Michael only the radiator was changed at first. After that the engine was heating up on the highway and the fan clutch was not engaging at highway speeds as in the past. I then purchased a new fan clutch, thermostat, radiator cap, gauge temp sender. The fan clutch is a hayden (sp) and it will not engage at highway speeds. I purchased it from NAPA auto parts. The water pump has not been changed with only 40K miles on the engine. Are fan clutches a variable speed unit? It seems to work for city driving. Maybe it is on or off with no in between.

 

As one of the other posters said, the fan clutch acts like it has 2 speeds, say 35% of water pump speed and 90% of water pump speed. I'm estimating those numbers, but there is a big difference between them. Your Newmar may be better insulated than my Winnebago, but there is a big increase in noise level when the fan clutch engages.

If all the baffling is working properly, then the clutch should not be engaged at highway speeds. This means you get low fan speed, with the viscous part of the clutch driving. If the radiator temp gets too hot, then the air coming through the radiator heats up and the fan clutch engages, speeding the fan up lots. At highway speeds
the noise is very noticeable.

So although your fan was turning before, at highway speeds its thermostatic clutch should not have been engaged.

Michael

 

You can really tell when the fan clutch engages as the noise increase is very noticable. All the rubber sealing parts are around the radiator top and sides and the air has no where to go but through the A/C condensor & radiator or possibly down around the bottom of the radiator. The only thing I can say is the clutch would engage on hot days 80+ while on the highway.

 

I guess different motorhome manufacturers have different standards, but my Winnebago had the baffle over the top of the radiator missing. On 100 degree days in west texas, AC on, the clutch would not be engaged at 65mph on the freeeway, but slowing down on the offramp it would engage at 58 mph. This is when I learned that the baffle was important, and I'm not only replacing it, but improving it.

If everything is working well, the fan shouldn't clutch in at highway speeds unless you're at unusually high loads.

Michael

 

Can you explain the battle in greater detail? Is it a device or just sealing the front of the motorhome so air has to go through the radiator.

 

The baffle that was missing from mine was supposed to be made of a stiff thick rubber, and it covered the gap above the radiator up to the firewall. Its purpose was to stop air avoiding the radiator by flowing over the top of it. Without it, there is an area of about 30 by 9 inches that th eair can go through instead.

There are holes in the rubber to allow several things to come through, like the oil dipstick, the oil filler tube, the thermactor air dump, the engine air cleaner intake, and maybe an AC hose or 2.

Nothing I've seen on these F53 chassis has any baffles to stop air entering the front cap (or fibreglass front bodywork) of the motorhome from escaping down the bottom or avoiding the radiator by going left or right. I suspect this makes the transmission cooler very ineffective.

I've looked at the V10 engines motorhomes, and they seem to have more ductwork, and also a transmission cooler that is about4 times the area of the 460 cooler.

Did that help? I do have the front cap off mine at the moment; maybe I can work out how to post a picture.

Are you finding an IR thermometer OK?

Michael

 

Going to try and test tomorrow for compression, radiator pressure test and temp test with IR. The only problem is that where it is stored you are not allow to work on your coach so I will need to be quick. Will let you know

 

All locations are as viewed standing behind the engine..

Right bank compression test
Cylinder 1 155
Cylinder 2 155
Cylinder 3 155
Cylinder 4 155

Left Bank compression test
Cylinder 4 155

I could not get the others as I did not have the correct tools. Will do later. Engine runs fine so I don't think I have a head or head gasket problem.

Radiator pressure test cold

Pressured system to 14 PSI. Had a leak in the lower radiator hose going from engine oil cooler to water pump. Leaking around the hose clamp. Don't have much experience with pressure tests but when I relieved the pressure via the button coolent would flow out under pressure. Is that normal?

IR Temp Testing

Mechanical water temp gauge 190 degrees
OEM Temp gauge mid normal range

Heater outlet hose 182
Heater return hose 175
Upper radiator hose 191
Lower Radiator hose 175
Radiator tank upper 185
Radiator tank lower 180
Left cylinder head rear 180
Right cylinder head rear 193

 

I haven't done much pressure testing either, but I would not be alarmed by fluid coming out as you release pressure.

