spray bottle test

[tony rodaway]

strange that having your heater on gives you actual movement in the gauge, I've never experienced this. It kinda sounds like your thermostat is stuck open!

hmm 2.5 ton is a hefty amount to stick in the back of these, you sure about that? It takes about half a ton to get the suspension bottoming. I've probably hauled close to a ton max on the rear axle and that was short distance. By the way gross weight for these trucks is about 3.5 ton I believe. That means about 800kg including fuel and people.

Well shayne it was heavy but was just a guess.
Now stat will prove wot exactly as wot if nothing wrong with mine how do I test without replaceing.

 

[Shayne]

The stat is a mechanical gate that regulates coolant circulation and so engine temp .

If you imagine half your coolant is in the engine getting hot and the other half in the rad getting cooled when a set temperature is reached the stat will open swapping cold from the rad with hot from the engine .

In my view there is no sense testing a stat because it is a simple and cheap but absolutely vital part of the engine so if it has to come out why not replace it - they last donkeys years .

http://www.roughtrax4x4.com/genuine-thermostat-6729.html

There is also a genuine Toyota towing stat that opens at 72 degrees if you prefer but i don't have a link for that .

 

[diggerdave]

This is the 76-degree thermostat I fitted http://www.yoyopart.com/oem/138783/herthbussjakoparts-j1532020.html

Google the name/part number and there are lots of buying options. I think I got mine via Amazon for around £24. Toyota do make one and it might be worth ringing your local Mr T parts desk to see if they are cheaper.

Standard thermostat opens at 82 degrees. The theory is that if it opens at a lower temperature (76), it will allow cold coolant in earlier resulting in a lower overall temperature of the coolant, and hence a slightly cooler cylinder head. It makes sense to me, and most people agree that its worth doing, but there are some alternative views out there as to whether its a wise modification.

 

[tony rodaway]

Yes and its all because of an emmision sensor built into the engine and comes up on the dash as an exhaust blowing fumes out but still drives but has to work harder so uses more fuel.
just got a fleet of hybrid double decker's this week and at around 10,,,15mph when breaking the whole bus jerks as cant change from diesel to electric at low speed.
Before you ask it costs £100s to replace the sensor hence low fuel mpg and means time off the road.
Buses run on add blue and diesel .

This is the 76-degree thermostat I fitted http://www.yoyopart.com/oem/138783/herthbussjakoparts-j1532020.html

Google the name/part number and there are lots of buying options. I think I got mine via Amazon for around £24. Toyota do make one and it might be worth ringing your local Mr T parts desk to see if they are cheaper.

Standard thermostat opens at 82 degrees. The theory is that if it opens at a lower temperature (76), it will allow cold coolant in earlier resulting in a lower overall temperature of the coolant, and hence a slightly cooler cylinder head. It makes sense to me, and most people agree that its worth doing, but there are some alternative views out there as to whether its a wise modification.[/QUOTE
Does it just twist in the bottom hose fitment as will get one and see if any difference.

 

[tony rodaway]

Thanks again guys and will find out more and fix it.

 

[Shayne]

Its a very simple job Tony pull the pipe off the bottom of your rad to drain coolant and follow the same pipe up to where it meets the engine , its just a cap and from memory its 3 bolts about 12mm , undo them and the stat will more or less fall out . Just put the new one in and bolt the cap back on .

I don't think the stat will fit in any way accept the correct way but take note of how the old one sits just to be sure .

 

[tony rodaway]

Its a very simple job Tony pull the pipe off the bottom of your rad to drain coolant and follow the same pipe up to where it meets the engine , its just a cap and from memory its 3 bolts about 12mm , undo them and the stat will more or less fall out . Just put the new one in and bolt the cap back on .

I don't think the stat will fit in any way accept the correct way but take note of how the old one sits just to be sure .

Thanks shayne your a star.

 

[Shayne]

just thinking its great this forum , we went from dodgy ideas about washing the intake to discovering a malfunctioning cooling system in a 1kz

You didn't just dodge a bullet mate you waltz through a minefield

 

[tony rodaway]

just thinking its great this forum , we went from dodgy ideas about washing the intake to discovering a malfunctioning cooling system in a 1kz

You didn't just dodge a bullet mate you waltz through a minefield

Well shayne thats me all over and the wife says i talk c,,,,p but if you dont ask then you will never learn.

