LS Cooling Issue

[MotoWells]

Wow, first off let me thank you all for your support and willingness to help.

I am running a stock GM harness, with stock settings. Looks like GM recommends to wire the fans direct from the wire provided off fuse block (image from documentation attached).

I am using Dakota digital VHX gauges with the BIM controller, this pulls the data right off the GM ECU through ODB II port.

I am running the stock thermostat.

Bypassed heater with no positive outcome.

Bottom hose is hot, top hose is hot as are both hoses for heater. Sounds like the thermostat is operating properly?

Fans come on but only one speed. Not sure if they can do two stages.

Starting to think the radiator or fans, I will attempt another burp session with an even more aggressive angle. Should I replace the thermostat with lower setting, maybe 160?

One thought, I could pull off the shroud and the two fans that came with the radiator. Put one large fan on and see what happens.


Thanks everyone!

[davepl]

But does the fan run the way it is now? The fact that running the heater helped makes me think your main fan isn't even running, but I can't tell yet.

[MotoWells]

Originally Posted by davepl

But does the fan run the way it is now? The fact that running the heater helped makes me think your main fan isn't even running, but I can't tell yet.

Yes, fans come on, single speed at ~ 200-207 deg just like GM says they will but have only heard one speed. Seems like too little too late on the fans and fan speed. NO low then high speed that I can tell. Sorry, updated my response above to include this information.

Thank you

[Hart_Rod]

Originally Posted by MotoWells

Yes, fans come on, single speed at ~ 200-207 deg just like GM says they will but have only heard one speed. Seems like too little too late on the fans and fan speed. NO low then high speed that I can tell. Sorry, updated my response above to include this information.

Thank you

Factory fan settings on a truck:

Fan 1 on: 226F
Fan 1 off: 219F

Fan 2 on: 235F
Fan 2 off: 227F

[MotoWells]

Originally Posted by Hart_Rod

Factory fan settings on a truck:

Fan 1 on: 226F
Fan 1 off: 219F

Fan 2 on: 235F
Fan 2 off: 227F

Thank you, with my setup I do have two fans however the GM Controller I have has one wire. GM said to attach that single wire from their relay / fuse box to the fan. I pigtailed that to drive both 12 inch fans and ground both directly to battery.

[MIKESAD50]

Are they puller or pusher fans?
If they are puller fans are the hooked up properly and pulling air from front thru radiator out the engine compartment?
Do you have have any cool spots in radiator core? if so you have a plugged radiator. check when hot.
My GMPP comes on about 200-205, what are the fans rated at?
Some times you need vents in the shroud to allow more flow while running down the road. alot of cars have little rubber flaps or doors that open up while driving down the road.

[mongocanfly]

mine has a relay for each fan..

[MotoWells]

Originally Posted by MIKESAD50

Are they puller or pusher fans?
If they are puller fans are the hooked up properly and pulling air from front thru radiator out the engine compartment?
Do you have have any cool spots in radiator core? if so you have a plugged radiator. check when hot.
My GMPP comes on about 200-205, what are the fans rated at?
Some times you need vents in the shroud to allow more flow while running down the road. alot of cars have little rubber flaps or doors that open up while driving down the road.

These are puller fans, not sure the rating on the fans though. I will ask RND (the folks I got the setup through) and see what they are to report back.

Very interesting point about allowing proper ventilation, I will run this by RND as well. I think one of those laser temp tools might detect a cool / hot spots. I will pick one up and take some readings.

Thank you for all the ideas

[72MARIO]

I think you still have air in the engine. I have the same rad in my suburban is runs cold all the time. Stock clutch fan that was not working properly. It took me 4 days of filling the rad before it was full. I had other things to complete so I just kept topping it off.

The transmission on the other hand you better add another cooler as in stop and.go traffic I was running 220 F.

[davepl]

Originally Posted by MotoWells

Thank you, with my setup I do have two fans however the GM Controller I have has one wire. GM said to attach that single wire from their relay / fuse box to the fan. I pigtailed that to drive both 12 inch fans and ground both directly to battery.

This is often true. On the GMPP LS3 controller, for example, the wiring harness they give you has the two fans (blue and green wires, if I recall correctly) tied together so that it's just one output.

I went into my harness and split the wires and then into the code and split the ON temps, but some harnesses come with them bundled together, which is fine, you just treat them like one fan.

So ignore my stuff about HI/LO and split operation - your fan should come on at 207 (or whatever) at FULL speed.

