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Mitsubishi 4m40 diesel - What goes wrong with em.

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Am looking a mid 90's paj with a 4m40 2.8 turbo , I hear these things are ticking time bombs in the engine department, does anyone know what fails on them ? (cause and effect)

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Pretty sure most of the associated bad stigma is speculation / carry over form the old 2.5 that had an appetite for cylinder heads.

Just get one and hoon around in some mud.

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if overheated they can blow head gaskets or even crack the heads. other than that fairly robust - there is no cam belt to need replacing.

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Pretty sure most of the associated bad stigma is speculation / carry over form the old 2.5 that had an appetite for cylinder heads.

Just get one and hoon around in some mud.

same with toyota, nissan, mazda diesels. the works. all jap diesels have problems with heads cracking or whatever, apparently. seems only the mitsis have held on to this stigma.

it's actually pretty sweet as it makes pajeros, which are packed with lushness, much cheaper than ANYTHING else. If they're looked after, then they'll likely not give you issues. I've now had two mitsi diesels. both 4d56. one turbo, one not. no problems. the turbo one i used to give a cunt of a life, but i never neglected to service it, and never neglected the cooling system. when you do, in any vehicle, then that's when you'll have problems.

from my research before i bought a v6 paj (for my own reasons, however, i might have been better with a 4m40 one in hindsight) I found that 4d56t gen 2 pajeros were only worth passing on due to their underpoweredness. when the 4m40 is on offer, they have a shit tonne more grunt, and therefore are the one to go for. when they were new (you could buy them in nz) they were the most powerful 4cyl 4x4 diesel on offer. toyota was pissing round with it's non turbo 3l 4runners, and nissan had rusty terranos. isuzu/holden had the not_quite_grunty_enough 4jg2-t. that was it. the 4m40 had the most grunt in it's class.

the bad points on 4m40s seem to be:

-timing chain. although seen as more reliable than a belt, a lot of them get mega timing chain stretch when around 150km. I'm not sure how many break but it's noisy as shit and detrimental to power as it fucks with the valve, and inejctor pump timing.

-egr system playing up: shit just stops working as it should. make a blanking plate to block it off but leave it all in situ so it wont throw any codes on teh later ones.

-glow plugs are a consumable: some people have to change them once a year or you get missing/white smoke on startup. seems to be the norm for even the 4d56 family, though. should be $80 max and is as simple as doing sparkplugs on any petrol engine.

that's about it. keep the cooling system in good condition and service it regularly and she'll be right. I'm not sure how they go for cranking fuel (and boost to match of course) for more neddies but i'm sure you'll find something. apparently they like a nice free flowing exhaust. what doesn't, though.

I went for a v6 as they're cheaper than diesel versions to buy and the rego and rucs i thought might not *quite* work out cheaper with the km i do. truth is, it would've been far cheaper to run, even taking these into account had I gone for a diesel. I can't complain at the power delivery of my v6 though. pulls like a bawse from idle. even in fairly deep soft sand I rarely bog down enough to need to change down until like 1200rpm. bulldozer engine spec hah. if you're getting an LWB then diesel would definitely be the way to go.

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My experience is perfectly explained in the above post, only had to do one timing chain though and a couple of head gaskets.

One a customer bought one from a high profile importer here which had never had a service and the oil was like grease, rather than whinging about it we just cleaned it all up explained to him it was likely a timebomb, unfazed he put about 80,000kms on it before trading. To me thats a pretty robust engine, interestingly they have gone back to the 4d56 in the latest Tritons although it seems to be of little relation to the previous engines.

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We've had our 96 SWB Pajero, 4m40T, since 30,000 k's, has just ticked over 180,000. Only thing that ever took it off the road was the front pulley delaminating. Popped a new one on and it's sweet as. Needs the glow plugs doing now.

Bloody good truck.

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4m40t is miles better than the older 4d56

I have had problems with the injector pumps, and they aren't cheap to rebuild, $500-$700

So just make sure it doesn't have any diesel leaks and as long as it runs fine during the warmup period it should be ok. (Symptoms can be intermittent stalling until it warms up to operating temp)

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I was woundern if I can get some help...I have a 1998 Mitsubishi challenger 4m40...it runs ok untill it warms up then it over heats on me is the any tips that I can use to sort the problem 

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2 hours ago, Seth1312 said:

I was woundern if I can get some help...I have a 1998 Mitsubishi challenger 4m40...it runs ok untill it warms up then it over heats on me is the any tips that I can use to sort the problem 

 Cracked head - they all do it 

usually starts with the radiator header tank bottle dying 

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Great engines, had 3 of them in Delica vans. As already said the only issue is cooling and glow plugs. The delicas have a system where the glow plugs stay on until engine is pretty well at operating temp, by-pass this crap and they last a lot longer. Had one van I bought at 180000ks, sold it with 345000km on it, all that I did (aside from regular oil changers) was a couple of glow plus and repairs to air cond. 

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11 hours ago, Seth1312 said:

I was woundern if I can get some help...I have a 1998 Mitsubishi challenger 4m40...it runs ok untill it warms up then it over heats on me is the any tips that I can use to sort the problem 

Replace or have your radiator professionally cleaned and checked, either way you'll need to do this and it may not have cracked it's head yet. Also make sure both radiator hoses are getting hot, if one hose is still cold the thermostat probably ain't opening which will let it get hot pretty quickly.

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I have replaced the radiator but it still kept heating up so my father had taken the thermostat out cause it was fucked the bottom pipe were the thermostat was, it stayed cold then the top. my father said it was ok to still drive it and then I blew the heater hose it started over heating so I turned of the engine st8 away and left it over night to cool right down before I had changed the blown hose...now it keeps over heating on me....do I need a new thermostat??

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Cracks heads

Timing chains fail

Diesel pump seal fail

 

overall not bad

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Diesel pump seal fail so they leak down overnight and then you drive 1km in the morning and conk out / bleed / go again 

$500 to fix - or electric fuel pump hidden under the battery box - ask me how I know lol 

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