[rexs73gto]

I just got done fighting an over heating concern on my car which I've kinda had for about 1 year or so but really bad fro the last month. When i put the engine back in my car this year I moved the fan closer to the rad. to see if being closer would help cool the car better. But I was wrong it made it over heat in about 5 or so miles if I would drive any where under 40 MPH. On the Hwy. it would stay cool & be right on the edge but would be ok as long as I was moving. But as soon as i slowed down the temp would climb up to & peg the temp gauge. Then when i stopped it would boil over. So I looked on line at a lot of other cars to see what I could learn from them but nothing stuck out. So I had moved the fan as close to the rad. as possible so I figured I'd go the other way. I took the fan out & put in just the 3/4 inch spacer & the flex fan. It was so close the tip of the fan blade hit the nut on the power steering pump. I trimmed the ends of the fan blade so it wouldn't hit & took it out for a drive. The fan is now almost out of the shroud , but it is now cooling the car the way it did when it was new. I took it out on the Hwy. & then directly to the city to get it in traffic. The temp never got past the 170 mark on the gauge no matter how slow or how much traffic I was in. The fan when it's close causes the air to stop flowing through the rad. which makes it heat up. Moving it back away from the rad as far as you can get it will cause the air flow to increase & keep your car cool no matter how hot it was getting before. If your having problems with your car overheating or running hotter then you want it to, use the smallest spacer you can find to get that fan away from the rad. & I will say that you will see a big improvement in your cars heating. By the way i tried the fan at different spacing before I got it to the point it's at now so if you want to solve your hot car engine concerns just get the fan back away form the rad. so the fan is just about even with the back edge of the shroud & i think your going to be very happy. It worked for me. I think it should work for you.

[george kujanski]

So the fan is almost out of the shroud and the cooling is better? Doesn't pass the giggle test.....why use a shroud at all?

May be some other variable at play.....having the fan too close to the rad? Don't see how that would cause it either.

Would be nice if you had some before pix, would like to see the current setup too.

George

[Old Tin Indian]

I agree with George. There's an engineering standard that's being defied here.
I'm not saying what you did is not helping you, but there has to be something else at work in your combination that's working in your favor.
I believe the whole idea behind the fan half-in half-out of the shroud is to create a turbulence to pull air at a high rate through the radiator to give sufficient cooling at low car speeds.
I think with your fan out of the shroud, it's only acting as a tunnel now, not working as efficiently as it should. I'm glad your running cool now, but I would really like to understand what's really happening here.
Tony

[george kujanski]

I also don't believe the half-in half out idea. Just thinking logically, the part of the blade that is out just moves the local air radially out along the blade rather thanmove the air inside the shroud out, which is what you want it to do.

a while back, one of our members did an experiment (sorry, don't remember who), blade half in, compared to fully in. His test conclusively showed the blade should be fully in.

i agree with his findings...look at any aircraft turbofan engine....the blades are fully encased iin the cowling....for a reason. Engineers do things for a reason.

when I get my shround installed, I'm getting the blades fully in.

George

[Old Tin Indian]

George, are you just talking about the fan just fully in?
tony

[george kujanski]

yes, so no part of it is on the engine side.

George

[Old Tin Indian]

I'm going to try this. I'm really tired of this running hot problem. 210* after a good 45 minute stop-and-go and highway drive @ 85*. I'm in the process of setting up the impeller to plate clearance again. The first time a few years ago I went from almost .290" to .060" with a big improvement. Now I'm going down to about .035". I was hoping that would help somewhat. It's really a problem when I'm sitting at a long light. The temp creeps right up. It comes down when the car is moving. The problem is airflow.
Hopefully the fan just inside the shroud will help with better airflow and cooling at idle.
Thanks George.
Tony

[george kujanski]

sure, at idle speeds the fan is what is moving air thru the rad. Anything you can do to move air thru the rad at slow/idle road speeds will help. If you have a clutch fan, it should also tighten up once it senses warmer air thru the rad.

george

[Old Tin Indian]

It is a clutch fan. I just have to get a new spacer. i have a 1" on it now.
I think I need a 2". Will post when I get this done.
Thanks again,
Tony

[fatguyterry]

I have a 2 inch one, let me know

[Old Tin Indian]

i see that ames sells the stock one from 1964-69. it's 2 1/2".
i might give that a try if i can't find one in my parts bin.
but, thanks anyway.
tony

[rexs73gto]

