Engine Another cooling system thread

LX Dave

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Jul 2, 2017
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Hey guys,

I'm having an annoyance with my '84 Mustang. When going down the road, the cooling system has no problem keeping the engine cool (normally runs between 197-203 degrees) with a Motorcraft 195 thermostat. The problem starts when I have to sit and idle for more than a couple of minutes. The temperature keeps creeping up until I just shut it down. That can get annoying at times. Yesterday I was in a drive through and had a long line to wait in. When I finally got out on the road, the temperature was at 118 degrees (I did shut it down a couple of times in line). Within a mile of going down the road (35mph speed limit, then up to 45 mph speed limit), it was back down to 197 degrees.

Specs on the car:
351W engine (mild build, approx 400 hp, 10:1 compression)
Holley Sniper EFI with stock dual snorkel air cleaner
NOS radiator (yes, I got lucky and found one for cheap)
New plastic fan
New fan clutch
Has full shroud and overflow tank.
All stock sized pulleys, no under-drive stuff here.
Stock off the shelf water pump
3G-130 amp alternator

This system has no problem keeping things cool while moving, even on the hottest and humid days. Even at 25-30 mph, the temperature will drop if it's gotten hot.

*I was thinking of adding an electric pusher fan in front of the radiator that will turn on in cases I have to idle for a while. What I don't want is that fan to hinder the flow of air while on the road, which I think it will do. I can also trigger that fan through the EFI controller. (EFI can trigger 2 fans, programmable temps on and off, or trigger 2 speed motor, hi/lo, as long as it has 2 separate power wires)

Is this a plausible fix, or should I do something else? One thing, I would like to retain the mechanical style fan, but am not opposed to going full electric if that's the only fix.

*Another question, does anybody know at what temperature the stock fan clutch goes into "full lock-up" to pull more air? Even when I hit 220 degrees, I never hear it engage more for more cooling. I know these clutches always slip a little, so "full lock-up" is kind of a distorted term.

Would going to a better water pump be a consideration? (I'm kind of a cheap ba$terd, so don't wanna spend the money if there's no positive results, and this is an idling only issue).

I'm not in any hurry to tear stuff apart and change things. It does good for now and will make the changes over winter, still want to drive it more this summer....and collect parts if necessary.

Appreciate the help and input.

20200726_122744.jpg
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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#1 adding stuff like an electric pusher fan is like a bandaid on a broken arm, the teenage mutant ninja turtles may be cool but the arm is still broken.
#2 is this a problem that just recently started, if so I would start with basics, make sure there is no junk blocking the flow through the radiator, test the clutch fan, should be a good amount of resistance turning the fan by hand when the engine is hot (and turned off of course). Check flow through the radiator when the engine is running, raising the idle should produce more flow, this can be difficult because you can't tell how well the lower tubes are flowing, a infrared temp gun can help there, watch the lower radiator hose when the rpms are raised, does it collapse?
You should also check the thermostat, a meat thermometer and a pan of water on the stove work well.
 

LX Dave

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Jul 2, 2017
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#1 adding stuff like an electric pusher fan is like a bandaid on a broken arm, the teenage mutant ninja turtles may be cool but the arm is still broken.
Agreed. That is why I was hesitant to do that and am looking for any experience with this.
#2 is this a problem that just recently started, if so I would start with basics, make sure there is no junk blocking the flow through the radiator, test the clutch fan, should be a good amount of resistance turning the fan by hand when the engine is hot (and turned off of course). Check flow through the radiator when the engine is running, raising the idle should produce more flow, this can be difficult because you can't tell how well the lower tubes are flowing, a infrared temp gun can help there, watch the lower radiator hose when the rpms are raised, does it collapse?
You should also check the thermostat, a meat thermometer and a pan of water on the stove work well.
I just finished the restoration this spring and it has always done this since it's been on the road.
The clutch does have good resistance when cold, but loosens up when warmed up....gonna do more research on this as new bad parts are more and more frequent.
The car idles at 900 rpm (cam related) and there seems to be a good amount of air flow being pulled from the fan.
Lower hose doesn't collapse.
Thermostat "seems" to be working correctly, but never tested it before install. Have to look into that too.

Click to expand as I have more written in there.

Headed out to double-check some of these things now. I'll have to pick up a temp gun soon (now I have a reason to get one :)).
The EFI has a digital temp readout on it and just letting it idle, I should hopefully be able to tell when it's opening...we'll see......
 
