Water pump? LS3 in 4th gen fbody
Thread Starter
Launching!
Joined: Feb 2017
Posts: 222
Likes: 18
Water pump? LS3 in 4th gen fbody Stroked/turbo’d LS3 has never cooled below 190 (even higher in 220’s at idle/traffic) w a few different 160 thermostat. Factory fans turn on at 165., Larger core earlier fbody radiator is newer. Motor is fresh.
Found out tonight that the LS1 Delco water pump I have (252-846) is the budget version.
jumped on this site a couple hours ago, and I’m still not ‘certain’ which water pump will work with my LS1 accessories.
I ‘believe’ these are my choices:
Delco 251-744 w my moto rad 456-160
Flowkooler 1670 ls gen 3/4 (my 160 moto rad thermo?)
Flowkooler 1698 ls3 Camaro (my 160 moto rad thermo?)
my first choice would be the Flowkooler, because I have experience with them working well in my classics at idle in traffic in hot/humid Midwest.
much appreciated.
Found out tonight that the LS1 Delco water pump I have (252-846) is the budget version.
jumped on this site a couple hours ago, and I’m still not ‘certain’ which water pump will work with my LS1 accessories.
I ‘believe’ these are my choices:
Delco 251-744 w my moto rad 456-160
Flowkooler 1670 ls gen 3/4 (my 160 moto rad thermo?)
Flowkooler 1698 ls3 Camaro (my 160 moto rad thermo?)
my first choice would be the Flowkooler, because I have experience with them working well in my classics at idle in traffic in hot/humid Midwest.
much appreciated.
Last edited by Pbarby; Jan 19, 2025 at 09:11 AM.
Joined: Apr 2006
Posts: 3,891
Likes: 1,137
From: Grand Rapids, Michigan
I don't know, I have a cheap parts store water pump on my turbo 5.3 with a 160 degree thermostat and my temps are almost exactly what you have. although I've never seen above 211 in mine. I take it your radiator is in the stock location if you're using stock fans? Is all of your plastic ducting in place for the radiator?
Thread Starter
Launching!
Joined: Feb 2017
Posts: 222
Likes: 18
I don't know, I have a cheap parts store water pump on my turbo 5.3 with a 160 degree thermostat and my temps are almost exactly what you have. although I've never seen above 211 in mine. I take it your radiator is in the stock location if you're using stock fans? Is all of your plastic ducting in place for the radiator?
I just now started it and let it run. Outside temps are in the single digits and car is in the ‘somewhat heated’ garage w ambient temps in the upper 30’s.
I used a temp gun: The front of the head gets up to 180, water pump about 168 and thermostat housing 105. After several/long revs the only change is the thermostat housing gets into the 120’s then cools back down to 105 a couple min later.
Thanks again for your reply. I’m just wondering if it is worth trying the Flowkooler or OEM water pump or am I not looking in the right place…hope some other replies help shed some more light.
Thread Starter
Launching!
Joined: Feb 2017
Posts: 222
Likes: 18
I’d love to have a Dewitt pro aluminum in there but need to justify if it’ll work (I realize you said this may not be the solve in your post). Thanks again
Joined: Apr 2006
Posts: 3,891
Likes: 1,137
From: Grand Rapids, Michigan
Why do you think you need such low temperatures? LS engines are not like the small blocks of old, they run better with slightly higher temps. I have 160 degree thermostats in both of my cars, and neither one will ever see an actual 160 degree temp in the engine. The only time there's an issue is if you can't keep a steady temperature, i.e. it's creeping up under all conditions. Not only that, but sometimes a low temp thermostat can actually increase temps because it's constantly open. The coolant doesn't stay in the radiator long enough to draw the temperature out of it. I'm contemplating a 180 degree thermostat in my turbo car for just that reason. I'm not really seeing a lot of creep except when I'm really hammering on it, though.
Trending Topics
Thread Starter
Launching!
Joined: Feb 2017
Posts: 222
Likes: 18
Why do you think you need such low temperatures? LS engines are not like the small blocks of old, they run better with slightly higher temps. I have 160 degree thermostats in both of my cars, and neither one will ever see an actual 160 degree temp in the engine. The only time there's an issue is if you can't keep a steady temperature, i.e. it's creeping up under all conditions. Not only that, but sometimes a low temp thermostat can actually increase temps because it's constantly open. The coolant doesn't stay in the radiator long enough to draw the temperature out of it. I'm contemplating a 180 degree thermostat in my turbo car for just that reason. I'm not really seeing a lot of creep except when I'm really hammering on it, though.
if the 160 thermo keeps me in the 180’s consistently I’ll be happy. We’ll see.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Joined: Apr 2006
Posts: 3,891
Likes: 1,137
From: Grand Rapids, Michigan
A good double pass radiator will make a difference for sure. Keeping all of your plastic ducting in place will also help. In addition, if you don't already have one, a higher pressure "racing" style radiator cap will prevent premature boiling.
Straub Technologies has some good information about LS cooling and sells a modified head gasket to help lower temps. There is a good read in the description. Another subject they discussed was the importance of steam port line design (keeping the between head hoses equal length) but I no longer see it on the site. It’s all in the little details when it comes to cooling.
Also assuming your heater is still in use, if lines are capped that’s another problem point. As said make sure all of your ducting and air dam are in place. It could also be something as simple as dirty/blocked fins on the radiator and condenser that need blowing out. I like to blow them out then soak with simple green and flood with water. Since yours is new this might not be the case.
I have ran FlowKooler pumps in the past on old SBC’s but I don’t think it will do much for what you are asking here being the LS system design is vastly more efficient. You also need to make sure your pump to stat compatibility is correct. It is possible to have the wrong stat/pump year combination.
Once you have the basics covered your next move would be into an aftermarket radiator from one of the reputable manufacturers such as Wizard or Ron Davis provided it fits the with APS kit mods. Check the little stuff first and then go from there.
Also assuming your heater is still in use, if lines are capped that’s another problem point. As said make sure all of your ducting and air dam are in place. It could also be something as simple as dirty/blocked fins on the radiator and condenser that need blowing out. I like to blow them out then soak with simple green and flood with water. Since yours is new this might not be the case.
I have ran FlowKooler pumps in the past on old SBC’s but I don’t think it will do much for what you are asking here being the LS system design is vastly more efficient. You also need to make sure your pump to stat compatibility is correct. It is possible to have the wrong stat/pump year combination.
Once you have the basics covered your next move would be into an aftermarket radiator from one of the reputable manufacturers such as Wizard or Ron Davis provided it fits the with APS kit mods. Check the little stuff first and then go from there.