Offroad-Express

Well it's sad to say but after only about 3 months of owning it, it appears the Prado may have cracked a head. It uses water like crazy and I couldn't find a leak so took it to the mechanic and he couldn't either . So he's gonna clean out he radiator tomorrow to make sure it's not a pressure issue but I think I've got my mind made up that it's probably going to be a cracked head (being it's a 1KZ). It's only done 182000kms which I thought was probably quite low for it to be doing that.

So I'm thinking I'll just chuck a new head on, but has anyone else had this happen? (what a question!) And are there any other options?

Some info from another thread......, may be good to look at these mods whilst its apart...., advice on here seems to be go with a genuine head....

I'm assuming that it is a 1KZ-TE
EGR can be removed completely and Blocked off and wiring disconnected. (Clean black crap out of manifold and off Sensors, made a huge difference to how mine runs.)
3" Turbo dump pipes can be ordered from Aus ,to go with the 3" exhaust.
Boost can be shimmed up to approx 12 psi

These engines have a habit of running real hot when put under load.
Change the thermostat to a 71deg one (90916-03121)
Flush out the cooling system, run Toyota Red coolant.
Re-new the viscous fan Silicone Oil.
get a 10 blade 5L fan (if you can find one)
Fit after market Temp Gauge , Oil Pressure , Boost Gauge.
(Factory ones are complete crap)

My first head went at 115K, second at 122K

My engine cracked its head at exactly 150000 km's.
It is important to not load up these engines.
I used to drive the top of Porters Pass in 4th gear at 1200 revs and full boost. I now know this creates upper cylinder temperatures that are way too high.
Now I drive up there in 3rd at 3500.

I suggest you definitely block off the EGR (Exhaust Gas Reticulation) valve. I liken putting hot filthy exhaust back into the inlet track, to shitting in your own nest!
I had to soak my inlet manifold in a 20l bucket of petrol for a week before the big test-tube brush would get all the tar (3mm thick) off.

There are several versions of the new heads. If possible get the later head with differing porting and valves and change to the later inlet manifold as well. Then get the intercooler that goes with the parts above and you will have a way better power plant.

I now wish I had known the later engine out of the 90 series Prado was slightly different. I would have done these mods when I did my head too.

wjw wrote:My first head went at 115K, second at 122K

Any ideas on the reason? 2 within 10k gives me the shivers.

my engine is still going sweet at 155k, doesn't blow any smoke etc, manual gear box not so good.

EGR block off is a must.
After market temp gauge is a must.
EGT gauge is recommended as well.

http://www.toyotasurf.asn.au/forum/viewtopic.php?t=195
really good thread here if you can be bothered reading 13 pages.

UBZ wrote:

wjw wrote:My first head went at 115K, second at 122K

Any ideas on the reason? 2 within 10k gives me the shivers.

my engine is still going sweet at 155k, doesn't blow any smoke etc, manual gear box not so good.

EGR block off is a must.
After market temp gauge is a must.
EGT gauge is recommended as well.

http://www.toyotasurf.asn.au/forum/viewtopic.php?t=195
really good thread here if you can be bothered reading 13 pages.

Yup, mine seems all good apart from it drinking too much. I'll have the truck back tomorrow with the radiator cleaned and a new thermostat, so I'll take it for a drive and I should know for sure what the problem is.

nobody knows ... first one was over heating... the second, they think something wasn't right when the first one was changed.

Make sure you put new heads bolts in...dont re-use the old ones..they will be stretched

IcedJohnno wrote:There are several versions of the new heads. If possible get the later head with differing porting and valves and change to the later inlet manifold as well. Then get the intercooler that goes with the parts above and you will have a way better power plant.

I now wish I had known the later engine out of the 90 series Prado was slightly different. I would have done these mods when I did my head too.

Is it possible to put the later model heads on the earlier blocks? I didnt think the post 96 moters eg kzn185 and 90 series prado heads fitted on the earlier pre 96 motors? Handy bit of information if its true!

It is a good idea to fit a pyrometer because these motors run very hot under load.

They are probably the worst motor for head trouble except the 2LT that toyota have made.

When a friend of mine cracked the head on his, Toyota said they had 30 on back order.

Another friend of mine got 2 genuine replacements and they had loose valve seats.
He solved the problem by throwing the motor away and putting the later intercooled motor in and to date has had no problems.

The service manager at Toyota also told me because of the excessive heat, under load they are prone to seizing pistons as well.

Get a pyrometer is my recommendation

Cheers Richard