Ok so I got my a/c working again and my cooling problems returned, like every season... I can’t remember exactly when I started having this issue, but it seemed to get progressively worse when I started modding the stock motor. Obviously more power will equal more heat, but I’ve done so many cooling system upgrades I’m at the point where I’m throwing money at it and getting nowhere. I had the same issues with my iron block 5.3. Same car, different engine, same problem.

Basically whenever the weather starts getting into the mid 80s, the car starts running hot. Idling with both fans on full speed the car sits at 205-206. Not terribly hot I know, but once the a/c comes on the temp creeps up to 230 or more unless I shut it down. Let it idle for a while and it eventually makes its way to 205 again. Driving on the highway with a/c blasting, it sits at 194. Current fan settings are 195 on, 185 off. In the spring or fall the car can idle down to 185 and the fans will turn off. Summer it won’t even come close. Getting on it trying to have some fun at legal speeds, it can get up to 220 with the a/c off. All these temps are being taken straight from my data log, no wonky stock gauge being referenced here. Here are the basics on my setup:

Iron block 6.0, LY6
Ported 823 Heads, steam vent only in the front.
Btr Stage 4 PDS blower cam
Lsa Blower
Summit racing 2 row aluminum radiator
Lingenfelter 160 t-stat
New but stock lsa water pump
Air dam is in place

I have two 12 Inch Spal puller fans, each with their own dedicated relays. Both come on high speed and at the same time. For the shroud I’m using a stamped ebay piece. I have a 2.5 inch Afco heat exchanger in front of the condenser, which is also new and clean, and I even tried removing that to see if it was obstructing the air flow. Made no difference..

Im using a Holley terminator x max for the ecu. Idle
timing was set to 21 degrees. I tried moving it in increments up to 32 but it made no difference after the car was warmed up. This was the last thing I tried, as all the obvious cooling system components have been tested. I had this same issue before putting the blower on, but I fixed it after going from ls1 to the Spal fans. Now with the blower the issue is back.

So my question is do I buy an even stronger set of fans, or a better flowing water pump? I can throw a paper bag in front of the condenser and it instantly sucks it in like a vacuum. Im thinking water pump because maybe it needs more flow at idle? My gut is telling me more fan because it cools down on the highway, but these Spals are pulling so much air I really don’t wanna blow another 500 bucks if I’m still gonna have this issue. I think they’re rated at 1300 cfm each. Im thinking about removing to test, or finding a high flow thermostat to maybe improve some coolant flow at idle. I’ll probably try that before dropping 500 on a pump, or fans..

Any input or personal experiences with this kind of issue are GREATLY appreciated. The car is currently running on a self learned base tune because I don’t wanna put it on a dyno until this cooling issue is under control. If it gets to 220 romping on it, I can’t imagine what a dyno will do.

 

What about running lean at idle? Do you have an AFR gauge to check? Just food for thoughts.
Cheers

 

I would probably do the fans. I recently had the same problems on my Jeep. It has had a history of running hot and overheating. It now has new fans and never overheats, even at idle in 110 degree heat with the a/c on. Today was 111 (Phoenix,AZ) and didn't even reach 200. Get the highest cfm fans you can find in your size, no matter the cost. Also, does air have a way to escape from under the hood? My GTA with 6.0 swap will be getting hood vents from trackspec. (My IROC, too, eventually)
DR.K.

 

A couple of things come to mind:
1) what does that ebay fan shroud look like?
2) are you turning the water pump in the correct direction?

 

It’s idling close to 14.7. Regardless I had the same issue when I was running my old setup.

 

I never looked into it, but with the stock pump and unmodified high mount accessory drive I would assume it is. I ran the same accessories before the blower and it would get down to 185, then the fans would cut off on a 90 degree day. It ran around 212 with ac, but was still way cooler than now. I’m also running the same two fans, radiator, and shroud.The shroud I have is basically this thing, I just used good fans and a summit radiator:




Im running two of these guys.

 

Are you sure that the fans are getting full power?
Check your voltage when they're running.

With that said, I kinda think they are on the small side for what you're doing.

