Cooling Issues

[Devil Pup]

So i have a 350 sb. with auto transmission, and ac with seperate collers for both with no thermostat now. i had a 180 in it, it was still gettin hot so i dropped it to a 160 and now i just put a housing in. when i sit at a light for just a minute or so my truck will jump above 220 or even when i am just driving around normally. i have a brand new radiator in it and its pumping correctly. so i went to jegs and they have dual electric fans that would eliminate my mechanical one and just pull more air according to them. i would like some advice from someone who has either done this or knows about it. . . any help?
thanks, Mark

[Jurassic-1]

I live on the face of the sun here in AZ. You may be going backwards with you're cooling problem. Out here we use a 195 degree thermostat. If you use a cooler one the water circulates at 160 degrees and does not cool as efficiently because it opens earlier. Also I use a 454 fan clutch which helps. I run at 1/8 on my c10 and 1/4 on my k5 Blazer.

[BAGNDRAGIT]

i run electric fans and love them, i have 2 15" fans and only run one in the summer here in the solar pit...and stay under 210.

if ou can afford them its worth it, it increases gas mileage, and power. but make sure you wire it correctly and have a good alternator.

how many core is your radiator?

[71swb4x4]

Put your thermostat back in.
Are you running a fan shroud that's correct for your fan?
Is your temp gauge accurate?

[BCOWANWHEELS]

my truck wont cool with a electric fan. always use a thermostat, 180 deg.

[j_cst_10]

Well you have a problem obviously. Like previous posters have mentioned
1. Check that you have a correct fan shroud.
2. If you have a clutch fan, make sure it is operating correctly.
3. Your vehicle will cool more efficiently with a correct electric fan set up but it should cool adequately with your current set up .
4. Without a thermostat, the water has no restriction and can actually cool less then with having a thermostat in.
5. Possibly check fuel mixture, timing, and gage accuracy if there seems to be no explanation.

[ChevLoRay]

I'd be sure that there is a shroud. The distance between the fan and the radiator is critical in that the fan placement within the opening in the shroud is also. The fan needs to be placed so that it pulls air through the radiator.

Coolant should be a 50/50 mix of water/antifreeze. That mixture gives the best cooling and freeze protection. More or less antifreeze will reduce the effects of the 50/50 mix.

Back to the shroud issue. I drive a school bus that has a Cummins 5.9 with an Allison 5-speed automatic. Last spring I had cooling issues with it. I found that the simple shroud that Bluebird included had been damaged by the yokels who had worked on the radiator/cooling system. So, our "mechanic" simply removed it. It wasn't but a piece of flexible rubber-like material that was approximatley 4 inches by 12 inches. Without that piece, my engine temp would climb to over 235 degrees. Today, the mech reinstalled another piece that serves to replace the damaged part. Today, with temps near 90 degrees, and sitting in traffic and idling or running down the road, the temp never got over 225 and mostly stayed at 210 or less. First time in nearly a year that it has acted normal. Mechanic was looking for stuff like a kinked hose and wanted to replace the new thermostats. Some people just don't ever learn.

[mclairmo]

I don't think you have an airflow problem since you have a mechanical fan and you still have overheating while driving around. When the truck is moving the force of the air through the radiator should be enough airflow even without a fan. I believe you have a coolant flow issue or excessive heat production. Make sure that your water pump pulley is significantly smaller than your crank pulley. This will keep the water pump spinning at the correct speed. Also, make sure that the water pump is working properly and that the impeller is not damaged, rusted or just free wheeling somehow. You may want to switch to a high volume unit. The Procomp one sold by Skip White and other Ebay vendors works well. Flowkoolers are nice, too. Make sure that the radiator is not clogged and the engine coolant passages are clear. Maybe try a good flush of the system. Make sure you are running a vacuum advance and that the carb is not running lean. Also, 100% water in the coolant system transfers heat best. Coolant is not as good at heat transfer, which is why you can only run 50% coolant. You need at least 50% water to ensure proper cooling. The coolant is actually an anti-freezing agent and includes a water pump lubricant and anti-rust agent. I run 100% distilled water and Water Wetter from Kragen or Autozone. Water Wetter eliminates the surface tension of the water so that it literally sits closer to the metal block and thus, transfers heat better. It also contains an anti-rust agent and water pump lubricant. This will cool better than anything else from my experience and is ok to use at race tracks that don't allow coolant. If you do run a T-Stat, use a high flow one, not the standard ones everyone carries. However, I am not convinced you need one out here in SoCal or Riverside. The purpose of the T-Stat is to allow the engine to get up to proper operating temp quickly so you can get going. Very necessary in cold climates and for best fuel efficiency. However, the T-Stat also restricts coolant flow and coolant flow is critical to cooling. The T-Stat can also trap air bubbles in the system which reduces heat transfer. In very warm climates where the engine will likely get up to operating temp without the T-Stat in a reasonable amount of time, I believe you can go without it. My truck does not have a T-Stat at all and it runs great, never gets too hot but still gets up to proper operating temp pretty quickly. I know others will disagree/argue with me but I've been studying/troubleshooting cooling system problems a long long time.

