Offroad-Express

So after a year or so using the surf consistently ironing out bugs with it i'm finally on to the last issue of overheating.

Details:
Running standard temp thermostat 82 degrees
Aftermarket 3 core alloy radiator single pass
16 inch 2100cfm fan mounted on front of rad (spinning correct way)
External trans cooler doesnt flow through rad at all
50/50 mix coolant
Factory ecu/ new genuine ecu water temp sensor
Aftermarket digital fan controller set on 92 off 86

All the following is based on 25 degree approx days

When driving on open road the rad is more than efficient enough to cool properly temp sits at approx 85-88 without the fan running.
When town driving approx the 90 degree mark and 92 when doing stop starts. The fan comes on at 92 and then coolant quickly drops to 86.

On the tracks is where the issues come up. low range up to 20kph approx.

The fan will keep up longs as i'm not climbing hills for more than 10-15 mins then temp will climb up to 105 maybe more but i stop moving and idle till it drops down again.
On flat stuff the fan will also keep up approx 90-94 as long as the radiator is fully clean but as soon as anything gets on the rad ie mud leaves etc even as little as 15% blocked then will begin to climb and then the fan cant keep up.

Here is some pics of current set up:




My plan is to move the radiator forward to where the radiator support is
Mount fan on back of radiator as there will be room now and hopefully be able to get a shroud made up also. and look as a way to make a removable screen to catch debris that can be taken out and washed anywhere

Now this is where i need your opinion/ experience:

To move the rad forward will mean i need to get a custom radiator made up as the current one is too tall because of the chassis cross-member and the bonnet

1- Will making the radiator 15% smaller height-wise cause more issues?
2- Will getting a triple pass radiator also help with more cooling?
3- Will setting up a coolant tank say 10L in line with radiator pipes to add capacity help at all? if so where would be the best location to put this inline be?
4- Will 1 16 inch fan or 2 10inch fans be better if total cfm was same as the 16 inch fan?
5- Is there a magic spacing measurement between radiator and fan when using a shroud?
6- When using a fan switch sensor is it better to be in the bottom tank of the radiator seen your trying to control the temp heading back into the motor?
7- How much difference would adding a oil cooler make to engine temp at slow speeds?

I know its a lot of questions but a custom radiator is not cheap so only want to to get made once.

I would like to stay away from adding vents to bonnet if possible as sometimes this can make it better at 1 speed but worse at another.

What is your opinion/ experience on issues with sorting out hot water temps?

feel free to ask more questions if need be

Get a hi flow thermostat for it.. Its what I did and lowered my operating temp by about 10-15 degs but more importantly the hot outlet was about the same (the hi flow just allows 35% more flow- same temp though I think) as I have an aftermarket temp gauge on the outlet to make sure its working.. BUT bear in mind though these engines will run happily at 100-105 so unless you are having real heat ( I have mine to 120 and it recovered very well)
Also having a look at how busi it is in the front of the truck.. maybe a couple side vents to help move hot air from out of the engine bay..?
Also noted that ur fan setup is in push and really to get the most out of your radiator you need a shroud and pull configuration.. But lux's just don't have enough room..
Maybe if you can move the radiator forward and place a shroud on the back side with the fan in pull mode then you might see some good results.

Good luck as I think you are going to need it.. But first off Hi flow thermostat.. it'll help..

After always having heating issues of some sort I reckon the fans are where you need to start. Aftermarket fans never seem to live up to their expectations. OEM double fan setups from manufacturers such as Ford seem to be the go (upwards of 3500cf I believe).
I have a 4 core alloy rad, double electric fans (12" and 10") full alloy shroud, and the large electric water pump set up (davis craig unit) and it still gets hot on crawl (well on the one decent trip it has done anyway). I will be going down the OEM fan set up next time I can be bothered dragging the POS out and working on it.

Roks right there too .. I have a OEM hydraulic fan setup and man the move air..

On my 1UZ LN130 I cut the radiator support panel so that I could run a much wider radiator which also allowed a lot more air through. I made sure that the radiator was fully sealed against the support panel so that any air had to go through the radiator and not around it.

As you can see on the front of your truck it's pretty busy with quite a bit of space either side of the radiator before you reach the headlights. I had to relocate the washer bottle and a couple of other bits but it was worth it to put the much bigger radiator in.

I also ran an EL Ford twin fan and shroud setup. This is the only way to get decent cooling. That single 16in fan isn't anywhere large enough to cool your truck and running in push mode is the least efficient.

