Relocating a radiator pros & cons ..

[lexsmaz]

Hi,

I have a 1JZ in a hilux, good thing obviously but it seems to suffer a fair bit of heat soak in the engine bay, ( still drives fine but things are pretty warm there ) & it also doesnt like the A/C on in very heavy traffic, temps rise quite a bit, ( fans cant cope & cant run / fit anything bigger either ) fine when moving though, i have bought a small Diahatsu charade radiator & fan to fit under the tray & was going to plumb it into the heater core piping, which i thiink will certainly help / fix the heavy traffic with A/C on situation but will not help much in the heat soak under the bonnet situation & so i have been thinking about putting the main radiator down under the tray in the back, i will put some shielding there to hopefully help direct the air, but my main thought / concern is will the standard water pump be strong enough to pump / draw the water over the increased distance, curious to hear peoples opinion's .. If the stock pump wont cope maybe run a electric water pump too inline with the stock pump as well ?? ..

[masterofsinanju]

Maybe I've missed your point, but wouldn't you be better off getting a new bigger/more efficient radiator in the stock spot?

By the time you've mucked about moving things to trays, upgrading pumps etc you'd probably save money.

[George]

In terms of cost efficiency, nothing beats driving around like this

[lexsmaz]

The radiator is about as big as you could fit for the spot unless i start chopping the radiator support up which i dont want to & i feel a lot of the heat soak into the intercoooler pipes etc even when i'm just cruising around is due to the now tightish engine bay & the close proximaty of the radiator to the intercooler pipes etc & the fact that 90 plus degrees of radiator temp is now constantly blowing over them, so if i can get rid of one heat source i feel it has to help ..

[twowheeldan]

burnout guys have been relocating radiators for years or even adding additional radiator to the boot etc so it can be done, as to whether the water pump would hack it - you may consider and electric water pump kit???

[lexsmaz]

As you said i realise it can be done, i'm just not sure on the water pumps ability either to draw water over that sort of distance & i did mention the electric water pump in my initial post just not sure as too wether to run it additionally with the stock pump or get rid of the stock water pump altogether ??

[Daddio]

Dunno if it helps, but way back (mid 80's) we used to put 3L Ford V6 engines in VW Kombis, and run copper water pipes under the floor to a front mount radiator (stock size for the Ford). Opposite way around to what you plan, but we used stock water pumps, a few extra hoses, 1 1/2 copper pipe, stock sized radiator. They worked fine in African heat, and later water cooled VW kombis ran a similar front mount radiator/rear engine configuration.
When we raced Minis, we added a second, front mount radiator to the original side mount, again, stock water pumps, and no issues.
I am not sure how a radiator under the tray would go, being exposed to all kinds of potential damage, dirt clogging, etc...but I think the water pump would be less of an issue than the location of the radiator.

[Hatta1978]

Hi,
I've seen a lot here in kota Kinabalu relocated their radiators to the back of their offroad 4x4 trucks most with stock water pumps. Some with 1jz power plant too. Should be ok as the pump is driven by the engine. Flow should be ok if the radiator is not clogged. For your info, the mr2 sw20 has a midship engine with the radiator up front. Hope this helps.
Regards.

[masterofsinanju]

What sort of radiator do you currently have?
I know this seems like going over old ground but the front of the vehicle is the most efficient place for a radiator.

You might be able to get a custom alloy radiator, more cores or some other material feature that makes it more efficient without compromising other design features.

Obviously I don't know your vehicle, but when was the last time you changed the coolant and flushed the system?

If you are worried about ambient temps in the engine bay, why not make some discreet body mods to allow a bit more airflow through the bay?

[lexsmaz]

Thanks for the feedback guys, i wonder with the SW20 MR2 do they run the exact same water pump in a front wheel drive car configuration by Toyota using the same motor, i'm assuming its a 3SGE or such ..

The radiator is clean & flows well i believe & is at least a 3 core unit & i cant run anything thicker as there really is no room, there is no over heating temp issues when driving its when in heavy traffic on a hot day with the A/C ON that the temps start climbing, ( so i then have to turn off the A/C ) as an example if you stop the car & pop the bonnet you cant really hold your hand on the intercooler pipes due to heat soak, even after just cruising around with no boosting ..

I certainly agree up front is the best spot for the radiator, but i just want to get rid of the some of the radiated heat by locating it back under the tray & there is a fair bit of room under the tray & should not get to dirty ? as its only a 2 wheel drive ute & only used on the roads, but i am concerned it might lack the air flow to it as the radiator will only have a slight fall to it, but at the worst the fans might have to run a bit more often, but in the end hopefully it will improve things up front ???? ..

