1hz cracked head

[howesy]

[/quote]

Hi all...Spot on,these engines just cant hack haveing a turbo on long term, driven in the real world,moreso if you use them as a work horse and or tourer with trailer long trips extreme temps up and down the great divide.Another problem is the the top ring grove in the pistons flog out and gets wider due to pistons not ment for turbo.Then you get gearbox problems where they dont live as long as they should.[/quote]

Gee you better wisper in my 1HZ's ear and tell it to lay down and die.
Turbo fitted under 200,000Km and its now pushing toward 430,000 max 11psi
And my mates factory turbo has the same box so I better tell him its gunna blow too.
Lots of blokes have had problems and there are a lot that have had great service and the same goes for the 1HDT's there are good and bad stories its
luckluck of the draw I reckon.

[thrashlux]

"I do my XD with the 393 stroker has a 950 holley on it. And the 351 in my fj45 has a holley

yeah you r right i see heaps of cars like that around like at least 90%

had EFI its to hard to blow fuel into a fuel injector when a fuel pump dies."

you dont have to!!! try bashing the fuel pump

""See just as many late model efi cars on the back of tow trucks mate look around.""

compared to when the 1990's

so if you have a lean cylinder it will get hotter and the rest of the head has to compensate

UMM NO

[flyology]

Aha!! that's why 1HZ's crack heads, because people put holleys on them!!!!


(sorry could not resist that....)

[thrashlux]

Aha!! that's why 1HZ's crack heads, because people put holleys on them!!!!


(sorry could not resist that....)

haha dont start me off on how good holleys are off road!!!

[thrashlux]

Gee you better wisper in my 1HZ's ear and tell it to lay down and die.
Turbo fitted under 200,000Km and its now pushing toward 430,000 max 11psi
And my mates factory turbo has the same box so I better tell him its gunna blow too.
Lots of blokes have had problems and there are a lot that have had great service and the same goes for the 1HDT's there are good and bad stories its
luckluck of the draw I reckon.

you should go buy a lottery ticket its your lucky day or year !!

[80's_delirious]

Thrashlux, instead of giving us all the doom and gloom story, for the sake of sharing information, can you tell us how your 1HZ was setup?

for every doom and gloom post, there are others who have good experiences, often people make a lot of noise about bad experience, but dont talk a lot about good experiences.

I have blown up a 1HD-T (inevitable as it was pushed beyond its limits and not treated accordingly ) I now have a 1HZ 105series and am contemplating going the turbo route, some real info would be great instead of the 'its gonna blow' or 'its awesome, I thrash it and it only needs one wire' BS

Can you give us some details??

ie:-
how much boost?
max EGTs?
A/F ratios?
intercooled?
cooling issues?
driving style?
professionally setup and tuned or backyard job?
was engine condition assessed professionally before turboing?
what do you think could have been done better or differently?

[Shadow]

It is the indirect injection design that is flawed. Firstly, you have a precombustion chamber made from a disimilar metal to the head.

So you get different expansion/contraction rates of the two metals which eventually, and inevitably, causes stress fractures in the head, and in the precombustion chamber itself.

For Indirect injection the diesel is injected into a precombustion chamber, where the heat of the engine and compressed air vaporizes and combust, the entire heat of the combustion enters the cylinder from one side. Which means the piston is heated unevenly which can cause cracking in the piston crown. Proper injector maintenance (spray pattern) will help the longevity of the precombustion chamber, but there is no way to stop the uneven heating of the piston crown.

In the 2H it is very common for the precombustion chamber to become very loose (from dissimilar expansion/contraction) and rattle around or even rotate in the head, common for small pieces of the precombustion chamber to break off and end up smashed into the top of your piston. Its Also very common for the top ring land to crack and break free on the precombustion chamber side.

Direct injection means the fuel is injected, at higher pressure into the cylinder chamber directly, usually aimed directly at the centre of the piston crown. If the injector nozzles are operating correctly the diesel droplets spread and vaporise evenly in the cylinder, leading to even heating of the piston crown.