Just as a random though - the later ones, like the LT1 and LT4, use a PWM (pulse width modulation) fan control scheme, meaning they use a high power transistor and they turn the fan motor off and on a hundred time s a second (or whatever) to give them speed control. That wouldn't work through another relay, so if you had that setup (and I do not know which you have), you couldn't use an additional relay, you'd need to use the wire from the ECM. I only mention it because some people use the fan control wire to trigger another relay, which doesn't work with PWM. But that's only on the fairly newest ECMs I think.

[OldGG]

After talking with you today I got to thinking, I heard about this before and someone had a Counterclockwise water pump and needed a clockwise pump not sure if this is what you have here but you never know.

[MotoWells]

Originally Posted by davepl

This is often true. On the GMPP LS3 controller, for example, the wiring harness they give you has the two fans (blue and green wires, if I recall correctly) tied together so that it's just one output.

I went into my harness and split the wires and then into the code and split the ON temps, but some harnesses come with them bundled together, which is fine, you just treat them like one fan.

So ignore my stuff about HI/LO and split operation - your fan should come on at 207 (or whatever) at FULL speed.

Just as a random though - the later ones, like the LT1 and LT4, use a PWM (pulse width modulation) fan control scheme, meaning they use a high power transistor and they turn the fan motor off and on a hundred time s a second (or whatever) to give them speed control. That wouldn't work through another relay, so if you had that setup (and I do not know which you have), you couldn't use an additional relay, you'd need to use the wire from the ECM. I only mention it because some people use the fan control wire to trigger another relay, which doesn't work with PWM. But that's only on the fairly newest ECMs I think.

Thanks, I went ahead last night and purchased a new 16 inch fan. It pulls 2500 CFM. Single wire test as well as more CFM's and without possible shroud interference. Its worth a test. I will report back.

[MotoWells]

Originally Posted by OldGG

After talking with you today I got to thinking, I heard about this before and someone had a Counterclockwise water pump and needed a clockwise pump not sure if this is what you have here but you never know.

Excellent thought, I will attempt to verify. I have Holley's aftermarket accessory drive, the pump is currently being driven counterclockwise when looking at the motor.

Updated -

From everything I am reading, counterclockwise is the correct orientation for GM Pump 12604630

[knomadd]

I've noticed a couple things here. You said the temps climb and don't really come back down unless you turn on your heater. That could mean a few things. 1) The heater isn't effected by the thermostat being open or closed, so your thermostat is possibly not allowing sufficient flow to cool the motor (unable to open completely - I had one not closing completely in my daily not too long ago). This also assumes your radiator isn't near the same temp as the engine. 2) The heater core is taking place of the radiator and fans, so either the radiator isn't working correctly or the fans aren't.

Things you already knew, right? Okay, moving on...

I would check to see if you have a bad thermostat first (it's the cheapest part to replace). You'll need to see what the temps are for the upper and lower radiator hoses, the radiator tanks, and the engine block/water pump area (go get one of those infrared thermometers if you haven't already). If it's all the same temp, or within a few degrees, your thermostat is probably fine.

I would not replace the thermostat with a lower temp unit. The computer will be expecting the coolant to reach a certain temp within a specific amount of time. If it doesn't get there in the allotted time, it will throw a code and turn on your check engine light.

[MotoWells]

Thanks knomadd, I will verify temps on hoses, block, and rad. I ordered up one of them laser temp deals so should be able to do this within Amazon Prime time.

[sincity64]

When you bypassed the heater, did you shut off the water flow? I have found that the thermostat housing requires that the water flow in and out of those two fittings at all times whether the heater is on or not. Put a curved hose on those two fittings coming out of the water pump maintaining water flow and see if that helps

[sincity64]

If that works, there are heater control bypass valves that gm uses on some trucks that redirect the water back into the thermostat housing whenever the heater valve is shut off

[MotoWells]

sincity64 - I used one large hose to connect both sides to create a loop. This did not help stabilize temps.

I am heading over to the garage tomorrow to attempt more troubleshooting on this issue. More to report tomorrow.

Thank you guys

[suburban99]

A couple of things I have learned doing my 72 LQ4 swap with stock rad.
I had a leak in the near the casting marks of the original water pump so I bought a new one.. and a thermostat. Installed the new water pump and thermostat filled from the top rad hose and started motor. Plugged in my bosch handheld that will read live data and watched the temp. Temp gauge is stock with the stock sensor tapped into the water pump. Gauge temp was cold but handheld temp was 200...then 230...then 240...bottom rad hose was cool...thermostat was not opening.
Removed new thermostat and compared with old one. See pictures...
Put the old thermostat in refilled block and started. Temps climbed again then thermostat opened at around 235 on handheld and all the water from the rad disappeared...topped up rad and it's been fine since.

