Cooling system issue....

[wwotr]

I have a 72 GMC, with a 350 put in by the P.O.
I was told it out of a 94 GMC Truck 1500.

When I lived up in Nor Cal, it would run at 190 Degrees,
all day in 90 degree weather.
Today was the 1st time I've taken it out in the Heat,
(since moving down here to So Cal, Palm Springs Area).
Left the House at 11 am, and it was 100 Degrees out.
Drove to the Gas Station (about 9 miles away), on City Streets doing 45-55 MPH, with the A/C Running.
Didn't even bother to look down at the Temp Gauge until after I got Gas.
It seemed a little hard to start after I filled up.
Looked at the Temp Gauge and it read about 210.
I started driving, and got about 1/4 of a mile and the Temp stayed around 205.
I took it straight home, as I knew if I got caught,
in any "Stop-n-Go" Traffic, it would overheat on me.
That got me to start looking under the Hood.

What I have is a Serpentine Belt System, with No Shroud and what looks to be a Cheap Brand "Flex Fan", mounted on a 2" Hub.
Now the Blades are about 2" from the radiator.

My 1st thought was to get a Shroud, Clutch Fan and Flush the Cooling System, and re-fill the Anti Freeze.

Money IS an issue, so if it WEREN'T, I'd be installing Dual Cooling Fans, and wouldn't need to post here.
I'm at the Tip of the Iceberg, looking through the Internet and researching this issue and what's available.
I was wondering if someone has made a shroud to fit our 67-72 Chevy/GMC's that has an electric Fan built into it already?

I was wondering if I'm headed in the right direction with the Shroud/Clutch Fan idea above, or if I should go straight to a electric cooling Fan?
I've seen some single Fans that clip onto your existing radiator ect.

This is a real Generalized question/Post.
I was just wondering what others did with the same problem as I have, and how you corrected it.

[Boog]

Roger is that a 4 row radiator? If so it should be plenty.
That "cheap" flex fan may be suspect.
2" from the rad isn't bad but could be better with a shroud. Or you might consider an electric pusher fan in front of the condensor.
Does it have a 160 or 195* thermostat?

[wwotr]

Originally Posted by Boog

Roger is that a 4 row radiator? If so it should be plenty.
That "cheap" flex fan may be suspect.
2" from the rad isn't bad but could be better with a shroud. Or you might consider an electric pusher fan in front of the condensor.
Does it have a 160 or 195* thermostat?

I believe its a 160, just because MOST of the time (up North),
that sucker would be HARD PRESSED to reach 190.
I'd say 75 % of the time it was running 165-180 tops.
Rarely would it ever get to 190.

So would this "Pusher Fan" be in addition to a shroud?
(Pusher Fan on the outside and shroud on the inside)?

[Lee H]

Please check the accuracy of the gauge before throwing any money at it. Then start with shroud followed by clutch fan. In stop and go with AC, 21x in 100 degree plus is not that bad.
Posted via Mobile Device

[wwotr]

Originally Posted by Lee H

Please check the accuracy of the gauge before throwing any money at it. Then start with shroud followed by clutch fan. In stop and go with AC, 21x in 100 degree plus is not that bad.
Posted via Mobile Device

Thanks Lee.
Gauges are fine and have all been re-wired/Tested when the Truck was in the Shop earlier this year. This has been the longest drive I've taken it on,
(in the Summer),since moving here 10 Months ago.
Before thisd I only took it out between November thru April,
because its so mild here, but I goit tired of watching it sit in the Garage,
so since it wasn't 119 out, I thought I'd take it for a "Test Summer Drive", before REALLY heading out for a longer Cruise.

[71swb4x4]

Have you seen the pictures of the flex fan blades through the hood? Scary deal.
I am certain that with a stock fan and shroud you won't have any problems. It may not be so simple though. That is a reverse rotation water pump right? So you would need to get a newer fan, but the older shroud. It may take a little work but I am sure you can get it to work.

[Andy4639]

My 1st question here. Is that flex fan blades for a reversable rotation water pump?
It looks to me like it's for a normal rotation pump which would mean it's not doing anything for you.
Can you crank the truck up and see if you feel air being pulled through the grille with it sitting still. If not get the correct clutch fan since you have AC and forget about it. Well you need a shroud also.

[wwotr]

Originally Posted by Andy4639

My 1st question here. Is that flex fan blades for a reversable rotation water pump?
It looks to me like it's for a normal rotation pump which would mean it's not doing anything for you.
Can you crank the truck up and see if you feel air being pulled through the grille with it sitting still. If not get the correct clutch fan since you have AC and forget about it. Well you need a shroud also.

