Large fan no shroud or small fan and shroud?

[Mark1972]

I'll look at my options for sealing the shroud when I get the car back. It's currently at the transmission shop I use where they are installing a new auxiliary tranny cooler and new cooler lines. I made kind of a mess of the cooler lines last year after the 440 went in. Also, with headers, it makes it even more tight where the lines go in to the tranny. I should have the car back Friday.

 

[Mark1972]

So an update on my cooling situation. A Hayden tranny cooler was installed in front of the rad, along with new tranny cooler lines throughout. The original clutch fan, a 7 blade, 20" diameter unit was removed, and replaced with a 6 blade, 17" diameter flex fan, which allows a shroud to be used. I also swapped in a 160 degree stat from the old 180. As well, and don't ask me why I didn't do this before, I installed a mechanical Auto Meter water temp gauge, while keeping the original gauge in the dash working so I can finally see the actual temps and how hot I was running according to the old gauge. A few hours ago after idling up to temp, allowing the stat to open, I topped up the rad, and went for a drive. Now it's only 78F here today, after a few days of 90-95F. While driving at 30-40mph, the temps stayed around 165. Any longer stops, like 5 minutes at idle, temps up to 180-190. 15 minutes at idle, after a 30 minutes drive, and 215. At 215, I shut it off. I'm running premix Prestone. I have some concerns and need advice, as usual, lol.
What temp would be considered maximum? As in if you hit that temp you would shut the motor off and let it cool down. Is it possible that the 20" 7 blade clutch fan was cooling better without a shroud than the 17" 6 blade fixed fan is with a shroud? I guess I can test the theory. What about Water Wetter? If the high temps don't change with either fan, any thoughts what to try next? These scorching summer temps have me keeping my car in the garage instead of enjoying it until I can figure this out.

 

[Ron H]

Posted earlier about some things I did to reduce temp. Some will disagree, but I was never a fan of a flex blade fan (there's a pun here huh). What kind of shroud was installed and how far from the rad is the fan sitting? Some aftermarket shrouds can be a problem creating a wind turbulence cooling everything but the motor. As mentioned, I reduced the ratio of coolant to around 70/30-ish as coolant can retain heat and used water-wetter. My ride never sees winter driving and sits in a heated garage. I reduced the weight of the engine oil as this can be an enemy of motor cooling (if using heavy visc oil). Did this work? All I can say is when I did all this and da other chit I posted - I got lower temps...

 

[oldbee]

From personal experience, a fan shroud is worth it's weight in gold.

For what it's worth, when I got my Road Runner, it was running 210° or more. I replaced the OEM 190° stat with a 180° and added a shroud. Now I rarely run over 190° with an OEM radiator and OEM 7 blade direct drive fan.

Don't listen to Ranger, he's a choke expert. Just kidding.( He always agrees with me on choke questions).Shrouds are always better!

 

[diesel_lv]

So an update on my cooling situation. A Hayden tranny cooler was installed in front of the rad, along with new tranny cooler lines throughout. The original clutch fan, a 7 blade, 20" diameter unit was removed, and replaced with a 6 blade, 17" diameter flex fan, which allows a shroud to be used. I also swapped in a 160 degree stat from the old 180. As well, and don't ask me why I didn't do this before, I installed a mechanical Auto Meter water temp gauge, while keeping the original gauge in the dash working so I can finally see the actual temps and how hot I was running according to the old gauge. A few hours ago after idling up to temp, allowing the stat to open, I topped up the rad, and went for a drive. Now it's only 78F here today, after a few days of 90-95F. While driving at 30-40mph, the temps stayed around 165. Any longer stops, like 5 minutes at idle, temps up to 180-190. 15 minutes at idle, after a 30 minutes drive, and 215. At 215, I shut it off. I'm running premix Prestone. I have some concerns and need advice, as usual, lol.
What temp would be considered maximum? As in if you hit that temp you would shut the motor off and let it cool down. Is it possible that the 20" 7 blade clutch fan was cooling better without a shroud than the 17" 6 blade fixed fan is with a shroud? I guess I can test the theory. What about Water Wetter? If the high temps don't change with either fan, any thoughts what to try next? These scorching summer temps have me keeping my car in the garage instead of enjoying it until I can figure this out.

