High Performance LS Radiator Fan Motors
- Thread starter CorkyE
- Start date
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dannyUAL767
Veteran Member
I'm almost 100% sure that you have a radiator fan problem. If you're cooling fine at highway speeds, anything above about 40mph, but are having trouble keeping cool at slower speeds, then you have a fan/shroud/ducting problem.
I have a 2002 Ram Air Trans Am that I ordered brand new waaay back in 2001. Those OEM fans cool great. Unless you know for sure, it's possible that a previous owner replaced the original motors with inferior chinesium replacements. About 2 years ago, I purchased a pair of OEM fan motors from Rock Auto just to have them on hand for the eventual replacement.
How is the fan assembly mounted to your radiator? Is it sealed well to the radiator or are there gaps? Are both fans running with the AC on?
I've been through a lot of this with my LS376/480, Tremec T56 Magnum swapped, 1991 Foxbody Mustang coupe. I've learned a lot about fans and radiators as well as sealing the entire cooling system "air path."
We can talk about radiators but I think that you have a fan problem.
I had to do some trimming on the shroud to make it fit. It fits "fairly" close to the radiator. As mentioned, I tried duct taping fan shroud to the radiator and didn't really see a difference. I think I need to pay more attention and try this again. Also, I'm about to order a set of GM motors from RA. At least I'll know it's the real thing.
CDB was right, the devil has come down to Georgia.
CDB was right, the devil has come down to Georgia.
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dannyUAL767
Veteran Member
I'll just post some of my radiator experience. As others have already mentioned, a "universal" radiator will be much less expensive than an "exact fit" radiator. The savings can be big.
Griffin radiators has been mentioned. I've owned three, made in the USA Griffins. One is for my 1980 Z28 that I purchased over 15 years ago. It's still in the box and has never been used. The aluminum radiator has two, 1 1/4" cores.
I've been through two Griffins for my LS swapped Mustang. The first one was purchased 9 1/2 years ago for my former, 1991 stock Mustang GT. The Griffin Mustang radiator was a two, 1" core radiator. I ran that radiator for 34 months when it started leaking. Griffin had a 3 year warranty and Summit Racing actually swapped the radiator out for me for free. I ran Griffin #2 for two months and parked the GT due to saltwater rust damage from when I lived by the beach in north Florida. OEM Lincoln MK VIII electric fan controlled by a Delta Current Control controller. BTW, the Griffin cooled great, even with the AC on.
Griffin #2 was removed from the GT and sat dry in my garage for about 5 years. I purchased the Mustang coupe and began my LS3 swap and installed the barely used, but about 5+ year old Griffin #2. Within 1 1/2 yrs of driving the LS3 swapped Mustang coupe, Griffin #2 started leaking! BTW, the Griffin cooled great, even with the AC on.
continued.....
Griffin radiators has been mentioned. I've owned three, made in the USA Griffins. One is for my 1980 Z28 that I purchased over 15 years ago. It's still in the box and has never been used. The aluminum radiator has two, 1 1/4" cores.
I've been through two Griffins for my LS swapped Mustang. The first one was purchased 9 1/2 years ago for my former, 1991 stock Mustang GT. The Griffin Mustang radiator was a two, 1" core radiator. I ran that radiator for 34 months when it started leaking. Griffin had a 3 year warranty and Summit Racing actually swapped the radiator out for me for free. I ran Griffin #2 for two months and parked the GT due to saltwater rust damage from when I lived by the beach in north Florida. OEM Lincoln MK VIII electric fan controlled by a Delta Current Control controller. BTW, the Griffin cooled great, even with the AC on.