[Devil Pup]

Thanks for all the feed back guys. . just to go over some things, the fan shroud is the correct one for the truck/radiator and the fan that is on it stuffs this shroud. its about half way in the shroud and half way out. "perfect according to the mechanic" i recently blew up the motor due to heat when the stock gauge went out and was reading normal. so i replaced the motor, flushed the radiator and made sure that the water pump was working and put the new gauge in. so im thinkin go back to the 180 degree T-stat at least? and i will check the coolant to make sure i have the right fluids in it. anything else i should be on the look out for or that i missed? thanks again everyone, Mark

[Devil Pup]

oh also someone recommended a cowl induction hood so the heat would be able to escape from the engine compartment??

[westofb]

Originally Posted by Devil Pup

Thanks for all the feed back guys. . just to go over some things, the fan shroud is the correct one for the truck/radiator and the fan that is on it stuffs this shroud. its about half way in the shroud and half way out. "perfect according to the mechanic" i recently blew up the motor due to heat when the stock gauge went out and was reading normal. so i replaced the motor, flushed the radiator and made sure that the water pump was working and put the new gauge in. so im thinkin go back to the 180 degree T-stat at least? and i will check the coolant to make sure i have the right fluids in it. anything else i should be on the look out for or that i missed? thanks again everyone, Mark

when you replaced the motor did you upgrade any parts? lots of guys go to serpentine belt systems which can be had cheap. the water pump from the serp belt system looks the same as an old long water pump, but it is made to spin the opposite dirrection. If you have the wrong water pump (turning the wrong dirrection) no matter what you do, it will over heat! just throwing this out there, may not be the case at all, but no one else mentioned it.

Did you replace motor with a new one or junk yard find? Could have a head gasket problem? Just some points to ponder.

[Sinister]

I would have replaced the water pump when you replaced the motor.

[70k52wd]

Put a 195 t-stat in it, big block fan clutch and blade, make sure the shroud is correct fit, and happy driving. You need the 195 t-stat.

[eagleuh1]

Looks like the common factor for overheating is your radiator. Old engine overheating, new engine overheating, same radiator? Get it rodded out and flushed.

[Stocker]

All good advice above, I will agree with a 195* thermostat, no t-stat lets the coolant go through the radiator so fast it doesn't have time to cool off, if that makes sense.

One thing you didn't mention is what type of fan you have. If you have a fixed-blade or a flex fan instead of a good clutch fan, I would strongly suspect that is the problem. My factory A/C 350 has a 7-blade clutch fan and zero cooling issues.

[IAFF2407]

I had the same problem, put on a pusher fan with a 190* relay just for the stop and go driving, this helped somewhat. I thought my clutch fan was fine, it had the proper drag when cold but I changed it anyways. viola! problem solved. the clutch fan will get old and not lock up at any speed.

Al.

[Devil Pup]

that may be the issue in itself. . i dont have a clutch fan on it because it push's the fan right up against the radiator and too far into the shroud to pull any air. any way around this?? i will def put a 195 T-Stat in then. and i believe i have a 6-7 blade fan on it. ill check and get a for sure answer.

[mclairmo]

Originally Posted by Devil Pup

that may be the issue in itself. . i dont have a clutch fan on it because it push's the fan right up against the radiator and too far into the shroud to pull any air. any way around this?? i will def put a 195 T-Stat in then. and i believe i have a 6-7 blade fan on it. ill check and get a for sure answer.

It's very odd that you say that the clutch pushes the fan too close to the radiator core. There should be enough room to mount the clutch and the fan. The clutch mounts directly to the water pump and not to any spacer or extension. Are you running the proper length water pump? Is the radiator mounted farther back than stock? Just trying to figure out why you seem to have less room between the water pump and radiator than is standard.

