AE86 4A-GE Cooling System

[xXxPigeonKickerxXx]

I have a 4AGE powered ADM Sprinter which came pre-converted when I bought it however along with the many problems which came with the car, the cooling system is a bit odd such as having the thermostat on the top outlet rather than the bottom, and it also has a custom made bottom outlet to the radiator and a custom thermostat housing on the top which I believe has a CA18 thermostat in it. Between the Top outlet from the smaller pipe which goes to the heater core there is a small outlet which is T'ed into the bottom outlet and then to an over flow type bottle. The over flow bottle thing has a radiator cap on it with 3 outlets/inlets one coming from the T, one at the top near the cap which goes to the original overflow bottle, and one which comes from the top of the radiator where the original overflow line used to go.

This can be seen in these photos.



Is this system alright to run? It seems to work ok, it doesn't have a radiator fan on it right now but it will will be at 3/4 on the gauge in about 20 mins or so. Even without the fan during normal driving with no extended periods of being stationary it doesn't appear to overheat. But that is coming from the sensor on the modified top water outlet.

Is it ok to remove the silver overflow bottle/cannister? as I just think it is unnecessary and is taking up valuable space.

Any help would be appreciated.

Have a Happy, safe and Merry Christmas. Drive safe now.

Cheers, David

[mullett]

Overflow bottle of some kind is very important, as the cooling system needs to stay full of water, with no air inclusion. So when the system warms up, the water expands, exceeds the pressure of the radiator cap (normally 13psi) and the water flows to the overflow bottle. When you turn the car off and the water cools, it creates negative pressure in the cooling system, and sucks the water back down through a valve in the radiator cap.

Apart from that, the conversion looks neat enough. If you're unsure of where those Tee'd lines go to, trace them to their termination and take some pics. normally there'll be an inlet and an outlet from the TB for the cold idle etc, and that looks like where those lines would go. Does the heater work? All the heater lines connected?

Where the thermostat comes from makes no difference, as long as the temp is OK (and they pretty much all are, most cooling systems operate at the same temp). On the other hand, if it's installed wrong, it can cause overheating, but if the car doesn't overheat, it's working. Having it in the top hose is pretty normal too, but it might not be normal for that motor.

That said, 20min to warm up is an awfully long time, does it get to mid-way quickly and hold, then slowly get hot? If that's the case, the rradiator might need flushing, but if it goes straight to 3/4 and stays there, I'd get an aftermarket temp gauge (or borrow one) and find out what it really runs at, because factory gauges can be inaccurate.

-RM.

[mullett]

Actually...sorry. I've just looked at the picture properly, there's 2 overflow bottles, one is plenty as long as it has enough capacity. Also, the silver one is a high-pressure overflow (as in it has a radiator cap) so it's basically acting as extra capacity for the cooling system, and if the car has 2 pressure caps (such as one on the radiator, and one on that cannister) then it's kinda redundant. I'd remove it, run the line straight to the factory overflow, and see if anything strange happens. If there's something wrong with the factory radiator cap, it might overflow, in which case...get a new cap

The other option, to free up a lot more space, is to remove the big factory bottle and get a smaller washer bottle and use the cannister, but you'll need to replace the high-pressure cap with one which has no resisance, otherwise overflow water will come out under 13psi, and cause air inclusion problems later.

-RM.

[SeptemberSquall]

that 'second overflow' may be being used as a header tank

3VZ-FE on VDV10 Camry uses two caps to allow the system to be properly bled becuase the radiator cap is below the highest coolant gallery in the engine

old falcons do it too, EA-EL 6cyl i think

if this is the case in your 4a-ge install i recommend you keep the header tank.

[xXxPigeonKickerxXx]

Thanks for the reply mullet,

In case I did not mention it in my first post the T'd piece between the top and bottom outlet goes to the bottom of the silver/aluminium overflow type canister. It's a weird setup which I have never seen before, most if not all of the 4age's I have seen would either have the proper rwd water outlets or they used the fwd outlets but had added in the remote thermostat assembly on the BOTTOM radiator hose. I read somewhere I belive it was on Phil Bradshaw's website about it aswell, but I don't know if anything bad could happen if the thermostat was on the top rather than the bottom. What I was trying to say before is that since the sensor for the gauge is on the top radiator outlet and when the thermostat is closed I don't think the reading would be accurate, Im also worried about how the water flows inside the engine.

