Permanent oil cooler vs thermostat

[Lt86]

Hi guys,

Another question I couldn't find an answer to using the search option.

The AE86 is very new to me so I'm learning new things every day . Anyways, as seems normal... when cold, the engine will idle around 2500 rpm and keep doing so for quite a long time because the oil stays cold for a long time when it's cool outside. Since I still have an exhaust that is too loud for my taste, I feel like a total dumb*ss at the traffic lights in the morning with the high idle. .

I'm puzzled why the AE86 has a permanent oil cooler instead of one that is connected to a thermostat. It seems to be beneficial to keep the oil from circulating through the cooler unless it's warm.

My question... does anyone else have this problem? What did you do about it? Did you fit a thermostat and if yes which one?

[allencr]

" idle around 2500 rpm and keep doing so for quite a long time because the oil stays cold"

This is not true.

[d3nso]

The AE86 oil cooler isn't a full flow design it depends on oil pressure if oil is going truth if i remember right. The oil temp doesn't afect your idle rpm. There must be something other causing this.

[Bean]

Hi Lt86,

a good resource to read you can find here http://www.billzilla.org/4agstock.htm he covers many things related to our engines. It's been written a long time ago but most of it still applies today.
Regarding the coldstart he only covers the fuel side so I won't go into that. The air needed for the coldstart is controlled by a small part underneath the throttle body and controlled by water rather than oil. There's a wax element in there which allows more air into the system when 'hard' as soon as it heats up it will close a passage way and idle will decrease to normal (750-850rpm if set right). The issue in cold weather winter is more down to the fact the plenum and throttlebody is 'cold soaked' and will take a while to warm up. Not much you can do about it, apart from waiting for summer.
Depending how cold it is it should take around 5min to warm up.

The oil cooler isn't very big and airflow through it is also not excellent so it doesn't do much harm even in Winter. you can tape a piece of cardboard over it (fully or partialy) and check the difference in oil pressure.

Hope that helps

[Dave W]

Remove the waxstat from the bottom of the TB. Verify that the water lines to the waxstat are actually functional. Spray or soak the waxstat in carb cleaner and re-assemble using a gasket sealer.
For the oil cooler, to reduce warm up time I place a thin sheet of fiberglass between the oil cooler frame and the fins. I added a hinge on the fiberglass sheet that allows me to uncover about half the area of the cooler. In spring and fall, I run half the area of the cooler, in winter it's completely closed off and in summer I remove the sheet. Dave W

[Lt86]

(03-19-2015 06:37 AM)allencr Wrote:  " idle around 2500 rpm and keep doing so for quite a long time because the oil stays cold"

This is not true.

Good to know! Unfortunately it's true for me at the moment...

(03-19-2015 07:53 AM)Bean Bandit Wrote:  Hi Lt86,

a good resource to read you can find here http://www.billzilla.org/4agstock.htm he covers many things related to our engines. It's been written a long time ago but most of it still applies today.
Regarding the coldstart he only covers the fuel side so I won't go into that. The air needed for the coldstart is controlled by a small part underneath the throttle body and controlled by water rather than oil. There's a wax element in there which allows more air into the system when 'hard' as soon as it heats up it will close a passage way and idle will decrease to normal (750-850rpm if set right). The issue in cold weather winter is more down to the fact the plenum and throttlebody is 'cold soaked' and will take a while to warm up. Not much you can do about it, apart from waiting for summer.
Depending how cold it is it should take around 5min to warm up.

The oil cooler isn't very big and airflow through it is also not excellent so it doesn't do much harm even in Winter. you can tape a piece of cardboard over it (fully or partialy) and check the difference in oil pressure.

Hope that helps

D3nso, Bean Bandit. Thanks for the helpful replies. There must be something wrong with the wax pellet then because I drove about 35 km to work yesterday morning and idle was still at 1500 rpm when I arrived. Later on the day, when I drove home or on longer trips the engine idles beautifully at 800 rpm.

(03-19-2015 01:22 PM)Dave W Wrote:  Remove the waxstat from the bottom of the TB. Verify that the water lines to the waxstat are actually functional. Spray or soak the waxstat in carb cleaner and re-assemble using a gasket sealer.
For the oil cooler, to reduce warm up time I place a thin sheet of fiberglass between the oil cooler frame and the fins. I added a hinge on the fiberglass sheet that allows me to uncover about half the area of the cooler. In spring and fall, I run half the area of the cooler, in winter it's completely closed off and in summer I remove the sheet. Dave W

Is that Waxstat the red and green plastic cilinder?


So I should disconnect it from the rubber hoses and clean it the best I can?

Thanks everyone. Learning a lot

[Deuce Cam]

From what you just described it sounds like the valve is sticking so it might be dirty or clogged. I had the same problem - it took a really long drive for the idle to drop completely.

I removed the valve and found there was some some type of loose debris (hard black pastic or something) causing an obstruction inside the valve assembly where the water passes through. Flow was really restricted when blowing air through the water tube on the valve. I cleaned it really good, got most of the debris out to open up the restriction, and now the valve works correctly.

[Lt86]

(03-19-2015 07:03 PM)Deuce Cam Wrote:  From what you just described it sounds like the valve is sticking so it might be dirty or clogged. I had the same problem - it took a really long drive for the idle to drop completely.

I removed the valve and found there was some some type of loose debris (hard black pastic or something) causing an obstruction inside the valve assembly where the water passes through. Flow was really restricted when blowing air through the water tube on the valve. I cleaned it really good, got most of the debris out to open up the restriction, and now the valve works correctly.

Oh, that would be great.
I found this picture on the internet. By valve, do you mean the part that has been circled in red?

[Deuce Cam]

I believe the technical term is idle air control valve (iacv). The unit is bolted to the bottom of the throttle body. It's easiest to remove the throttle body, and then disconnect the iacv from the throttle body. Reference pics below:



Shown disconnected on the left:

[allencr]

Do the TB's small coolant lines quickly(1-3 min) get warm/hot or don't they?
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"because the oil stays cold" is not True.