Measure the inside diameter of your shroud. A factory shroud for a 26" radiator is about 21" diameter, at least my '67 factory one is. More than 1" between fan tips and shroud reduces fan efficiency. If yours is 17" fan and 21" opening, you are not going to cool properly at idle. A 6 blade 17" fan will be very inefficient at idle. An 18" 7 blade is the appropriate fan for big block w automatic n a/c. I'm running a serpentine so I had to change my fan to a counter-clockwise fan, I'm using 19" 11 blade in stock shroud and 180 t-stat. 2 weeks ago in 125° temps, after 30 minute drive then idling for 10 minutes w a/c on, my engine was 222°. No boil over or puking. Start driving n temps went back down, no runaway overheating.

 

[Mark1972]

Posted earlier about some things I did to reduce temp. Some will disagree, but I was never a fan of a flex blade fan (there's a pun here huh). What kind of shroud was installed and how far from the rad is the fan sitting? Some aftermarket shrouds can be a problem creating a wind turbulence cooling everything but the motor. As mentioned, I reduced the ratio of coolant to around 70/30-ish as coolant can retain heat and used water-wetter. My ride never sees winter driving and sits in a heated garage. I reduced the weight of the engine oil as this can be an enemy of motor cooling (if using heavy visc oil). Did this work? All I can say is when I did all this and da other chit I posted - I got lower temps...

The shroud is a classic plastic Mopar shroud from Mancini racing. I had read that they pretty much bolted up to my Champion CC375 rad, and with a little work, it did. There is 1" between the fan and the radiator, as was suggested in the instructions of the fan. A spacer was installed to make this distance possible. There is a 3/4" gap between the rad and the shroud though, which I must seal up, as you can feel air pulling thru there which if course takes away from the air being pulled thru the rad. I really need to get that done, and since my car also sits in heated storage during winter, I'll also adjust my glycol/water ratio, and use Water Wetter. Then I'll see what happens. I run Driven 10w40 high zinc hotrod oil, as this was suggested by the engine builder. Not sure if I'll change that or not. The diameter of my shroud and fan is a problem I'll need to address as well.

 

[RJRENTON]

Posted earlier about some things I did to reduce temp. Some will disagree, but I was never a fan of a flex blade fan (there's a pun here huh). What kind of shroud was installed and how far from the rad is the fan sitting? Some aftermarket shrouds can be a problem creating a wind turbulence cooling everything but the motor. As mentioned, I reduced the ratio of coolant to around 70/30-ish as coolant can retain heat and used water-wetter. My ride never sees winter driving and sits in a heated garage. I reduced the weight of the engine oil as this can be an enemy of motor cooling (if using heavy visc oil). Did this work? All I can say is when I did all this and da other chit I posted - I got lower temps...

What were your before and after temperatures?? One degree differences or 10 degree or ????. Yes....reduction of coolant concentrations can be beneficial, as it allows the coolant's specific heat characteristics to transfer the entrained heat slightly more effectively but at the cost of lower corrosion inhibitors effectiveness. A "water wetter" is nothing more than an ionic surfactant designed to reduce the inherent surface tension of water. Perhaps you could consider using "FINISH" jet dry additive (as recommended by your wife's dishwasher manufacturer), which is the same thing as your considerably more expensive water wetter at the auto parts store. They are both ionic surfactants...... points to ponder.....
BOB RENTON

 

[Ron H]

What were your before and after temperatures?? One degree differences or 10 degree or ????. Yes....reduction of coolant concentrations can be beneficial, as it allows the coolant's specific heat characteristics to transfer the entrained heat slightly more effectively but at the cost of lower corrosion inhibitors effectiveness. A "water wetter" is nothing more than an ionic surfactant designed to reduce the inherent surface tension of water. Perhaps you could consider using "FINISH" jet dry additive (as recommended by your wife's dishwasher manufacturer), which is the same thing as your considerably more expensive water wetter at the auto parts store. They are both ionic surfactants...... points to ponder.....
BOB RENTON

I don't recollect the temps Bob - been about 3 years. My dash gauge pert near maxed out shutting it down to cool down and when using a hand-held thermo at the thermostat seemed as though the gauge wasn't far off...220-ish. Didn't take long before watching my gauge get near max maybe a 25 mile cruise. On the wetter thing...no debate hey, something I didn't think about.