If the injector nozzles are not operating properly, you can get the same uneven heating of the piston crown as an indirect injected engine, which can lead to cracks or even holes melted straight through the piston.

Adding a turbo means you increase the heat, and increased heat means the uneven heating becomes more of a problem.

This is why every single Toyota Turbo Diesel is direct injected.

[cambo-84]

I have a 1hz in a 75 series

Turbo has been on for 200 000km, 300 000km on the truck. prior to installing the turbo i had a compression test done. Installed a new injector pump and injectors Was all set up by MTQ in rocky. I run 12psi, post turbo pyro and a boost guage.

pyro very rarely goes over 400.

If the 1hz is set up properly, not over fueled and the EGT's are monitered they will be reliable.

Too many sour stories about 1hz's dropping there guts on the highway usually from turbo's that weren't set up properly in the first place. over fueling is the biggest killer of turbo 1hz's.

Parts are cheap, rebuild kits are cheap and their an easy engine to work on, well within the reach of the average bloke. Sure the direct injection turbo motors are good but for the price of one of them i'd rather stick with a 1hz, set it up properly and spend the change on other mods

[thrashlux]

yeah can do heres an old post with some extra stuff thrown in

when i bought my 80 it had a safari turbo kit installed

shortly after i bought it the injector pump died so i bought a rebuilt engine with a fresh head
plus got injectors and pump overhauled
then i fitted a pyro
took it down to get the fuel set up on a 4x4 dyno they set it up so that it would not excead 500-550 on the dyno at sustained full load
i then confirmed this on mountain ranges
max of 10 psi boost
the car had a 3 inch exhaust with dump pipe
it was not used for towing anything for any great distance just the odd car or box trailer around town
i got a boost compensator this is when i got 600km per tank
this engine did 100000 before the head cracked

the driving style was a mixture of holiday cruising driven by me 30%
around town by my wife (she drives like a grandma)70% the car was rarely thrashed off road (thats what my ute is for)

used to tow some times only a box trailer not for any great distance

the boost compensator helped for fuel economy, soot and keeping the oil cleaner

it never had any cooling issues till after the head cracked due to the regular precom expansion issues

there is nothing wrong with a 1hz turbo it is just that it pales in comparison to a factory turbo motor for power, fuel enconomy,longevityand oil cleanliness

Arb stopped selling the safari turbos due to 1HZ's blowing up

I think if you have an old 1hz that is running fine the best option is to sell it and buy a factory turbo motor
there is not much in it in the money stakes if you add it up
plus you can floor them up a hill with no fear

so you can see for your self maybe you should try and drive a few diferent trucks one with a 1HZ turbo one with a 1HDT one with a 1HDFT and one with a 1HDFTE each one is a step above the last for power, fuel economy, smoothnees torque band width and revability.

[80's_delirious]

hmmm thanks, food for thought.

as I said, I had a 1HD-T and killed it, the 1HZ goes OK, but having almost everything needed to add the factory turbo to it is tempting me, (I would only need to make oil feed lines)

1HD-T, FT, FTE are all out of the question due to cost in the foreseeable future.

[thrashlux]

hmmm thanks, food for thought.

as I said, I had a 1HD-T and killed it, the 1HZ goes OK, but having almost everything needed to add the factory turbo to it is tempting me, (I would only need to make oil feed lines)

1HD-T, FT, FTE are all out of the question due to cost in the foreseeable future.

the way i looked at it is i added up the cost of the fte it was around the 10k mark i just bought one last week for $8800 with loom computer flywheel the lot from a 100

if you sell your good running 1HZ for say $2500 then add the cost of a turbo kit say 2000 bucks then an injector rebuild and boost compensator fitment which are all nessary to make it run more economically and clean thats another 2000 bucks
you are up for 4000 to turbo it
if you add the cost of selling yours you effectively have 6500 to play with so add 2000 to that and you can buy a really good 1hd or an fte
more food for thought its only an extra 2 grand for all that extra reliability , power and fuel economy
i know its different in your case if you already have all the hardware
what about doing a rebuild on your other donk and selling the 1hz to finance it??

