Thinking of towing with a 1KZTE?....Think again…

[Henry]

Hi

I would like to know how to test a Viscous Fan Coupling.

My experience with a 1KZ in a Prado is the truck was over heating as I bought it. I had the radiator cleaned out by a professional. Top tank was replaced. I then did a new thermostat, new radiator cap and radiator hoses. New water pump, new cam belt and tensioner and idler bearing.
It is a auto with a auto fluid cooler in front of the radiator.

I went for a drive after that in a 29 degree c norwester up a local hill in a 50 kph zone. the Truck was still over heating. I went and bought a genuine Toyota viscous coupling and fitted it. I waited for a month and went up the same hill in another north wester and the truck was fine. I towed the caravan over Arthurs Pass and all good.

Henry

[crazyclark31]

Thanks for your replies.
To go over some of the points raised in the forum:
EGR soot in the intake: The 2 intake pipes where cleaned out 3 years ago when the head was replaced. It will be interesting to see how much is in there now. I have disabled the EGR and the intake auxiliary butterfly is been configured to always be fully open, except during shutdown.
New timing belt 9000kM ago.
Exhaust: I will initially replace the muffler with a straight through unit. I’m also thinking about replacing the dump pipe. The standard exhaust is 2.4” internal diameter so I’m not sure how much would be gained by changing to 2.5” so would need to go to 3”. I will probably do the exhaust changes in stages to see how it effects the temperature.
The radiator is new and is 40% thicker than stock. I refilled the fan viscous clutch and it seems to flow a lot of air, but it is difficult to tell how much slip there actually is.
Lower temperature thermostat: A curly one. As has been said above, 88°C is the optimum combustion temperature. Running the motor cooler than this may reduce the engine efficiency and possibly cause more sludge in the oil.
My Surf has the standard 82°C unit fitted. It is interesting to note that the Surf V6 motor also has an 82°C thermostat in the bottom hose, where is the 2.7 4 cylinder has an 88°C thermostat located in the usual position on the head. I think possibly Toyota has just said that the radiator will drop the temperature about 6°C and so stuck in a lower temperature thermostat to compensate. This assumes that the temperature drop across the radiator is a constant, which I doubt. I would be a lot happier if the thermostat was in the conventional place, regulating the actual water temperature leaving the engine.
If the standard 82°C thermostat is fully open by 95°C, the question is what gain, if any, would be made dropping this temperature if (as some say above) 95°C isn’t too hot. Possibly the answer is a thermostat that opens at the usual temperature but is fully open a little sooner.
I need to get a thermocouple into the bottom hose to see what the radiator temperature drop actually is and the temperature of the water going into the engine.

At the end of the day I still think the crux of the problem is the EGT’s generated that are threatening to take out my head, valves and pistons. I am pinning my hopes on the exhaust mods but I will also try the hill climb method described above.

to me if the egts are still really high the i'd say there is to much fuel or not enough air.
Air wise Is the turbo in good nick? air filter regularly changed?
Has the timing been check since the head was done. Is very easy for the timing to be out.
Fuel wise. Is the pump/injectors still okay?
also were is your egt guage fitted? Also do have anything fitted to front of your truck? Winch/lights/bars?

[tweake]

kow1.....

i would not call 100c over heating. tho i would check the fan, it should not spin freely. tho i assume it should be ok if it was refilled. also i think on those ones you tweak the thermostat on it to make it come on a bit earlier.

you main thing is to stop the head cracking. best thing is to keep the egt's down a bit lower than normal.
exhaust helps, try the muffler first as its cheap an easy. i understand the dump pipe is fairly restrictive so thats probably the next thing.

you mentioned cleaning out intake pipes but did you clean out intake manifold and the port runners in the head?

the intake butterfly, what you have done is ok but probably better with the main butterfly removed. i havn't had to much to do with that setup as i just rip mine right out and threw it away.

fitting a cheap manual boost controller will help. just bump the boost up a little, but more importantly get more air flowing sooner. just don't go silly with the boost without an intercooler.