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LX Dave

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Update on some things checked.
Home Depot was the only one that had the infrared thermometers in stock, kind of surprised as I used to see them everywhere.
Drove this car there to get it up to temp.

Temp results:
Pass side tank (upper) 197
Drivers side tank (upper) 181
Top of core 193
Center of core (in the middle both directions) 169
Lower pass side of core 174
Lower drivers side of core 141
Top radiator hose 187
Lower radiator hose 170

I started it from cold and let it idle up to temp. Held my hand behind the fan and when the air got warm I looked at the gauge. Showed right about 200 degrees. The temp sensor is located on the left front side of intake (you can see it it the first pic behind the distributor).


Another thing I noticed when waiting for the thermostat to open is it seems to be loosing a lot of air laterally around the fan. You can see how far out of the shroud the fan is. I can only assume that that air is still going through the radiator, but not positive. Going to check on clutch part numbers and depths and see if there's different clutches being made. With the hood closed, you can feel it pull air through the grill and through the vents under the bumper between the foglights.

20200726_152335.jpg


Now on the '87, it's tucked right inside the shroud.
20200726_152356.jpg


That has me wondering if I got the wrong clutch or what's going on. On my '86 F-150, (351W truck factory) the fan is half way out of the shroud too and that one can idle all day and never get hot. It is 8.3:1 compression too though. More investigating to do.

ETA: When the thermostat is closed and the engine is revved up, the lower hose pulls together just a little bit (1/4" or less). When the thermostat is open, it doesn't move at all.
 

7991LXnSHO

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Things I’d first suspect -
-Fan clutch, make sure it’s a thermal fan clutch and the right length like you suspect.
There is an optional distance from the radiator and blade insertion in the shroud for best airflow.
- the lower air dam and other air seals around the radiator need to be right. It will do no good at idle to be recycling hot air.
- make sure the system is air free, burped or bled.

I would not consider a pusher fan until those two things are confirmed good. (Ninja Turtle bandaids are cool.)

The radiator and water pump are less suspect since it is cool while moving.
If you do not have a coil/spring in the lower hose, it would be a good idea. That will prevent problems while reviving, usually not at idle,
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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You are using an aftermarket two wire electric temp gauge?
And just to be clear, the gauge uses a sender, the computer uses a sensor.
Temps between 200 and 215 are not unusual sitting in traffic on a hot day.
I noticed you don't have ac.
I would also have the radiator checked, the odd temps concern me, mostly the 141* temp on the lower drivers side.
I also think the fan needs to be a little farther into the shroud.
 

LX Dave

Active Member
Jul 2, 2017
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Things I’d first suspect -
-Fan clutch, make sure it’s a thermal fan clutch and the right length like you suspect.
There is an optional distance from the radiator and blade insertion in the shroud for best airflow.
- the lower air dam and other air seals around the radiator need to be right. It will do no good at idle to be recycling hot air.
- make sure the system is air free, burped or bled.

I would not consider a pusher fan until those two things are confirmed good. (Ninja Turtle bandaids are cool.)

The radiator and water pump are less suspect since it is cool while moving.
If you do not have a coil/spring in the lower hose, it would be a good idea. That will prevent problems while reviving, usually not at idle,

The part in red I definitely need to check out. Not sure what this car came with factory for extra shrouding as some of it was ripped apart before I got it.



You are using an aftermarket two wire electric temp gauge?
And just to be clear, the gauge uses a sender, the computer uses a sensor.
Temps between 200 and 215 are not unusual sitting in traffic on a hot day.
I noticed you don't have ac.
I would also have the radiator checked, the odd temps concern me, mostly the 141* temp on the lower drivers side.
I also think the fan needs to be a little farther into the shroud.

The temp sender/sensor is for the fuel injection but gives a read out on the screen, soooo, I'm gonna say sensor? :shrug:

For checking the radiator and the odd temps around it, I'll give the radiator shop a call and see what they can do for it. Might have to open it up and do some cleaning or something.

I did check on the fan clutches and the only depth I could find is 1.75" from fan to mount. It is a thermal fan too. It's the Four Seasons #36990.

Oh, I did check the resistance of the clutch when everything is hot and it has just a little bit less resistance than when cold.

Not sure what to do about the fan depth into the shroud, a spacer would be OK, but it would have to be about an inch long one and at that length, the shaft is getting fairly long.

The research continues.....
 

LX Dave

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Ended up going with the full Holley Sniper fuel injection, Distributor, and CDI box...which reminds me I gotta do a write-up on that too. The good and the bad.
 
