Cooling problems on my V8 Hilux

[Zantus Design]

This has probably been discussed, but I've searched and haven't found the answers I'm looking for.

When I got my hilux from the guys who did my 1UZ-FE conversion, the heat was fine onroad, but as soon as I went offroad it started to get hot. They then replaced the first radiator with one from a 730 BMW. It was much better, but still warmed up once in a while. This radiator had a 14" puller electric fan on the inside and a 10" pusher on the outside of an unknown brand and unknown CFM performance.
I then broke an engine mount which also ripped the radiator apart and I decided to go bigger on the radiator and went for the biggest BMW radiator I could find.

I didn't have time to do the work myself and a friend did the mods to make the new radiator fit. At the same time I wanted to fit the aircon condensor which dissapeared during the original conversion. Since there is no space in front of the radiator, 2x12" fans were fitted on the inside. Unfortunately my friend didn't pay attention and the fans sit about 10mm away from the radiator. These 2 fans deliver a total of 1600CFM.

Now my problem is that the cooling is much worse than with the smaller radiator and the previous fan set-up.

It's fine while I'm driving above 20-30km/h and the fans never come on, but as soon as I start driving slow offroad and labouring the engine, the temp climbs and doesn't drop after at least 10-15 minutes of idling.

The condensor only covers 60% of the radiator and is not in use yet, so that will make things worse when that gets connected and used.

I've looked at fans from all over the world and the best performance I can get is with a combination of a 17" and 2x8" fans which will give a total of 3600CFM. Plus I can add 2x8" fans to the bottom half of the condensor which will push 800CFM of air through that.

Now thw question is, should I invest in the better fans and mount them properly against the core with some rubber seals around the enge, or do I need an even bigger radiator?

Please help!
Thanks

 

[Muzza_NZ]

Have you had a look at these links:

http://lextreme.com/forums/showthread.php?t=5975&highlight=radiator+hilux

http://lextreme.com/forums/showthread.php?t=4806&highlight=radiator+hilux

 

[mshawari1]

I didn't suggest you to put pusher fans in front of puller fans .. the performance will be worse … I install aluminum radiator from 2004 Camry (75X45X5) cm with two Sunny fans (12"X2) .. and its work in the extremely hot condition ​

 

[Big]

This might sound somewhat silly but.... are the heat sheilds on the manufolds..? are the rubber splash thingies that stop water/mud and depre on, as I looked at the things that would have a effect on temp when I did my conversion..try to keep heat out or slow the rate of how it would affect the engine..ie rap exhaust material around the manufolds and down the exhaust a little..think about how hot the exhaust is coming straight outta the heads..when I got mine running,the first trip out saw the exhaust pipe glowing red hot,fortunatly for me I don't have a temp prob..Radiator..I have a 4 row standard landcruiser one..? can one of those fit..
Just things I've thought about ,hope it might help
cheers

 

[Zantus Design]

No, my manifolds don't have heat shields. I think I must wrap them.

I'd like to keep the big BMW radiator as we had to do a lot off work and spend a lot of money to make it fit, and I thought it would work great since the smaller BMW rad was almost there.
The current radiator is 640x470x42mm(core size, not outside dimension) and I've already cut half way into the body mounts, there is just no way to fit anything wider or higher. I can only go thicker, but not much either.
I read something interesting I haven't consired yet on the threads Muzza posted. That's the idea of fitting a second radiator somewhere else on the vehicle.
Since I have 35" tyres, I don't keep the tyre under the load bed anymore, so I've got lots of space under there. I also have the radiator plus fans from an Australian Holden 6.0 V8 lying here in my workshop. These are actually built 5km from my house here in South Africa and shipped half way around the world to be fitted to the Holden cars.
I couldn't fit it in the front, but how viable is it to put it under the bed and run it in series with the front radiator? If possible, what type of pipe should one use to run from the front to the back? Thinking my me exhaust builder friend could make up a set of stainless pipes.
This might be overkill, but since I have the Holden rad, it will be a really cheap solution for me and solve the problem in the worst imaginable conditions.

Give me your thoughts please :dunno:

 

[duza]

I've been having probs with my Hilux since the conversion also and I have experimented with lots of different combinations of possible solutions. Gradually it is getting better.