[Cass]

it should not spin freely

they do spin fairly freely when not needed.
There is a valve inside the viscous hub which can be tweaked so it starts to lock up at a lower temp, also the fan hubs are underfilled from factory.
Turbo down pipe is a bit on the small side, I have been told that the prado's have a larger downpipe and dont have the overheating problem so much, unsure of how true that is though, intercooler will also help.
Ive got a collection of parts to go on my 185, just havnt been able to take it off the road long enough to put them on yet.

[tweake]

when you spin it by hand the fan should be able to spin a small amount, it should not spin freely.
they work by basically pumping silicone oil. if its spinning freely then its not pumping anything and needs a refill.

[mfrsr]

...though a tek screw works just as well.

[boon]

Just gonna throw it out there, as I come from a performance petrol engine background, but in that area really high EGT can mean you're leaning out. And lowering IAT usually has a pretty big effect on EGT, if you're spending a long time on relatively high boost (i.e. chugging up a hill) then an intercooler would probably help hugely.

[crazyclark31]

Just gonna throw it out there, as I come from a performance petrol engine background, but in that area really high EGT can mean you're leaning out. And lowering IAT usually has a pretty big effect on EGT, if you're spending a long time on relatively high boost (i.e. chugging up a hill) then an intercooler would probably help hugely.

Yep but desiels work the other way. If you have to much fuel it pushes you egts up. You want it to lean out at full boost.
IMHO if your using a turbo desiel for towing you should definatly add a decent frount mount cooler and a bigger dia exhuast minimum

[klompy]

I reckon running 35" tires is about the same load as towing a trailer.

[GNTONC]

Dump pipe , the best cooling you can get

and dump pipe

a 1KZTE owner needs to know what exactly is a dump pipe ?

cheers,
steve

[Jerry]

try this thread

http://www.offroadexpress.co.nz/Forums/ ... 0&start=60

[GNTONC]

try this thread

http://www.offroadexpress.co.nz/Forums/ ... 0&start=60

thanks...

steve w.

[lateral]

Toyota guages lie sometimes
They will crack heads (later if cared for)
drop a gear if crawling up a hill (over 2000rpm is good)
3inch exhaust on mine helps
maybe fit an intercooler (so much difference in power)

And pray often.

I feel I have some experience in cooking 1kz-te's.
1. 1991 swapped out a 2.4 EFi diesel for a 1Kz-te. Got about 150000Km's
and got lazy with the cooling system-overheated, cracked the head.
2. Installed 1kz-te (ex Granvia) and it cracked a head within 50000Km's.
With an engine guardian installed! I have suspicions this engine had been
overheated before I installed it as it used a little coolant from day one.
I worked both these engines hard, but did not overheat the second one. It just cracked and started using more and more coolant until it became a hassle.
3. Bought a granvia van, Did 100000 k's in it an left the rad cap off for two days. Did not have the alarm fitted-cracked head.
4. Bought a KZN185 @ 130000k's, fitted the guardian, 2.5" exhaust, well maintained. No overheating whilst I drove it. It is now spitting coolant from the balance reservoir, and bubbling like Rotorua. @ 180000K's.
Try telling me that isn't a problem.
Toyota you nearly made an awesome engine.

[Crash bandicoot]

yep Boon, when it comes to petrol engines something around 14:1 A/F ratio is usually pretty damned good but diesel is governed by the amount of fuel issued to the engine, the injector pump doesn't really care how much air is going in there, just putting in the fuel your right foot dictates....with the restrictive airflow and clogged up intake = too much fuel = too much heat.

In another thread we discussed putting a custom inlet manifold on with the shortest runners possible along the lines of what nissan do

. might be an idea for the yota motors

[tweake]

4. Bought a KZN185 @ 130000k's, fitted the guardian, 2.5" exhaust, well maintained. No overheating whilst I drove it. It is now spitting coolant from the balance reservoir, and bubbling like Rotorua. @ 180000K's.
Try telling me that isn't a problem.
Toyota you nearly made an awesome engine.

what engine gardian was it and where was the sensor placed?