 

I wonder if venting the engine bay might help. A free way to test that Idea would be to remove the hood and look for an improvement. You seem to be moving a huge amount of air and have a limited amount of space for it to get back out of the engine bay

 

I have a 2 inch cowl hood and the back part has open holes. Im not sure how much air flow is actually exiting through there, but it has some flow. The underside is also mostly cut open to allow for clearance with the blower. I ran it with the hood open and it would sit around 199, but with the a/c it still climbs to the sun.

 

My heat exchanger would normally be installed here.


Please excuse the zip ties and upper radiator mount, I’m working on having an aluminum piece made.

 

What are you basing it off when you say it is "running hot"? And where are your temp sensors and are they screwed into thread adapters?

 

Is the radiator really a 2 core as you listed it? Whats the condition of your airdam?

 

New temp sensor screwed into the driver side front of the head. The gauge also reads the same as the laptop and that uses a different sensor on the passenger side. Also no thread adapters, they’re oe ls parts.

 

The air damn is new. It use to climb to 230 on the highway with the a/c on before I installed it. That issue got fixed immediately and now it runs at 194. Here’s the radiator I’m running:

 

Just wanted to cover that base since no one else asked. I had a problem with sensors in thread adapters being influenced by manifold heat when moving slow or stopped. I thought the engine was overheating, but the Holley saw consistent normal temps when I hooked up the laptop. It would creep up, but way slower than the dash gauge would have led me to believe

 

No problem, good to know! The a/c starts blowing significantly warmer when the temp gets to 230 so we’re definitely getting hot.

 

I'm not an LS guy, but I ran across this article? https://lsxinnovations.com/lsa-swap-guide/
Read what it says about the intercooler pump and water pump.

 

Good to hear about the airdam. At this point the only things I can think of for cooling is are the front air baffles that go in front of the radiator area to create the negative and positive pressure at speed to force the air through the radiator with the help aid the airdam. It looks like in one of your pictures all of these are removed. A 3 core radiator would make a difference . What temps are you seeing in the intercooler system?

 

I had the whole baffle assembly in there before I put the blower on. I might actually still have them somewhere. Unfortunately with the size of my heat exchanger there’s just no room for them! I hate the air dam because it literally scrapes on every minor dip in the road causing a really painful sound that makes passengers think the chin spoiler got scraped. But with that being said it does what it was designed to do so I keep a backup for whenever it wears down to nothing😂

I was looking at a 3 core when I ordered the 2, but honestly it didn’t help the temps over the stock radiator. The biggest change I saw was going from ls1 fans to the current Spal’s. The car would sit at 198 with no a/c and both fans running. Went to the Spal’s and it dropped to 185 and cycled the fans in 90 degree heat. This leads me to believe I probably need to go up in fan flow again..

For the heat exchanger it works well. Its actually A direct fit Afco made for a Raptor. I have a 10 gallon ice tank in the hatch, and during a track run I’ll hit around 127 iat, let off after the trap and the temp drops to ambient within seconds.

 

Wow I didn't realize how large the exchanger was.I see how you don't have much room. I always thought the LS engines ran much cooler then the original engines. Through the years I found the champion 2 core radiators didnt cool any better then the stocker. 3 core even 4 core radiators would do much better. Be cool works well but are pricey.

 

I was planning on a be cool, and then I saw the price! I think I’m just gonna pick up another set of fans and hope for the best. The current fans are rated at about 1300cfm each. I’m trying to decide between these two. I’m just not sure if the derale shroud will be too bulky and interfere with stuff. Both of these options would net me around 4000 cfm. The Spal will just get used with my current ebay shroud.

 

What is your radiator cap rated at? I chased a cooling problem in a friends car, turns out it had a 12 lb cap on it.

LS motors use an 18 lb cap. Swapped it out and problem fixed.

 

I have to check, but I’m pretty sure I have a 3rd gen cap on it.

 

It had a 16psi cap on it. I swapped it with a new 18, but I dont think 2 psi will make much of a difference. Its only 65 right now so I won’t know if it did anything yet.

 

How about performing a dye test, for combustion products in the cooling system?

 

Are you running the stock AC condenser? It flows pretty terribly from what I understand. I was told by a reputable hot rod shop that they run the smaller vintage air condensers only, because the stock units are often inadequate. They are 1/3 the size of OEM and are much less like a sail. Frees up surface area on the front of the radiator also.