On to the 1kzte overheat i read the post regarding overheating and head gasket blowing.
One of the points raised and dont think ever proved was the viscos coupling fan kicking in at engine temp .I no it has been mentioned but if no fan then its going to over heat when the car gets to temp everybody pointing to the thermo but take the thermostat been tested many times.The radiator cap i believe is another thing probably over looked but i am probably overlooking the bigger picture but when a car overheats and head gasket is compromised without replacing every part new the blame can only be a guess and many pounds later.
Think it was bob who wrote it but he says he fixed the problem and good on him as well but my point is has one thing alone been the problem or a part of the jigsaw
falling apart
rant over sorry.

P;S JUST GETTING TO GRIPS WITH HOW PROBLEMS START AND HOW PEOPLE FIND ANSWERS PLUS ALWAY S GOOD TO NO THERE ARE STILL MEMBERS OUT THERE WHO STILL HAVE A LOVE FOR THERE CAR.

 

[diggerdave]

my point is has one thing alone been the problem or a part of the jigsaw
falling apart

Nobody knows the answer to that. To my knowledge no forensic engineer has ever picked over the bones of a failed 1KZTE head (like they would in the event of an airplane engine fail or something). What we have had is a series of extremely well-informed (and some not so!) amateurs or non-specialist professional mechanics come up with a series of ideas and theories. These are scattered over the internet like gold dust

The general consensus appears to be:

The cooling system is fine on the 1KZTE, but it is marginal (although some say it is not quite good enough to sustain heavy, long-distance towing). If any element is less than perfect there could be problems.

Possible common failure points have been identified:

- viscous fan, oil leaks out of its clutch meaning it doesn't reach top operating speed when it should
- radiator, missing fins or blocked/corroded internally. ALways used Toyota red to avoid the latter, buy a decent quality replacement radiator
- thermostat can fail, the 82-degree one is fine, but some suggest the 76-degree one for long distance, hot country use or towing (although some people disagree)
-don't rely on the Toyota temp guage which won't indicate overheating until it's too late. Some people fit their own temp guages, either measuring the coolant temp or the exhaust temp
-heater pipes to the rear heater can corrode, leading to loss of coolant
-going at sustained high speed for long periods!

 

[tony rodaway]

Nobody knows the answer to that. To my knowledge no forensic engineer has ever picked over the bones of a failed 1KZTE head (like they would in the event of an airplane engine fail or something). What we have had is a series of extremely well-informed (and some not so!) amateurs or non-specialist professional mechanics come up with a series of ideas and theories. These are scattered over the internet like gold dust

The general consensus appears to be:

The cooling system is fine on the 1KZTE, but it is marginal (although some say it is not quite good enough to sustain heavy, long-distance towing). If any element is less than perfect there could be problems.

Possible common failure points have been identified:

- viscous fan, oil leaks out of its clutch meaning it doesn't reach top operating speed when it should
- radiator, missing fins or blocked/corroded internally. ALways used Toyota red to avoid the latter, buy a decent quality replacement radiator
- thermostat can fail, the 82-degree one is fine, but some suggest the 76-degree one for long distance, hot country use or towing (although some people disagree)
-don't rely on the Toyota temp guage which won't indicate overheating until it's too late. Some people fit their own temp guages, either measuring the coolant temp or the exhaust temp
-heater pipes to the rear heater can corrode, leading to loss of coolant
-going at sustained high speed for long periods!

thats why i said im missing the big picture and i read the post but not being machanic minded just wanted to understand so i can start my own work on my own car save relying on other people.

Thanks dave for your reply and pointing out valueable points.

 

[Shayne]

I think its fair to say the 1kz cooling system is adequate but only adequate so any component failure is gonna hurt if not caught early .

I can't remember if i fitted my 76 stat before or after towing this 4000 miles ish to Romania and back regularly moving at 80mph , but it doesn't tell us much in any case because my truck is slightly modified .

 

[Beau]

Though I agree that the temp issue is a problem with these heads cracking, my cruiser cracked it's head at 70,000 miles out of no where. My dad had the cruiser 2/3 year old and babied it. Oil changes every 3000 miles with synthetic ect. Back then it was a lot of money. And he was one of the first to have this problem. So in this case I would put it down to a defect/poor quality of cylinder head made.

Last year when I overheated severely, when I spotted the temp it was already maxed out on the temp gauge and when I pulled over all water done. My fault due to replacement water hose failing and not noticing the temp gauge. Anyway, I pulled the head out and no cracks found what so ever. Managed to straighten the head out and am currently running with that head.

On top of this, With the common replacement AMC heads, I am yet to here of one of these failing.

 

[tony rodaway]

Though I agree that the temp issue is a problem with these heads cracking, my cruiser cracked it's head at 70,000 miles out of no where. My dad had the cruiser 2/3 year old and babied it. Oil changes every 3000 miles with synthetic ect. Back then it was a lot of money. And he was one of the first to have this problem. So in this case I would put it down to a defect/poor quality of cylinder head made.