[mclairmo]

I think it's a myth that the coolant will flow too fast to absorb heat without a T-Stat. In the real world, there are enough obstructions to coolant flow in a cooling system that allow absorbtion of heat by the water/coolant. I may be wrong, but I believe a 195 degree T-Stat will not help anything and may make your problem worse. Also, a pusher fan may just block airflow and cause more problems. How big is the radiator and how many rows? You may want to upgrade to one with more rows, like a 4 row. Also, a new radiator will usually perform better than one that has been rodded out. Also, a flush may not get all the gunk out of the radiator. Adding a clutch will not help cooling. A rigid fan should cool the engine unless the blades are flattened for some odd reason. You should not need a cowl hood to cool your engine. I would also replace that water pump since it is old and was on the old engine that blew. The radiator and water pump are still old and one of them may have caused the old engine to blow. Most mechanics I know recommend replacing the water pump and radiator on an engine rebuild and in your case, it seems even more prudent to do so.

[piecesparts]

#1 Have your radiator checked for more than a flush (get it rodded out or replaced).

#2 Put at least a 180 degree T/stat in and go with one that is noted as a "SuperStat" Every brand has one in their product line. This T/stat moderates in midrange better than a standard T/stat.

#3 Why is your fan so close to the radiator in this model of truck years? Has this truck had a different engine installed than the original? If so, was it an upgrade to a V-8 over a 6 cylilnder? Do you have the right size radiator? Go back to item #1 Replace if radiator is too small.

#4 Too much water flow or too fast of flow is just as bad as too little water flow. You have to be able to absorb the heat from the engine's components to remove heat.

#5 Do you have the right water pump? If it just happens to be a pump for a serpentine system and NOT a standard belt driven setup, then you are turning the pump the wrong direction and no cooling will be in effect.

#6 Is the fan actually moving air? Is the radiator or A/C condensor plugged with dirt or bugs? It can be as simple as that.

#7 The cowl hood will help you when in slow traffic, but on the open highway the air will go down through the hood into the engine compartment, vice going out the hood.

[69GMCLonghorn]

On something that is known to have overheating problems, I would say possibly look into a toy fan.

But fact of the matter is, when these trucks' stock cooling system is in good shape and there are no peripheral problems, they just don't overheat. If installing an electric fan is just what you want to do, that's fine. There are certainly worse things you could do. But just know that it is not a necessity to keep it running cool.

[piecesparts]

Let's go back to the first input on ths thread. You stated that you put in a new radiator, new pulleys, new engine, and you claim the system is pumping properly. The first engine blew up due to the heat, so you understand that the proplem was there before the change out of the engine. Now you have put in a set of aluminum pulleys that are the same size as before and have removed the T/stat. I would think that there has to be something that you have NOT changed that is causing the problem, since it is still present with your new setup.

Do you believe that the air flow through your radiator is good? You stated that you have a cooler for your tranny and an A/C coil up front, have you verified that the fins are clean and letting air through them to your radiator? I have an 84 truck with a stroker motor along with a tranny cooler and A/C coil with basically the same pulleys that you are running and I do not have an issue with the cooling. I used to run a standard radiator with a stock fan connected to the water pump. I now run an aluminum radiator with a set of electric fans from "BeCool" and they work great. The change was my choice, since the system was cooling properly prior to the change. I definitely would look at the coils in front of the radiator and make sure that you are getting air into the core. I would also look for ANY place that air could be "short circuiting" the radiator and not going through the fins for cooling. In other words, is it coming from behind the radiator and feeding into the fan? If the shroud is gapped improperly, that could cause this. Put at least a 180 degree T/stat in (that is what I run with no issue, but the 195 will work also). The problem is inside the engine bay and not inside the engine, it has to be part of the truck's setup--since the problem has not changed with the updates that you have performed.

[piecesparts]

There IS something that we have NOT talked about, yet. What is your timing set at on the engine? If you are running retarded too much, the eninge wioll run hot and not perform well. also, it could have been your reason for the last engine's death. just a thought.....

[Stocker]

Oops -- edited for a bonehead mistake....

[Devil Pup]

the fins on the ac cooler are fresh and still as clean as can be, the tranny cooler is as well. so i need to check the gap in the fan shroud for sure and put a T-stat in it. and to be honest i have no clue what the timing is at