I also think the radiator might be on the small side. What size are the internal tubes?

 

A temp that creeps high at idle is not cool at all but im with on the fan upgrade Mishimoto has a race line fan worth checking into.

 

I'm don't have any experience with LSX but FWIW I would recommend one of these if they make it for your application:

https://smile.amazon.com/Mr-Gasket-2...s%2C278&sr=8-7

It's been a great sanity check against my gauges and ECM scanner

Also, I might recommend installing two pusher fans that come on with the cooling fans. Mount them directly to the front of the condenser. That will guarantee the coolest air will be pushed through the condenser and then pulled through the radiator by the cooling fans.

 

The spal fans do not flow their rated cfm. The 1300 only pulls something like 900 cfm. I was using a pair of spal 2200's in a staggered push/pull setup. A single 3000 cfm flex-a-lite, and my longtime cooling problems are gone. I'll never buy the spal's again. You seem to have adequate ventilation with your hood, I would bet going to the high quality flex-a-lite fans Will fix your problems.
DR.K.

 

Im considering just going for the lincoln mark viii fan. My wiring to the fans will need to be redone, but I can control high and low speeds with a couple of these relays. I have to measure the space available between the radiator and accessory drive, but I think it will fit. I can easily activate the high and low speed relays with the terminator software.

 

My dad has a Lincoln Mark VIII with 30k original miles. The fan's not for sale though (LOL!!!)...

 

Actually it looks like a taurus 3.8 fan might be a better fit. They only go for about 100 bucks new and still seem to flow a lot.

 

That Taurus fan is the same as a Mark VIII fan; only the shroud is different.
In fact, Ford used those on Mustangs, Crown Vics, Thunderbirds, etc.

I used a '00 Mustang GT fan on my car because I happened to have one laying around.

It took me a long time to get the setup just right, because those fans pull A LOT OF AMPS when they start up (about 80 amps), and I kept burning up relays and terminals every few months.

Those 120 amp relays look like they'll be fine.
Use 8-gauge wires for the main relay power.

Fitting that thing in there was a pain in the ***, though. There are easier options, though.

Have you considered a GM dual fan setup? Here's a thread where I install a mid - '00s Malibu fan setup in an '89 Firebird.

 

From what I found the taurus fan is a 16 and the mark viii is an 18. The 16 looks like it should fit in pretty easy, plus the shroud design seems like it would work a lot better than that shallow aluminum thing I have on there now. Here’s the tread I was looking at:

https://www.thirdgen.org/forums/cool...put-3-8-a.html

 

You are right, 2 lbs isn't going to make a huge difference.

I have had my best luck with the factory 3rd gen radiator and stock 4th gen fans. My car doesn't make the power yours does though. my 383 only put down 420 to the wheels.

Are your fans wired for low and high speed?

 

They’re both wired for high speed only. The pcm triggers the relay and they both come on at the same time. Same for a/c. I had ls1 fans before the blower and I had the same issue, although I bought them used on craigslist so I don’t know if the motors can wear out and become weak over time.

 

My Ls swap ran about 220 on the highway with AC and would creep up to 235 while idling with the AC on. These temps occurred with the factory radiator and single electric fan setup. Last year I installed a three row Champion and a dual 3000 cfm Flex-a-lite (2-12 inch S shaped fans) unit with shroud from Summit. My temps with AC on and moving are now 195 and will go to 210 while idling in the 100 degree, high humidity Texas heat. I think the fans made the bulk of the difference but my radiator was original so I decided to replace for peace of mind. Airflow is the key.
https://www.summitracing.com/parts/flx-480?filters=

 

So I decided to order an early 90’s taurus fan. I got a new dorman from summitracing for 100 bucks. I bought a volvo relay from ebay to control it. I also grabbed the oem circuit breaker for each fan speed. I’ve heard nothing but the best from this fan, so even if it turns out to not be enough with my setup I should be able to easily sell it, or I’ll probably just use it on my trans am. Best part is everything cost about 150 bucks, less than one of those high cfm fans from Spal. I’m a little concerned with going from dual fans to a single, but I think the shroud design of the taurus fan will be an improvement alone over my current setup.