Your problem seems to be not the radiator being too small, as the cooling is alright when travelling at speed. It is only overheating at slower speeds and this points to the fans not being able to pull of push enough air thru the core. I have a 16 inch inside the engine bay and a 14 inch outside and in traffic now on a really hot day the thermos switch on and off keeping the temp at about 92 degrees C. The engine bay fan has a shroud I made which completely covers the radiator, maximising the air flow. I have been told that the fans should be mounted hard up against the radiator, not an inch off like mine currently are. I intend to change that to see what difference it will make, if any. Derale make a brilliant 16 inch fan which is low profile and about 2900cfm. Quite expensive, but very good quality. The cheaper fans on Ebay etc are crap IMO and will not last and the sellers make unsubstantiated claims about air flow rates, so I would stay away from those.

It is a very time consuming and expensive exercise this cooling problem, but I think you have gone the right way with your radiator at least.
Ric

 

[Zantus Design]

A local company makes a 17" fan that puts out 2800CFM and it's only 65mm high, but still very expensive. The thing that concerns me is that my aircon condensor sits in front so there is no space for a fan from the front. The aircon also isn't connected up yet, so I'm afraid that will push it over the edge and the current radiator won't be good enough....decisions, decisions.....

 

[Tacoma_Kyle]

Its the fans. Even people with V6 Tacomas have cooling problems when switching to Flex-a-Lite electric fans...dual fans. There seems to be very few aftermarket fans (electric) that can keep up to the needs of pretty much any truck. Tacoma stock fans are somethin like 3500-4000 cfm I recall.

Solution? Ford taurus. No joke. There are **** loads at junk yards and the proper fan is bad ass for 30 bucks. There hasnt been any official testing I have read on, but people typically say they are 3000 to 4500 (those are the extremes of the numbers I have seen) cfm. After the initial load of start up they pull somethin like 25 amps. It is a single fan.

The fan is a single fan with 3 wires goin to it. Easy to identify. It is a two speed fan. One is ground, the other two wires are the power to the individual speeds. You already have a fan controller.

I have one of those taurus fans I got for like 36 bucks with a fuse box. Meaning cheap. (from a wrecking yard) I also have a couple others from taurus's because they were cheap and I got confused when buying them lol. But yeah I have a few options for when I get the engine swap progressing.

 

[Zantus Design]

This is Africa, not Ford Tauruses around:dunno:

I do have a fan here from a 2007 E90 BMW 3 series, wonder what it's performance will be like.

 

[Tacoma_Kyle]

Maybe find a larger single fan and just run two?

 

[sideshow]

i have wired up over 60 1uzs

unfortunately half of them do get slightly warmer than most like

they dont overheat but they just creep hi

best thing to do is fit a massive alloy radiator on back in the tray

but this is impractacle

i have a 16 in thermo and on a very hot day say over 30 degrees celcius

my engine gets up to around 105

ive had my 1uz up to 120 and stil it runs good hehehe

now with new alloy rad and 15in thermo it hits 105 sometimes
still ok but i try to keep it below 90

unfortunately with gettting all the info from all the shps i work for

there is no easy cure for a 1uz into a tight hilux body

my fan only covers probably only 50 to 60% of the radiator

and i dont have a shroud

i think this could be a big no no

adding more fans is a waste

just get 1 or 2 good fans and shroud them so the fans suck air thru all the radiator

it might work im not sure

still havnt heard of a 100% common fix for these 1uzs

 

[Zantus Design]

I'm going to temporarily hook up the Holden radiator and see what it does. It won't cost me much as I have the rad and I'll borrow some flexible pipe from a place I used to work at that does engine dyno testing.

 

[cribbj]

Listen to Sideshow.

The most important parameter for the cooling system is the frontal area of the radiator. If you have a choice between a larger area 2 row, or a smaller area 4 row, go with the bigger two row.

The 2nd most important point for a good radiator setup is to make sure you have good airflow through the entire core. That means a well designed shroud.

What's the use in having a big frontal area, if your fan(s) are only sucking air through half of it?

