Cooling the 1KZ-TE motor:

[Beau]

Best 3 core i can find is for a Surf Beau http://www.ebay.co.uk/itm/56MM-CORE...544?pt=LH_DefaultDomain_3&hash=item3f4dff0a18

Dimensions are 600mm x 645mm x 65mm compared to an aftermarket 90 series 2 core rad found on ebay Oz which offers 720mm x 680mm x 60mm , so height and width are smaller with only 5mm depth difference so yeah it should be easy enough to fit what are them small lugs with the blue caps on at the bottom will i have to cap them ?

I'm not sure its worth the extra price and messing about even if it does offer some small benefit over a factory rad especially as its an open question as to whether or not it will show an improvement at all .

The surf rad's are smaller than the cruiser one's so I don't think it's worth messing around with them! If it was a direct fit, it would be tempting! The plugs at the bottom is for the automatic box cooler, which you won't need. With the manual rad, you'll in theory have more cooling surface area and water capacity so I wouldn't use the auto rad on a manual. Like you said, it's probably not worth the hassle unless you can find a direct replacement 3 core for a reasonable price.

Regarding the rad and AC difference, I too have read that the gap should be as close as possible. Some cars have a shroud in between these two so that the airflow doesn't escape in between the gap! I worked on a Volvo XC90 and the AC and Rad are sandwiched. Having the AC on will increase temps in two ways. The AC clutch kicking in will draw some power from the engine, and the AC rad heats up the air before the same air cools off the main rad.

 

[Beau]

Just thought will i need a gasket if i am changing the thermostat ? will halfrauds instant do ?

There would be a gasket in place. Not sure if possible to re-use it or not. I know a lot of people say to use new ones but I've often go away with re-using the gasket once it's still in good condition. You can always make your own as well. Some RTV gasket stuff might work as well!

 

[Shayne]

i deleted the post because i found a big rubber seal in the packaging and so assumed a gasket wasn't necessary i will find out once its apart i guess .

 

[Beau]

Was just browsing pradopoint forum.

Apparently the 120 series 08 model has a 71 degree stat fitted standard that can be used in the 1KZ engine without any mods....

 

[froggy Steve]

best get one of these then! I have a 76 deg in at mo

 

[Shayne]

A closer look reveals my aircon rad and coolant rad are separated by about an inch and both A/C and engine coolant work great , everything i've read on the subject including ideal spacing for intercoolers tells me this is fine .

 

[Shayne]

Well i know now why my temperature only rises at stupid speeds , i modified my fan cowl when i did a body lift so i didn't have to move the rad and though its never been evident before a bit of a challenge from an overfinch on Sunday has left blatantly obvious scars to show whats happening . The Cowl distorts and comes into contact with the viscous fan and increases the load on an engine that's already being pushed hard .



A very individual problem i guess but something to be aware of nevertheless who would have thought such minor resistance at the fan could have such a knock on effect .

To explain the Overfinch thing my factory gauge didn't move beyond the usual slightly lower than midway on a 6 hour drive travelling mostly at 80 but then this guy in an Overfinch RR came alongside me and pulled ahead which i thought nothing of until about the 5th time he did it , so i slowed down to 70 to see if he would return and he did so i floored it . I didn't see him again but a couple of minutes of this made my gauge start to rise . Childish tomfoolery admitted but hey we only live once .

 

[mrdelmonti]

Shayne in case you're unaware the standard temp. gauge is very unresponsive, they struggle to rise above the standard halfway point until the engine is REALLY starting to run hot. I'm pretty sure Trevor and others have linked to some electronic gauges in the past that are much better at judging coolant temp.

Appreciate the fan fouling is obviously an issue (did that not make a hell of a clatter?!) but I'd also fit a better gauge so that you can really see what's going on.

 

[Shayne]

I am aware of the gauge issue mrD and i do have a fancy multi gauge here to fit which will show me egt and coolant temps (as well as boost pressure) . I am inclined to think the factory gauge starts climbing from the norm when actual temp hits 100 degrees but i guess i will never know for sure as a new rad and stat will accompany the cowl fix .

No it didn't make a noise , i'm half deaf and my truck roars when you give it some boot but Helen was with me and she can hear a pin drop , i've asked her so many times to identify unusual noises in my truck she does it automatically now i guess it was rubbing on a smooth surface rather than catching an edge if you get what i mean .

 

[Shayne]

I was pleasantly surprised that changing the stat is not a difficult thing to do at all , the oil dipstick is a minor nuisance being in the way but other than its easy . Sadly the 71 degree TRD stat i bought doesn't fit but hey it wasn't intended for my vehicle and nothing ventured nothing gained . The TRD is 6mm smaller in diameter .