 

Hope that takes care of it, looks like you've done everything that could be reasonably asked to do. A co-worker of mine had to replace the engine in his truck late last year and the new (to him) one kept getting hot. Turned out one of the new rad hoses was blocked internally. Sometimes you just have to check the stupid things, they're usually what can send you down the rabbit hole the farthest.

 

Nobody mentioned checking your radiator hoses for collapsing yet.
Do they have the springs in them?

 

No springs, but I checked them when I dropped the new motor in couple of months ago.

 

I wonder if the shroud is too close to the radiator?
Do you have full flow through the water pump heater hose outlet & return?
What are you using for an overflow tank? Is it large and made for hairy chested men with real cars, or is it a cute little boutique model?

 

ive had good luck with the dual fan flex-a-lite setups. usually LS engines run a little hot but thats a bit hot. you do have quite a bit of things in front of the radiator but i think i saw somewhere you said you tried it without all that stuff and it still ran hot. also cowl hoods dont let air out while driving, they bring air in. they only sorta vent out when sitting but the vent is soo far back it cant vent fast enough. i usually try to do a vented hood. actually building one for my car at the moment. my previous swap i used a gt500 hood vent. temps always stayed fairly cool even when i had a fan relay take a crap in 100 degree weather. if you ever watch roadkill they always solve theyre cooling issues with taking the hood off. lol

not my video but a perfect example of how it works.

 

Thanks for sharing that, I've been told that they're used for venting by many people, but then you have the cowl induction hoods from years ago. That high pressure zone is also why every car ever has the fresh air inlet for the heater and a/c there. Got any pics of that vented hood? I'd love to get one set up like some of the 6th gens or C7 vettes. They literally have a duct from right behind the fans (covering about the center 1/3 to 1/2 of the radiator) up to the hood vent.

 

Thats what I’m thinking with the shroud. For the overflow its a 4th gen tank mounted under the battery. I’m assuming the heater hose flow is good as the heat works fine and the core has been replaced a few years back.

 

So just as a reference point, the only cooling upgrade I have is a larger radiator. Stock dual fans, stock radiator cap, stock water pump, stock thermostat. Engine runs between 190F - 195F, and has never been over 205F even on dyno. I'm thinking you're trying to crutch what may be an undersized radiator (your set up needs more cooling capacity than me and more than most LS swaps). Or perhaps the radiator shroud is too close to the radiator, limiting effective surface area of cooling.

Low temp thermostats are a gimmick IMO. Any thermostat will be wide open when racing, so no advantage there. And in normal driving it just screws up the cooling system to have thermostat open all time, which isn't helping your situation.

 

What size radiator do you have? I have a summit racing unit and the core size is around 2.5 inches thick. I was looking at a 4 core but I was concerned with space being I knew the blower drive would be coming. I was running the stock radiator for years without issue, even after the ls swap and cam. The only reason I upgraded it was to combat this issue, and it made no difference for my n/a setup. Going from the ls1 to Spal fans after the radiator swap fixed it, until I added the blower.

 

Looks like 1.5" of zip tie before it pokes through the other side. It's an old Modine brass radiator that was a favorite with the big block swap crowd back in the 1990's.

Quick search of CTS-V and looks like it is normal for coolant temps to be in the 210-220F range normal driving. Just for kicks and grins, have you cracked open the bleed ports on the heads with engine running to see if air comes out?

 

HP Tuner software is a free download. Maybe open up a stock CTS-V tune and see how they handle idle speed and ignition timing as coolant temps rise. I did that recently with a stock LS7 tune and it was helpful to me. I changed bits of my tune because of it. Gave me a good sense of Ignition Timing retard vs. CTS, and also increase idle speed if coolant gets too warm. I know it won't solve any problems but it'll make it work just that much better, right?

 

Thats a good idea, I’ll have to grab a stock tune and check it out. This came in today, so hopefully I’ll have it hooked up by tomorrow or Tuesday. Im going for tuning on the 27th, so hopefully this issue will be somewhat resolved or at least improved by Saturday. I popped the fan in for a dry fit, and it fits great. I’m gonna run to Lowe’s to grab some stick on foam to seal it against the radiator, then I have to figure out a secure way to mount it. I ended up jumping power to it will some 10 gauge from the battery, and this thing feels like a monster.