2 things I learned. ---get a handheld that reads live data, even a cheap one like mine. And all thermostats are not the same.

[MotoWells]

Spent the day over working on the rig, I have little more data to share with you fellas.

Quick Synopsis if you don't want to read details:

- Found wires were reversed on fans - I'm an idiot
- Put heater hoses back on
- Burped system for entire day
- Ran coolest it ever has (longest trip to date)
- Ran 190-200 for quite a few miles after hill climbed it jumped to 240 and stayed there and backed down to 230 ~225 with heater running (technically stabilizing ?)
- Heater helps pull down temps
- From temp readings it appears to be a thermostat issue?

Details

Steps Taken Today:

1. Removed one of the two fans from the fan pigtail

2. Reversed leads to what I had and immediately got a lot more CFM
!! I had these wired wrong (black is not always ground)!!

!! I really thought I had found the silver bullet here. !!

3. Reconnected the heater top and bottom hose. The loop back didn't help from previous test so put it back.

4. Wired up one of the fans to come on immediately once the car was started.

5. Burped system for entire day on incline as recommended

Results:

Heater and fan on, took drive, longest drive to date.

Temps were good for quite some time (8 miles) 190 - 210

On the way home they started to climb as headed up a slight grade

Temps went from 205 to 220 and then to 230

I give it a bit more gas to get more airflow through and the temp starts to climb a bit more - 240.

Pulled into driveway and popped hood. Temps stabilize around 240 and then with heater blasting slowly came down to 230 and then 225.

Let it cool down and then attempted further burping.

Ran it one more time with similar results.

Took some readings with the new laser temp deal. Interesting results.

Temps seem to be cooler around the thermostat. Could that be the next step? Replace the stock / new thermostat?

Readings:

> Thermostat Housing - 150 -170 (highest maybe 182)
> Radiator - 224
> Engine Block - (191 - 210)

Let me know your thoughts

Thank you

[MotoWells]

Originally Posted by suburban99

2 things I learned. ---get a handheld that reads live data, even a cheap one like mine. And all thermostats are not the same.

Thank you for sharing. I am thinking this very well might be the next course of action, swapping out the thermostat. It just doesn't seem to be circulating that water.

Appreciate the tip on the live data too. I am pulling this gauge off the ODB II port so I do feel its reading what the engine is reading...hopefully Might have to confirm that too. I was confident I had the fan wired properly and look what happened there.

[ls1nova71]

I would get a good scanner and see what the PCM is actually seeing. I'm having my doubts that the gauge is really accurate since your showing the block to be 190-210 but the gauge shows 240. Also on a side note, although I'm sure it has nothing to do with the cooling issue, but running Dexcool in a swap is kind of asking for trouble since you most likely dont have a fully sealed cooling system. Any time air is introduced into the system, such as when its cooling down, it turns the coolant into a mud like mess, ask me how I know.....

[MotoWells]

Originally Posted by ls1nova71

...Dexcool in a swap is kind of asking for trouble since you most likely dont have a fully sealed cooling system. Any time air is introduced into the system, such as when its cooling down, it turns the coolant into a mud like mess, ask me how I know.....

Thanks for the tip, I will purge and start over with regular antifreeze. I don't want that sludge on top of everything else.


Jeff

[a.c.ward]

we had similar issues with a 5.7 ls1 swap recently. Three water pumps, two radiators, 7 thermostats, multiple different fans, playing with settings in computer for fan control, using scanner for live data while driving, burping system for days, seeing 210-215 on scanner, still seeing 240 ish temps on dash, also using Dakota Digital.

used reverse pressure bleeder to get all air out, still same.

took vehicle to another buddies shop for his help, reported that when driving with heater on, temps never climbed above 215 on gauge.

moved Dakota Digital temp sender to upper radiator hose to check for differences in reading.

here is my final summary, we put the Dakota sender in the passenger rear temp port originally. that is the hottest portion of the engine. when we moved it, the gauge seemed to settle down and 'see' similar readings as the computer was, the PCM temp sensor is in the driver front cylinder head.

Laser temp probe is showing very similar temps across the engine, not overheating any more.

our setup:

LS1 04 GTO
Entropy radiator ls swap specific
2 10" 2250 CFM fans
factory GM thermostat 165 thermostat for 01 Corvette

installed in 87 El Camino. drives great, not overheating any more, even in 107 degree central Texas weather with AC running

hope you get yours figured out

[homemade87]

Originally Posted by MotoWells

Thanks for the tip, I will purge and start over with regular antifreeze. I don't want that sludge on top of everything else.


Jeff

Also use distilled water as well . To many chemicals in tape water that will stop up the flutes in the radiator over time .