Cracked Heads

[MattR]

Several people have commented that there seems to be an increasing number of cracked heads being reported. (mine included)
Has anyone done any research to see if there is a link between cracked heads and the use of Biofuel / WVO?

I use it, but I wonder how many others are there that have suffered a cracked head and use it?

Also, how many people are there that have never used it but have had cracked heads?

[Wolfracer]

Untechnically,
The heads go due to excessive heat from poor circulation/design. Heat is produced from combustion. WVO "probably" has less energy to combust than diesel, so temps could be lower....therefore...!
Probably....

[Hazzo]

I only tried veg once, about 50 50 mix, the truck ran great on it, actually felt and sounded very smooth but starting was a pain, very lumpy and flattened the batterys the second day so I went back on straight diesel, head cracked a lot later on and nothing to do with fuel, I reckon it was more to do with towing two ton on a hot summers day with the viscous fan operating wrong due to worn out viscous oil and the tranny overheating the fluids to the point of no return, service the fan, fit an aftermarket temp guage and a tranny oil cooler and the head should be fine imo. H

[MattR]

You may be right, but it seems a bit of a coincidence that all these heads are going now after all this time. The only common denominator I can see is the marked increase in people using biodeisel etc.

I wonder if there is a poll tool on this forum that can used to test peoples experiences with cracked heads and WVO etc?

[MattR]

You may be right, but it seems a bit of a coincidence that all these heads are going now after all this time. The only common denominator I can see is the marked increase in people using biodeisel etc.

I wonder if there is a poll tool on this forum that can used to test peoples experiences with cracked heads and WVO etc?

I answered my own question there! Please vote in the Poll!

[Hazzo]

I honestly reckon its down to 15 year old silicone viscous oil losing its correct properties/viscosity, possibly combined with the heat activated spring being gunged up/corroded which prevents the fan from locking up properly to drag more air through the rad cooling the coolant which is being superheated by the transmission oil when the system is under load.

The temperature guage is useless, mine stayed at normal at all times, so don't rely on it, these are the reasons for my "mods", aftermarket guage, new silicone oil in the fan and an external transmission oil cooler, since doing these cheap things, (cooler from scrapman) the car has not seen 91deg, which I reckon is well within the limits.

New thermostat/coolant/rad cap too, change these every two years and do the viscous fan at the same time and I reckon these trucks will outlast me. H

ps. by the way the last couple of days have been quite cool here and though my stock guage showed normal, my aftermarket stayed below 60deg, real cool.

[Albannach]

That's a biased poll.

There are no no cracked head answers. The heads crack because of poor cooling system maintenance or design, not what fuel is used.

There's already a thread trying to find a common factor with the failures, perhaps you should look/post there?

[Bogus]

my stock guage showed normal, my aftermarket stayed below 60deg, real cool.

That sounds a bit too cool, I thought that optimum jacket temp for a diesel was around 85-90 and that your stat should be controlling it at that. I suppose cooler is better than overheating, but 60 doesnt sound right. and surely running too cold has some effect on engine life ??

Bogus

[Hazzo]

It was on a drive to town, 6 mile, pouring rain n chilly, like I said the onboard guage was showing normal after roughly a mile, in fact anything between 40-Headbusted shows as normal and the reason not to trust the guage, on the return trip I used the dueller at 65-70 and the aftermarket guage showed 85deg.

Next time I do the tranny oil I'll fit an inline thermostat to regulate the tranny oil temps but at the time I fitted the cooler/head/temp/etc I had no cash left for anything else, at least I know my mods are working and I have cool water going to the head/engine, rather than it boiling, blowing the head, pi$$ing out the expansion tank etc etc, I'd rather use a bit more fuel than have to fit another head, wouldn't you. H

[MattR]

That's a biased poll.

There are no no cracked head answers. The heads crack because of poor cooling system maintenance or design, not what fuel is used.

There's already a thread trying to find a common factor with the failures, perhaps you should look/post there?

