I think I need a better Radiator - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**hogfarm** · 08-22-2016, 06:37 AM

My 54 with a 355 motor seems to do OK,but on the real hot days even going down the Hwy the temp climbs.The fan I installed works great,in town the fan will come on and cools it right off. The thing that bothers me is the last 10 miles to my house,it is a slow winding road up hill all the way (I climb from 150' elavation to 3000')and average 35MPH

**mr48chev** · 08-22-2016, 04:03 PM

How high is it going? 190-200-210- 225 or?

I'm not sure what temp the fan sensor is set to kick on but if it is adjustable you might set it to kick on a bit lower as it sounds like you might have an air flow issue an not be getting enough air though the radiator at that 35mph. You might even think about adding a switch to bypass the sensor in the radiator to switch the fan on manually and see if it helps with the problem.

MiraclePieCo · 08-22-2016, 06:09 PM

Read some of my recent posts on the "What did you do with your truck today" thread on this forum. I had exactly the same problem as you: truck ran cool in town with the fan on, but heated up on the highway - especially on inclines.

Running hot at cruise speed is usually an indicator of restricted air flow. My problem turned out the be the fan shroud; since a shroud covers most of the radiator it was blocking air flow. Removing the shroud cooled my truck 20* on the highway. I also relocated my transmission cooler beneath the radiator, instead of in front. And make sure your factory air deflector between grill and radiator is in good condition; I've seen them cut out for V8 installations.

Otherwise, have you blasted the bugs out of your radiator core lately?

**hogfarm** · 08-23-2016, 05:57 AM

Fan works good kicks on at 185deg,like you said works fine in town.Works fine driving down the Hwy.It's just the slow speed up hill on 90deg plus days.Engine will get up to 200deg

**hogfarm** · 08-23-2016, 05:58 AM

Also as soon a I hit the topof the hill it will be cooling down in a half miles or so

**mr48chev** · 08-23-2016, 04:53 PM

200 isn't even close to hot for that engine. you aren't dealing with a hot water 216 six you have a V8 that normally runs down the road at between 195 and 215 in the car it came from the factory in. 200 won't even get the coolant up to boiling temp where it puts pressure on the radiator cap yet.

HUSSEY · 08-23-2016, 05:02 PM

^^^^
+1 on that. It may seem to be of alarm because it's higher than your normal baseline but I would have no problem with 200° F.

My 2007 Chevy truck with a V8 runs right at 220° F all the time. Doesn't seem to matter whether it's hot/cold/idle/load or whatever.

solidaxel · 08-24-2016, 06:40 PM

Are you using a 190* thermostat?
That should keep the water at 190-200* in the engine
Is your timing adjusted properly

08-22-2016, 06:37 AM	#1
hogfarm Senior Member Join Date: Jan 2016 Location: Appleton Washington Posts: 592	I think I need a better Radiator My 54 with a 355 motor seems to do OK,but on the real hot days even going down the Hwy the temp climbs.The fan I installed works great,in town the fan will come on and cools it right off. The thing that bothers me is the last 10 miles to my house,it is a slow winding road up hill all the way (I climb from 150' elavation to 3000')and average 35MPH

08-22-2016, 04:03 PM	#2
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,705	Re: I think I need a better Radiator How high is it going? 190-200-210- 225 or? I'm not sure what temp the fan sensor is set to kick on but if it is adjustable you might set it to kick on a bit lower as it sounds like you might have an air flow issue an not be getting enough air though the radiator at that 35mph. You might even think about adding a switch to bypass the sensor in the radiator to switch the fan on manually and see if it helps with the problem. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

08-22-2016, 06:09 PM	#3
MiraclePieCo Registered User Join Date: Sep 2014 Location: USA Posts: 2,249	Re: I think I need a better Radiator Read some of my recent posts on the "What did you do with your truck today" thread on this forum. I had exactly the same problem as you: truck ran cool in town with the fan on, but heated up on the highway - especially on inclines. Running hot at cruise speed is usually an indicator of restricted air flow. My problem turned out the be the fan shroud; since a shroud covers most of the radiator it was blocking air flow. Removing the shroud cooled my truck 20* on the highway. I also relocated my transmission cooler beneath the radiator, instead of in front. And make sure your factory air deflector between grill and radiator is in good condition; I've seen them cut out for V8 installations. Otherwise, have you blasted the bugs out of your radiator core lately? __________________ 1951 Chevy Panel Truck Last edited by MiraclePieCo; 08-22-2016 at 06:19 PM.

08-23-2016, 05:57 AM	#4
hogfarm Senior Member Join Date: Jan 2016 Location: Appleton Washington Posts: 592	Re: I think I need a better Radiator Fan works good kicks on at 185deg,like you said works fine in town.Works fine driving down the Hwy.It's just the slow speed up hill on 90deg plus days.Engine will get up to 200deg

08-23-2016, 05:58 AM	#5
hogfarm Senior Member Join Date: Jan 2016 Location: Appleton Washington Posts: 592	Re: I think I need a better Radiator Also as soon a I hit the topof the hill it will be cooling down in a half miles or so

08-23-2016, 04:53 PM	#6
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,705	Re: I think I need a better Radiator 200 isn't even close to hot for that engine. you aren't dealing with a hot water 216 six you have a V8 that normally runs down the road at between 195 and 215 in the car it came from the factory in. 200 won't even get the coolant up to boiling temp where it puts pressure on the radiator cap yet. __________________ Founding member of the too many projects, too little time and money club. My ongoing truck projects: 48 Chev 3100 that will run a 292 Six. 71 GMC 2500 that is getting a Cad 500 transplant. 77 C 30 dualie, 454, 4 speed with a 10 foot flatbed and hoist. It does the heavy work and hauls the projects around.

08-23-2016, 05:02 PM	#7
HUSSEY Registered User Join Date: May 2013 Location: Kansas City Posts: 572	Re: I think I need a better Radiator ^^^^ +1 on that. It may seem to be of alarm because it's higher than your normal baseline but I would have no problem with 200° F. My 2007 Chevy truck with a V8 runs right at 220° F all the time. Doesn't seem to matter whether it's hot/cold/idle/load or whatever. __________________ My 49 AD Build / S10 Chassis -- Thread -- Pictures -- S10 Conversion Mounts

08-24-2016, 06:40 PM	#8
solidaxel Registered User Join Date: Dec 2002 Location: Cactus Patch So. Az Posts: 4,749	Re: I think I need a better Radiator Are you using a 190* thermostat? That should keep the water at 190-200* in the engine Is your timing adjusted properly __________________ 53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42



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