It took a bit longer for it to get hot but it still overheated with the AC on. I'm at a loss for words. I took it to LSX Powertuning and they took a heat gun to it and it really is getting as hot as the digital readout says. they're going to take it from here for all the issues including the overheating problems. Atlanta opened back up and I have to leave town.

 

Hope its an easy fix for you mate, you had a crack

 

Yeah. I'm thinking it's either the water pump or possibly more air in the system I'm unable to get to.. I'm unsure though. I ordered a brand new ACDelco unit and told them to install it on the motor but I'm skeptical they may have used my older Duralast WP that was on the LS1.

 

Welp, system was bled by a machine and all the air was taken out. The water pump was also replaced but unfortunately its still overheating. Given this was also happening on the old motor, we're suspecting an airflow problem of some sort. The Air-dam is there and intact but it is beveled in the center:



I'm worried my body kit in some way may be blocking airflow to the air dam but it looks like the air dam is considerably lower than my front valence. I'm going to order a replacement Air Dam anyway. I found a few places that carry them new and even have them in stock which shocked me.

Tomorrow it gets dialed in and tuned with the new fuel pump and MAF. I hope to beable to fix the overheating problem.

If this doesn't fix it, the only thing I can think of is maybe a cracked head. Im not getting smoke out the exhaust or anything abnormal like that though. Would this be something I would notice outside of the motor overheating?

 

Cracked head? You losing coolant as well? Is oil in your coolant?


My car holds 195 no matter what and it’s hacked to crap. no air damn... intercooler in front of everything. And I don’t even have all 4 head steam ports hooked up. Engine fans almost never come off low speed.

So Something is funny here.

My car i has when I was 19 I fought a lot and ended up jacking the front of the car up. I Filled it and bled the back steam ports and the front. I added coolant in the top hose till the engine was full and out the hose on and topped the radiator off. I also had the heater ports plugged so I drilled a 1/4 bypass hole next to the thermostat. This helped the thermostat open and shut more reliably at the right temp. Then I’d run it and top it off... put the cap on... and take it off the jack. Didn’t have a problem after that.

Current cars I do the same thing minus jacking the front up. But I figure jacking the car up gets all the air in the motor to float to the top and front of the engine.. getting it burped. Can’t hurt. Does seem to help

I do the same in my 2007 Silverado with good luck.

 

You've been fighting this car for a long time. Hope you get it sorted out so you can finally enjoy it

 

Is there any other way to tell if you have a cracked head without pulling the head? I mean, it would be really odd for a problem like that to occur on both motors. Another thing is my IAT are high too like its not getting cool air for some reason. Is there any other thing it can be?

 

Just re-read the thread. High IAT i suspect is the bottom of the lid box cut out, so radiant heat from the radiator is heat soaking the sensor. This could also be causing a lean condition, since the car adjusts fueling for high IAT. Would also result in timing cut, since there is a table in the tune that will pull timing with high IAT.

If you have a cracked head, I don't think it would be you somehow got a second cracked head -- more like whatever caused the first one to crack also cracked the second one. A leak down test would tell you if there is a possible cracked head. If all eight pass the leak down, then I would not jump to cracked head. If one fails, it could be the gasket or head, but either way, you'd have to pull a head to fix it.

I ended up going to all four corner cooling. Helps a lot with cylinder head temps. as well as giving the coolant at the back of the block an alternate path back to the radiator.

This is more spitballing here -- were you persistently lean as reported by the tuner on the old motor also? He posted he was unable no matter how much fuel was commanded to get AFR to come in line. I'm wondering - honest question - if the car is lean AND retarding the timing, would that cause the heat load on the cooling system to increase?

Another spitball -- Did you ditch your cats? If not, have you checked to see if they're plugged? Low power combined with overheating -- had that in the early days of my TA, and it was plugged cats. I had a catted Y from pace setters. brand new. Cats plugged up. Might be worth checking out also.

 

Lol, I was reading this thread and thinking the same thing.
I would never go from an LS1 to an LS3 though, just modify the LS1.
An LS3 in a 4th gen should put down 350whp without any mods!

 

Welp.. ..I ordered another Air-Dam. Assuming we don't incur another national crisis, it should be here next week.

