Over Heat fron Fan Shroud?

[ck5566]

I read some time ago that Fan Shrouds can cause your Temps for the engine to rise a little more then normal, true or not true and how much would it rise the Temp if it did it at all?

[GASoline71]

Never heard that at all. Lack of a shroud can do that.

Gary

[StingRay]

It won't if it fits the rad and fan correctly. Start swapping parts and don't correct the fitment of all the components and you could certainly impede cooling from what is ideal.

[davepl]

Hard to envision a shroud making things worse. I can't think of a way it could.

[HO455]

Originally Posted by StingRay

It won't if it fits the rad and fan correctly. Start swapping parts and don't correct the fitment of all the components and you could certainly impede cooling from what is ideal.

Agreed. Higher engine temps at highway speeds can be an issue if your system is not properly thought out. Shrouds help cooling at low speeds. Prior to stop and go traffic cars didn't need them. 4th generation Camaro's for one have flappers in the shrouds to allow more air to pass through the radiator at highway speeds. My understanding is that air can bunch up in front of the car and create a pressure wall preventing air from flowing into radiator and a low pressure area around the fan. It's simple to add flaps if you have this issue.

[ck5566]

How about the I6's only having that small piece of metal on the top of radiator that looks like a Safety shield? I have had a few I6 cars & truck that had that little "safety shield" and didn't have any heat or over heating problems but maybe that was 20 to 40 + years ago and with out even using any Coolant at all. Got me a little confused here.

[HO455]

Back in the day being stuck in stop and go traffic for 10 minutes wasn't an issue. Only after traffic jams became so common that Detroit was forced start putting shrouds on cars. Trucks got shrouds later as it wasn't till the seventies that people started using trucks as commuter vehicles. I was fortunate to spend some time with a retired GM engineer years ago and one of the stories he shared was of GM hiring a third party to buy a new 67 or 68 ( he didn't remember exactly what year) Japanese car to evaluate it and then disassemble it. One of the issues they were struggling with was how to keep the cars from over heating. The GM engineers were supposed to go look at the car after hours so no one would know they worked for GM.

[GRX]

Proper fan placement in relation to shroud opening is the key. Blades should be roughly third to half way in. Too far inside and air is not drawn across the entire area of the radiator. Less critical at cruising speeds of course. Yet even then it can still be a factor since you are creating turbulence points at the blade tips within the shroud. Have seen more than a couple instances when correcting this, and nothing else, has solved heat issues.

[GASoline71]

Originally Posted by ck5566

How about the I6's only having that small piece of metal on the top of radiator that looks like a Safety shield? I have had a few I6 cars & truck that had that little "safety shield" and didn't have any heat or over heating problems but maybe that was 20 to 40 + years ago and with out even using any Coolant at all. Got me a little confused here.

1967 technology. The 250 didn't need a shroud because the engineers deemed it not necessary. I believe that there weren't many complaints about over heating either. But try that with a 350 or a 402... different story

Gary

[67ChevyRedneck]

My 67 never overheated with its 250, 3 speed, 2 row radiator, and no shroud, but I also lived in NY. A 93* day in August was an extreme heat wave

I moved to SC, added A/C and a 350/700R and I needed a 4 row and shroud to keep it cool.

The only shrouds that I can think of that might make a truck run warmer are the aftermarket ones that are completely flat that efans mount to. They need some kind or pitch so the air can move at interstate speeds or it just hits a wall and creates hot spots (I figured that out on my 65 Mustang.)

[ck5566]

Originally Posted by 67ChevyRedneck

My 67 never overheated with its 250, 3 speed, 2 row radiator, and no shroud, but I also lived in NY. A 93* day in August was an extreme heat wave

I moved to SC, added A/C and a 350/700R and I needed a 4 row and shroud to keep it cool.

The only shrouds that I can think of that might make a truck run warmer are the aftermarket ones that are completely flat that efans mount to. They need some kind or pitch so the air can move at interstate speeds or it just hits a wall and creates hot spots (I figured that out on my 65 Mustang.)

Wow 93* was an extreme heat wave for you, Huh we sleep at night with temps like that LOL and on the other hand we also get temps down in the single digit area like one day it got down to 9* and stayed there for about 4 to 5 days.

[Coley]

Originally Posted by ck5566

I read some time ago that Fan Shrouds can cause your Temps for the engine to rise a little more then normal, true or not true and how much would it rise the Temp if it did it at all?

Fan Shrouds causing overheating?
From an (thermal) engineering standpoint i don't see how that could happen at all.
The fact that the shroud helps more airflow through the radiator simply negates the rumour in my opinion.
If you are having overheating problems....post up where mechanical arrangement and we should be able to offer some insight on what the problem might be.
All Good
Coley

[ck5566]

Originally Posted by Coley

Fan Shrouds causing overheating?
From an (thermal) engineering standpoint i don't see how that could happen at all.
The fact that the shroud helps more airflow through the radiator simply negates the rumour in my opinion.
If you are having overheating problems....post up where mechanical arrangement and we should be able to offer some insight on what the problem might be.
All Good
Coley

Did you read the starting #1 post (mine) in what was stated. I "HRARD" that from another person on this Forum say that & that is why I started the thread. It didn't make sense too me ether!

[67ChevyRedneck]

They will if they look like this (65/66 Mustang). I put one on my car and it was fine when temps were 90's and below... took it on the power tour and with the A/C off in 100-110* in Texas on the interstate my car was running 210-220*. Not cool... literally. Got home. Took all that crap off and put the factory shroud back on... same outside temps, 200* down interstate with A/C ON. But now I'm back to running hot in traffic with A/C on, so I'm going with a much larger 24" 69 radiator (stock is only 17" wide).

The best I could figure was that it was so flat and so close to the radiator that the air was literally hitting a wall and could not get "through" creating hot spots where the shroud was, which is like 25% of the radiator.

But to reiterate... "stock" fan shroud on a "stock" vehicle. No way. Will never "cause" overheating.

[Andy4639]

Go over to the LS section and look at the post there on radiator's and shrouds. As Jesse stated aftermarket shrouds can stop air movement if it's flat like in his picture and other's. This is why I decided against the flat shroud I had made for my LS swap and went with the Camaro dual fan setup.

My 6.0 will run all day long at 179* with air temp in upper 80's. No shroud other than what the camaro fans have made to them.

This is all I have in my truck.
Going on 4 years now in the truck.

[jeh]

This thread is interesting to me, when I first got my truck finished I had 2 elec fans mounted right on the radiator. Driving down the road it ran cool as could be, stop at a red light or in slow traffic the temp would start rising. So meanwhile after round 2 with the engine I decided to build an aluminum shroud the height and width of the radiator with a 1" lip on it and cut holes for the fans. It will set and idle around 175-180 now but cruising down the road sometimes it will increase in temp. What I thought it was doing it all the flowing air is bunching up against the flat alum shroud. A buddy of mine mentioned the idea of a couple flaps made of thin rubber that would stay shut with the suction created while not moving and then the air pressure while driving should push them open. We'll see what happens???

[HO455]

Picture of a LT1 f-body shroud with the cutouts two cut outs for the flappers. It isn't a thermal engineering issue but an aerodynamic engineering issue on those cars. The next generation f-bodies didn't need flaps. So yes the wrong shroud could cause overheating. I also know that 1985 Camaro's will run hot on the highway with out that little chin spoiler under the radiator.