I don't know how high your heater is, but mine is the high point of the system, so I'd expect the pressure would compress the air in the system, and when you release the pressure that air expands and pushes whatever's at the cap out the overflow.

Your compressions sound fine.

The temperatures you measured just confirm that all is normal at idling speed. However what you can also do while the RV is parked is to log the temperatures every 30 seconds or so as it warms up. You should see the bypass circuit warm up first while the top and bottom radiator hoses stay much colder.

(The bypass circuit is the bypass hose between the intake manifold and the water pump which you can't really get at, and also the heater hose with the heater turned on, and you can get at that.)

Once the bypass gets up to close to 170, the thermostat will be opening soon, and if you can log the top and bottom hose temps during this opening period, and get an idea of how fast the top hose warms up, then you can get an idea of whether the thermostat is opening properly.

Even if the thermostat doesn't open much, the temps will eventually stabilize just where you already measured them.

Then if you want to drive it again, you can stop before it gets very host and measure radiator top and bottom hose temperatures. You should see a noticeable difference.

Did you say you'd measured the radiator top tank and bottom tank? Or did you just mean the top and bottom?

My F53 has a crossflow radiator, probably the original, so it has a left and right tank, not top and bottom.

So if you drive it and as it gets hotter and hotter, then if there is a significantly bigger than at idle difference between top and bottom hose temps, measure by IR, then you probably have good air flow through the radiator, cooling the water, and you don't have enough flow through the engine.

If the temp difference is about the same, and the bottom hose temp is higher, then the radiator isn't cooling the water enough, either because of not enough airflow, or wrong radiator, but the water flow through the radiator is probably OK.

Even though we know you've changed the thermostat already, it's still possible it's sticking, or not opening enough. Also the genuine Ford OEM one is a balanced flow design (and 192F) and probably opens wider than the average aftermarket one 195F one.

If your next temperature test is not conclusive, I would try a run with no thermostat, and the heater on cold. Bad for warmup, not a good permanent solution, but good for removing all restrictions and seeing if the radiator can keep up.

Michael

 

Thanks Michael. The radiator has side tanks like the oem but this one is all metal. I think I will take the thermostat out to see if the system still heats up at speed. If it does then I guess it may be the water pump or the wrong radiator. I'm sure the shop who replaced the radiator will disagree with the radiator being the problem.

 

When did Ford start having a #4 on the left bank? 5, 6, 7 & 8 maybe but a 4, nope. Besides that your engine has two #4 cylinders.

 

Yes, it all sounds very frustrating. Something seemed familiar about these issues, and I found your threads on both trailer Life and RV.net. While it's difficult to do long distance diagnosis, it's also amazing how willing and eager people are to give bad and irrelevant advice.

I assume that you don't want to take it to a shop because there isn't one you trust, and they could easily change more stuff, you'd pay through the nose, and it still might overheat. I think with your IR sensor, you'll be able to track this down, and avoid just changing parts and paying until it gets fixed.

However 2 things from those other forums caught my attention.

One is that you said that the dash temp gauge said it was overheating while your mechanical gauge said it wasn't. Is that really true? If so, why is it that you believe it overheats at highway speeds.

The other is that I gather you had a transmission overheat and lost some fluid. It's my belief that these motorhomes have the transmission cooler starved of airflow, and that especially at parking speeds it's easy to overheat the fluid.I fitted both a transmission temp gauge and also a second cooler plumbed after the factory cooler with a thermostatically switched electric fan. After a trip, if I have to line up with a gate, or go very slow past obstacles, I'm surprised how often the fan comes on.

Michael

 

Michael I installed the mechanical temp gauge in the out going heater core line. The first time I ran the test I did not have the heater on so the coolent did not circulate and the temp stayed arounf 180 to 190. After I realized this I opened the heater valve and that is when the water temp went to 230 before I pulled over.

To the other person I indicated I was viewing the engine from the rear and I identified a right and left bank numbering 1 through 4 starting from the front of the engine. I have no idea what the firing order is and/or which cylinder is #1. For my purpose this was not required.