Griffin #2 was removed from the GT and sat dry in my garage for about 5 years. I purchased the Mustang coupe and began my LS3 swap and installed the barely used, but about 5+ year old Griffin #2. Within 1 1/2 yrs of driving the LS3 swapped Mustang coupe, Griffin #2 started leaking! BTW, the Griffin cooled great, even with the AC on.
continued.....
dannyUAL767
Veteran Member
At this point, I started searching all the different companies (except Griffin!) looking for a alternative. I really wanted the bigger, 1 1/4" cores and I didn't want to pay the $1000 price tag of some of the exact fit radiators, which, IIRC, didn't have the big tubes. I ended up settling for genuine chinesium: Cold Case polished aluminum with two, 1 1/4" cores and a lifetime warranty. My philosophy is, "I'd rather have a china radiator that doesn't leak vs a USA radiator that leaks. This Mustang radiator is actually an LS swap radiator with the inlet and outlet on the passenger side.
This big core radiator cools even better than the smaller core Griffin did driving down the highway. I have a 187F thermostat and the temperature varies between 189F-197F in Houston heat with the AC blasting.
At slow speeds, the fan which is a brand new, OEM C7 Corvette PWM, brushless, made by Spal, controlled by my Holley Dominator, is the limiting factor. In stop and go traffic, the temperature will vary from upper 190's to 207F. This is with a fan duty cycle of only about 65%. I need to get into the Dominator and up the fan duty cycle by 15% in all rows and columns in the fan speed table. I suspect that will lower my slow speed coolant temp to about 200F. None of these temperatures are remotely "hot" for an LS engine.
I'm so impressed with the Cold Case radiator that I purchased another one for my current project car, an LS7/570, Tremec T56 Magnum F swapped, 1987 IROC Z with only 28,200 miles on it. The Cold Case has the same two, 1 1/4" cores and is an LS swap radiator with both inlet and outlet on the passenger side. I have no doubt that it will cool the LS7 just fine even with the AC on in Houston heat.
This big core radiator cools even better than the smaller core Griffin did driving down the highway. I have a 187F thermostat and the temperature varies between 189F-197F in Houston heat with the AC blasting.
At slow speeds, the fan which is a brand new, OEM C7 Corvette PWM, brushless, made by Spal, controlled by my Holley Dominator, is the limiting factor. In stop and go traffic, the temperature will vary from upper 190's to 207F. This is with a fan duty cycle of only about 65%. I need to get into the Dominator and up the fan duty cycle by 15% in all rows and columns in the fan speed table. I suspect that will lower my slow speed coolant temp to about 200F. None of these temperatures are remotely "hot" for an LS engine.
I'm so impressed with the Cold Case radiator that I purchased another one for my current project car, an LS7/570, Tremec T56 Magnum F swapped, 1987 IROC Z with only 28,200 miles on it. The Cold Case has the same two, 1 1/4" cores and is an LS swap radiator with both inlet and outlet on the passenger side. I have no doubt that it will cool the LS7 just fine even with the AC on in Houston heat.
dannyUAL767
Veteran Member
I had to do some trimming on the shroud to make it fit. It fits "fairly" close to the radiator. As mentioned, I tried duct taping fan shroud to the radiator and didn't really see a difference. I think I need to pay more attention and try this again. Also, I'm about to order a set of GM motors from RA. At least I'll know it's the real thing.
CDB was right, the devil has come down to Georgia.
Yes! This is a great idea and will take the guessing out of it.
My previous, Lincoln MK VIII electric fan and my current C7 fan assemblies are smaller than the radiator. In other words, they sit flush against the radiator core (fins.) I use soft silicone tubing split lengthwise to cover and seal the edge of the plastic shroud to the radiator fins for a nice tight fit. Virtually none of the fan pulled air is leaked/wasted.
Thanks Danny. I'll go the motors and sealing the shroud first. If that doesn't work, It'll be a new radiator with 1.25" tubes.
dannyUAL767
Veteran Member
You're welcome, Corky.
Honestly, I don't think that you have a radiator problem because your car cools just fine at highway speeds. You have a fan problem. Either the fan(s) themselves or how their shroud seals to your radiator.
Honestly, I don't think that you have a radiator problem because your car cools just fine at highway speeds. You have a fan problem. Either the fan(s) themselves or how their shroud seals to your radiator.
76z28
Veteran Member
What accessory drive system are you using? Are the pulleys stock? There should be enough fan there to cool the car
Stock GM serpentine setup, LS fans.
