Lemans Posted September 10, 2011 Share Posted September 10, 2011 Have got a 1994 mitsi vr4 with a v6 twin turbo 6A12. When it starts it makes no noise but when it warms up it sounds like some one is trying to get out of the motor and they are useing a pick hammer to get out. It sounds evil. If i thrash it it makes no noise and when i am gentle with it it sounds shocking. A mechanic things it is not internal. It sounds like a bearing to me but i am a panelbeater not a mechanic. May be there is a common problem with this v6 or maybe this has happened to you. Any help will be gratefully accepted. Quote Link to comment Share on other sites More sharing options...
mjrstar Posted September 10, 2011 Share Posted September 10, 2011 sounds like it could be noisy lifters, maybe try a screwdriver up to your ear to narrow down the source of the noise... Quote Link to comment Share on other sites More sharing options...
84_S12 Posted September 10, 2011 Share Posted September 10, 2011 Mitsubishi hydraulic lifters get very noisy if they get gummed up. Try changing the oil and slapping some promar in there. A lot of the Evo guys change them out for ones that have larger orifices to overcome this - they pretty much become solid lifters if the pressure can't relieve itself. Quote Link to comment Share on other sites More sharing options...
fuel Posted September 10, 2011 Share Posted September 10, 2011 Most Mitsubishi engines of that era are prone to noises from the hydraulic lifters (and in your case there are 24 of them). Usually it's caused by poor servicing (ie too long between oil changes), incorrect oil grade/viscosity or sometimes they just tap away for the hell of it. I know with my E39A VR-4 the lifters will start tapping away around 5,000kms since its last oil change which is usually a good indicator to change the oil. Having said that the 6A series V6 engines are also prone to damaging the big end and main bearings because they are quite small in size and don't have a large surface area to dissipate the forces on the bearings. This is also generally caused by poor servicing. A hydraulic lifter noise will sound like a top end 'tap tap tap' and will usually happen from first start up right through the rev range. A big end bearing will be a deeper 'nugga nugga nugga' sound coming from deep in the engine and will often start out happening only within a specific rev range (2000-4000rpm) and only under light/moderate throttle but it will get worse over time until the bearing fully wears out and the crown of the piston will hit the underside of the cylinder head resulting in this mess: What I would do, is buy a bottle of Proma MBL8 (from Repco, any Mitsubishi Motors dealer, BNT, Trademe etc), a quality oil filter (genuine Mitsubishi or a proper Ryco one), and some quality semi-synthetic 10W50 or 15W50 engine oil like Penrite HPR10 (I wouldn't go below a 40 weight oil, ie nothing less than 5W40 or 10W40 etc with the 6A V6) and do an oil change following the instructions of the Proma MBL8 bottle. If that doesn't quieten down the hydraulic lifters then either the lifters are absolutely fucked, or the noise is coming from elsewhere. Hope that helps. Quote Link to comment Share on other sites More sharing options...
fuel Posted September 10, 2011 Share Posted September 10, 2011 re-reading the original post with the noise being more prevalent when warmed up and under light load then it does sound like it is your big end bearings. I would get onto fixing it ASAP otherwise you will suffer catastrophic damage as above. Those 6A12 V6 engines do NOT like being neglected and pushed to the limits unlike the earlier 4G63 which is much stronger and resilient. Quote Link to comment Share on other sites More sharing options...
Ranter Posted September 11, 2011 Share Posted September 11, 2011 I had a Diamante in last week with similar sounding problem, owner/carshark thought motor was stuffed and it sounded like it. Different engine but it was the cambelt tensioner and thats why the noise went away with revs. When I removed the inspection panel behind the wheel I could see oil had leaked out of it and was simple enough to replace without having to remove the large alloy mounting bracket. Quote Link to comment Share on other sites More sharing options...
Crownin_Round Posted September 12, 2011 Share Posted September 12, 2011 sounds like you also might have poor oil preasure Quote Link to comment Share on other sites More sharing options...
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