Pajero Owners Club of South Africa

I've had my DiD now for about a year and a half and about 43k kms (now has 105k kms on the odo). Its always had a slight high pitch tone at around 2000 rpm - which I queried with mitspro and he said all die paj diesels sound like that. Indeed, since then I've listened to a few other engines, newer and much older and they all sound the same.

Recently, at exactly 1850 rpm (between the two markings, and ONLY there), a new chord / 2 tones have developed. When accelerating normally you typically dont even hear it. But when accelerating in such a way that the revs remain at the above mentioned level with the torque converter allowing gears to be changed as the revs stay level, you can distinctly hear this new 'whistle'.

The best way i can think to describe is it that it sounds like someone playing a 'bek-vluitjie' / harmonica at a higher pitch that the engine/turbe normally whines.

So - I am quite sensitive to new sounds and noises the engine makes, so I might be overly so in this case. Is it a good sign that the sound is only at that specific rev amount, and not for any higher revs?

If it is not good... what does one do? Take it to Mitspro for inspection? Or to a turbo specialist?

... what if nothing is wrong, and now I'm going to have someone open it, which they might not put back together again correctly...?

Does it have any resonance to it? Can you replicate it while standing still? Have you had the same on two tanks of fuel now? Might just be different quality fuel?

There was a thread somewhere about the exhaust heat shield on gen4 Pajero starting to resonate in certain cases. Is it more prevalent on the left/passenger side and maybe even felt? Then I would investigate this avenue further.

CATS
Ps - aint it nice to drive a Pajero when your worst worry is a slightly different pitch in the turbo whistle!

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CATS wrote:Does it have any resonance to it? Can you replicate it while standing still? Have you had the same on two tanks of fuel now? Might just be different quality fuel?

There was a thread somewhere about the exhaust heat shield on gen4 Pajero starting to resonate in certain cases. Is it more prevalent on the left/passenger side and maybe even felt? Then I would investigate this avenue further.

Resonance... I think so...
Have not been able to replicate while stationary, and it only seems to happen when the engine is warm
Been happening over a few tanks of fuel - so not the fuel (sasol, shell and caltex).
The sound cant be felt - its just a noise. Not sure if its more prevalent on the other side but will check.

take the cold side turbo hose off and feel for play on the turbine shaft

[BBvideo 425,350]http://www.youtube.com/watch?v=ahbCMhPhjnM[/BBvideo]

A fan turning at 100 000+ rpm will make a noise.
The air this fan pushes through an inlet tract with irregularities, twists and turns, will make a noise.
(Think of your vacuum cleaner - it makes more noise than just the electric motor's noises).

The 4m40 has a 'resonance tube' next to the intercooler, to limit the resonant noise.

The bearing on the shaft is not in contact with the housing, it runs on a thin layer of oil.
Mechanical noise will be so obvious, that you won't have any doubts. This usually happens when a vane is damaged, or the shaft seal has worn so much that the vanes touch the housing.

Thanks 4Es!

Karl,

I think you and I have the same, or similar, issue. Mine started at about 90k. The turbo whistle is high pitched and normal, but at about 1450rpm for about 100 rpm I get this additional sound, like a very high-pitched vibration. Only when the car is hot, and not while stationary. I can induce the sound in the first 4 gears. Most irritating when in the game reserve with cruise-control set to 40km\h as the engine turns over at ... 1451rpm!

I at first thought it was turbo but now i'm don't think so. I think its more in line with CATS explaination. If it was turbo it wouldn't have lasted another 30k kilos... It happens less frequently now since i bashed the sump t Kungwini so something shifted, but it still happens a few times a week.

Redcat, I'm not sure it is the same... Mine occurs at higher revs, but the sound is closer to a wind howling sound. (its not as high as the typical turbo sound you would get from TD vehicles)

Also, since the first post I've been struggling to replicate the sound. I'll be doing some longer distance driving in December - will see if I can get it to make the sound again.

Hi, I'm thinking along similar lines to 4epajero on this - turbine noise becomes a LOT my audible when the intake side of the engine is opened up - I would check everything on the inlet side of the turbo - perhaps the lid of the airbox is on slightly skew or the airfiler has holed, or the inlet resonator is loose, etc, etc...