LS Cooling Issue

[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.

[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.....

[72MARIO]

I read thru your post but couldn't find the answer. Where is your tempature sending unit ? And are you using dakota digital sender or the GM in drivers front of block and the BIM-2 interface to display what the pcm is seeing ?

[MotoWells]

Originally Posted by 72MARIO

I read thru your post but couldn't find the answer. Where is your tempature sending unit ? And are you using dakota digital sender or the GM in drivers front of block and the BIM-2 interface to display what the pcm is seeing ?

Yes, I'm using Dakota Digital with the BIM-2 module that plugs into the diagnostic port (ODBII). No sensors, gauges should be getting PCM data.

• I did pickup a code scanner, data reader
  
• New coolant
  
• New thermostat
  
• Manual temp gauge

Will attempt to pull data on cool start this morning to see if numbers are different than Dakota Digital.

[knomadd]

I've been meaning to ask, did you program the DD gauges to use the "BUS F" sensor for the water temp gauge so it will read from the BIM module? If not, you'll need to do that. Otherwise, if you're running the DD water temp sensor, you'll have to program the DD gauges to "DD F" (or use "C" for celcius in place of "F" if you so desire). If you install both the DD sensor and keep the factory sensor you can switch your gauge setting to see if one reads different from the other.

[MotoWells]

Originally Posted by knomadd

I've been meaning to ask, did you program the DD gauges to use the "BUS F" sensor for the water temp gauge so it will read from the BIM module?

Yes sir, configured the gauges to read from BIM.

Good point about being able to switch between sensors to double check readings. Might have to go there.

[MotoWells]

Update for you fellas

Spoiler alert, no fix yet.

Confirmed the gauges are displaying the same data as found on the reader.

Observations:

After running truck and tempurtures started to climb to the 225-230 mark I pulled into driveway. Turned off heater to see what would happen. Temps started to climb. Turned on heater and the temp started to decrease. Only shift 3-5 deg over 3-5 minutes but it was craving more heat dispersion.

Got her up to 45-50 MPH and temp didnt seem to come down in fact it did the opposite. Thinking more validation to pull thermostat.

Next steps:

• Replace thermostat
  
• Replace fans
  
• Pull shroud from fans

Any thoughts on next steps, anything else to try? Should I borrow a pressure tester for radiators?

[72MARIO]

You say new thermostat. What brand are you using ?

[MotoWells]

Originally Posted by 72MARIO

You say new thermostat. What brand are you using ?

The one that's in there now is the OE GM that came with the crate motor. I picked up a new one from Napa the other day. New 180, I thought it was AC Delco but I will confirm.

Is there a better brand?

[mongocanfly]

if you change thermostat don't forget to repeat the engine block fill procedure by filling thru the top hose...
also have you verified the belt routing yet? making sure the pump is rotating in the right direction...I know a guy that had his backwards . .his pump mounted fan was pushing air thru the radiator to the front. .

[MotoWells]

Originally Posted by mongocanfly

...also have you verified the belt routing yet? making sure the pump is rotating in the right direction......

Yes sir, verified that the pump is indeed rotating in the recommended counterclockwise direction.

I also hardwired one of the two fans to come on immediately after fire up to test that theory. I would say that helped a little but not much.

[Hart_Rod]

Originally Posted by MotoWells

Yes sir, verified that the pump is indeed rotating in the recommended counterclockwise direction.

I also hardwired one of the two fans to come on immediately after fire up to test that theory. I would say that helped a little but not much.

You should be able to see the water in the radiator "churning/flowing" once the thermostat opens up (195/200F). If you are not, then you have a restriction in the coolant system, either thermostat or radiator. Personally, I would just pull your current thermostat and leave it out. Restart truck, leave the radiator cap off and let it warm up. If it's still getting hot and you can't see the flow in the radiator, then then you have a radiator restriction. If you do see good flow, it's your thermostat.

[indymachinist]

If you are seeing an improvement in temperature control when you run the heater then the short answer is your system is just not able to keep up with demand.

I am looking at these 2 cute little fans and the flat aluminum shroud and thinking GUILTY.

Unless they are Spal, those fans likely don't move much CFM. From a look at your picture they appear to have 2 wires each. Power and ground. This means that they will not have a high and low speed. (I think I saw you posting about this earlier) They are either on or off. They should each have a relay with a large gage power wire feeding them and the PCM only turning the relay on or off.

How close is the shroud to the back of the actual radiator core? If it is very close at all, you are essentially blocking off what looks to be half or more of your core. This is not good.

I know it is not always the most visually appealing, but a junkyard dual fan with its proper shroud would run circles around your current set up.

[homemade87]

I agree with indy . It does look like the flat alum is right on the core . The fans can not pull air from the rest of the radiator and also when running down the road the forced air can not make it thru because it is dead heading against the flat alum shroud . Regardless if it fixes it or not I would add a 1" spacer or more to the alum shroud and get it away from the radiator ( Dont just add washers , it needs to be sealed around the whole radiator ) . This will allow the use of the whole radiator .