The heater does work now, previously when I bought the car on the long trip back home I tired to turn on the heater and put in DEF mode but it wouldn't defog the windscreen but I could feel the heat inside the car. The proper RWD outlets I believe have a little pipe which connects to the bottom water outlet which is similar to this setup however the size of the pipe hwich joins the two is much larger about 12mm+. The Lines which used to go to the TB and that thing that it used to connect up to has been removed and replaced with a gasket and an alloy plate.

Would be interesting to hear other peoples comments and opinions on this setup.

Cheers,

[xXxPigeonKickerxXx]

Thanks for the reply SeptemberSquall,

Hmm that does sound like a reasonable explanation however the JDM AE86's had the 4AGE in them from factory and I'm quite sure they did not have them and also that the big port cooling system is similar to the small port if not the same. Unless there is something which I am not aware of.

Also forgot to add in previous post engine is a Small port 4AGE, and when I said it took 20 mins to warm up it took about that time to start over heating or close to it at 3/4 of the gauge. However it took about 7-10 mins to get to normal operating temperature, I had to idle the engine for 10mins then let cool for 20 and then idle it again for 20 and let cool for 20 and the drive for 30 in order to let the paint on the headers harden. So pretty much it was idling for 10 mins which just about got it half way up the gauge, then it cooled for 20 and the restarted and idled for 20 when at about 18mins in the gauge was at 3/4.

Cheers, David

[mullett]

Does it overheat when you're driving it? Having no cooling fan means that it will happily overheat at idle if the car's sitting, because the main function of the fan is to keep some air moving while the car is stationary. I'd get some electric fans ASAP (a single Davies-Craig 12" thermo would be perfect, and not too expensive), and that should solve it.

If it's still overheating, you've got problems, especially at idle. It could be poor coolant flow (common at low engine speeds if the waterpump is a bit sad), or a blocked radiator.

As far as the rest of the system goes, if it works, it might be easier not to mess with it, but I'd check that header tank. If it's for bleeding air off, use a small needle valve with a hose instead of the tank if you're concerned for the room.

The alloy plate/gasket solution is probably OK, I used this on my GZE (albeit with an aftermarket ECU), and it was never a problem. I think the main idea is to stop the TB icing up in freezing temperatures, and for cold idle-up.

A 12mm feed is pretty normal for a heater core, check that there's a tap in the system and that it's connected correctly. I'm still curious about that Tee peice, someone's put it there for a reason I'm sure, it's too much effort otherwise.

My plan of attack would be:

1: Install thermofan and make sure it functions correctly, and that the car no longer gets hot.

2: bypass the extra coolant tank by running a hose straight from the radiator to the factory overflow, and cap off the hose which runs from the Tee peice to the extra tank, cutting it out of the system completely. Make sure the system is bled down (it should be unless you let too much water escape), and then drive the car for a while, get it to operating temp, give it a good thrash, let it idle for a while with the fan off...just give it a working over basically. If nothing strange happens, like blowing water out of the std overflow tank, then I'd just remove it. If the cooling system doesn't work properly, put it back in as it was before.

-RM.

[xXxPigeonKickerxXx]

Well Today I have removed the alloy bottle and all the lines including the T piece and replaced the T piece with a hose and clamped it down. Tried starting it today but I think Im out of fuel and will get some tomorrow. I was going to install a thermo fan but haven't got the funds or time to it yet as I have been busy rewiring the engine and main relays, I was also thinking bout using a 12 inch fan as that's the only one which will fit and cover a large portion of the radiator.

Do you know how much a Davies Craig 12" thermo would cost? as I was thinking of getting one off ebay they seem to go for about $50 posted without any relays just the fan itself.

Also what would be a good way in terms of this odd setup to turn on the thermo's as I have seen the Davies Craig adjustable switch with the probe thing which cost about 80 bucks which I think is too much, and then I have seen people use the smaller switches which have a set temp for switching on and off.

According to Phils page ( http://home.clear.net.nz/pages/phil....stallation.htm ) on the 4AGE he says the thermostat is on the bottom hose ratehr than the top as it allows cold water in rather than hot water out but he doesnt mention anything on it being on the top or and issues relating to it. Quote from Phil's page "Radiator and Thermostat
The 4AGE comes stock in RWD form with a 5.6 litre cooling system. The use of an oil cooler in later engines with oil cooled pistons may enable a smaller radiator to be used due to the amount of cooling done by the oil. Note that all 4AGEs use the thermostat to let cold water into the engine (as opposed to letting the hot water out), hence the thermostat side of the plumbing should be connected to the bottom radiator tank.

