Engine cooling fan modification and wiring diagram.

[BigLee]

There are a lot of guys on here who have tuned in the past, currently tune, or datalog. To tell these people that KR comes on constantly is like

GM ECMs for the last few decades have all had multiple spark maps for low and high test gas. Ign retard on KR sensor isn't common unless WOT or high torque demand at low load.

& Jesus, the meth inj wouldnt cool the motor as this mod would cool down coolant slightly quicker. That would cool the combustion chamber or IAT if placed in or before charge tubes.

I don't think theres any other way for the PCM to gauge fuel grade than by probing the detonation threshold and monitoring for knock.

That has to be the explanation for improved fuel economy from using higher octane fuel.
We've switched back and forth many times, and the fuel economy trend is quite consistent.

This has to be a fairly detonation prone engine, being a port injected, turbocharged, relatively high static compression (for a turbocharged engine), high operating temps, with high weight loading for its displacement.
It also engages torque converter lockup quite early, which further increases engine loading.
Especially on 87 octane...

And wether they use three different timing tables, or they simply tune around the one optimized table by subtracting timing at load/speed ranges, based on previous trends needed to keep the KS quiet.
Once it establishes what's needed to do that, you won't get much KS activity.

 

[palpullero]

I just performed this mod and is working great; many thanks to BigLee for posting the technical docs. If you are in stop and go traffic, this will certainly help. I'll post pics later.

Cheers,

Dorian

 

[yt400pmd]

I just performed this mod and is working great; many thanks to BigLee for posting the technical docs. If you are in stop and go traffic, this will certainly help. I'll post pics later.



Cheers,



Dorian

could you post a link to the thermostat you used to activate the fans please.

I want to use this mod in conjunction with this mod that I have already done

https://www.cruzetalk.com/forum/34-gen1-1-4l-turbo/225041-1-4-eco-thermostat-swap-221-f-176-f.html




Sent from my iPhone using Tapatalk

 

[palpullero]

could you post a link to the thermostat you used to activate the fans please.

I want to use this mod in conjunction with this mod that I have already done

https://www.cruzetalk.com/forum/34-gen1-1-4l-turbo/225041-1-4-eco-thermostat-swap-221-f-176-f.html




Sent from my iPhone using Tapatalk

I didn't use a thermostat; I wired it with a switch that controls a 40A relay and then completes the circuit (I used the relay for isolating the circuits plus the switch I used has an LED and I needed 12V to make it light up). My car is running the Trifecta tune and it keeps the temperatures between 195 and 215 degrees F (one of the reasons for the tune) so I am already running cooler temps; since I moslty do highway driving, I decided to manually control the fan when in city driving.

Check with BigLee to see what thermostat he used.

 

[BigLee]

I just performed this mod and is working great; many thanks to BigLee for posting the technical docs. If you are in stop and go traffic, this will certainly help. I'll post pics later.

Cheers,

Dorian

I'm glad you liked this mod!
I believe this mod, a lower temp thermostat, and a lower pressure surge tank cap will prevent most, if not all of the
cooling system maladies these cars are notorious for.
I've had practically all of them: FOUR water pumps, two reservoirs, a water outlet, a thermostat, and a leaking radiator header tank ....
It's been over 11K miles since i implemented all of these mods, and no signs of any more issues. More time and miles will tell if this has truly solved these common issues for good.

 

[BigLee]

I didn't use a thermostat; I wired it with a switch that controls a 40A relay and then completes the circuit (I used the relay for isolating the circuits plus the switch I used has an LED and I needed 12V to make it light up). My car is running the Trifecta tune and it keeps the temperatures between 195 and 215 degrees F (one of the reasons for the tune) so I am already running cooler temps; since I moslty do highway driving, I decided to manually control the fan when in city driving.

Check with BigLee to see what thermostat he used.

This is what I'm using on the Sonic right now.
Is a 160°F on, 145° off thermostatic fan switch from Americanvolt.com. they also sell on Ebay.
Its the one that is designed to thread onto a push-in probe.
I dont use the probe. I just drill a small (and shallow) hole into the bottom radiator support header, apply some adhesive to the base. I also cut a small amount off of the threads to make sure they dont cut into the coolant tube just above it.