I didnt intend it to be biased and in fact as a WVO user myself, I will be happy to see a result that shows the use of WVO does not mean an increased risk of a cracked head.

Hopefully if more members vote in the poll we will have a clear illustration that we can all use to help make the decision about whether to use WVO or not.

I have read some stuff on the subject, but I have not seen any conclusive results. Hopefully the poll will give us an indication of the problem.

My head cracked and I changed the Rad, the water pump, thermostat, coolant etc. But when I checked the stuff I was taking off there was nothing wrong with it (anyone want a radiator?) and now with the new stuff fitted, my guage shows exactly the same as it did before. My temp guage did go into the red when I lost all of the coolant due to pressurisation from the head cracks, but other than that it always stays just below halfway.

[TonyN]

Personally I tihnk its a none starter, and is what Andy is trying to say, Running veg oil cannot have anything to do with cracking heads.

It has a much lower cetane rating than derv, and also a lower BTU, so derv detonates easier, and prduces more energy, so Veg oil if anything is easier on the engine in all depts.

Don't take it personally, its just going to lead to a thread that has no real value, and could just cause more veg oil confusion.

[tonupteabag]

my heads been cracked for years.....but the trucks head is fine and dandy...oops shouldn't have mentioned that!!!!!

[Hazzo]

Yeah, so was mine and overly maintained, in fact it ran fine for over six months even when loosing coolant by 1/2 inch disappearing from the rad after a days running around, no oil in water or water in oil, nothing. Thermostat stuck one day, still didn't register on the temp guage as overheating and still ran great, and I mean great. The day before it hydrolocked I was doing 90 up an incline after changing filters and "driving like I stole it" with the filter full of atf.

If you haven't done anything with respect to preventing the problem on your own cars then imo its just a matter of time. H

[NeilT]

I honestly reckon its down to 15 year old silicone viscous oil losing its correct properties/viscosity, possibly combined with the heat activated spring being gunged up/corroded which prevents the fan from locking up properly

My money's on the pin that passes through the housing from the middle of bi-metal coil getting corroded. Is this a colder country than Japan? More salt on the roads? I guess that pin rotates less often here allowing it to crud up. It's easy to check and fix, take the fan off and heat the coil with a hot air gun or boiling water and check the pin rotates (it only needs to move about 20-30 degrees to open the channels that allow the silicone oil to circulate) If it doesn't rotate you can use needle nose pliers to pull it outward (it'll give a couple of mm at most) then tap back in, repeat a few times and WD40 until it's free, some ACF-50 to finish.

Silicone is used because it is very resistant to heat, it stays viscose even at high temp where other fluids become less viscose. I don't think it would be much effected by age but it should be possible to tell if the oil is still viscous by seeing if the fan is stiff first thing in the morning, if the fluid is ever viscose i would think it is still ok. I could imagine that something could become less viscous with use but if it is still viscous at all i doubt silicone will lose it's heat resistant properties over time. If you need more convincing you could try opening up the coupling and seeing if you can blow the fluid around with a heat gun (i tried once with a 20 year old Daihatsu fourtrack and it remained like treacle even with a scorching heat on it.)

If that pin is corroded that would be enough to cause overheating under heavy load with nothing else wrong, but if something else is less than 100% the viscous coupling should lock up as needed to make up for it, in fact it is one way to tell that there is another cooling problem developing; when you notice the fan is coming full on more than usual. In normal use you might only hear it rarely when you are stuck in traffic, it should come on for just 10 -20 seconds as it will take the heat out of the rad very quickly and once the heat is gone the coil returns back to the closed position. If it comes on and stays on you have a big problem somewhere else.

I don't know if the coils could change over time but i doubt they would unless they are severely corroded or broken. From doing a couple of these the coils looked fine and it's just the pin that is stuck.

[Justbrad]

Nothing to do with what fuel your using.

The trucks are now getting older and heads are failing.

People could possibly stop this be using a rad flush one in a while to keep all the waterways clear to improve circulation.