Hey guys,

I have some cooling issues with my buggy. Around town it sits between 85-90deg. with the fans coming on at around 92deg.

This is fine until you get on the freeway. At 80km/h it's fine and 90km/h, ok, but from 100km/h upwards it slowly gets warm (from 95-100deg) and won't come down until you significantly slow down.

The funny thing is, on country roads you can sit on 100km/h and it doesn't get hot at all, sitting on about 90deg consistently.

There is no air lock and the fans cool the engine very well when stopped, so I know it's not internal but rather airflow.

I am about to put a fan shroud on to have the fans more efficient.

I did some testing on the freeway to see where the air is going round the car at the back. Seems there is a vacuum at the back and not much air is being drawn through the radiator. This is encouraging, coz it tels me if we can get some air to it it will cool really well.

Also, there is heaps of air going over the back guards, so I am gonna scoop some off the drivers side. I am planning to entirely box the radiator in and have the scoop feeding it exclusively.

The rad is 750x400 approx. (standard radiator)

any ideas about;

How much volume the ducting should have?

What should be the intake area of the scoop?

would be great.

were are your fans?
i had the same prob with my car and put the fan behind the rad and it fixed it, also make the air go through the rad with duct, and make sure air only goes through the rad and cant escape around it

are you certain that the head gasket is perfect? a slight leak will similar simptoms. To verify I half fill a two liter coke bottle and put that down the rad filler. When the engine get to operating temp, if there is a problem then you will see a steady trickel of bubbles in the bottle, reving the car to a constant 4~5k will intensify the problem. I only mention this as the 2.5l subys are known to have failures in this area. Cheers Stephen

I looked into this not long ago and this is what I came up with:
Where you put the fan depends on the blade pitch. Some fans are designed to 'suck' and are positioned behind the radiator, while others are designed to 'blow' and are positioned in front of the radiator. The ones that suck are more efficient and are even better when fitted with a shroud.

The required grill or duct opening is the total core area less the area of the fins and tubes. This equates to about 1/3 the total core area. So if your radiator core (not including the tanks where the top & bottom hoses connect) is 750 x 400 = 300000mm sqr then you'd need an opening/duct of 10000mm sqr, (eg. 100 x 100mm).

I've said this before, and I will say it again. I don't think it's getting hot. Thermostats don't start to open until 91 degrees (most common). So what your describing is that your engine is actually only getting up to operating temperature. Alot of thermostats aren't fully open until 103 degrees.

100 degrees is not hot for cooling water. The corrosion inhibitors also have additives to raise the boiling point, and the system is pressurized so the boiling point is raised further again (about 25 deg C by the pressure alone).

Start getting worried when the temp reaches 120 deg C.

I'm just not sure you have a problem to fix. If you think it's hot, stop and look at the overflow bottle. If it is full and boiling over then it is probably actually hot. Also remember your temp gauge might not be 100% accurate. So instead of going by definitive numbers, work out what is normal for the car.

oh, and are you sure your fans aren't coming on too early, before the thermostat is fully open? How is your fans triggered, by a switch you installed or by the Subaru ECU?

[Edited on 23-9-2004 by Baja Wes]

the fans are switched by a thermatic switch, not the ecu circuit. A reliable source told me that after market fans and the factory ecu don't like eachother.

555bug,
it's not a head gasket. it's not going through water and there is no gray film on the inside of the oil cap or the rad cap.

Does anyone know safe operating temps for an EJ motor?

BTW, the old thermostat I had in it had 78deg on it.

[Edited on 24-9-2004 by pete wood]

hmm, 78deg is the lowest I've seen. I checked a pulsar one in my shed and it's 91deg. It's the most common I've seen.

The aftermarket switch for the fans may turn on long before the engine needs them or could be considered hot.

If it's not bubbling out the overflow, it isn't overheating.

With my V6, if the ECU detects it is getting too hot it will change the fuel and ignition mapping to help cool the motor. If it keeps getting hotter it will go into a limp home mode and eventually shut the motor down. The subaru may have something similar.

remember ej motors have the thermostate in the cooled coolent after the radiater
probabley why it`s so low temp
do you still have the bypass hose from the hot side going to the back of the thermostate?
aftermarket fans will run fine from the factory ecu
(it just turns a relay on)
i`ve run out of money but i`m geting close
ej20t manx andrew

Whats a radiator?

thanx lowbug,
move out of the 1940s and you'll find them all over the place.

hotdog008 is right. There are two temperature sensors on the motor, one is for the temp gauge and the other connects to the ecu. The ecu controls the fans by switching the relay that the fans are wired to, so you should be able to use any fans provided they don't exceed the relay rating.

You can look up the temps in the manual. You can download the manuals for yourself, if you haven't done so already, from the info/archive/links post.

Had a look in the manual for the SOHC motors, but should be the same for DOHC motors.
Like hotdog008 said, the thermostat is located after the radiator & lets the cooled water into the bottom of the motor. The specs: starts to open between 76 to 80 deg and fully open at 91 deg. Rad cap opening pressure is 88 +/-10 kPa.
The ECU is programed to switch the fan on at about 95 deg.