[mickbeny]

Hi all...Spot on,these engines just cant hack haveing a turbo on long term, driven in the real world,moreso if you use them as a work horse and or tourer with trailer long trips extreme temps up and down the great divide.Another problem is the the top ring grove in the pistons flog out and gets wider due to pistons not ment for turbo.Then you get gearbox problems where they dont live as long as they should.[/quote]

Gee you better wisper in my 1HZ's ear and tell it to lay down and die.
Turbo fitted under 200,000Km and its now pushing toward 430,000 max 11psi
And my mates factory turbo has the same box so I better tell him its gunna blow too.
Lots of blokes have had problems and there are a lot that have had great service and the same goes for the 1HDT's there are good and bad stories its
luckluck of the draw I reckon.[/quote]

Hi all...Well Toyota must be a stupid bunch if they wasted money on changing the head design and put ing stronger gearboxes in the factory turbo engines.Or maybee they know something.

Look,My Turboed 1HZ only let me down once when the gearbox broke.I had boost comp fitted 3inch exhaust egts would not go over 550 under any circumstances..I had the bigend bearing replace to satisfy myself for reliability/longevity.Once we had a look at the pistons,the top ring groove on most pistons was worn badly.So we replaced with turbo spec slugs.We decided to rip the head off,Precoms were cracked.Fixed it and fitted a thicker head gasket.Racket up another 20000 klm and sold it because i wanted reliability due to big trips with big loads in remote areas,I just couldnt trust it.Bought a factory turbo,goes better stock standard,uses less fuel,and oils always clean and i have faith in the engine that it wont let me down.At the end of the day the factort turbo was/is a cheaper option for me with a newer model vehicle.
If any of you guys could have a sneak peak inside your engine and reliability was of upmost impotance,you would see the rapid wear and change your minds or maybee not.

[Z()LTAN]

ill endoscope the bores of my 1hz for shits and giggles.

Let you know what it looks like after a year of 25psi, a few bouts of 700deg and 5000rpm.

[SimonInAustralia]

I had the bigend bearing replace to satisfy myself for reliability/longevity.Once we had a look at the pistons,the top ring groove on most pistons was worn badly.So we replaced with turbo spec slugs.We decided to rip the head off,Precoms were cracked.Fixed it and fitted a thicker head gasket.

What does this preventative maintenance cost?

Have thought about possibly doing similar to my 1HZ turbo.

[thrashlux]

ill endoscope the bores of my 1hz for shits and giggles.

Let you know what it looks like after a year of 25psi, a few bouts of 700deg and 5000rpm.

if you are going to do a boreascope if you can get a 180 degree attachment to look a the precom chambers and for cracks in the head near the valves originating from the precom insert

[dow50r]

a comp truck and a tow rig are two different beasts.....tow 3 tonnes up a long hill at 5000 rpm and 25 psi and see how long it takes for the crank to get an alloy coating...luckily, you only do that on the obsticles, and idle down the other side.......looking at this conversation from another view point....i onse spoke to a ranger driving a navara 3 litre on its 4th motor in 70000kms....he gave me the speel about them being crap etc.....we asked what maintenance was done on it and he said drive till it blows up then its all new again...the red bull dust was 2 feet thick...and he was dark skinned....in Mootwingie National Park, the blacks dont pay for anything, we do....so they drive them till the air cleaner clogs up and less air/more diesel equals too much heat and bang.
IF....you dont maintain a motor, it will fail...if you maintain it incorrectly, it will fail....if you dont do preventitive maintenance, chances are it will die earlier than expected too, by loss of water is the most prevalent cause of death.....but....by adding boost and not monitoring whats coming out....thats a recipe for disaster, because air filters do get dirty, and at a guess. 1hz ones get dirtier than petrol ones simply because they are bought with adventure in mind over shopping trolleys in suburbia
Andrew fzj80

[mickbeny]

I had the bigend bearing replace to satisfy myself for reliability/longevity.Once we had a look at the pistons,the top ring groove on most pistons was worn badly.So we replaced with turbo spec slugs.We decided to rip the head off,Precoms were cracked.Fixed it and fitted a thicker head gasket.