I havent yet, but I was told by a Friend to start it up and drape a tee shirt in front of the Grill, to see if it Pulls/Blows it.

[ChevLoRay]

AC trucks had 4-row radiators, with shrouds and thermostatic fan clutches. I'm thinking that if you don't have all of those, you're probably going to overheat....as it has.

[RUSHNBOBO]

Originally Posted by wwotr

What I have is a Serpentine Belt System, with No Shroud and what looks to be a Cheap Brand "Flex Fan", mounted on a 2" Hub.
Now the Blades are about 2" from the radiator.

My 1st thought was to get a Shroud, Clutch Fan and Flush the Cooling System, and re-fill the Anti Freeze.

Money IS an issue, so if it WEREN'T, I'd be installing Dual Cooling Fans, and wouldn't need to post here.
I'm at the Tip of the Iceberg, looking through the Internet and researching this issue and what's available.
I was wondering if someone has made a shroud to fit our 67-72 Chevy/GMC's that has an electric Fan built into it already?

I was wondering if I'm headed in the right direction with the Shroud/Clutch Fan idea above, or if I should go straight to a electric cooling Fan?
I've seen some single Fans that clip onto your existing radiator ect.

First off you need to determine if it's a air flow problem a coolant flow problem or possibly both, if it's getting hot going over 45-50 mph it ain't the fan. Way more air flows through your grill at those speeds than any fan setup.....matter of fact most automatic controlled fans aren't even doing anything at 50 mph no matter how hot it is. The fan is really for stop and go or slow speed driving. 4000+ cfm can flow through most grills at 50mph

So take notes on when its overheating both sitting still and cruising. If it ONLY overheats when setting still its most likely a airflow problem, inadequate or not properly working fan setup, or possibly dirty or crushed fins. If it ONLY overheats cruising over 50 mph it's most likely a fluid flow problem.

If it's overheating all the time ...this is usually some sort of restriction in fluid flow not air flow. Flush the system chemically and inspect the best you can with a flashlight inside the radiator for heavy deposits (you may have to have a shop clean it if its really bad.) Now take the radiator cap, and the thermostat off and throw them in the trash ...why? because there cheap and the easiest things to eliminate, these two items alone can cause all sorts of problems and together they only cost between $15 and $20 tops.

Make sure to use the correct temp thermostat for your engine...removing the thermostat WILL NOT fix overheating problems, and will make your engine run worse because of the constant temp fluctuations.

Now refill the system like this: drive the front wheels up on ramps so the cap is the absolute highest place in the system and turn the heater on high, fill the radiator to the top and start the engine ...leave the cap off!!!...now when the thermostat opens the level should drop considerably, keep adding coolant and wait till it cycles for a while. If you have a closed system that has a reservoir and recirculates, fill it completely full. If you don't have a recirculating system leave a couple inches at the top for expansion, otherwise it will just blow the excess out through the cap and on the ground. Now put the cap on and fill the reservoir (if you have one) to the mark only. Use the least amount of antifreeze you can get away within your climate conditions (straight water cools better than any antifreeze mixture)....but you need some in there for anti corrosion purposes and it does raise the boil over point a little ....along with the pressure in the system.

If all this doesn't solve the problem the water pump may be inadequate for your motor .... though this is very unlikely until you get into the high rpm modified engines.

If it still overheats, write back and describe the details and we'll get it figured out.

All right I'm spent ....hope this helps ...later.......Rushnbobo

[leddzepp]

lots of good advice here.

i am running a big block with a/c full blast all the time under the same conditions you are. i have the factory setup and have never had an overheating issue. if you never had problems before moving to palm springs, i would suspect your cooling system is functioning and adequate. the first problem i see is the lack of a shroud. air takes the least path of resistance, and without a shroud to channel it through the radiator, it largely goes around it. many other things listed above could also be the issue.....but i would definitely start with a shroud. if that does not solve the issue, it is not money wasted because you need it regardless.
Posted via Mobile Device

[fastwillie 696969]

wet wetter to coolant

[chevytruckluver]

Originally Posted by fastwillie 696969

wet wetter to coolant

I think he meant to say "Water Wetter" a cooling system additive by Redline

[fastwillie 696969]

Originally Posted by chevytruckluver

I think he meant to say "Water Wetter" a cooling system additive by Redline

yeah water wet same thing or even 40 below is good to add

[lolife99]

The serpentine set-up require a fan for the reverse rotation of the water pump.
That appears to be the correct fan for that application.