[tweake]

In another thread we discussed putting a custom inlet manifold on with the shortest runners possible along the lines of what nissan do

. might be an idea for the yota motors

the problem with 1kz manifold is the flow is uneven. tends to feed no3 really well and no1 and 2 poorly. good write up on ARE site.

[lateral]

4. Bought a KZN185 @ 130000k's, fitted the guardian, 2.5" exhaust, well maintained. No overheating whilst I drove it. It is now spitting coolant from the balance reservoir, and bubbling like Rotorua. @ 180000K's.
Try telling me that isn't a problem.
Toyota you nearly made an awesome engine.

what engine gardian was it and where was the sensor placed?

Under a bolt to head on the water outlet to radiator. (Top hose)
http://www.ebay.com/itm/Engine-BLOCK-HE ... 8c&vxp=mtr
95deg on EG2 = half way on Toyota factory.
Two of my engines cracked without going over 100 deg.C
They heat a little as the ballast is full. Not to mention makeing a friggin mess of the engine bay.
Oh and my daughters Prado blew a bottom hose.......& seized. Probably bad luck or bad cap & micro cracks pressurizing the system. No EG!
So, we are a 5KZ family. What a distinction.
Tow at your peril.

[mudbugga]

Just as a side note on 1KZ thermostats -
When we do a head replacement at work (Toyota dealership), we fit a cooler thermostat that is usually for Hiace's (76 degree from memory).
There is another cooler thermostat that can be got if you can get the parts dept to track it down.

[tweake]

4. Bought a KZN185 @ 130000k's, fitted the guardian, 2.5" exhaust, well maintained. No overheating whilst I drove it. It is now spitting coolant from the balance reservoir, and bubbling like Rotorua. @ 180000K's.
Try telling me that isn't a problem.
Toyota you nearly made an awesome engine.

what engine gardian was it and where was the sensor placed?

Under a bolt to head on the water outlet to radiator. (Top hose)
http://www.ebay.com/itm/Engine-BLOCK-HE ... 8c&vxp=mtr

i suspect that temp gauge is to slow to react. bolt on sensor on the outside tend to be slow and more than likely read a bit low.
sensor in the water flow is better, until the hose blows off and you loose water.

a lot of the aussies fit 72c thermostats, details on au surf site.
but thermostat is there to keep the engine hot, not cool it down. often its just a bandaid to hide the problem rather than fix it.

[andrew007]

i have a 1kz in a ln106;plazaman water to air i/cooler,3" exhaust,preformance diesil pump,20psi boost;exhaust temp 250 at 100kms,4.5 diffs & 35's. i think i/cooler worth looking at.
cheers andy

[lateral]

[/quote]

what engine gardian was it and where was the sensor placed?[/quote]

Under a bolt to head on the water outlet to radiator. (Top hose)
http://www.ebay.com/itm/Engine-BLOCK-HE ... 8c&vxp=mtr
[/quote]

i suspect that temp gauge is to slow to react. bolt on sensor on the outside tend to be slow and more than likely read a bit low.
sensor in the water flow is better, until the hose blows off and you loose water.

Or, exhaust pressure in the cooling system blows sufficient water into the balance tank & overflow that the sensor is no longer in water, then you have to rely something else other than a coolant fluid sensor.
After my head is repaired I will add anothr sensor to the rear of the head & a level indicator in the top of the rad. Make it an even number & hopefully get one past 200K.

Really all in vain tho, because of the micro cracks that have already started, from birth are growing ever so slowly.
As you said previously, uneven manifold flow, uneven temperatures, bolts torqued past yield, alloy head. They will crack in the end whether you over heat 'em or not. Disposable item.
M2CW

[prado_boon]

I love this thread. It's probably the most truthful thread on overheating 1kz's out there!

Summary: 1KZTE's regularly crack heads
Why: Various reasons!
Fix: All the usual preventative stuff
Conclusion: Toyota almost made an awesome engine!

[Crash bandicoot]

Are there any other yota head's that will bolt on to that block, or are toyota quite anal and don't make there vehicles with the ability to change parts between models.

