Must be getting close to summer. Our 7.3 / B-1B was roaring yesterday rolling down the interstate. Going to check to see if the radiator is all cleaned up this weekend to minimize the frequency of the fan kicking in and out, and tune up the stereo amp! Good times!

 

Yeah Mine has been roaring for a little bit but I believe I need to get off my butt and just replace the fan clutch.
Cleaning the radiator...I haven't really looked close at it but now that I am living where there is alot more trees, pollen and such on the air,,,may have to take a look at that.

 

A set of radiator/fin combs will come in handy and they are cheap. I got this idea from Wes444 after he pulled a lot of debris out from his, as did I. I was able to straighten a few bird strike and large bug strike places too. I also cleaned up the power steering fluid cooler. I then used Simple Green and the foaming coil cleaner. That helped quite a bit when running down the road towing, but I figure as long as the fan is not acting erratically, it is doing what it was intended to do.

As for the B-1B, those are some loud jets. I think the U-2 is probably one of the loudest take off jets I have seen other than a fighter taking off at maximum effort.

EDIT: Forgot to include a picture...

 

This is one of the best mods I did to my truck. Pulley is slightly larger in diameter. It increases the mechanical advantage at the pulley for the belt to turn the fan. It doesn't take up so much that you have to change anything else. The factory spring tensioner sits within it's designed range of motion once the belt is on and seated. Getting the belt installed is tighter than before, but not impossible.
https://www.riffraffdiesel.com/water-pump-pulley-94-97/

 

What kind of oil temps are you guys seeing when the roar happens? Being that I am in South Florida I would imagine that I would hear this roar more often but I believe I have only heard it once in the past 7 to 8 years. My oil temps rarely exceed 215° though...

 

You may want to test your fan clutch function. What I recommend is drive with the AC on for a while with whatever gear it takes to maintain 2500 rpm or higher at 65 or so on the highway. Fan should come on very noticably if you're in a warmer place like the southern states. If it's not locking up nicely under those conditions, then I would replace it.

 

Found a birds nest above the light bar in the middle. Pulling radiator now.

 

Thank you for the idea. Got to see if the local NAPA has them today while I have it out. Got the coil cleaner and Simple green.

Use to love to go to Heathrow and watch the Concord land. Wasn’t loud until they reversed the engines after landing. Very cool to watch it come in. Love those A-10’s Warthogs as well. Very unique sound! Thanks again!

 

I figured the clutch is functioning properly because it does cycle. Going to visually inspect it thoroughly though. Thank you for the idea on the larger pulley. That sounds like an EXCELLENT idea for N Florida. I think we are going to have a repeat of last years heat again shortly.

 

You are welcome, but I am only passing along the great advice from Wesley.

I was stationed at RAF Lakenheath for 6 years and flew in and out of Heathrow many, many times. We had four F-15 fighter squadrons at Lakenheath and when they would take off they would take off in groups of four. We had a "Lakenheath pause" when having conversations outside.

The A-10 is an amazing aircraft and there is nothing else like it. A tank in the sky is what we used to call it.

 

If your just driving the truck not pulling anything or working it hard you will very seldom hear the fan come on. They have a very efficient cooling system.

 

We still have the A-10’s flying over at tree top all the time. Really sad to see them go. We had a fly over recently at dark of 12 blacked out helicopters that we thought were Blackhawks. Heard them coming for 4 minutes. That was the loudest thing we have ever heard. Would hate to be on receiving end. They actually moved the trees.

 

Yeah that’s what we thought too! Did it again this morning when it was 70 degrees. It is always at higher speeds like above 80. All gauges are normal except EGT’s. They rise slightly due to the draw of the fan. Apparently it uses some HP when on!

 

So, just to clarify, you aren't actually using the comb on the radiator, or even the intercooler. You are using it on the AC condenser. That's the first thing in the cooling stack for manual transmissions, autos should have the transmission cooler in front of that I believe.

If the 1st thing has bent fins the air flow will be nearly completely blocked to everything behind that spot, some air will work it's way in behind the damage, but very little compared to straight fins. Be prepared to be surprised at how many sand pebbles you pull out. So do the whole thing. Pull the grille off for much easier access, and run the comb from top to bottom and work the fins straight. Expect to spend a few hours doing it, and a small thin flat bladed screwdriver will be a great help to the comb on bird strikes.

Once you are done go to a carwash, remove the grille and spray the condenser/atf cooler with degreaser. Then use the "high pressure" setting and blast it. Keep the water jet as close to straight on as possible and blast the wee out of it. Don't get off to the side or at an angle, you'll bend the fins over if there are split ones from fixing damage.

The light oil buildup from years of driving behind other vehicles kicking up oily rain spatter from the pavement will attract dust, which insulates the cooling fins, decreasing efficiency.

Don't use your manly pressure washer @ 4500psi at home, you'll bend the fins back over with true high pressure. Car washes use a higher volume of water at a safe pressure, they don't want to have to pay for removing trim and pin stripes from vehicles, so the pressure there is safe to blast point blank up into the grille

Remember you have 3 to 4 stacks of cooling systems to degrease, don't be shy about it. Blast it in deep and rinse well. If the motor isn't wet you didn't get the radiator rinsed

 

In my opinion a larger pump pulley should slow down the fan. Just want to make sure everyone is on the same page.