I would install a correct fan shroud and clutch fan (reverse rotation), and you should be good!

[wwotr]

Thanks Guys.
An update......

I went looking for a Fan Shroud, and every aftermarket parts dealer seemed to be in the $99.00-$140.00 Range!

I found a new shroud, Clips, Screws at LMC, shipped to my Door for $78.00.
Gonna have my Mechanic get the Clutch Fan.
So I'm gonna have the Shroud put on, New Clutch Fan, New 160 Degree Thermostat and Flush the Cooling System and add new Coolant.

One question though....
When I looked at Clutch Fans online in the application, they wanted to know the "Rear end Gear Ratio"!!??
I thought maybe I was outta my mind until my Mechanic got asked the SAME THING, by HIS Parts Guy.

I'm pretty sure its got to do with the RPM's the Engine will turn, with the Clutch Fan that would Determine WHAT the Correct Fan is?

I thought the more knowledgable could simplify/spell it out for me?

[chevytruckluver]

I would run a 180 deg thermostat if it were me. If you think about this when the water is circulating through the engine it is stopped inlarge part by the t-stat until the t-stat reaches its setpoint in your case 160 then it opens and then water moves through the radiator. When the t-stat is closed and water is stopped in the engine it is also stopped in the radiator allowing the air moving through the radiator to cool the water back down. If you run a cooler t-stat the water wont stay in the radiator long enough to cool back down. just my .02
good luck with it

[406 Q-ship]

Originally Posted by wwotr

Thanks Guys.
An update......

I went looking for a Fan Shroud, and every aftermarket parts dealer seemed to be in the $99.00-$140.00 Range!

I found a new shroud, Clips, Screws at LMC, shipped to my Door for $78.00.
Gonna have my Mechanic get the Clutch Fan.
So I'm gonna have the Shroud put on, New Clutch Fan, New 160 Degree Thermostat and Flush the Cooling System and add new Coolant.

One question though....
When I looked at Clutch Fans online in the application, they wanted to know the "Rear end Gear Ratio"!!??
I thought maybe I was outta my mind until my Mechanic got asked the SAME THING, by HIS Parts Guy.

I'm pretty sure its got to do with the RPM's the Engine will turn, with the Clutch Fan that would Determine WHAT the Correct Fan is?

I thought the more knowledgable could simplify/spell it out for me?

Well to make it easy for you, the truck that you would be using the fan from had 3.08, 3.42, and 3.73 as the common gear ratio. Pick something close what is in your truck. Besides if it heat soaked when getting gas and only got to 210° and ran around town at 205° in 100° outside temp, then you do not have a overheating problem at all. It still needs a clutch fan and shroud (all vehicles should have them).

[landsurvey1]

Originally Posted by chevytruckluver

I would run a 180 deg thermostat if it were me. If you think about this when the water is circulating through the engine it is stopped inlarge part by the t-stat until the t-stat reaches its setpoint in your case 160 then it opens and then water moves through the radiator. When the t-stat is closed and water is stopped in the engine it is also stopped in the radiator allowing the air moving through the radiator to cool the water back down. If you run a cooler t-stat the water wont stay in the radiator long enough to cool back down. just my .02
good luck with it

I agree, I live in Phoenix and run a 180 degree thermostat in a BB454. I average around a 195 degree temp with the a/c on.

[RUSHNBOBO]

Originally Posted by chevytruckluver

I would run a 180 deg thermostat if it were me. If you think about this when the water is circulating through the engine it is stopped inlarge part by the t-stat until the t-stat reaches its setpoint in your case 160 then it opens and then water moves through the radiator. When the t-stat is closed and water is stopped in the engine it is also stopped in the radiator allowing the air moving through the radiator to cool the water back down. If you run a cooler t-stat the water wont stay in the radiator long enough to cool back down. just my .02
good luck with it

ummm...not really...this is copied from Stewart Warner FAQ

"A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures."

Basically moving coolant is better than idle coolant....and a higher velocity is better than slow moving...thats why we have high flow water pumps if slow or idle were better we should all use stock flow pumps ...even race cars

[RUSHNBOBO]

Originally Posted by 406 Q-ship

Besides if it heat soaked when getting gas and only got to 210° and ran around town at 205° in 100° outside temp, then you do not have a overheating problem at all. It still needs a clutch fan and shroud (all vehicles should have them).