What does this preventative maintenance cost?

Have thought about possibly doing similar to my 1HZ turbo.

Hi all...About 3 grand if i remember correctly.There is nothing you can do for the precombustion chambers from cracking though,Thats why i got rid of it.I need reliability and longevity for what i do for piece of mind.

[lshobie]

I love the 1HZ, I've turbo'd, H2O intercooled it and flog the crap out of it a few times a year, I put about 10K kms on it a year or less. I'm running 15 lbs boost and beat it hard, but only tow light loads and it only gets worked really hard for short bursts - so I don't expect to see a problem with it.

But..... as much as I love it I know that if I really put high kms on it every year or towed big loads often I would swap it out to a 1HDT at a minimum - just for reliability.

One good thing about the 1HZ here is that I can have a new one on the doorstep in under a week if mine does blow - not so for the 1HDT. So I factor that in.

Regards,

Louis

[skootin]

Yeah a std Holley is shit offroad thats why i put the offroad needle and seats in and vent tube extensions and jet extensions in so i can drive it on any angle its easy when you actually know what your doing with a carby so many people get defeated by such a simple fuel delivery device. Have a look its all available and Holley in all there wisdom decided to fit the stuff in the Offroad range of carbies they also do some good marine carbies so your ski boat goes better.
I did hit the fuel pump to make it work but after 3mths of doin that i was over it especially when it rained.

Never seen what happens to a piston when its leaned out?

Rich does more damage over a longer time. Detonation.

Toyota recognised the problem with the old head design with the release of the 79/100ser in 99 they put a radius on the precom hole in the head which helps but isnt a solution to the real problem.

Hey ive been wrong before but heat is the killer and never believe anyone who says they have fitted a rebuilt head to a 1HZ. What you need to know is when a cast iron head gets hot and bends simply machining the head surface flat again does sweet F$%k All cause the top is still goin to be bent.
I spent 3yrs straight doin 1HZ heads for the toyota workshop during summer nearly 1 a day.
Simple and regular maintanance is the only way to any engine surviving.

[Z()LTAN]

All new precombs have a radius on the outlet.

The problem is when people get their heads machined the precombs get machined along with them. This takes the radius off the outlet mouth.

Your best bet is to get new precombs fitted after the head has been machined. Im pretty sure the poofteenth that it will protrude wont be an issue.

[skootin]

The correct procedure is to machine the head with the precom fitted then remove them and take a finish cut 1-2 thou so they actually protude the gasket takes the extra squish but not many people do it that way anymore.

[lshobie]

Ok, what would you guys do - I have a 2003 HZJ79, about 4600 mine hours on it, 600-620 psi on the cylinders, runs great, I've had it turbo'd for 3 years and have had no probs. It is getting hard to start in the winter here in Canada - I think the pump might need a rebuild. I'll have the tranny/transfer out of it for a rebuild this month, was going to take the engine out as well and swap it with a 1HZ from a 1991 HZJ73 Japanese import engine with low kms on it. I was also going to ceramic coat the manifold/turbo housings to keep the EGT's a little lower.

So because of the different precup design should I just keep my 2003 engine in it???? Either way it doesn't matter. My 2003 engine also sounds like a diesel, not like a 1HZ should sound, I was going to do a valve shim adjust on it - that and the injection pump and was hoping it would be quieter.

If I did swap the engines would I be into a head removal and new precup install???

Thanks

Louis

[mickbeny]

Toyota recognised the problem with the old head design with the release of the 79/100ser in 99 they put a radius on the precom hole in the head which helps but isnt a solution to the real problem.