Funny enough throughout the entire process of swapping the LS3 into the F-Body I've put over 20,000 miles on my 6th Gen SS between driving to and from Austin / Atlanta and now my warranty is expired meaning there's nothing holding me back now from modding it. I'm thinking of doing an E85 tune, Airbox and full Exhaust on that car now... maybe a cam, not sure on that - either that or just put a S/C ontop of it. After the 4th Gen is running properly I'm probably going to forfeit further plans for it asside from getting a stronger rear. It's just not worth it overall. The 6th Gen is just light years more advance. Admittedly Im kinda regretting I went this route .. it is what it is though. I still like my 4th Gen but Im now looking at the costs vs performance and all the hassles I've been through and modding the 6th Gen was really the better way to go.

Oh well live and learn.

 

I wouldn't take those odds...

 

Yea, we could definitely use a break, these last few months have been crazy to say the least.

Didn't notice this at first.

I replaced the Lid Box before taking it to get retuned (it literally arrived just minutes before I had to drive to the tuner) so there's no hole cut out from the bottom of the lid-box to the radiator anymore and is 100% factory but IAT's were still high even at speed. I'll see about a leakdown test.

What is four corner cooling?

I have Hi-Flo cats on there that are new but it was overheating before I had those installed (was running straight pipes from the shop who did the physical work till I got to an exhaust shop).

 

Is your car parked on a door in this pic?

 

The door is between the the wheels so its not technically 'on' the door, but the door is under it. Story behind that is, I bought a new house in January but my LS1 motor pre LS3 swap had a horrible oil leak, to the point it was nearly gushing. Rear Main seal was replaced twice but the oil pan gasket never was and I didn't feel like going through the hastle knowing I was going to replace the motor anyway. The door in that pic was the old front door that I took down and left the house completely open to the public as to prevent oil from spilling all over my precious garage floor...

...kidding, the previous owner left it there because the front door was replaced to accommodate for a fancier door and I figured it would be the best way to ensure no oil got on the garage floor.

 

I wasn't sure if the next thing to hit would be out of Revelations or a plot point from V for Vendetta. I flipped a coin. Sorry guys. Next one is coming from Revelations...
I would still consider moving the IAT sensor to the bumper area. or maybe as a test, run the resistor trick and see if the car does better on temps
Four corner cooling is like the original LS1. All four steam vents flowing, not just the fronts. I run the ERL fittings and an Ebay -4AN kit. Gets really good flow through the heads back to the radiator. I also drill a 1/8 hole in the thermostat flange. Like the old SBC thermostats used to have with that jiggle pin in there.

Thanks for answering up about the cats. It was worth a shot, but I as totally spitballing on that one.

 

They put a fan directly under the car underneath the radiator duct area to make sure it was getting air. While running on the Dyno at 80 MPH, it still ran hot. They said it got to about 220* I'm completely lost now. not sure what else to do or check. No steam coming out the exhaust, not losing coolant, no coolant in oil.. ...but why is it running so hot?

 

Coolant is being measured with a gauge or with the PCM? New sensor or old?

 

OK -- stretching a bit, but some possibilities:

1. Based on the description of how well the AC used to work, possibility AC compressor is bad and dragging, making the motor run hot? Even the clutch dragging on the compressor while AC system is off? try removing the AC belt to test if this is possibly the issue.

2. I could not read your tune file, but verify the temps in the tune are set to bring the fans on at the right temps. Have you verified the fans are indeed running at full speed at the commanded temps?

3. Alternator bearing or water pump bearing going out creating extra drag?

4. Still suggest relocating IAT to bumper area to get away from radiator - or at least try the resistor trick to command a more normal IAT.

5. Has the shroud been damaged or cut up so it is not sealing decently with the radiator? This will kill the effectiveness of the fans.

6. Have you cut open the oil filter to look for glitter?

 

Brand new sensor

I was kind of wondering about the belt compressor dragging or serpentine resistance but I think that would have made itself apparent. Water Pump is new. I'm really thinking of having the heads pulled at this point.

 

If you're not losing coolant there isn't much sense to pull a head. Use an IR temp gun and see if you can find a hot spot first. I don't know if an LS3 coolant temp sensor is the same as an LS1, hopefully it's not a scaling issue on the sensor or something stupid.
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