Naturally, you want to be VERY careful not to drill in too deep...
This is mounted on the bottom of the radiator, close to the passenger side. You can see I had to cut a small amount of the fan shroud off for access.
The reason I mounted it on the bottom, is so that if the coolant level ever gets low, the switch can still function well.
If its mounted on the top side, low coolant level in the radiator can cause the switch to not activate properly.
These switches cost about $20 each, and come in a variety of temperature ranges of about 10 degree increments.

I also have a 150°F on/135 off switch that I plan to try a different mounting method that will not require drilling into the radiator reinforcement to install it. I will cut to size and drill a hole in a piece of 1/4" thick aluminum stock I have, and glue it into the reinforcement channel.
I'll let you know how this works out...

 

[BigLee]

could you post a link to the thermostat you used to activate the fans please.

I want to use this mod in conjunction with this mod that I have already done

https://www.cruzetalk.com/forum/34-gen1-1-4l-turbo/225041-1-4-eco-thermostat-swap-221-f-176-f.html

I was not aware of this lower temp Dorman 902-2080 thermostat.
I was intrigued by the idea and possibilities it could offer, so I bought one last week, and installed it early this week.
All I can say is, it works great!
I presume that this Dorman thermostat was originally designed for use in markets somewhere that dont have super strict emissions regulations.
I noticed when I had the stock and Dorman thermostats apart that the GM spring was just a tiny bit shorter, and seemed to have a bit less tension when compressed than the one from the Dorman.
Wether this is by design, or just a production variance, or if the used spring had just "settled in" some, I dont know.
So I installed the spring from the GM thermostat back in with the Dorman guts into the stock housing.
This spring change MAY have reduced the opening temperatures by several degrees.
Mine is operating at 174-178°F now, with swings up to 180 under sustained moderate load, and as low as 172° during deceleration.
Now, for the "possibilities" I mentioned above.
Since this Dorman thermostat still has the heating element in it, and I am still using a resistor in the heater plug to satisfy the PCM that the heater circuit is ok, while using my homemade cooler thermostat.
I fabricated a temporary test wiring circuit today, so that I could manually control the heater element from inside the car.
With ambient temp at ~85°, and the engine at operating temp of ~176°, I triggered the circuit at about 50 mph, and within 30 seconds the coolant temp had dropped to 158°F...
I used a 2 ohm/50W resistor inline in my test circuit to reduce current flow by about 8-10% to reduce the potential of burning out the heater element.
Upon turning the circuit off, the engine returned to ~176° in about 40-50 seconds.
This ability to manually command a lower operating temp could be useful for racing or high performance use, or for pre-cooling the engine prior to shutdown in hot weather.
Thus far, no "check engine" light has triggered...
I'll keep you updated...
BTW, if you are concerned that the Dorman thermostat is of lesser quality, both the GM (ACDelco) and the Dorman say "made in Czech Republic" on them, have the same type of laser etched numbers on them, and you can see where the GM thermostat housing has a small sticker on the side with the part# on it, this sticker has been peeled off of the Dorman housing, as evidenced by the leftover adhesive residue, so I'm gonna go out on a limb here and say that both thermostats are made by the same company...

Thanks to you for sharing this info, and to "Cruise-Cruze" for coming up with this discovery...

 

[BigLee]

One more helpful tip:
The replacement thermostat housing gaskets arent exactly cheap, as they are usually over $10 apiece.
But you can get a "6-piece oil cooler seal set" from Ebay, that includes a thermostat seal. They can be had from U.S. sellers for about $6-7 a set, or if you arent in any hurry, you can get them from China for as little as $3.50-4.00 per set.
I ordered 2 sets, and paid just over $7 total.
They arrived in less than 2 weeks.
Just make sure the set is for the 1.4, and not the 1.8L...
I cant say wether they are the same quality as the GM seals, which are made in Europe, and I'm not sure I would use them on the oil cooler or not, but I figured I would give the thermostat seal a shot, as it isnt too much trouble to replace...

