Cooling question

[mtully79]

I recently took out my radiator and replaced it with a 3 row aluminum. I also added (2) 12" fans that came in a kit with a control and relay that kicks on at 185 and turns off at 170. I took out my 180 degree thermostat and replaced it with a 160 to run with the controller/relay set up. At idle it worked peachy, coming on and cutting off consistently, I took it on the highway for 20 mins and when I parked it the fans kicked on as usual, but wouldn't cut off as the engine temp didn't drop low enough.

My question is do these 350s run hot? I spoke with the radiator company and they assured me the setup was right for my truck, but I'm wondering if I need to go with a larger fan? Plan this weekend is to plug in a temp gauge and see what's actually happening with the temps when the controller asks for the fans to cut on and off. Has anyone seen a similar issue?

[Tom Vogel]

You say when "you parked it". Does that mean after you shut off the motor? If so, Im surprised the fans dont shut off after you kill the motor.

[mtully79]

No I parked in in the driveway and let it run to see what she did after being out on the highway. Temp never dropped low enough to kill the fans after running for nearly 15 mins in park.

[jaros44sr]

Any chance you have air in the system, do the hoses get hot?

[ssxty8]

Make sure you don't have this problem; hot air recirculation. Some radiator installations allow air from the hot side of the radiator to flow back around to the cool side, and be heated further. This continues, and the system gets hotter and hotter. Recirculation is usually more a problem on parked cars, or at low speed, as the forward motion does not create enough air flow. For that reason newer cars have this plastic cover under the engine. Another issue some people argue is, excessive water flow, which didn't let the water do its job of extracting the heat from the engine block.
"Peter Bryant,the designer of the Shadow Can-Am and Formula cars states in one of his books that they kept putting biggger and bigger radiators on the first Shadow Can-Am car and all that was wrong was that the water pump was moving the water to fast and it did not stay in the radiators long enough to cool." Although a low water flow can adversely affect cooling system too.

[mtully79]

Originally Posted by jaros44sr

Any chance you have air in the system, do the hoses get hot?

Filled the radiator and let it gurgle, got all the air out. Temp into radiator was around 160 and temp out was about 140 measured with a laser thermometer. Hoses never got above 185. The rain puts a damper on me working on it, hoping to get back into it tomorrow.

I'll he knows out the water circulation, although my old single core radiator worked fine...it would overheat in traffic and I think when I had a leak plugged they gummed it up. I hope to have more info tomorrow.

[mtully79]

Originally Posted by ssxty8

Make sure you don't have this problem; hot air recirculation. Some radiator installations allow air from the hot side of the radiator to flow back around to the cool side, and be heated further. This continues, and the system gets hotter and hotter. Recirculation is usually more a problem on parked cars, or at low speed, as the forward motion does not create enough air flow. For that reason newer cars have this plastic cover under the engine. Another issue some people argue is, excessive water flow, which didn't let the water do its job of extracting the heat from the engine block.
"Peter Bryant,the designer of the Shadow Can-Am and Formula cars states in one of his books that they kept putting biggger and bigger radiators on the first Shadow Can-Am car and all that was wrong was that the water pump was moving the water to fast and it did not stay in the radiators long enough to cool." Although a low water flow can adversely affect cooling system too.

The temp never climbed, just held steady around 150 and didn't allow the thermostat to close and shut off the fans. Thanks for all that info...gives me more things to check and helps me isolate the issue.

[mtully79]

Did some looking around and found that the fans I had didn't cover enough of the radiator, on top of that they were only pushing around 2500 CFM and a few sites said I needed roughly 3500 CFM. Going to go with a 14" fan(16" are too big and won't fit my application), along with replace the water pump.

Gonna search some parts out and hope to have it all buttoned up by the 4th of July.

[jaros44sr]

Sounds like you have all your bases covered, let us know how you make out....

[mtully79]

Ordered up Spal 14" fans which will give me the 3500 cfm and will also get a stewart phase 2 pump. Need to order another relay for the fans as they'll put out more amps than what I had originally. I'll post some pics when I start the install.

[mtully79]

Installed the new parts over the weekend which included a Stewart Phase 2 water pump, new thermostat, new relay, 2 new Spal 14" fans and the blazer seems to be happy. Fans kick on around 184 and off around 170, with a run time of about 90 seconds which I'm thrilled with. New pump pushed water through the coils like a champ, with a 24 degree difference between the hoses. Had to cut my fan shroud to fit the larger fans and fabbed a piece of aluminum to fill the void, see pics below. Truck was tested in 90 degree weather on the highway and performed like a champ!

It never ends though, on my ride back to the house the brakes got real squishy and the brake light came on...fun!

[mtully79]

Pics of the gap after cutting out larger diameter for fans.

[mtully79]

Stewart's pump wasn't vented at the base, they cover the hole going into the block and instead use a vented thermostat to equal out the pressure. Pretty cool engineering that I learned during the build.

[tjsblazer]

What Radiator did you get?

[jaros44sr]

Nice work tully, thanks for posting up

[mtully79]

TJ, I went with a 3 core aluminum radiator from DNAMotoring. It was part of a kit that included the relay and (2) 12" fans for $210, although I scrapped the fans for a set of Spal 14" S blades. Radiator fins are noticeably thinner than the radiator I had in it, and I needed more boost from the water pump to get better circulation, hence the phase 2 from Stewart.

Thanks Jim! Following your thread...can't wait to see it on the road!