 

[Mark1972]

What were your before and after temperatures?? One degree differences or 10 degree or ????. Yes....reduction of coolant concentrations can be beneficial, as it allows the coolant's specific heat characteristics to transfer the entrained heat slightly more effectively but at the cost of lower corrosion inhibitors effectiveness. A "water wetter" is nothing more than an ionic surfactant designed to reduce the inherent surface tension of water. Perhaps you could consider using "FINISH" jet dry additive (as recommended by your wife's dishwasher manufacturer), which is the same thing as your considerably more expensive water wetter at the auto parts store. They are both ionic surfactants...... points to ponder.....
BOB RENTON

It's hard to give before and after because I've only driven the car a few times this year, and outdoor temps have changed wildly. But, now that I have an actual gauge, I'll be able to give more accurate numbers. I will say though that there has been no reduction of temps with this fan/shroud set up from the old fan/no shroud setup. As was pointed out earlier, my fan and shroud diameter are not sized correctly.

 

[Ranger16]

What temp would be considered maximum? As in if you hit that temp you would shut the motor off and let it cool down.

For what it's worth, first year I had this car ('69 Road Runner - 383) I was stuck in a long traffic jamb at the Power Tour. Factory fan and radiator, no shroud and factory thermostat (190°). Temp climbed to 230°. I was sweating it, expecting vapor lock, but it never happened. Just an observation, not a recommendation.

P.S.
After I got home I went to a 180° stat and added a shroud. I rarely ever go over 190° now.

 

[diesel_lv]

A larger diameter fan and definitely close off the gap between shroud n radiator. I use the 2 inch wide metal a/c duct tape on mine. Top n bottom. I've also fabbed up a large sheet metal cover over the top of the hood latch area and ducts between headlight buckets and front of radiator to direct all air through radiator, not allowing any around it.

 

[RJRENTON]

A larger diameter fan and definitely close off the gap between shroud n radiator. I use the 2 inch wide metal a/c duct tape on mine. Top n bottom. I've also fabbed up a large sheet metal cover over the top of the hood latch area and ducts between headlight buckets and front of radiator to direct all air through radiator, not allowing any around it.

WHEN the vehicle came with the factory designed and installed A/C system, especially with a B/RB engine (NOT INCLUDING THE HEMI OR 440+6), the car came with a 2" air dam projecting down from the bottom core support, the width of the core support, a flexible rubber air dam across the top width of the core support to force all air flow thru the condenser and radiator, a thermal drive fan clutch with a 18" diameter, 20° pitch angle., 7 blade fan with shroud, and an overdrive water pump sheave (~ 2.5x the crank shaft diameter sheave) to provide high velocity coolant flow thru the engine and radiator AND a radiator with 18-20 fins/inch of surface area for maximum heat transfer efficiency and a 16# cap to increase the boiling point of the 50%/50% coolant to 265°F. Out of curiosity, WHY would you not try and replicate this design if you were having temperature issues? AND, where did the 190°- 200° F not to exceed number become the gospel number? My RS23V0A****** GTX will run between 190-220°F on a hot day (95+ degrees) with out the world coming to an end. Just my opinion of course.
BOB RENTON

 

[SuperRatBastid]

PM sent

 

[diesel_lv]

WHEN the vehicle came with the factory designed and installed A/C system, especially with a B/RB engine (NOT INCLUDING THE HEMI OR 440+6), the car came with a 2" air dam projecting down from the bottom core support, the width of the core support, a flexible rubber air dam across the top width of the core support to force all air flow thru the condenser and radiator, a thermal drive fan clutch with a 18" diameter, 20° pitch angle., 7 blade fan with shroud, and an overdrive water pump sheave (~ 2.5x the crank shaft diameter sheave) to provide high velocity coolant flow thru the engine and radiator AND a radiator with 18-20 fins/inch of surface area for maximum heat transfer efficiency and a 16# cap to increase the boiling point of the 50%/50% coolant to 265°F. Out of curiosity, WHY would you not try and replicate this design if you were having temperature issues? AND, where did the 190°- 200° F not to exceed number become the gospel number? My RS23V0A****** GTX will run between 190-220°F on a hot day (95+ degrees) with out the world coming to an end. Just my opinion of course.
BOB RENTON

My car has all of that except flowkooler wp, I cannot run a clockwise fan due to serpentine setup. Without the additional air direction, my engine would go well over 220 regularly. It now cruises down the interstate in 120+ weather around 194ish which is just about right w a 180 t-stat. I agree that 200+ is no big deal. It was around the early 90's when Chevy's TPI was popular and chip tuners started turning w 160 t-stats and then internet "phd's" started telling everyone that cars make more power w a 160 stat and that 190 is way too hot. Non a/c cars had factory 195 stats which meant a fully open stat at 210. I agree w you on the warmer temps being ok. I hear people always saying our "older" engines were never designed to run as hot as new ones. They may not have been designed for 220-240 temps, but they are iron and steel and can handle the temps if tuned correctly.