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7991LXnSHO

wanna catch the space herp
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If the fan clutch is only a little stiffer when hot, that’s not a good sign! It should be the difference between having thick grease in the bearings and a really stiff to turn when hot.
4-seasons has been a good brand, but defects still happen.
 

Blown88GT

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Nov 13, 1999
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Update on some things checked.
Home Depot was the only one that had the infrared thermometers in stock, kind of surprised as I used to see them everywhere.
Drove this car there to get it up to temp.

Temp results:
Pass side tank (upper) 197
Drivers side tank (upper) 181
Top of core 193
Center of core (in the middle both directions) 169
Lower pass side of core 174
Lower drivers side of core 141
Top radiator hose 187
Lower radiator hose 170

I started it from cold and let it idle up to temp. Held my hand behind the fan and when the air got warm I looked at the gauge. Showed right about 200 degrees. The temp sensor is located on the left front side of intake (you can see it it the first pic behind the distributor).


Another thing I noticed when waiting for the thermostat to open is it seems to be loosing a lot of air laterally around the fan. You can see how far out of the shroud the fan is. I can only assume that that air is still going through the radiator, but not positive. Going to check on clutch part numbers and depths and see if there's different clutches being made. With the hood closed, you can feel it pull air through the grill and through the vents under the bumper between the foglights.

20200726_152335.jpg


Now on the '87, it's tucked right inside the shroud.
20200726_152356.jpg


That has me wondering if I got the wrong clutch or what's going on. On my '86 F-150, (351W truck factory) the fan is half way out of the shroud too and that one can idle all day and never get hot. It is 8.3:1 compression too though. More investigating to do.

ETA: When the thermostat is closed and the engine is revved up, the lower hose pulls together just a little bit (1/4" or less). When the thermostat is open, it doesn't move at all.
You temps look normal for a 195 t-stat, but I have to agree with you, i.e. you're losing a lot of efficiency with the fan blades not 100% inside the shroud.
 

LX Dave

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Jul 2, 2017
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The local radiator shop had a NOS one on the shelf all these years. I just happen to ask if they had anything for mustangs and he found that one. They forgot they even had it. And for the price of 130 bucks, figured I couldn't go wrong.
 
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Monkeybutt2000

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What is wrong with stock?
Nothing, but this car's is hardly "stock" either. OP,you could've got a Champion 2 core for $180. My turbo'd 331 runs this radiator with a hd waer pump and hd clutch fan. Car runs 190ish in 90* heat. Also,my fan is fully enclosed by the radiator. That's with the fancy Mr.Gasket 180* stat and underdrives.
 
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LX Dave

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Found this little tid bit of info from Flex-A-Lite fans "If you have a fan shroud, the position of the fan blades in the shroud is very important to maximize airflow. Looking from the side of the engine, the fan blades should be half in and half out of the shroud. "
This theory matches my truck which is completely factory. But, that makes me wonder why my '87 is tucked all the way inside the shroud. Still going to look for a fan spacer and see what happens.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
Found this little tid bit of info from Flex-A-Lite fans "If you have a fan shroud, the position of the fan blades in the shroud is very important to maximize airflow. Looking from the side of the engine, the fan blades should be half in and half out of the shroud. "
This theory matches my truck which is completely factory. But, that makes me wonder why my '87 is tucked all the way inside the shroud. Still going to look for a fan spacer and see what happens.
this is probably dependent on fan blade design, notice that some, I believe this includes the fox body 5.0 fan blades, have a curve at the end of the blade, this may allow for a deeper blade placement in the shroud, I will look at the stock fan/shroud on the dump truck and the fan I bought for the exxon valdez and report back.
 

LX Dave

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Decided to Google pics of Fox engine bays and am a little surprised of the results. Its about 50/50 for the fan being tucked all the way in the shroud or an inch out on the sides (flush at the top). For now, gonna call that part good as I can't seem to find any rhyme or reason as to why they are like that.

After doing some research on the clutch, that is seeming to be the culprit. Got a new, more expensive one on order. Went with a Car Quest one this time. We'll see how that one does this weekend. Basically no resistance change from cold to hot and reading other people's problems kind of directed me that way. If that doesn't work, at least I'll have a good clutch in there.:doh:
 

7991LXnSHO

wanna catch the space herp
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The 4 seasons clutch should have been as good as the car quest one should be, and I am glad you listened on the possible defect.

I have sold and tried flexalite fans. A stock style fan with a good thermal clutch seems like a much better deal. The flex fans are always working full force and are noisy on the road.