If anybody has used this Chinese seal set on the oil cooler, let me know if they are holding up long term or not.

 

[yt400pmd]

I was not aware of this lower temp Dorman 902-2080 thermostat.
I was intrigued by the idea and possibilities it could offer, so I bought one last week, and installed it early this week.
All I can say is, it works great!
I presume that this Dorman thermostat was originally designed for use in markets somewhere that dont have super strict emissions regulations.
I noticed when I had the stock and Dorman thermostats apart that the GM spring was just a tiny bit shorter, and seemed to have a bit less tension when compressed than the one from the Dorman.
Wether this is by design, or just a production variance, I dont know.
So I installed the spring from the GM thermostat back in with the Dorman guts into the stock housing.
This spring change MAY have reduced the opening temperatures by several degrees.
Mine is operating at 174-178°F now, with swings up to 180 under sustained moderate load, and as low as 172° during deceleration.
Now, for the "possibilities" I mentioned above.
Since this Dorman thermostat still has the heating element in it, and I am still using a resistor in the heater plug to satisfy the PCM that the heater circuit is ok, while using my homemade cooler thermostat.
I fabricated a temporary test wiring circuit today, so that I could manually control the heater element from inside the car.
With ambient temp at ~85°, and the engine at operating temp of ~176°, I triggered the circuit at about 50 mph, and within 30 seconds the coolant temp had dropped to 158°F...
I used a 2 ohm/50W resistor inline in my test circuit to reduce current flow by about 8-10% to reduce the potential of burning out the heater element.
Upon turning the circuit off, the engine returned to ~176° in about 40-50 seconds.
This ability to manually command a lower operating temp could be useful for racing or high performance use, or for pre-cooling the engine prior to shutdown in hot weather.
Thus far, no "check engine" light has triggered...
I'll keep you updated...
BTW, if you are concerned that the Dorman thermostat is of lesser quality, both the GM (ACDelco) and the Dorman say "made in Czech Republic" on them, have the same type of laser etched numbers on them, and you can see where the GM thermostat housing has a small sticker on the side with the part# on it, this sticker has been peeled off of the Dorman housing, as evidenced by the leftover adhesive residue, so I'm gonna go out on a limb here and say that both thermostats are made by the same company...

Thanks to you for sharing this info, and to "Cruise-Cruze" for coming up with this discovery...

do you think that the fan mod is still needed with the thermostat mod? i still havent ordered the fan switch. since you have done both, what is your opinion?

 

[BigLee]

do you think that the fan mod is still needed with the thermostat mod? i still havent ordered the fan switch. since you have done both, what is your opinion?

Yes. They are both recomended. They work in conjunction with each other.
With the cooler thermostat, but without the fan switch mod, engine temps will still soar at low speeds/in traffic if A/C isnt on. Even with the A/C on, you may still get some temp rise as the fan turns off as the compressor cycles on/off.
Without A/C on, the PCM doesnt typically turn the fan on until coolant temp reaches 224 deg.

 

[BigLee]

One more helpful tip:
The replacement thermostat housing gaskets arent exactly cheap, as they are usually over $10 apiece.
But you can get a "6-piece oil cooler seal set" from Ebay, that includes a thermostat seal. They can be had from U.S. sellers for about $6-7 a set, or if you arent in any hurry, you can get them from China for as little as $3.50-4.00 per set.
I ordered 2 sets, and paid just over $7 total.
They arrived in less than 2 weeks.
Just make sure the set is for the 1.4, and not the 1.8L...
I cant say wether they are the same quality as the GM seals, which are made in Europe, and I'm not sure I would use them on the oil cooler or not, but I figured I would give the thermostat seal a shot, as it isnt too much trouble to replace...

If anybody has used this Chinese seal set on the oil cooler, let me know if they are holding up long term or not.

UPDATE:
I no longer recomend the use of these low cost Chinese made gaskets/seals.
My wife's Trax developed a coolant leak after about 10 months due to the thermostat gasket basically giving out and start leaking.
Apparently the rubber material is not as good as the GM gaskets...