Offroad-Express

Hi all,

We are planning to tow the jetboat over to the west coast soon and wondering if anyone has any tips to keep the old 1KZ cool.

It's a 93 KZJ78 with a 1KZ-TE, 290k's, good radiator, good viscous fan, external oil cooler and I have fitted a EGT gauge.

I'm scared that going over those big hills on a hot day might crack the head! I normally try and keep it under 650degrees Celsius, usually the very max I want to see.

What are some tricks? (eg. keep it in a low gear and high RPM) etc etc etc?

Thanks,
Tim

probably not the best in summer but , when going up big hills turn the heater on hot and the fan on full speed , acts as a second radiator of sorts

prado_boon wrote: I normally try and keep it under 650degrees Celsius, usually the very max I want to see.

egt sensor pre turbo or after it?

tweake wrote:egt sensor pre turbo or after it?

Pre turbo:

nice!
egt temps are fine if not a bit on the cold side.
whats the water temps like?

only advice for towing is don't lug it. more rpm less throttle.

and make sure air filter is clean.

edit: if its not intercooled then its running quite cool for standard engine. egt gauge reading ok?

tweake wrote:whats the water temps like?

I only have the factory water temp, that never moves over half.

I'll give the filter a good clean, cheers!

So more RPM, less throttle... good tip.

do your self a favour and get an aftermarket temp gauge and put the sensor engine side of thermostat (replace factory sensor).
main reason for them head cracking is due to overheating because of cooling system failure. like a leak or blocked radiator.

Hi,
If it is an auto, make sure you minimise use of the overdrive in particular if there is any slight rise make sure it is off.

I towed a caravan around the bottom of the south with kzn185 auto. Going up the Kilmog and up past the Roxbourgh dam I kept the to egt 650 max, and kept the revs up, mid of a hot Feb (32C typical) and had no problems with overheating.

At this time I hadn't got around to connecting the trans cooler but trans behaved itself with fresh fluid that looked just as good after.

Maurice

tweake wrote:do your self a favour and get an aftermarket temp gauge and put the sensor engine side of thermostat (replace factory sensor).
main reason for them head cracking is due to overheating because of cooling system failure. like a leak or blocked radiator.

What Is the max temp the water temp should get to?
Mine gets up to 105 deg c up the very top of porters pass
But not sure if my after market gauge is the right spot
I have a trans cooler and a big 3 core 50mm thick radiator

off the top of my head 115c. will have to double check.

All good tips, basically keep the revs high and easy on the gas. Does anyone know a good test to see if the viscous fan is working okay?

Hi

That is a very good question.

My test is up the port hills with a hot norwester behind you. The after market water temp gauge should really not move very much.....

I bought a new coupling from toyota and then 6 months later did the test in the following link.

http://www.offroad80s.com/how-to-top-up ... t1160.html

I have asked several mechanics and only got old wifes tales from them........

Henry wrote:Hi

That is a very good question.

My test is up the port hills with a hot norwester behind you. The after market water temp gauge should really not move very much.....

I bought a new coupling from toyota and then 6 months later did the test in the following link.

http://www.offroad80s.com/how-to-top-up ... t1160.html

I have asked several mechanics and only got old wifes tales from them........

I want to top up the oil to see what difference it makes, are these toyota "blue" clutch fan assemblies the same on the kzj78's ?

my 1kz prado i never go over 700 egt don't go long in high 600s
i just keep a eye on egts and it keeps cool

Aftermarket temp gauge allways sits on 80-85ish. in the year I've owned it it has only gone over 90° once driveibg a bit hard on hills.

I tow behind my kzj78 1kz prado all the time. Just gotta remember its a deisel and you cant go racing up hills. If your that worried, or it does start to get hot, then put it low box and go slow. That will bring your egts down as more torque available with less jandal. I drive mine to a max of 700 degrees. In saying that ive not looked a couple times and seen 1200 when I checkd and still sweet. I held that for about 30 secs to make the pass. If your colling system sweet then just cruise and you'll be fine. Up hills pushing it my coolant hits 105, but normal towing up a hill will stay below 100. Even with 2.5t behind and rolling on 35s.
And as LikeMagic said, stay out of overdrive as much as possible when towing.

micahb wrote:In saying that ive not looked a couple times and seen 1200 when I checkd and still sweet.

1200 degrees Celsius? Surely not.

Geees! I hope not 1200!!!!

I'm re-doing my viscous fan tonight, repacking and trying to adjust the valve so it opens earlier. I don't really mind if it's "on" all the time...

So many people don't understand how important this is to your cooling system.

Towing the boat over some big hills this summer in the 1KZ-TE. I aim not to go anywhere near 700. If it does I'm pulling over! So if you see a KZJ78 going slow.... just passs me, I don't care!

if it goes over 700 which it can, either change down a gear to keep the revs up above 2000rpm or back off the loud pedal

Mehrts wrote:

micahb wrote:In saying that ive not looked a couple times and seen 1200 when I checkd and still sweet.

1200 degrees Celsius? Surely not.

Easy to spike it up there if you jam the gas on, mind, im running manual pump and 20psi here. When it happened it was either carry on or pray. Chose to carry on and prayed afterward! Ha. Unless your holding at 700 for a bloody long time, it wont do any damage, well mines been fine. They are not as easy to blow as people think. Ive had 4 vehicles with 1kz, still currently have 2. Each done over 300k on original head, no worries. Regular maintenance is key i say. Only had egt sensor on my prado too.
You look like your on top of it all so it should be no worries.

Modified the viscous fan last night. Wow! what a difference.

It's all in the valve adjustment. It's on 80% of the time now. Bit loud, but I don't really care!

Might re-adjust it after summer again so it's only on when it's HOT!

prado_boon wrote:Modified the viscous fan last night. Wow! what a difference.

It's all in the valve adjustment. It's on 80% of the time now. Bit loud, but I don't really care!

Might re-adjust it after summer again so it's only on when it's HOT!

Hey mate, care to tell us what you did?

Have a read thru this and its links...

http://neuralfibre.com/paul/4wd/tuning- ... fan-clutch