I've been dismantling the grill area of my truck one piece at a time in an attempt to improve air flow so I can tow in hot weather with the A/C on and not have to endure the noise of the radiator cooling fan coming on so often in full lockup mode. Over the past year I've given reports of this noise on various threads, and described it as sounding like the prop noise my old Cessna 150 made when I revved up its engine prior to take off. I should've paid more attention to my own posts, because the unique sound I described was trying to tell me what the problem was with my truck!

The fixed pitch on a Cessna 150 prop is designed for efficiency during 120 mph cruising. When you rev the prop prior to takeoff it tends to cavitate because of the reduced air flow when the plane is stopped. As the plane gains speed during its takeoff roll and the air flow past the prop increases, this cavitation noise diminishes because the angle of the incoming airflow better matches the design angle of the prop pitch.

After only one good test day towing with my new Genedad 2 mod, I've concluded that most of the annoying radiator fan noise was due to cavitation because the fan couldn't pull a high enough air flow through my restrictive A/C condenser. The fan blades were making a beating noise as they churned the relatively stagnant air that's trapped between the rear fan shroud and the front shroud (which I removed) that normally forces all the air to flow through the restrictive A/C condenser. For those who have no idea what a Genedad is, I'll give that background before unveiling my latest version of it.

The Genedad 1 was done in Bozeman just before I towed down to Yellowstone, and that seemed to help some, as the cooling fan didn't come on as often when pulling grades, but when it did come on it made the same annoying noise as always. As can be seen here https://www.ford-trucks.com/forums/642354-my-zoodad-gave-birth-to-a-genedad-comments-welcomed.html the Genedad 1 was done primarily to increase the RAM air flow into the air box inlet, but it did provide some additional spillover air flow to the right hand side of the IC and into the engine compartment.

Before I left Yellowstone I was cleaning the bugs off the A/C condenser with my special brush, and I noticed that the rubber mat (shown in pic #1) that seals the top gap between the A/C condenser and the IC also has a several inch lip that sticks down in the front to stop any air from flowing over the top of the A/C condenser and directly to the IC and radiator. This OEM configuration forces ALL the air to flow through the A/C condenser so that all that WASTE HEAT can then flow through the IC and radiator! That design might keep the occupants nice and cool (the A/C mod does it even better), however, the OEM design isn't at all optimum for cooling the IC and radiator.

I was thinking about just reaching in there and cutting the lip off, but then I remembered a recent post, something about crap I just punctured my A/C condenser and let all the coolant escape. So I decided to remove the whole mat to cut it, but when I got it off and looked in through the grill and saw how wide open the air flow was directly to the IC and radiator, I decided to run without the mat as an experiment.

I was only supposed to tow down to Salt Lake City and spend several weeks there, but when I arrived they claimed to have never heard of me and were all filled up, as the state fair was in town. After calling several more RV parks and getting the same "were all full" story, the wife and I decided we didn't care all that much about visiting there anyway so we headed west on I-80 towards or original destination of Reno that we'd started out for 3 months ago.

We made it to Wendover without the fan coming on at all, and on day 2 we had a lot of grades on the stretch of I-80 the rest of the way to Reno, and the sun was bright and the temp was in the 90's, and I kept waiting for the dreaded fan noise! Finally after running the A/C for several hours, the fan locked up near the top of a long 5% grade, but it sounded much more subdued than before. More like a gentle whine and the sound of rushing air, not the cavitation noise like a flag flapping due to the fan blades beating against the restriction of trying to force all the air through the A/C condenser. So based on that, I'd say the Genedad 2 is a success, and it doesn't disfigure the truck much because with the hood closed you have to bend over and look up through the grill to even see it. As pic #2 shows, the mod is very noticeable with the hood open, and you lose a handy place to lay your tools, but you can now easily brush the bugs, hay, chicken feathers, etc... from both the A/C condenser and the IC.

I'm showing pic #3 because Sparks Marina RV Park is by far the most ritzy (and most $) place we've ever stayed in. Turns out that 30,000 motorcycle types are headed this way, the Reno air races start next week, and several other things are going on so that only the most $ place was available. That green stuff is artificial turf, and you can't put anything on it, including your satellite dish, chairs, etc.., at least those were the rules I was given. When the motorcycle guys arrive, I'm going to share a 6 pack or two and see if I can't induce someone to demo a good wheelie or two through some of this Astroturf just to see how well it holds up to that. I suspect they'll be pieces of it flying all over the RV park! One thing for sure is that I won't be able to do my own oil change here.

 

when I saw this picture:



I couldn't help it but the first thought that popped in to my head was "for all the craziness that Eugene does, that's one plain looking truck"

I will say that I definitely appreciate the testing, experimenting, and sharing of information. (but if you get near my truck with a roll of duct tape there's gonna be problems!! LOL)

 

Glad your ok Gene. There is a spot on the west side of town I stayed at a few months ago. I am pretty sure it was called the keystone or something like that. Not nearly as nice as the park where your at though.

