Poll question: Everyone! Please let us know, head issues?

[legionnair]

Aluminum on a diesel is fine, in fact I think you will start seeing it more often. The duramax uses aluminum heads, its not the aluminum head its the cooling system design. I believe a big factor is the unknown history of these little vans. I have said it before I am running mine until it blows then swapping in a different motor most likely a 22R. They make a lot of cheap performance parts for this motor it would be very easy to get over 100hp and that would move the delica easy

[FalcoColumbarius]

I think one thing with the cooling system is in Japan the water is hard, not soft (at least that's what I've heard), consequently there's a lime build-up. I know I had to re-core my main radiator as it was operating at around 80% capacity? Around there. When I looked into the rad you could see the build-up on the fins.

Falco.

[glenn]

Many of us have new radiators - as a preventative measure. Correct me if I am wrong, but many of the big importers routinely sold/sell their vans with new radiators. New hoses too. I still maintain that some of these heads just crack over time. I had a re-cored rad, which was stolen, believe it or not, then I had a brand new rad. Some of us abuse their engines (nxski - this means you) and nothing happens. Some of us take reasonable precautions, yet they still crack.

[nxski]

I hardly abuse my engine, the circstances I noted were in extreme conditions due to extenuating circumstances. I brought them up to show the extremes. I do in fact baby my vehicle and when driving with other L300's usually fall behind for fear of pushing the van too hard. I said I don't mind if I crack a head because I'll just swap in a different engine but that doesn't mean I'm not going to try to get the longest life possible out of the one I have.

[glenn]

I'm just giving you a hard time because you made yourself an easy target! After all, you do put champagne in your engine instead of oil.

And I'm the one who cracked two heads, and am trying to post-rationalize it into an "inherent flaw" in the design of the engine.

But, out of curiosity, you said you nearly redlined your temperature before. Was this before you installed an EGT gauge or after? I would be interested to know how hot the engine got. Your extenuating circumstances are exactly the kind of events that people point to as the cause of other people's cracked heads. So, I think you are agreeing with me, that some of these heads are just going to crack, and others (most of them) never have a problem.

[nxski]

Correct, I am agreeing with you, when I see temperatures like this especially when I'm far away from home it scares the sh!t out of me.

I redlined the water temperature coming back from Whipsaw because the air filter was full of dust and the radiator covered in mud. It's the reason I got a pyro.

The 17 egr reading came when I had an exhaust manifold leak and was climbing a very long hill with an outside temp of 42C. In this case the heaters were on full blast and my water temp never went above half. I've also seen the temp go up to 3/4 on flats in similar conditions but with an egr reading of 8.

The other cause of cracked heads is people turning off the engine when the heat is too high which is a point that hasn't really been discussed.

[psilosin]

One of the things that always gets overlooked on the Hilux Surfs (head cracking world champion) even by guys that spend big cash on new heads new rads and evans coolant etc etc that I think is a big deal is the condition of the viscous fan clutch. After 15 years the silicone fluid has often disapeared and that means your engine fan never properly locks up and fails to deliver adequate air (ie you can stop the fan spinning with your finger...*obviously do not try that as a test). The Toyota ones are servicable. You can use Toyota oil or go to your Hobby store and buy shock oil for 1/5 the price and have the option to use different weights of silicone oil that way. I use 10,000wt so the fan locks up at a bit lower temps quicker than stock. You can also adjust the temperature setting that the fan will lock up at. For more details search ih8mud for something along the lines of blue fan hub service and also on australian hilux surf for more chat on different wt oils.

Assume on the L300 and L400 they are also similarly servicable. Never bothered to look into it since figures the dealer and their super duper pre-sale service (sarcastic) should have already looked into that but maybe I should with all these cracker stories surfacing.

[mapleridge818]

I think Nissan uses a similar clutch fan in their early 90s vehicles, but from my experience, when they fail, they lock up too much. They are designed to slip, so at 6000rpm, the fan isn't doing 6000rpm. The more resistance, the more it slips (ie higher rpms) I find when they wear out, they don't slip enough. I though I had a problem with mine, so I changed it and got an extra 2 mile per gallon because the old worn out one was causing way too much drag at freeway speeds. I've also seen them lock solid, and that makes a racket, and probably isn't safe. I doubt those fans are designed to spin at that high of a rpm.
Maybe Mits ones are different.

[konadog]

I reckon that having a pyro gauge may lead to many cracked heads...
I suggest this because having one lets drivers get close to the edge - to push the limits, to focus only on that flashing number on the dash, perhaps ignoring other signs to slow down and go easy.
Just a thought...

[Rattlenbang]

I think it's design, because it's not just this model or manufacturer. Look to ford diesel forums, and guys there talk about the same problem when they tow huge heavy loads. Work the snot out of a turbodiesel with an aluminum head, you are looking for cracks. If it was normally aspirated, not so much. With steel heads, not so much. Don't work the engine so hard, not so much. But in our case, the only way to not work her hard is to keep off highways.

It seems that 150k is about when the heads pack it in. Time will tell if that holds for the next 150k.

Talk to machinists about this and they'll also tell you about the quality of the castings. To save weight and materials, casting have become incredibly thin, and in so many cases unworkable after a problem. Heads are becoming throw-away when a generation ago they were intended to be rebuilt. The 1.5 Britsh Leyland diesel in my boat had an iron head that weighed almost 100 lbs. That mother would never crack.

[Jedidiahwiebe]

Mine didn't crack but it warped during (or causing) an overheating event! Which came first? The chicken or the egg?

[thedjjack]

....... Which came first? The chicken or the egg?

Egg came first, chicken is a mutation..... however the first true "chicken egg" came after the mutation and came after the chicken...

loving my 6.2L NA diesel... cast iron head and block...