I wasn't running a trans cooler just a power steer cooler so had a lot more open space at the front. I don't think your issue will be helped much by running a header tank of any sort - as you note as soon as the radiator gets even a tiny bit covered it heats up and that shows that you don't have enough airflow through the radiator. The header tank would just delay this momentarily.

As Big says though these motor's don't mind a bit of heat and mine regularly ran at 100-105%. I think the stock ECU has an overheat cutout at about 110.

Matt.

Mattman wrote:That single 16in fan isn't anywhere large enough to cool your truck and running in push mode is the least efficient.

i think matt has said it all.

the fan is the big issue. small air flow and only cooling a small part of the radiator, push setups are poor.

the other small thing is to turn the big oil cooler around so its like the other one with the outlet at the top.

The above is all good advice in my experience.

jonossiksilvia wrote:1- Will making the radiator 15% smaller height-wise cause more issues?

If you are cutting the radiator support panel why not select a shorter but wider radiator, such that you don't lose any surface area. Ideally gain some. Also you may be able to find a "standard" rad that fits and you can then buy an alloy after market version of what ever it is. I used a Holden V6 rad in my truck.

jonossiksilvia wrote:
7- How much difference would adding a oil cooler make to engine temp at slow speeds?

In my experience, None. Running my truck with and without an oil cooler, I noticed no engine operating temp difference. I think an oil cooler is more about keeping your oil at a temp such that it is within spec and does it's lubing job properly, not so much about cooling the engine.

oil cooler can do quite a decent amount of cooling. but its not going to make up for an under sized water cooling.
theres a few sites that show all the tech/math behind it.
i would check the oil temps first to see if its hot enough to warrant adding a cooler.

myself and my brother both had 1uz hiluxs;no heating issues at all.we run a monaro radiator,wider than stock,same height,subaru electric.you could push them as hard as you like,no over heating

Cool cheers guys for confirming my thoughts

Plan is to move radiator forward and fit fan/fans and shroud from a car.

So what ill do is pull apart the surf measure the maximum size i can cut and then find a replacement radiator that is as close as possible before i start cutting. And find one that suits whatever fans i can find - will try get some falcon ones

So any idea on modding the rad to a 3 pass design or keep as a single pass?
And what are your thoughts on best location for the fan switch sensor? Measure the water entering the rad or exiting?

try all that shit mate but the key to cooling is air flow, that's how the heat gets transferred out of the radiator and that's how you get cooler coolant going back into the engine. I might be wrong but that push fan looks like a useless Chinese thing that moves very little air, try looking through the wrecking yards for a good heavy duty looking fan off a big car that looks like it'll move some serious air. Been there and done that with cooling problems, so long as your radiator cores are free of mud and you've got good air flow through the Radiator your problems should go away.

jonossiksilvia wrote:And what are your thoughts on best location for the fan switch sensor? Measure the water entering the rad or exiting?

Any thoughts on this? way i see it is, it's the radiators job is to supply the engine with colder water and a radiator fans job is to aid in the cooling affect of the radiator. my thinking is its better to regulate the temp leaving the radiator than regulate the temp leaving the motor. if the factory thermostat temp is 82 degrees and it is inline with the water coming from the radiator then if im measuring the temp coming from the rad for the fans what would be a suitable temp to turn on the fans?

Its the engine temp that you want to monitor and regulate so the temp sensor should be on the exit out of the head.

Ideally before the thermostat but that's usually not possible so insert it into the rad hose.

Matt.

Mattman wrote:Its the engine temp that you want to monitor and regulate so the temp sensor should be on the exit out of the head.

Ideally before the thermostat but that's usually not possible so insert it into the rad hose.

Matt.

I concur, most factory sensors are located on the coolant exit of the engine.

From an old and wise mechanic who taught me many years ago......

If it overheats below 15 mph i.e in traffic or off road then you need more air.
If it overheats above 15 mph i.e hooning or driving fast up hills then you need more water.

So I would agree with all the above posts and get more air through it with a shrouded pull fan.

Matt

Sweet, cheers guys.

Time to pull the surf apart and start measuring rad sizes.

On a positive note. i have a set of xr6t fans ready for it

Hey come and have a look at mine if you want. I have almost finished putting the ls1 in my surf. I cut the front to move my radiator forward so I could fit a hydraulic fan. The fan is bloody impressive to listen to. Just sorting out a couple of last things and it will be done. I have a custom alloy radiator.

Sam

Forgot about this thread. I have sorted the cooling side and had it out and it stays at temp now I'll update my build shortly and post link in here

I've got a 94 DC Hilux with original radiator and electric cooling fan. Is a daily driver on our farm and haven't had any cooling issues.