94 K3500 Cooling Problem - Was swapped from 350 to 454

[louieb416]

Hello everybody!

I have a 1994 K3500 that I purchased not long ago. The truck came factory with a 350 SBC and now has a GEN V 454 BBC swapped in. I noticed the fan shroud was trimmed, assuming to add clearance for the 454. I'm curious if the shroud should get swapped and if maybe the cooling stack is for a 350 and not a 454, including the fan and clutch? The truck seems to run a good temp when cruising, but boy does she heat up quick when you slow it down! How would I tell if I have the correct radiator, fan, and clutch?

 

[Super454]

Hello. The 454 has a bigger radiator(more passes)to keep things cool. If they didn’t change the radiator that your issue. If they did easiest thing to do is ditch the shroud and fan. Go with dual electric fans and never look back.

 

[454cid]

At some point GM went to a taller radiator for the 454, but I'm unsure on the year. You likely don't need to do that. It takes different brackets and shroud. I probably wouldn't worry about the clutch too much. Mine uses a "severe duty" clutch. I did change the fan to a newer 11 blade plastic/nylon fan.

I'd check Rockauto for radiators for a 94 3500 with the 454, and see how they compare to what you have now.

Also, do you know when your cooling system was last flushed? What kind of shape does it seem to be in?

I do not recommend electric fans, as they tend to need a lot of money and time to get something close to a factory mechanical fan.

 

[L31MaxExpress]

I also do not recomeend electric fans. Stick with a clutch fan and proper shroud. Clutch fan cools alot better. My 99 Tahoe has a 34 x19 dual core cooling the 8100 in it.

 

[KansasOBS]

Looking at your upper radiator brackets, they appear to drop down. That would be the smaller radiator I'm guessing. Hard to tell from the pics. Mine on my big block radiator are higher than the top of the core support. Speaking of elec fans, the NBS dual unit I put in, with the stock big block radiator been cooling the 6.0 real nice, but haven't seen the heat of summer yet.

 

[louieb416]

At some point GM went to a taller radiator for the 454, but I'm unsure on the year. You likely don't need to do that. It takes different brackets and shroud. I probably wouldn't worry about the clutch too much. Mine uses a "severe duty" clutch. I did change the fan to a newer 11 blade plastic/nylon fan.

I'd check Rockauto for radiators for a 94 3500 with the 454, and see how they compare to what you have now.

Also, do you know when your cooling system was last flushed? What kind of shape does it seem to be in?

I do not recommend electric fans, as they tend to need a lot of money and time to get something close to a factory mechanical fan.

So after researching and then checking the truck out, looks like I have a 5 Blade fan off a 350 AND a 350 fan shroud. The fan is literally buried into the shroud which has got to be making things worse. Radiator looks like the right one though its like 34" which is the bigger one. I'm looking at getting a severe duty clutch, new fan, and a new shroud. Hopefully that will remedy my temps a lot. Where did you get the 11 blade fan from?

 

[454cid]

So after researching and then checking the truck out, looks like I have a 5 Blade fan off a 350 AND a 350 fan shroud. The fan is literally buried into the shroud which has got to be making things worse. Radiator looks like the right one though its like 34" which is the bigger one. I'm looking at getting a severe duty clutch, new fan, and a new shroud. Hopefully that will remedy my temps a lot. Where did you get the 11 blade fan from?

Ebay from a gm dealership. If you do a search for my username and fan, you should be able to findy thread on it.

 

[GoToGuy]

Most are 34 inches wide. The heavy cooling big block radiator is another 2 inches taller. And has 3 or 4 rows of tubes.
To swap a BB radiator correctly you need, upper and lower fan shroud, Z shaped upper radiator brackets, and the stepped cover between grill and radiator.
Or get a K2500 radiator standard demintions 3 tube core, plenty of cooling. You can add the aux fan up front to boost if needed.