Possible Crack in Head- Prado 1KZ Motor

[jeza4WD Lurker Find all posts View Profile Close jeza4WD]

I own a 2004 diesel, with a 170,000km on speedo.

Prado had a new HM/GEM motor (1KZ) put in at 85,000km as a result of the previous owner cooking motor with bush stick punching bottom radiator hose. Full service history on HM/GEM and normal service log books.

Previous owner also supplied receipts and one receipt showed a head repair at 152,000km or it was at 67,000km according to new HM/GEM motor! This was 3 years ago. They repaired the head, vacuum tested and checked straightness?

Prado then did very little kms over next 3 years- about 6,000kms, then I bought it in private sale.

I’ve bought the Prado 12 months ago at 158,000 and now its got 170,000km and it has had a ‘very’ small coolant leak for past 12months or since 158,000km. Just needing a litre of coolant each month for about every 600kms. Just enough to annoy.

In the past two weeks white smoke develops out of exhaust- only on small trips – but coolant still reducing as small amount as previously.

Local Mechanic undertook ‘sniffer’ test which apparently measures carbon dioxide in the coolant system and says a strong indication of head gasket or cracked head.

My Prado goes in Monday to have head removed and inspected.

Forums show strong evidence of 1KZ cracking heads and am trying to figure out whether to fix Prado and move onto some other 4WD type or feel comfortable with HM/GEM motor quality and upcoming repairs???

If its head gasket- quote was $1,900 or new head is $3,500 and will come with 12 months warranty.

What non genuine head should I ask for? Use genuine head gasket and bolts?

What other areas should I be checking and or fixing given new HM/GEM motor only done 85,000km since being installed?

PS Not feeling thed Prado love at the moment.....

[Corigator Avid PP Poster! Find all posts View Profile Close Corigator]

... or a bottle of chemiweld - $20.00

[clarkie383 Member Find all posts View Profile Close clarkie383]

http://www.pradopoint.com/showthread...Z-Cracked-Head

Have a read and it will help you find your answers.

[prado2004 Advanced Member Find all posts View Profile Close prado2004]

fair few old posts regarding the heads, the roo always recommended a specific brand (AMC) as it was much cheaper and better than genuine in his opinion.

[mackayvx Advanced Member Find all posts View Profile Close mackayvx]

Hey there. I know your pain.
Yes only get AMC brand head.
It comes complete with new cam etc fully assembled.
Also get a genuine Toyota Valve grind kit.
It has all the gaskets etc needed for the job.
I will reinforce this with 'Only use genuine head gasket' - dont let your mechanic tell you different.
Get new head bolts too as they 'stretch' and wont tourqe properly if used a second time.

All of this stuff will cost anywhere up to 2000- 2500 $ including coolant oils etc.
Expect the job to be around 5k all up.

Using these qualty components will ensure a good run for you.

[jeza4WD Lurker Find all posts View Profile Close jeza4WD]

Well news is in…head was removed and tested, two cracks in the pre combustion chamber!.
But that’s not all…..apparently the head was a Toyota Hilux Head- something HM/GEM motors apparently build/ modify their new motors. I didn’t realise this was possible?? Must be a cost savings for HM /GEM- can’t imagine it’s for increased quality or performance.
So new Toyota Hilux Head ordered and a new piston value clearance adjustment to be made…something the mechanic said wasn’t right from the new HM/GEM motor when he measured and checked it. Apparently the performance should be better with the correct piston valve clearance.
Head Gasket was okay, but new gasket to be installed. Timing belt inspected and okay at 85,000kms it must have been new with the new HM/GEM motor.
Bottom end inspected and in good conditions- so that’s good news.
So with new bottom and top radiator hoses, radiator flush, x3 new fan belts- I will pick up the Prado tomorrow all going well. Lets see what the quote versus bill turns out to be. 12 months warranty on repairs so I’ll have to put some kms on it to be sure its fixed.
So feeling more comfortable about the repairs and the long jeopardy of the motor even though it sounds a bit of a hybrid of a Hilux Head and pistons and Prado bottom end.
Anyone ever heard of this Hilux/ Prado combination possibility?

[t303 Senior Member Find all posts View Profile Close t303]

I gather it is possible to fit the hilux head to any 1kz bottom end, but the prado head is approx 1-2mm taller (I think the valves are longer on the prado also) and I understood that the reason was to put more meat in the head to.......
sorry you won't like this....
stop the heads from cracking due to the slightly higher tune of the prado donk!
At least that is what I recall from somewhere, anyone else know?

[scottkz Senior Member Find all posts View Profile Close scottkz]

Heads are the same ... The surfs up till 96 had a short valve head from 96 on they were all long valve versions
There are even certain bolt holes that are on the 1Kd that were used on the early surfs and not used since then
1KZ/1KD is the same block with minor machining differences

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

Heads are not a big problem.
Get the AMC head & get the job done right.
Then you might feel some Prado love.

[t303 Senior Member Find all posts View Profile Close t303]

Heads are the same ... The surfs up till 96 had a short valve head from 96 on they were all long valve versions
There are even certain bolt holes that are on the 1Kd that were used on the early surfs and not used since then
1KZ/1KD is the same block with minor machining differences

Yeah, now it's all coming back to me...

Only other thing I would urge: if you can at all afford it I would replace the radiator either with a Denso or a GOOD alloy one. Aus Desert Coolers do a higher capacity one that apparently has a litre or two more coolant in it; that's what I will get to replace the Denso that I put in at the head change. A couple of extra litres would make me feel far more comfortable that it won't go again. Also highly recommend a temp sensor in the top hose because the stock temp needle doesn't move until the temp is pushing 100c, and I'm happier if I can keep an alloy head under that, especially a high compression diesel!

[scottkz Senior Member Find all posts View Profile Close scottkz]

I put a brand new "fenix" rad when I did my conversion my motor has 254 on it now an was an ex mine car, check your thermostat 1kd ones are 71' an genuine are cheap enough

[jeza4WD Lurker Find all posts View Profile Close jeza4WD]

I pick up the Prado tody- I'll ask the nechanic his view on the extra 1-2mm taller head/ extra meat and the probability of cracking a head again. The mechanic did say the motor did have the wrong valves ie it had higher ones...I wonder whether incorrect value height/ clearnance was a contributing factor to cracking the head- especially being highly tuned Prado donk??.

[mackayvx Advanced Member Find all posts View Profile Close mackayvx]

So what is it costing?

[jeza4WD Lurker Find all posts View Profile Close jeza4WD]

Picked up Prado today and opened the wallet to the tune of $3,600.
New AMC head from Japan, new head gasket, new head bolts, new valves, coolant and flush, 3 new belts and new top radiator hose – ( thought it was worth replacing to protect my investment), new oil and filter, new battery. All 12 months warranty on the work.
So time will tell how things hold up…..must admit the Prado starting well and running nicely.
Keep you posted on next few months of travel.

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

Picked up Prado today and opened the wallet to the tune of $3,600.
New AMC head from Japan, new head gasket, new head bolts, new valves, coolant and flush, 3 new belts and new top radiator hose – ( thought it was worth replacing to protect my investment), new oil and filter, new battery. All 12 months warranty on the work.
So time will tell how things hold up…..must admit the Prado starting well and running nicely.
Keep you posted on next few months of travel.

Enjoy some love.