1JZ Hydro Fan... How does it work

[AeRoKaBn]

After taking my car on the longest drive its been on since my MZ20 was converted to 1JZ from a JZA70 i noticed the temp go up slightly near the end of a 20 min drive along the highway. It was a fairly warm day but i didnt really sting it just drove like normal, and when i turned car off it went to about 3/4 on the digital temp guage ive never seen it like that, everything in the engine bay was hot, wasnt leaking coolant or frothing like the old 7M loved to (coolant and oil are clean)

I didnt have the undertray on i know that would of helped, i dont have a water temp sensor on the radiator but that should make fan run full bore all the time yeah? Also ive heard about the fan control unit that runs the hydro fan but i cant find one anywhere (little black box?)

Would like to keep the hydro in as ive heard good things about them but not all that fussed if its too much of a hassle to get going properly.

Now to my question... how does this all work? Do they run depending on revs or temp? When its cold/warm/hot (like today) it runs the same speed at idle and whilst revving i can stop the fan with my fingers in about 3 seconds? i can feel it draw through warm air but i heard these things are sposed to piss i wouldnt think what ive described as normal

[JZA70 R]

you know the big solenoid coming off the top of the pump, that has a 2 wire plug on it, we accidentally left that unplugged once and the car would slowly overheat on a hot day, even quicker with the a/c turned on. this is after 20 minutes or so of driving.

apparently its the high speed solenoid which is activated when temps are high, maybe check the wires coming off the top of it since they are fragile.

[AeRoKaBn]

had a quick look and theres a one of those black fabric covers over the wires so cant see if there still connected or corroded etc. Tried tracing them but it dissapears under the thermostat im guessing thats where it plugs in.

Is this solenoid activated with 12v? I think i remember reading someone had an idea of connecting that solenoid direct to 12v and trigger it with a switch inside the cab. I wouldnt mind that sort of setup if it works, my eyes are glued to the temp guage now anyway after owning two BHG 7Ms

Also this fan control unit that the JZA70s need to run the hydro fan, where abouts is it sposed to plug in? Ive found a fan control unit for sale but just want to make sure ive got a plug for it somewhere

[richzx]

Send a pm to Mos as he knows all about these things wiring wise. You need the box though because it doesn't run flat stick all the tiem it varies the speeddepending on temp etc. At full noise it moves 4000cfm of air! I didn't have the sender plugged in for ages on mine and it didn't over heat in my MX83 Cressida but it's heaps colder here. Anyway Mos is the man to ask IMO.

[AeRoKaBn]

will do richzx... cheers dude

and cheers jza70r got a bit better understanding how it works now (You must spread the reputation around before girving it to JZA70 R again)

So from what ive figured out the fan will run at slow speed (can stop it with your fingers) when cold or with AC off, and when it gets upto temp or when AC is turned on the fan control unit tells the solenoid to let it run at full bore. Is that about right?

Ive had a look under my dash and cant find my fan control box anywhere and it appears i have 3 spare plugs that it could plug into can anyone confirm what the plug looks like before i buy a fan control unit? eg amount of pins, wire colours etc

[manny]

We recently went over this, - have a read here

http://www.toymods.net/forums/showth...933#post610933

and here

http://www.toymods.net/forums/showth...166#post585166

for some more info.

[AeRoKaBn]

Thanks for that manny, i did read pete05's post but it didnt tell me everything i wanted to know. Anyways thats the point of the thread to let anyone else (including myself whos havving trouble with it) who wants to know how it all works, what controls what etc.

So from what uve said manny, i should have a 10 pin plug somewhere behind the glovebox for the fan control unit to plug into? Is this plug part of the engine loom that comes through the firewall to the ecu with all the other plugs?

[manny]

It's been a few years since I owned my old JZA70, so I can't recall if it was part of the body or engine loom, but I do recall it's a grey plug and sits behind the glovebox.

Have you got a hydro fan specific brown moulded plug temp sensor for the radiator? I've got a spare if you get stuck, same with the ECU.

If the hydro pump's loom is unplugged, the fan should run at max speed, should not overheat and shouldn't be able to be easily stopped by hand - I've got a couple of hydro pumps spare as well if you get stuck.

After all the mucking around I had, I very recently ended up switching back to a viscous fan on my setup as the Aristo hydro setup could not handle towing at freeway speeds with AC on and boost on hot days, 95-98 degrees recorded vs a constant 88-89 degrees on the viscous setup under similar conditions..

[BigWorm]

In regard to temps at freeway speed, usually any speed over 60km/h is going to make whatever fan you're using redundant, and will most likely causing a restriction to airflow.

As for what I know about the hydro fan, it's supposed to be a pretty good thing, the solenoid is controlled by a pwm signal, and the fan controller is seperate the the ECU (but I think is part of the engine loom IIRC).

[AeRoKaBn]

manny, i have the temp sensor at the bottom of radiator but theres no plug for it.

Its just a 2 pin plug so going by ur pinouts, i should be able to run two wires from the sensor to fan ecu pins 9 and 10? Unless i can find a plug but even if i do where does the other end of the plug go?

Bigworm, my temp went one bar over normal after 15 mins or so and stayed there and when i shut it off it crept up to 3 quarters. I was doing about 70-80 on the highway in heavy traffic, stopping at lights etc with no undertray so im hoping with the fan going full speed and with my undertray back on it should be right for long drives

From what ive gathered so far:

no fan ecu connected the fan will go slow

ecu connected but solenoid not connected fan will go slow

ecu connected but no temp sensor input fan will run fast

and when all connect properly fan speed varies depending on idle, revs, AC on/off, water temp

[Gavatron]

In my JZX81 front cut, the fan control ECU is in the drivers side kick panel, and the temp sensor plug and the plug to the solenoid it part of the body loom in the engine bay.

[EldarO]

from what i remember dude, you neither had the thermo switch wiring for the bottom of the rad, nor did you have the hydro fan box.

the ECU is entirely needed, and if you dont have one, find one.

[AeRoKaBn]

gavatron, that probably sounds about right... spewin cos the body loom from the halfcut is long gone, i cant see where the solenoid wires go they dissapear around under thermostat housing but theres no plug i can see for the temp sensor. Ill have a look in the drivers side for the fan ecu, its definately not in the engine bay or passenger side

ill wait for someone to confirm this is the case for JZA70.

What do you guys rekon should i buy a fan control unit and wire it the hard way to the solenoid, temp sensor, tacho signal etc or take the hydro out and go with some falcon thermos? The falcon thermos sound a bit easier im thinking

[AeRoKaBn]

from what i remember dude, you neither had the thermo switch wiring for the bottom of the rad, nor did you have the hydro fan box.

the ECU is entirely needed, and if you dont have one, find one.

Eldar wheres the box sposed to go? And will it be too much hassle to wire if im missing some of the loom? Im guessing the solenoid wiring is part of the engine loom and the ecu is behind the glovebox as theres 3 spare 10-12 pin plugs.

I have an ecu lined up but i want to know if i plug it in wherever its sposed to go will the solenoid open up and let my fan do its job. I dont care if it runs flat out all the time il rig a switch to cut power to solenoid when cold or not needed i just dont want it getting hot

[EldarO]

the box is in your passenger side kick panel from memory, definately left side of the glove box.

its all in the loom.

the only thing you'll have to wire in is the temp sender (which i fucken remember putting in, god knows what happened to it), which again, is two wires that are already there, you just need the plug.