One thing i was thinking of not sure how well it would work though ??? is that it has a smallish under tray up front of the engine & i was thinking if i was to mount a thermo fan in the under tray which was wired to come on with the main thermo fans or maybe the brake light switch etc, so when stationery etc it would come on to help draw the air out from the engine bay & maybe leave everything else much the same as far as the cooling system placement goes or just put the small daihatsu radiator out the back as the only addition ...

I'm not really into body mods if i can help it in ..

[Hatta1978]

Hi,
I think that locating the additional radiator and cooling fan at the back tray should be no problem, Because its just an additional cooling device. make sure that the airflow is not blocked, and the plumbing should be 99% good if not 100%. A radiator without a cap is probably suitable.

As for the engine compartment temp issue, have you tried to tilt up the front hood rear section? Just remove the mounting screws and add a few washers to raise the position. While driving/cooling fan operation, the extra air should flow up out there easy plus the air flowing under the body. Should reduce the temp a little i suppose.
Regards.

[crownv8]

Air flow is definitely your problem. Now that the engine bay is clogged up with engine and turbos. Three row cores are good if you have a real good fan behind it or are moving fairly well. I fitted three row core once and had worse overheating in traffic until i fitted a massive fan behind it. The thicker the core the more air flow it needs to cool as the air gets hotter as it goes through the radiator and you will find that the third row is barely being cooled at all. That is why modern cars have wide radiators with only one or two rows.

I am having similar issues with trying to come up with a suitable conversion for my Hilux. I just wish the engine bay was three inches longer so I could put a decent fan there. Plus mine is 4x4 so a decent fan is critical as most of the time I'm doing slow driving.

I think the rear mounted radiator has a lot of advantages unless you can somehow free up the air flow under the bonnet. I would try raising the back of the bonnet a bit or fit a reverse type bonnet vent near the back of the radiator to let the air straight out the top. Bonnet vents have proven to reduce under bonnet temps really quite a bit.

[lexsmaz]

Thanks again guys, i have thought already if i leave the radiator in its place of fitting a thinner radiator as the fans are mounted out front & they are trying to blow air through the condensor & then the big radiator too & i have checked already & i felt that there doesnt seem to be a lot of air exiting the back of the radiator the way it is now with the fans running & if i fit an additional small radiator in the back that will help too, the thing is i'm a bit of a tight ass & the current big radiator is in good nick & i didnt really want to throw out the core & start again, hence fitting it up the back, but its something i will need to weigh up, i even thought of putting the condensor out back but that will definately add up with the plumbing & recharging the system etc ..

As far as lifting the back of the bonnet i think i have heard guys say that around the bottom of the windscreen area is a high pressurre area ?? not 100 % sure i have the facts right there though ..

[Duk]

I would try raising the back of the bonnet a bit............

This doesn't work. The cabin ventilation inlet is located at the base of the windscreen/back of the bonnet because it is a high pressure area when the car is moving at reasonable speed.
With the back of the bonnet raised, air will flow into the engine bay through this gap. This will have a negative effect on the cooling capacity of the radiator as it needs a pressure differential between the front of the radiator and the back of the radiator to cause air to flow through the radiator. By allowing air to bleed into the engine bay via the high pressure area at the base of the windscreen, there will be less pressure differential between the front and rear of the radiator and so no or greatly reduced air flow through the radiator.

Big fan helping to draw air through the radiator: Yes. But make sure your alternator, relay and wiring can deal with the current draw from a big fan. Make sure the radiator fan shroud is snug against the core and ensures all of the air that the fan moves must first pass through the radiator. Any little path of least resistance for the air to travel through, it will. The radiator core (as mentioned) restricts air flow.

Correctly located and designed bonnet outlet towards the front of the engine bay (Like the ST185/205 GT4 and Evo Lancers): Yes. But these types of vents are located in an area just behind the leading edge of the bonnet that will be in a low pressure area when the car is traveling at speed.

[crownv8]

Lifting the back of the bonnet can help plus the gaps down the side of the bonnet are increased when you raise the rear allowing air to escape. Yeah there is a high pressure area at the bottom of the windscreen but is it greater than the high pressure at the front of the car???? Correctly positioned bonnet vents will obviously be better but its a lot cheaper to buy four longer bolts and some square tube for packing and drive it to see what difference there is.

Also, I just read that your fans are out front. That's not good.

It is a hard situation because there is just no room left in there, especially if you want to keep the air conditioning working. I want to put a 7mge in my 4runner but I'm staying away from it because of the same troubles you are having. The only solutions I have found are moving the radiator to the back or extending the front out a bit and modifying panels. If you could run the standard viscous fan you would have no dramas.