In this manner when the water in the head heats up the thermostat will open and let cool water (from the radiator bottom tank) into the engine. Hot water leaves the engine and returns to the top radiator tank. All engines have a thermostat bypass so that water will still circulate (due to the water pump) around the engine when the thermostat is shut, thus eliminating any hot spots caused by the water not moving and also preventing the water pump cavitating."

So I'm Still stumped on this issue, I guess if it runs fine without the second alloy overflow bottle thing then ill just leave it.

Cheers David

[mullett]

Exactly what I would do. If you're unsure of the cooling system in any way, get an aftermarket temp gauge, even if it's only temporary and ensure that everything works well. A $30 speco gauge will be more than enough.

A davies craig fan with all the bits costs about $120-150, that's the fan, relay, harness etc, but no switch (I think). If you're getting it from Ebay, make sure it's a genuine brand-name one, although I guess most things will get you out of trouble for now.

I've forgotten most of what i used to know about 4AGE ECUs but I'm pretty sure there's an output somewhere for thermofans? Or there's a temp switch on the motor somewhere. Either way, find that and use it, but make sure you use a relay as well. When my factory switch failed in the MR2 I had both fans running constantly, which caused no problems at all (apart from the wear and tear on the fans and the noise).

if you have major problems finding a factory switch you can use, go to a good motoring store and buy the cheapest 90deg switch they have (anywhere from 82-95deg is probably ok), and drill/tap a hole to suit it, again use a relay.

A thermo fan is extremely important, I'd be wary of driving the car without it

-RM.

[mullett]

Switch one

Switch two

There's a couple of DIY options from Jaycar if you're of that mind...

-RM.

[xXxPigeonKickerxXx]

Hmm thanks for the links they look like a good idea, I usually only get wires and the typical small things from jaycar and forogot all about their kits. Damn $150 for a thermo fan I guess your paying for quality, I think that the eBay thermo will last me the year that I will have the car for and its only $50 do I don't see why not. When I required the engine on the diagrams and pin outs I have there is no output for thermos, IIRC most cars will have that small switch I was talking about on either the bottom of the radiator or on the top outlet where the sensor is. I could probably get one of them from an old radiator which I have laying around although where would I be able to mount it, or where would I have to drill. Is there like a hole somewhere that I could just screw the sucker in?

Cheers, David

[mullett]

If you're really lucky, there might be an unused port somewhere, otherwise you can tap into the aluminium that the top outlet/thermo housing has been made out of, most sensors use a 1/8 BSPT thread, a tap will be about $10, and I *think* it takes an 8.5mm drill bit. Otherwise you can buy those china bits, the aluminium couplings for putting gauge sensors in, they're dirt cheap, and again usually use a 1/8BSPT fitting (note that 1/8 NPT thread is almost identical, and in aluminium, and at such low pressures, will hold fine with some thread tape.)

The Ebay fans will most likely be fine, and most of them probably have a warranty. Why selling after a year?

-RM.

[xXxPigeonKickerxXx]

What do you call them aluminium couplings I've seen them on eBay before but I cant rememebr the name of it, would you know how much it costs? As im trying to keep the costs down. The reason I'm selling is that I don't think the car is for me, I'm not sure what I was thinking when I bought it. I haven't driven it much yet as I've been busy fixing stuff here and there. Its due for rego in a month and I have quite alot of things to do go get a RWC.

Cheers,David

[mullett]

I think they just call them gauge adaptors, here's some from JJR, and a thermo fan. The small adaptor 'fuel rail adaptor' would likely fit in the small line near that Tee peice (but check the hose size) and the bigger adaptors are sized to suit radiator hoses, make sure you get one to suit yours (I think they come from 30-38mm).

JJR Alloy adaptors

JJR 12" thermo fan

Small adaptor

You can most likely find this stuff on Ebay too, but this will give you an idea of what you're looking for. Also, I can recomment JJR stuff as pretty decent gear for the money, at least what I've had so far.

-RM.

[mullett]

Just had a look on ebay, couldn't find much. The other option is still to drill and tap an existing portal, or find an unused sensor. You mentioned that there was a factory temp switch for the fans, is the port still there? Or was it removed with the custom piping? Either way, if you'd rather have a hole drilled and tapped, pull off a peice with a thick wall, and take it to a mechanic or metalworking shop, they could do it for you in 5 min if you don;t have the gear.

-RM.

Edit:

Fan and switch combo