The state of my radiator on removal tells me beyond a doubt that the 1kz head problems do not relate to the cooling system . Please note i have made considerable efforts to clean the radiator with a pressure washer and hose many at a time and the muck shown is not recent .

 

[froggy Steve]

Wow! thats mucky!
I have been doing lots of research like you do and with the overheating problems we had (occasional, under load) everthing points to changing the rad. After that, the issue is no more (I hope....) Just waiting for my man to come back off his hollybobs then its going in, new Rad, and a super cooler for the transmission, fitted before the rad! The rad on mine was changed 8 years ago apparently, so its due a change anyway.

 

[Shayne]

I think you miss my point Steve which is even with a radiator in the above state i have no cooling issues with my truck while below the speed limit and heat only says hello 20 or 30mph beyond that . And the cowl distorting is the reason why

 

[froggy Steve]

IIRC, you dont have an after market Temp gauge, but rely on the Toyota one? My Toyota gauge didnt move until my digital after market one said over 100 degrees! (105 I think it was) And to think I 'think' have cooling problems at 95 degrees ...........the Toyota gauge wont tell you this.

Normal flat roads legal speed running, temps at 78-85, big hills and it creeps up to 90-95, big longish hill 95 + (and the one time scary 100+) I dont EVER want to see the Toyota gauge rise again, hence new rad!

 

[Shayne]

Very true i had sort of guestimated as a result of research that the factory gauge starts climbing at around 100 degrees . My trucks far from standard as well with an oversized exhaust and intercooler etc i also have a TRD rad cap which is supposed to allow coolant to boil at 110 degrees (iirc) before opening which as far as i'm aware has never happened .

Obviously a well maintained cooling system is a must but i don't believe the cooling system itself is the cause of the head problem we all fear .

 

[MarkW]

Toyota Red coolant shouldn't boil until 129 Centigrade with a system pressurized to 15psi, if your boiling lower than that you may have a problem with the pressurizartion or elsewhere

Running a turbo charged track car that hits 110 degrees in 24 degree ambient temps flat out on track at 1.8bar or boost, I can't help thinking the discussion is looking a race spec solutions for a fairly crude engine (in comparison). Yes Toyota may well have a fundamental design flaw somewhere but to further diagnose potential issue you need a good accurate water temp gauge and an oil temp gauge to get a better understanding of how the cooling system behaves.

 

[StarCruiser]

Two things strike me here Shayne,
1, with your fan touching down, there is the chance of it stalling or at least slowing down on the viscous coupling
2, with your fan that much away from the housing, the pull of the fan through the rad will be severely impeded, a, cos it's dragging air around the side of it through the gap between fan and cowl
B, because the fan isn't rotating in a close circle it will have losses in efficiency
C, the air that the fan is pulling through the rad is only being pulled through part of it.

If I were you I would be looking at having a suitable cowl made up and fitted so that these issues are addressed before worrying about other things. At speed, you will see less of a problem, probably none due to the ram air while you are moving. Sitting in traffic on a hot day and you will almost certainly start to see a rise in temperature as you are running purely on fan then.

 

[Shayne]

I don't have a problem (or at least one i'm aware of) i need to fix the cowl but other than that i'm just swapping the rad and stat as i don't know how old either are , can't hurt and better safe than sorry as they say .

I was just continuing the discussion on the open question of why does the 1kz have a reputation for cracked heads .

 

[Beau]

From experience plus what I've read Shayne, I'd say the cooling system is the problem. However this isn't concrete as my previous post about how I cracked my first head didn't seem heat related at all.

However from the state of your rad, I will certainly say your engine will be running noticeably cooler once you clean/replace that rad! Mine was like that once and my gauge would move about half way occasionally when pushing the truck hard up hills and towing. Then I changed it, and since then the needle has not moved and sits just below half way. Now I know Toyota's gauges hardly say much, but that's my experience showing how a slightly blocked rad (similar to yours) can make that little difference in cooling these trucks.

 

[Beau]

Also I'll be purchasing this thermostat soon! http://www.ebay.co.uk/itm/111048520023?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Let me know if you're interested. Maybe the buyer will do a better deal on multiple purchases.

 

[Shayne]

Thanks Beau but my trucks in bits and i have ordered a 76 stat from Simon just because i can , I do have to wonder if its even necessary to put a lower rated stat in given my truck shows no problems that aren't caused by the broken cowl even with 1/3 of its radiator blocked and serving no purpose .

Can i ask did you by any chance buy your truck from a gentle soul who probably only drove it when it was too wet to ride a bicycle ?