Hey Gentlemen,My subie runs 65degrees at race temp and only uses afermo at idle,iwould maybe cheking if noth air getting around rad.JVLRacing

I have been reliably told that 76-85deg is a good operating temp. 65 is probably abit low for the oil to working properly I would have thought.

Wes,
as far as ducting and things go, do you have your rad boxed in?
if so what is the volume of the box relative to the core area?
and,
what is the area of the scoop relative to the core area.

Rich Olafson (ricola speedster guy) said the rule of thumb for scoop area is about a third the area of the core.

any thoughts?

BTW,
thanx Jenny,
I'll change my thermo fan switching point to 95deg.

[Disagree 65 water temp is right and runs a thermo.If running oil to hot theres more chance of cooking the oil.You want the oil to last longer by using a oil cooler like a setrad.Water at 100 degrees is boiling point to me especially on my subie.JVLRacing

ok gayanne,

any thoughts on the whole scoop area thing?

Hi

Have you thought of putting some wool tuffs on the radiator outlet and getting another person to video the results at speed. There maybe some issues with negative pressure at higher speeds. With my old WBX car my temps would go down on the freeway.

Steve

Pete,if iam reading this right you have the rad at the back of the car,standard rads are not design for putting at the back of the cars.No matter what you do the quantity of air fed to air vents is not the same as having arad at the front of the car.The temps iam reading on this site are much to high.My car runs 300hp+ 65 rad at front.Iam 100% sure that your car is not getting a noth cold air at the rad.Simple fix rad at front, long aluminuim water pipes, more volume of water flow heaps more cooler.Idont know much about buggies but thats what i would do.JVLRacing WRXpowed

thanx guys,
steve I have done that, there is not much flow behind the car but heaps over the back guards, hence I am thinking of scooping it off one of the back guards.

gayanne,
i have thought about putting the rad up the front but have not for two reasons.
1. getting the thermostat to work properly with all that water heading for the front, (not to mention price and pipe work).
2. the danger off debree holing it offroad.

For some great info on cooling systems, see Tech Tip #1 through #5 and Advanced Cooling System Basics at this web site http://www.stewartcomponents.com/Tech_Tips.htm 
That's where I got the info on the 1/3 area of core for grill/duct opening

gayanne, where are you measuring the 65 degrees?

Pete,

I have no box, and no scoops.

I don't know what temp mine runs, as I am using the stock temp guage with has a C and a H and that's it.

Mine does climb a bit further towards the H at high speeds >100kph. Because of this I need to add some small scoops, cos at high speed the air obviously isn't curving up towards the radiator above the gearbox.

I still think 65 deg is too low if that's the temp of the water in the engine. if it's after the radiator then it isn't as bad. When coasting off the throttle the cylinder temp will probably approach the cooling water temp. If the cylinder wall temp is <70 deg C then the combustion by-products condense on the cylinder wall and accelerate wear. That's why cars have thermostats. And the engine runs more efficiently when hotter (but not too hot).

Here's an interesting link, it has the chart of boiling point VS radiator pressure for two different radiator fluid mixes.
http://www.are.com.au/techtalk/coolants.htm

My radiator cap is 90kPa. So that gives me a boiling point of around 123-127deg C depending on the glycol mix. So my advice of get worried at 120deg C was good, cos you know it's gunna start boiling shortly after.

[Edited on 28-9-2004 by Baja Wes]

Hey Jenny,Running a temp switch from the block.The readings come back to microtec digital dash.JVLRacing

found a tiny pin hole in one of the tubes last night...

shouldn't have welded near it :cussing:

have to fix that as well.:o

Hey Pete,was it leaking water?JVLRacing

yeah, but only the tiniest bit,

spose that's gonna have an effect as well.

Hi

There was a guy in buggy at Valla with 2.5 in it, I didnt talk to him but someone said that he didnnt have any cooling issues, his radaitor is in the front. The water pump vs front mounting of the radiator is not really an issue apart from the work you would have to do.

Steve

one fixed rad shame it was 80 bucks later, but I digress

Steve,
for me to front mount the rad would be a hassle.

firstly,
it would mean alot of cost. I would have to buy a different rad or i'd have to make up a different front bar. Then i'd have to run pipes to the front. my missus is allergic to me spending money, i'm sure you know what i mean.

secondly,
getting the pipe work right minus airpockets and temp surging with the thermostat, is a hassle from what i have heard. not only that, but i'd need to run pipes up under the guards as their is no place to run them under the car. that makes the likelihood of airpockets higher.

thirdly,
and this might be petty, it'd totally screw the look of the car from the front. my wife is happy with it as is and i love it. besides people have no idea whats in the car, most think it's aircoolled...suckers!:thumb:.

lastly,
putting the rad at the front makes it more likely to get holed offroad and would decrease my angle of approach.

gotta go, my 8 month old daughter is sending my wife barmy...:duh

thanx for the thought though, who owned the 2.5l buggy?