A well designed and properly operating system can and ideally should run at the temp of the themostat once the motor warms up. no more no less...thats why its called a thermostat ...it automatically regulates the flow to keep the temp at the same degree.

Can you go a little over? sure ...but a system with the right combo of water pump, radiator, thermostat, fan, and shroud. Should not go over the thermostat temp, if it does something is either not adequate enough for the application or is not functioning correctly.

I run a 4 row copper brass radiator, Stewart Warner high velocity pump and a 160 degree thermostat, with a stock clutch fan setup.

With a 400 hp 355 sbc I can drive up a 10 mile grade with a C/30 dually weighing 4400 lbs........ at 20-30 mph on a 100 degree day and the needle never moves off 160. It will also sit at idle in traffic at the same temps ....still never overheat. This is because the components are very efficient at heat exchanging.

[landsurvey1]

Originally Posted by RUSHNBOBO

A well designed and properly operating system can and ideally should run at the temp of the themostat once the motor warms up. no more no less...thats why its called a thermostat ...it automatically regulates the flow to keep the temp at the same degree.

Can you go a little over? sure ...but a system with the right combo of water pump, radiator, thermostat, fan, and shroud. Should not go over the thermostat temp, if it does something is either not adequate enough for the application or is not functioning correctly.

I run a 4 row copper brass radiator, Stewart Warner high velocity pump and a 160 degree thermostat, with a stock clutch fan setup.

With a 400 hp 355 sbc I can drive up a 10 mile grade with a C/30 dually weighing 4400 lbs........ at 20-30 mph on a 100 degree day and the needle never moves off 160. It will also sit at idle in traffic at the same temps ....still never overheat. This is because the components are very efficient at heat exchanging.

Just curious, I am no mechanic by any means. Why would you want your engine to run at such a cool temp. I thought the most efficient engine temp. is around 195 degrees. All the new engines run at 210 all day long?

[RUSHNBOBO]

Originally Posted by landsurvey1

Just curious, I am no mechanic by any means. Why would you want your engine to run at such a cool temp. I thought the most efficient engine temp. is around 195 degrees. All the new engines run at 210 all day long?

New motors are a completely different animal than the old technology...most of the high degree thermostats have to do with the emissions and new combustion chamber technology. Most all early Gen 1 sbc came from the factory with 180 degree thermostats if 195 would have been more optimal for these engines that's what they would have used. Especially pre 1971 when smog equip was virtually non existent. Horsepower was king and the comparatively low tech motors of the time were built to run best overall at this temp.

A 160 degree temp can sometimes make a little more power, and curb detonation issues in some high compression engines. But the downside can be too cold of a cumbustion chamber temp which will eventually lead to excessive carbon buildup and possibly an incomplete burn. So on the street a 180 in gen 1 sbc is usually considered the best compromise for both power and clean efficient combustion.

I swapped out the 180 to the 160, because of the detonation, but have since installed an in cab MSD ignition dialback which I can on the fly, adjust the initial and overall timing when I change elevation. Where I live at 2000 ft. the setting is perfect, if I drive to 1000 ft. it will begin to ping, "more dense air". Since max power is made right on the edge of ping or no ping I can now just dial it back to the sweet spot a couple degrees at a time.
I will eventually go back to the 180 so I don't worry about carbon buildup problems and possibly "loading up" the plugs at idle.

[wwotr]

Originally Posted by landsurvey1

I agree, I live in Phoenix and run a 180 degree thermostat in a BB454. I average around a 195 degree temp with the a/c on.

Landsurvey...
Is that driving around town in stop-n-Go traffic?
That's my issue, as I rarely do any Freeway Driving.

[GASoline71]

Originally Posted by 406 Q-ship

Well to make it easy for you, the truck that you would be using the fan from had 3.08, 3.42, and 3.73 as the common gear ratio. Pick something close what is in your truck. Besides if it heat soaked when getting gas and only got to 210° and ran around town at 205° in 100° outside temp, then you do not have a overheating problem at all. It still needs a clutch fan and shroud (all vehicles should have them).

Yep... those 1990's TBI 350's had 195 degree t-stats from the factory. My 1994 GMC ran around 200 to 210 all the time. Normal operating temp. My '06 Silverado 2500HD runs around 210 all the time. Whether it's hot, cold, towing, or hauling. So if your around 205 - 210 in the 100 degree heat... I'd say it's doing okay.

Sticking a 160 degree t-stat won't help. The earlyier 350's had 180 t-stats in them. Thats' all I have ran in all my 1st gen, non-fuel injected engines. No probs.

Gary