Last year when I overheated severely, when I spotted the temp it was already maxed out on the temp gauge and when I pulled over all water done. My fault due to replacement water hose failing and not noticing the temp gauge. Anyway, I pulled the head out and no cracks found what so ever. Managed to straighten the head out and am currently running with that head.

On top of this, With the common replacement AMC heads, I am yet to here of one of these failing.

So beau its not just down to towing up hills that causes the overheat it could be at anytime as u state but I have had my lc90 for over 2 yrs now and been on long trips and off rd in hot weather and carried heavy items.
My point is is it every car with fault waiting to happen or jusr were hearing a lot

I think its fair to say the 1kz cooling system is adequate but only adequate so any component failure is gonna hurt if not caught early .

I can't remember if i fitted my 76 stat before or after towing this 4000 miles ish to Romania and back regularly moving at 80mph , but it doesn't tell us much in any case because my truck is slightly modified .

View attachment 123200

Nice wheels shayne but how do you see out the rear window towing that monster.

 

[tony rodaway]

Though I agree that the temp issue is a problem with these heads cracking, my cruiser cracked it's head at 70,000 miles out of no where. My dad had the cruiser 2/3 year old and babied it. Oil changes every 3000 miles with synthetic ect. Back then it was a lot of money. And he was one of the first to have this problem. So in this case I would put it down to a defect/poor quality of cylinder head made.

Last year when I overheated severely, when I spotted the temp it was already maxed out on the temp gauge and when I pulled over all water done. My fault due to replacement water hose failing and not noticing the temp gauge. Anyway, I pulled the head out and no cracks found what so ever. Managed to straighten the head out and am currently running with that head.

On top of this, With the common replacement AMC heads, I am yet to here of one of these failing.

Well beau you sort of answered my next question and if bad parts are to blame cos 70,000 miles is nothing as a rep can do that in a year or two is wear and tear not a bigger factor as these cars are no spring chickens anymore.
Mine and thousands of other drivers of l,cs are still motoring around with original parts from new but just takes that towing uphill to change all that and is that a toyota fault or wear and tear.
My brother worked in vauxhall ellsemere port and told me that cars were leaving the plant with known faults that would appear in so many years down the line.
This was simply a way of making more money from people as by the time the faulty part fails vauxhall will have changed shape many times and same with toyota and other companys.


DO TOYOTA USE LC PARTS ON OTHER CARS
CORROLLA
YARIS
AVENSIS ETC

and do they have the same faults or is it just the 1kzte.

 

[Shayne]

The trailer is about the same height as my spare wheel Tony which is ideal for reversing because i can see it and where i'm going .

I doubt you would find any 1kz 3.0 td parts in a car .

I wonder if failed injector seals would explain your low mileage cracked head Beau ?

 

[Beau]

hmm doubt it shayne, and even if it's the case it doesn't make things any better. At 70k miles no major items like that should fail. Plus she never ran rough/smoked prior to the injectors won't make sense.

And to add to this, I'm running on my original injectors right now with 200k miles on them, with no Visible issues. I'm sure they could do with a service, but these engines aren't built like modern high tech, high tolerance engines. I had the valves well out of spec and it still ran like a champ... Even with cracked heads and low compression these engines will run moderately well.

Not much parts share with other toyota's. Only a couple things come to mind like coolant temp sensors, Throttle position sensor, turbo (not internally though). However driveline wise, 4runnners' surfs, hiaces, hiluxs will share similar things. Breaks are the same as 80 series. I'm sure there's a few more but that's off the top of my head.

 

[diggerdave]

I always though there should be a thread/sticky with interchangeable parts on it. It could potentially save a fortune by allowing you to shop around.

To add to your list Beau:

- reverse light switch is universal Toyota of that age (and it doubles as a the difflock switch). New about £10
- Drivers side window switch is same as contemporary Toyota Yaris (about a quarter of the price second hand)

 

[Shayne]

It was just something that crossed my mind Beau because i'm thinking about doing something with my own injectors right now and while investigating overhaul/replace options (suggestions welcome) I chanced upon something that reminded me of CAT saying in the tuning thread that the electric to manual fuel pump specialists in New Zealand or wherever they might be blame the injectors for 80% of 1kz cracked heads .

As Dave said some very clever heads have all drawn a blank over the problem but how do you factor in human error , i assume the injectors are fitted by hand on the assembly line .

I think my 5 speed gear knob is from a Yaris .

 

[frank rabbets]

Here is the 13th commandment :-

13. Though shalt NEVER spray ANYTHING down the inlet manifold.