Pajero Owners Club of South Africa

We have had a clattering noise (after cold starts) intermittently on our Pajero 3.8 petrol (6G75 engine) for approx the last 60,000km. Started at around 90,000km and initially was only after standing for longer than 48 hrs and worse in winter. Disappears after between 30 secs and 3 minutes depending on how long it stood (and how cold it was). However recently has been worsening - only 12 hrs standing required to get the clatter on start-up.
I deduced this pointed to something like a faulty or dirty non return valve in a hydraulically operated tensioner (oil drains out and the longer it stands the more air gets in - hence longer time to fill-up and restore tensioner operation) - and therefore tried similar oil flushing type "fixes" as sometimes work with noisy VLA's in the 6G74 DOHC motors (of which I have had four). This involves using a high detergency / high spec diesel engine oil (SAE 15W-40 / API-CD or higher). This didn't have much effect so then went a step further by flushing with super low viscosity (same diesel spec - but hydraulic grade (SAE10W / API-CD or higher). This did help - but did not cure. NOTE: the vehicle must NOT be driven with this oil or serious damage will result! It is simply drained of normal oil while hot and then immediately refilled with the very thin 10W oil. Allow to IDLE - DO NOT REV) until operating temp is reached - then switch off and allow to cool. Repeat once or twice then drain and refill with normal oil. The idea is to simulate the "diesel washing procedure" for the VLA (valve lash adjusters) Mitsubishi describe in the Workshop manual. I have had success with this on the 6G74 motors (clicking VLA’s) - but it was not that successful on the 6G75 tensioner.
Anybody else had experience with this? Or is it now time to fork out for a new one before it jumps a tooth!

Hi 7Pajeros. You have obviously done your research.
Was the tensioner replaced with the belt at the 90k service?
Why would a faulty tensioner cause clatter?
To answer your question: if I doubted the integrity of the belt tensioner on my 3.8, then I will have it replaced as soon as possible.

PS: It is only R30k to your next belt replacement service, why don't you bring it forward and throw in a new water pump when the front is stripped.

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Hello Roelf,
I honestly don't know whether the tensioner was replaced before - didn't get it new - and it is my wife's car - does low mileage so several years ago.
I am not sure exactly what part generates the clatter - but suspect that the loose side of the belt "flaps" hard against the plastic covers - until pressure builds up again.
Have already ordered parts - (your tip on the water pump is a good idea - I had forgotten that).
Interestingly the adjuster / tensioner is only R429 + VAT. But then there are two other idlers @ about the same (R400) and the cambelt which is a whopping R1369 + VAT. Total R3038 incl VAT. Don't know what the water pump costs yet.

You are doing the right thing. Don't delay.

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7pajeros,

My two cents worth: If and when you start replacing do the whole lot - belt, pump, all pulleys and tensioner. Also consider replacing the poly-v belt. It will safe money in the long term.

Cloyd

OK - Final chapter.
I was wrong about the theory that the tensioner was assisted by engine oil pressure - so that explains why the engine oil flushing made no difference.
However the noise was caused by the tensioner - it is now gone completely. Interestingly we could not detect any significant difference between the new and old tensioner - both seemed to compress on a vice exactly the same (no proper means of measuring the pressure available). I did do all associated stuff even though it wasn't needed - i.e new cambelt, idler pulleys and water pump... so it is now very sweet and quiet.

That is good news, nothing better than a sweet sounding 3.8V6. What did the pump cost and where did you get it from? If you don't mind sharing.

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