 

Glad to hear you are ok, too.

 

I just wish I could say the same thing for the air race pilots! There's been 3 killed since we arrived on Wed. One biplane during takeoff, one jet that was practicing, and the races were just canceled for the rest of the day due to a midair collision with one fatality.

 

Gene , just what is going to happin in stop an go traffic when the fan can't suck enough air through the condenser,wouldn't that get the 134a HOT.

 

well did you notice any drop in engine compartment temps or egts for having more air flowing directly into the intercooler?

 

Glad you made it here to RENO finally. If you need anything PM me, I am usually on in the PM.

Going to the air races tomorrow, hope they have some planes left.

 

Sorry to hear about those pilots. Three killed in one year makes me think there are going to be some revisions to the safety protocols there. Racing is risky but that's too much.
Hijack over.
Gene your comment about the fan stalling - I never hear that sort of thing with my truck and I have plenty of stuff in the way. I'm strongly considering removing my winch mount and selling it because it's becoming more of a liability than an asset.
But it's right in the way of air flow for the radiator and the fan locks up hard even driving empty with the AC on.
Your experiments have shown me that it would be good to remove all that and see how it goes.
Enjoy the races.

 

O.K. Kwikk, here is where you say (in the spirit of the 7.3 brotherhood) its up for grabs somebody just pay shipping, and the winch comes with. I'll pay. Yeah, I know "shut up Brandon".

But seriously, have you checked your fan clutch? Look at my gallery, those big lights of mine take up alot of room, but my fan only engages sometimes. I know your 5er is heavier than mine but still, it shouldnt be locked up all the time. Maybe the altitude has something to do with it, IDK Seattle is pretty low isn't it? we are at 200' here in the wiregrass of Bama.

 

Washington state is a combination of sea level to 4000 feet elevation with very little level ground on which to put a road. Sort of like a little brother to San Fransisco's hills.
There is one good hill for severly testing your cooling system's capabilities: A ten mile stretch of grade that pulls up out of the Columbia river basin westbound towards Ellensberg. There are signs at the bottom of the grade stating to turn off the AC to avoid boilover. My truck pulls that grade just fine with the AC on.
Where the problems begin is if I go too fast. Anytime the engine rpm exceeds 2500 for any length of time and the fan locks up, the belt begins to slip. If I drop the speed down, the fan remains locked up and roaring, but the belt quit's slipping.
So what I do is set the cruise at 66-67 mph which is a touch under 2400 rpm and the truck is happy. I can climb any hill at WOT with the AC on in 95 degree weather, fan roaring without boiling over, or any other such inconvenience.
Last time I was out I had to pass through Las Vegas in 107 degree bake oven heat. I never had to shut off the AC and the fan was locked up. I just cannot go over 2500 when the fan is locked or I get this horrid shreiking from the belt slipping. And I can understand why, that fan moves a LOT of air.
This behavior happens whether I am pulling the trailer or not and the AC is on. I simply cannot cruise along at 75 mph=2800 rpm with the AC on.
Too much heat is generated and the fan kicks in and then the belt slips.
Turn off the AC, the fan soon quiets down and then I can run it to the rev limiter all day long, but I like my climate control when it's hot outside.
.
Maybe I'm looking at the wrong thing here, but I'm really scratching my head over this one as the belt ( Gates brand ) was new a while back and the tensioner is in good shape.

 

Have you ever removed the belt and checked the water pump pulley to see if it's glazed, maybe it has something on it from the last belt, and it's not shiney metal contact... Try some fine grit sandpaper on the pulley maybe?

 

I can tell you right now that the belt is glazed pretty good from all the slipping.
What I'll probably end up doing is going to Ford and getting a whole new tensioner assembly and a Motorcraft belt.
While I'm there I'll pick up an ambulance upper hose so I can quick change to a new belt every six months or whatever. This current belt is over two years old now, but showing no cracks. And serps are supposed to last a lot longer than that.

 

Im sure you guys have considered this but here it is, I have been running a dual electric fan set up for the last 2yrs, I live on the MS gulf coast, HOT AND HUMID, I have a toy hauler 24 ft. Nothing like yalls fiver but I run my A/C full time and I have never seen any cooling temps above 215-220 since installing them. Its claimed that the clutch fan pulls 15-25 HP from our engines, I know It felt like I added another chip to the truck when I removed mine and my fuel milage increased 2 MPG.

Rich

 

Maybe its the combination of the lower gears for the 550, and the fact that the centrifugal(sp) fan clutch may be designed to lock up at that RPM prolonged. which would lead to glazing of the belt, and pulley.