They seem awfully weak. I struggle to under stand how they crack from operator error such as coolant, judging from pictures it's not like the head sit's level or above the radiator.

They have seemed to have gone backward in development, the LN56 I used to own was bullet proof, I'd suspect if it were to be dug up from the grave it's buried in on the farm it'd probably still run turn over with a good battery and a can of start ya bastard.

[tweake]

they are built light and very close to the limits for emission purposes.
only takes things like egr soot build up in the intake, worn injectors, blocked up fuel filters (retards timing) etc to bump up the temps.
egt damage is accumulative so the cracks start and keep growing.

typically jap diesels run higher oil temps, internal oil cooler is not the greatest way to cool oil, water temps are reasonable high which is good for emissions etc but not fault tolerant.

[SMOKEY]

As this title says "thinking of towing with a 1KZTE .....think again" well I have and do. Yes history will tell you they have their Head problems but how do people drive them ? . We have been to Motueka and back to CHCH towing a 15ft caravan (caravan and vehicle heavily loaded) with our 1996 95# Prado 1KZTE, the day we traveled up the temp was 34+deg and strong north west winds and only cooled down on the west coast side of the Lewis and was then hot again through the Hope to Mot. The return journey was high temperatures from Motueka to CHCH. I do keep an eye on the water temp gauge but my main focus is on the Exhaust Pyro and a must with any Diesel, you have to Drive By IT, at times I have to button right off to keep the Ex temps down, as I have said repeatedly a Pyro gauge changes your style of driving, I'm not saying that I won't one day blow a head but I believe I will improve my chances and in the mean time will enjoy holidaying in the caravan towed by the 1KZTE. The main concern I had was the Tyre and Wheel Bearing temperature of the Caravan ----- as in

BURN THE FINGERS ---- HOT,

FITZY.

[prado_boon]

I change my driving style to the EGT's. I've towed my 1 ton jetboat over the same places in my 1993 prado 1kz-te with 300,000k's on the original head. Obviously I've kept the cooling system tip top, but like Fitzy says you have to drive to the EGT's. Sometimes I'm going voer a hill @ 30km/h... must piss people off but I don't really care!

Oh yeah and just to relate to the hot trailer bearings...I lost an entire hub assembly (wheel and everything) off my old trailer with boat attached because the bloody thing got so hot it shattered into a million peices then came off the hub! Wasn't a fun holiday.

[ChurchurDan]

Another thing to think about is the fact that in Japan no one tows trailers. So it would stand to reason that no jap import 4x4's are built to tow a trailer, let alone tow 2 ton uphill into a head wind on a 30 degree day with an alloy head and a half blocked radiator.
I'm not saying that is the cause of 1kz heads cracking but it probably doesn't help if the previous owner did it.

[imsohi]

I disagree with the title of this thread, yes if you think you can jump into a 1kz vehicle and think you can tow a big trailer cause its got the power you will run into issues but with the right things done to the motors they can be great. in saying this every motor i have got has had a head cracked previous to me getting it and i have replaced it with a GENUINE replacement also doing waterpump thermostat and getting the radiator striped and cleaned at the same time then throw a egt and in my case a manual injector pump and front mount intercooler to date i have had no issues. Last year we did around 10-15 thousand kms towing around both the north and south island, this wasnt easy towing either 3 1/2 ton of competition truck/trailer and spares,

along with this we also have done a south island tour and a trip to raglan all in the same vehicle without an issue. My egts get up around 680-700 max pulling uphill around 60-70 kms at 16psi before i will back off and that takes around 60 sec. IMHO i think The 1kz are a great motor to tow with if you spend the money and do the right things to get them right for towing.

[lateral]

Pulled the current head & no visible cracks. Although presure test revealed it wouldn't hold pressure.
One injector had a piss poor spray & leaked. Strange that this wasn't visible in
the exhaust gas.
I wonder if this was a contributing factor to the head failure as no overheat occurred.
I think the OP had the title right.
Think again & mod/drive to suit.