 

[Mark1972]

Well after draining back the rad, and adding a bottle of Water Wetter, and more water to get the water to glycol ratio to 3/1, I then found a 2" wide firm rubber strip and secured it to the top of the shroud to fill the gap between the shroud and rad. I ran the car until the stat opened, and topped up the rad with water. Took it for a 15 minute drive, and came back to let it idle for a few minutes to see what the temp would come up to. it came up to 190F, and stayed there. It was 165F driving. Mind you it also thankfully got down to 67F air temperature tonight while driving, unlike the 91F last night. So that I'm sure made a difference. Either way, sealing the shroud to the rad and reducing the glycol seemed to make a difference. Tomorrow I'll look at a few more things. This coming weekend will be a good test as temps supposed to hit 90F again.

 

[RJRENTON]

My car has all of that except flowkooler wp, I cannot run a clockwise fan due to serpentine setup. Without the additional air direction, my engine would go well over 220 regularly. It now cruises down the interstate in 120+ weather around 194ish which is just about right w a 180 t-stat. I agree that 200+ is no big deal. It was around the early 90's when Chevy's TPI was popular and chip tuners started turning w 160 t-stats and then internet "phd's" started telling everyone that cars make more power w a 160 stat and that 190 is way too hot. Non a/c cars had factory 195 stats which meant a fully open stat at 210. I agree w you on the warmer temps being ok. I hear people always saying our "older" engines were never designed to run as hot as new ones. They may not have been designed for 220-240 temps, but they are iron and steel and can handle the temps if tuned correctly.

THANK YOU for the information. Yes, most serpentine drives require a reverse rotation fan AND water pump, becsuse of the routing of the belt. Its amazing just how gullible people are to accept as gospel, undocumented data, as you noted in the reference to the Chev's TPI system and the results....a classic example of the "they said rule" or the "my brother in law's next door's neighbors cousin's sister's husband's buddy's friend" who knows more about everything......a truely awesome responsibly.
BOB RENTON

 

[Ron H]

THANK YOU for the information. Yes, most serpentine drives require a reverse rotation fan AND water pump, becsuse of the routing of the belt. Its amazing just how gullible people are to accept as gospel, undocumented data, as you noted in the reference to the Chev's TPI system and the results....a classic example of the "they said rule" or the "my brother in law's next door's neighbors cousin's sister's husband's buddy's friend" who knows more about everything......a truely awesome responsibly.
BOB RENTON

Lol - somehow reminds me of the Abbott & Costello skit "Who's on first?"

 

[Mark1972]

My crank pulley diameter and water pump pulley diameter are the same. I've just ordered a Flowkooler pump. I'm wondering if I should try to locate a smaller diameter water pump pulley to overdrive it a little, to assist in cooling when at idle, which is where I'm having the issue. Both pulleys measure out at 6.75" as best as I can tell. Maybe the Flowkooler pump alone will do the job.

 

[RJRENTON]

My crank pulley diameter and water pump pulley diameter are the same. I've just ordered a Flowkooler pump. I'm wondering if I should try to locate a smaller diameter water pump pulley to overdrive it a little, to assist in cooling when at idle, which is where I'm having the issue. Both pulleys measure out at 6.75" as best as I can tell. Maybe the Flowkooler pump alone will do the job.

Good plan....remember, the faster the coolant circulates thru the system (both velocity and quantity) the more efficient will be the heat transfer.
BOB RENTON

 

[Purepony]

There’s gotta be something else to get that high temp

I run my challenger with a 360 fairly stock. Reg fan, smaller copper radiator not the 28 and no shroud. Cars hasnt overheated and I drive it when the weather was 102 about two weeks ago
I did however put a new pump,new thermostat, new belts, and hoses. Since I was doing the four speed swap

shrouds do work and it’s always better to have one but I’m waiting out since eventually I’ll do a hemi swap so I’ll need a different radiator.
donr see the point on spending 200 on the smaller shroud