Delica Canada | Mitsubishi Van Club

I know people post if they do have the cylinder head crack, on their beloved Delica, but no one would bother posting if they HAVEN'T had a problem. So maybe if we do a survey, we can find out, what percentage of the Delica's are having a problem.

If you own a Delica, please take a quick second to fill this out. The more people that do, the better idea we will have of the likelihood of a head failure.
If you know that your Delica had the head fixed, before you bought it, please mark it down as having a head problem, even though it didn't happen to you.

Please note, I'm surveying for diesel engines only.

It's worth noting that these polls are anonymous so no one need feel ashamed about their driving habits as was a reason some think most don't mention whether theirs did on the forum.

you should be able to select more than one option as many L400 owners had L300's or Pajero's (4D56T - some with cracked heads)

Have / had and maybe add Pajero!?

Ok, fixed so you can have more than one choice, as I'm sure people have owned multiple Deilcas before, and added Pajeros.

Oh, and sorry, it looks like because I edited the poll, it erased peoples votes, so please revote if you already did. Thanks.

Love it! Should be interesting. Only I have cracked two heads, but can only claim one.

Over 90,000 kms on my 92 L-300 that came with 65,000 on the odo and no head issues - yet at any rate.... I did have the full meal deal refit when I got it and keep up the maintenance by regular servicing at CCA. I haul a utility trailer on a daily basis and often have reasonably heavy loads.

My '94 2.8 L400 has had the equivalent of 4700 CAD spent on it on parts only (plus countless hours of labour) in the last 18 months with a view to making an older vehicle as reliable as possible. Like the rest of the mechanics of the vehicle, the cooling system is in tip-top order. I fitted an aluminium header tank with integral probe wired to a low-coolant level alarm and a digital temperature gauge with the sender in the top hose. With these exceptions, the mechanical side is completely standard and un-modified.
My head cracked returning from a camping trip. The only indication I had was that the coolant was being lost out of the overflow. The temperature never went above 94 degrees either before or after and getting home the last 200kms was no problem other than topping up from time to time.
The head I removed appeared original and the vehicle has covered approx 150,000 kms.

buddy if your worried i will recommend one of these http://www.ebay.com.au/itm/ENGINE-WATCH ... 1e71b6efa3

Over the last few days, I have been looking for evidence that supports my theory that aluminium heads can and do crack over time due to normal engine use. While a single overheating event can expedite such a failure, this failure may have already been inevitable.

The first line of investigation came from surveying the common knowledge of mechanics, and car junkies, etc. Almost without exception, the finger is pointed to overheating events. However, there are always a percentage heads that just seem to crack, under normal use.

So, I next turned to material science, and the physics of cast metals - specifically aluminium. ***disclaimer - the following interpretation comes from a wood worker with a degree in Archaeology and an MA in Architecture, so are presented here for entertainment purposes only****

First: as atoms of melted metal begin to pack together to form a crystal lattice at the freezing point, groups of these atoms form tiny crystals. These tiny crystals increase in size by the progressive addition of atoms. The resulting solid is not one crystal but actually many smaller crystals, called grains. These grains grow until they impinge upon adjacent growing crystals. The interface formed between them is called a grain boundary. Grains are sometimes large enough to be visible under an ordinary light microscope or even to the unaided eye. The size of these grains depends largely on the rate of cooling.

Second:Metallic crystals are not perfect. Sometimes there are empty spaces called vacancies, where an atom is missing. Another common defect in metals are dislocations, which are lines of defective bonding. These and other imperfections, as well as the existence of grains and grain boundaries, determine many of the mechanical properties of metals. When a stress is applied to a metal, dislocations are generated and move, allowing the metal to deform.

Third: Fatigue performance is a function of the crystal structure of the given metal, the size and shape of the grains, and the frequency and magnitude of the crystalline imperfections. It has been observed that minute casting defects have a detrimental effect on fatigue life by shortening not only the crack propagation period, but also the initiation period. Experimenters do not study IF a crack will occur, but after how much fatigue. The decrease in fatigue life is directly correlated to the increase of defect size. There seems to exist a critical defect size for fatigue crack initiation, below which fatigue crack initiates from other competing initiators such as slip bands (The appearance of fragmented crystals and spaces indicating that a metal is about to break).

So, my conclusions are that under normal operating conditions, minute defects within a cast aluminum head are subject to fatigue - from heating/cooling cycles, differential stresses between the aluminum head and cast iron block, and from inherent design weaknesses, (like the well documented weak spot at cylinder #3 on L300’s). Over time these stresses work to increase the defect size of the minute defects until they reach a critical defect size and crack initiation occurs. This critical size for initiation may very well, and often does, occur during an overheating event - but would most likely still occur, albeit more gradually, under normal use.

My final observation is that casting an aluminum head is a relatively crude industrial process. This process inherently leads to inconsistent and imperfect crystalline structures, due not simply to physical design of the object, but more critically to differential cooling during fabrication of the cast part which leads to variations in crystalline structures. This could very conceivably result in a consistent weak spot within a particular casted product. It could similarly lead to occasional, but common weaknesses between similarly cast pieces. Some heads will crack, others won’t

In conclusion: given all the above factors, aluminum heads are a consumable component of modern autos (this problem is not unique to deli’s). Cast aluminum does have a lifespan, and a new head should give some security over an older head (this is completely unconfirmed by me) That being said, new heads could also contain minute defects that could also cause premature failure, which of course could be initiated by an overheating event.

So, build head replacement into the lifecycle cost of your car - it is very common, and not necessarily your fault. And don’t buy a car with dual overhead cams

I think it is possible or even likely that the head does get weaker over time, and an overheating can push it to make the final failure. But it seems the Delica has a weak point. I've been around a lot of cars and worked on all of them, and I don't find that aluminum heads are a problem. I've dealt a lot with the Nissan KA24DE and the SR20DET, gas 4 cylinders with alum heads. I've seen many people, and have myself, installed turbos on the KA24DE and the SR20DET is turbo from the factory. These engines take much abuse, revving upwards of 8500RPM, and get overheated regularly. I've seen 400hp from the 2.0 liter engines. I'm on a couple of forums about these engines and very rarely, if ever, have I heard of a head cracking. Pistons melting, head gaskets blowing, dropping valves, etc, etc but not cracked heads. These too are older engines (89-mid 90s).
I think it's ridiculous to put an aluminum head on a diesel, especially a turbo diesel. With the extremely high compression ratios, you are putting major strain on the head. If you have a tiny flaw in the casting, or in the design, pounding it with a 21:1 compression ratio will help you find those flaws.
I'm kind of confused as to why Mits used aluminum heads. It's more expensive and is usually used to save weight and for added performance. The Delica is a freaking tank and I don't really think race car when I see one either, so why not go with bulletproof cast iron?

What I uncovered (with gas engines) is that manufacturers go with aluminium specifically because they are more ductile than cast iron. Apparently, cast iron is much more likely to crack, and when it does crack is unlikely to be repairable - aluminium is more weld-able.

However, like you said, some aluminium heads are inherently more likely to crack than others.

Not sure if this means anything but when muscle car guys have the choice between aluminium and iron - they almost always choose aluminium.

Most muscle car guys take aluminum because it shaves a lot of weight off the car (2 big heads on a v8). Better flowing, higher performance aftermarket is almost always aluminum. There was a lot of horse power to be gained switching from a poorly stamped out iron head vs a well ported, aftermarket aluminum head.

I know it's a Strada but for now i think that my 4d56 head is ok.