 

[sideshow]

my fan is 5mm off hitting pulleyon engne so i cant move it back any more

i just put up with it

these are cheap thro away enignes and mine has done 230 thou kms

so if it blows ill by a new one

 

[richonenz]

Are you running a 3 core alloy radiator ?
alloy is 30 % more efficient than copper and you need the three cores for the capacity .
Are you running a closed system with an overflow bottle like the engine has standard ?
Is the thermostat fitted , if you have removed the thermostat you can increase the velocity of the coolant through the radiator and it doesn't stay in the radiator long enough to be cooled properly .
A good ploy is to remove the " guts " of the thermostat from the plate and then put the plate back in , this way you have no thermostat but the velocity is as it should be .
As to fans they need to be right on the radiator face itself preferably with a shroud , even moving it back from the face by 5 mmm drops it's efficiency by as much as 30 % , it's also preferable to have the fans on the engine side as then when you are moving the fans don't impede any flow coming through from the front .
If I was building a V8 FJ40 again like I had 20 years ago I would go to the trouble of using the hydraulic ECU controlled system , saves HP in the long run as the fan speed is infinitely variable , so the fan only goes as fast as it needs to , absolutely what you want in a four wheel drive situation .

 

[duza]

If you're worried about the air cond condenser, I shifted mine to the rear of the underside of the tray. I have a dropside tray, so there was heaps of room to locate it in front of and above the tow bar hitch. There is a little extra piping to fit of course, but the air is just as cold. It did make quite a deal of difference to the engine cooling, but did not solve it entirely. I believe part of the problem with Hiluxes, at least 4x4s, is the bull bars we insist on having which blocks off at least a third of the airflow. Not only that, but it deflects airflow away from the radiator as your speed increases. I am now in the process of fitting a little spoiler under the bullbar to deflect air back up onto the radiator.

Another mod I did recently was to increase the coolant capacity. I made up a steel tank of about 3.5lt and plumbed it in series with the radiator hoses. It fits up under the car, in front of the sump. This has made an enormous difference to the slow speed cooling. If I idle the vehicle in the carport for half an hour on a hot day now, the thermo fans don't ever come on, the temp sits just below their come-on temp and in traffic, so far, the temp will not go above about 92 deg. I am using an alloy radiator from a later model diesel Hilux. I think its about 35mm thick.
Ric

 

[1uzvl]

I wouldnt recommend cutting the centre out of these thermostats as they are dual acting,shuts of iternal bypass when the motor starts to warm up to operating temp.I full cowling around a set off puller fans would be the best.

Ive tried to make many radiators for hiluxs with v8 conversions(mainly 253/308 holden v8,s)with triple pass/fine fin/close tube pitch etc copper/brass rads with little result.When speaking to people who make radiator cores,they all tell me there is not enough room to get the hot air out as the motors are so big and engine bays are so small.

 

[richonenz]

When I had my alloy engined Range Rover the under bonnet tempatures were very very hot , when you opened the bonnet you got this huge blast of hot air .
I had to fit a scoop to clear the LPG mixer which sat on top of the carb , I put a really wide low scoop on as the RR bonnet is so big , a welcome side effect was that the under bonnet tempatures dropped by 20 degrees as the hot air was able to get out , I think the air flowing over the scoop helped pull the air through and out as well .
So maybe that's an option .
But like 1uzvl said using copper/brass rad's won't work as there is not enough room for the size required , going to an alloy rad which is 30 % more efficient almost eliminates this problem .
There is unlikely to be just a single big fix , you need to get everything working for you...most efficient alloy rad you can get , fans right on the face of the radiator and with a good shroud , the coolant flow as it should be with a closed system and an overflow bottle and a bonnet scoop to allow the hot air to escape easily .
I'm sure if you do all of this you will have the problem licked !!

 

[mshawari1]

The temperature here in the summer above 50C !! and going into the sand with air condition running >>>> A LOT of heat …
Any one here need extreme cooling system install a Nissan Patrol (alloy radiator) – its short in width – and viscous big fan in the engine (OEM one) with two pushing electrical fans in the front ….. Some people also use two pulling 14" fans comes from Subaru (two speed) very efficient . ​

 

[duza]

The temperature here in the summer above 50C !! and going into the sand with air condition running >>>> A LOT of heat …
Any one here need extreme cooling system install a Nissan Patrol (alloy radiator) – its short in width – and viscous big fan in the engine (OEM one) with two pushing electrical fans in the front ….. Some people also use two pulling 14" fans comes from Subaru (two speed) very efficient .
​

Thats all very well, but I'd like to see anyone get something like that into a Hilux. There just isn't room. With a 38mm thick radiator, I have 80mm clearance to the engine. The radiator can't be moved forward and the motor is sitting back pretty much hard up against the fire wall after some serious massaging of the firewall. Thats it, end of story. We have to work with what we have. Basically, the 1UZ wasn't meant to go into this engine bay and I would dearly love to have a little extra room to fit an engine driven fan, or the hydraulic one but unfortunately it won't go.
Ric