blu-print ones, instead of generic horrors from the likes of Milners.

 

[brucemillar]

OK another test with the engine warm. The car has been stood for 2 hours after a drive this morning.

The fan does not spin with the engine off. It turns but is not freewheeling.

With the engine on at idle. The fan will not stop. It will chop through wood and shredded a rolled up newspaper.

This sounds like too much resistance.

I will remove the fan and see if I can figure out how to oil it. I do have another fan (new) but the locating holes are very very slightly out for the studs. I may just enlarge the holes. That will not allow it to run eccentric but will allow it fit.

 

[texterted]

You need the proper grade silicon oil for the fan so I'd just leave it.

They work like this... stiff to turn when cold... freewheel when warm.... then go stiff to turn again when hot.

So you need to test it during the warm phase to see if it's producing the noise.

 

[brucemillar]

Thanks Ted

I am pretty sure it is stuck on. It is running continuously at engine speed. No freewheel when warm.

I will try swapping it out later and report back.

 

[texterted]

Sometimes people fix them to run like that to aid cooling, the downside is extra noise and fuel consumption. However, having the 3.5 v6 you'll be used to the latter!

Good luck!