I will try to get some pics of the fan as to where it's at right now. The fan hub is even right now with the edge of the shroud & the fan blade just splits the blades at the edge of the shroud. As I said I tried it with the 2 3/4 spacer which put the fan about 1 1/2-2 inches inside the shroud & the temps still where creeping up to the 250 mark while driving in traffic & slower speeds. So I came back & as I stated I used the 3/4 inch spacer which is where it is now. Today I took it to another cruise in & I drove it about 25 miles & the temps stayed right at the 170 mark & went down a bit when I got going about 50 mph. I'll try to post some pics of the fan tomorrow so yo can see exactly where the fan placement is. But this is the coolest its run for over 2 years with the fan at this point. The fan is an 18 inch flex blade fan , one that you an buy from Summit for about $ 35.00 or so. As stated I had to cut the tips of the blades off so it wouldn't hit the nut on the power steering pump. Before I couldn't drive it & stop some where for about 5 min's & then start it right up as it would hot soak so bad it would turn over so slow it wouldn't restart. I'd have to wait for 1/2 hour & then go. Today I just stopped like normal for gas , filled it up got back in started it up & away I went. Haven't been able to do that for a couple of years. Now no problem. I'm sure now if I put in a 165 deg. t-stat it would run at that temp to with no problem now. I had the fan before this way mounted on the 2 spacers the 2 3/4 & the 1 inch together which put the fan hub at 2 inches away from the rad. core. It ran super hot there . I couldn't go around the block without it over heating. Thats why I did this. Now it's fine. I'll get some pics tomorrow for you.

[Old Tin Indian]

I ordered the stock fan spacer from Ames today. I have to wait for it to arrive. I think I'm also going to run some type of weatherstrip foam-type tape around the shroud to make sure it is sealed properly. Another thing, does anyone make a thermostatic clutch for a 1967 or earlier car. I've read that they come in at around 180* instead of the 1968 & later which comes in at 210*. I must say that I'm truly sick of this running hot problem.
Tony

[Old Tin Indian]

So sorry I stole this thread.

[Chicagogoat]

If you take a look at your A/C condenser outside if you have HVAC at home, they always have the fan blade all the way in the shroud with the blade tip barely out on the positive side. Same idea with cars, this will focus the low pressure thru the shroud, and if the shroud is sealed well, thru the radiator. Now the flex fan seems to be a little different as the design of those sheet metal blades flatten out at higher rpm so maybe your experiments are showing that flex fans need not be all the way in the shroud because as the blades flatten out at higher RPM that may bring the blades inside the shroud causing turbulence greatly reducing its efficiency. Just a thought, clearly the remedy you gave it was effective.

[rexs73gto]

Ok I've got some pics to post of my fan & the rad. As I said my fan which is a flex fan is mounted so the fan blades are just outside the shroud & the hub of the fan is even with the edge of the shroud & it is now keeping my car at a nice 170 degs' in hot weather or while in heavy traffic as I've done both & it works fine now. I had the fan in the shroud all the way so the fan blades were only about 2 inches away from the rad. It got so hot that way I couldn't go 500 feet without it over heating. It was ok (stayed about 220) if I was moving but other wise it would over heat. I had moved it in by using a 1 inch & 2 1/2 spacer which was really bad. Now with it mounted where it is I can go anywhere & drive in any type of traffic & it won't overheat or even get hot on me. I've been told that it shouldn't work like this but sorry it does & it's running as it did when the car was new,,,, back in 1973. Because of the way my power steering pump is mounted the flex fan is a bit close to it & I had to trim the edge of it about 1/4 inch so it wouldn't hit the nut on the front of the pump. That how far the fan is out of the shroud. Well I've tried a few times to post the pics but they won't post to the site. I'll get this figured out & post the pics soon as I can. ????

[Engine-Ear]

This is a good thread...in addition to the sage, "big picture" thinking posted above, it reminds of an independent book that was written about 20 years back called "How to run cool".

I wonder if that is still in print...there was a lot of useful ideas in it.

[rexs73gto]

Help, I'm still having problems uploading the pics of the fan & rad. on to the site. Is there something I'm not doing correct here. I've done it before & now I can't. Did something change about the upload process??

[72LuxuryLeMansLa.]

Originally Posted by george kujanski

I also don't believe the half-in half out idea. Just thinking logically, the part of the blade that is out just moves the local air radially out along the blade rather thanmove the air inside the shroud out, which is what you want it to do.

a while back, one of our members did an experiment (sorry, don't remember who), blade half in, compared to fully in. His test conclusively showed the blade should be fully in.

i agree with his findings...look at any aircraft turbofan engine....the blades are fully encased iin the cowling....for a reason. Engineers do things for a reason.

when I get my shround installed, I'm getting the blades fully in.

George

George,

I'm with you on the fan relationship to the shroud. I have a 1972 Luxury LeMans that has a dealership sticker on the shroud so I'm fairly certain it is O.E. along with the fan. It is 98% inside the shroud. With the factory fan and a Hayden heavy duty thermal clutch this thing blows some serious volume. I can't keep a fender cover on the passenger side with the car running; it just gets blown right off. So when I'm working on that side I lay it on the ground when I'm not actually leaning over it.

[torqjunki]

Rex....there is a limit on file size. May have to upload one or two pics per post to stay under limit.