Hi all...Mine was a 2000 79 series,They were all cracked.

[SimonInAustralia]

How bad is cracked precombs for the engine?

Is it normal/expected in the design?

[lshobie]

Toyota recognised the problem with the old head design with the release of the 79/100ser in 99 they put a radius on the precom hole in the head which helps but isnt a solution to the real problem.

Hi all...Mine was a 2000 79 series,They were all cracked.

Turbo or non turbo - how many kms on it and did it fail?

[oldmate]

The correct procedure is to machine the head with the precom fitted then remove them and take a finish cut 1-2 thou so they actually protude the gasket takes the extra squish but not many people do it that way anymore.

x2. the other point people ignore is how oversize tyres affects the gearing and loads the motor up. Also driving habits can be terrible. I've seen people lugging these motors up hills, smoke pouring out and they wonder why their motors don't last.

There seems to be some mentality that the factory turbo motors are bullet proof compared to the non turbos, but that is mostly crap. they are only marginly more forgiving to bad driving habits thanks to a boost compensator.

[me3@neuralfibre.com]

I can only comment on mine.

a) The Auto is the same across all of them
b) Turbo'd at 10,000km. Now at 260,000km
c) Boost 10PSI, fueling as per fitted
d) Third owner. First towed a van. I do all sorts of stuff
e) 720 peak EGT pre turbo
f) Had cooling issues, fixed with fan clutch and radiator changes.

I suspect the head is "dubious", but I also suspect it'll keep going for a long time.

12K is not worth spending for the changeover. I doubt I would get $4K for the motor plus turbo, leaving an $8K hole. I also think the car would sell for LESS due to the non factory motor.

I love the idea of a 1HDFTE, but the coin doesn't add up.

Maybe I should just go for IFS

Paul

[skootin]

Ok, what would you guys do - I have a 2003 HZJ79, about 4600 mine hours on it, 600-620 psi on the cylinders, runs great, I've had it turbo'd for 3 years and have had no probs. It is getting hard to start in the winter here in Canada - I think the pump might need a rebuild. I'll have the tranny/transfer out of it for a rebuild this month, was going to take the engine out as well and swap it with a 1HZ from a 1991 HZJ73 Japanese import engine with low kms on it. I was also going to ceramic coat the manifold/turbo housings to keep the EGT's a little lower.

So because of the different precup design should I just keep my 2003 engine in it???? Either way it doesn't matter. My 2003 engine also sounds like a diesel, not like a 1HZ should sound, I was going to do a valve shim adjust on it - that and the injection pump and was hoping it would be quieter.

If I did swap the engines would I be into a head removal and new precup install???

Thanks

Louis

Check your glow plugs and wiring for them clean connections.
First thing to do.

[skootin]

Toyota recognised the problem with the old head design with the release of the 79/100ser in 99 they put a radius on the precom hole in the head which helps but isnt a solution to the real problem.

Hi all...Mine was a 2000 79 series,They were all cracked.

They will always be cracked unfortunatly.
They are where the combustion starts and the flame comes out the hole in them they get hot.

[skootin]

I can only comment on mine.

a) The Auto is the same across all of them
b) Turbo'd at 10,000km. Now at 260,000km
c) Boost 10PSI, fueling as per fitted
d) Third owner. First towed a van. I do all sorts of stuff
e) 720 peak EGT pre turbo
f) Had cooling issues, fixed with fan clutch and radiator changes.

I suspect the head is "dubious", but I also suspect it'll keep going for a long time.

12K is not worth spending for the changeover. I doubt I would get $4K for the motor plus turbo, leaving an $8K hole. I also think the car would sell for LESS due to the non factory motor.

I love the idea of a 1HDFTE, but the coin doesn't add up.

Maybe I should just go for IFS

Paul

If you do end up doing a head mate they are $1000 approx for a brand new casting and with all your valves fitted and clearances done with a vrs $2000 if you can replace it yourself or with some help still $$$$'ssss in front.