Geoff Weeks

Never seen the "nut type" on anything this new. IIRC it is a very modern Eaton he is working on.

If you can't explain it you don't understand it! You are claiming phase change is happening below the boil point! That is not how thermal dynamics is. Phase change happens when either the pressure is below the boil point at a given temp, or the temp is above the boil point at a given pressure, period! We are talking about a full system that is enclosed. You can't rip the liquid apart by physical action alone.

Phase change is phase change! Explain "separating" and why it happens there and not elsewhere.

Liquid changing to gas, has a term, it is the boil point. If you are boiling at the return from the radiator, you are already overheating before any coolant has entered the engine to cool it. At 50/50 and atmospheric that point is around 223 deg F. And this is on the return side of the radiator. Where as the de aeration tank is where the pressure cap is and also directly connected to the lower pressure side of the waterpump, that is above atmospheric, often around 10 psi.

So, how low does the pressure have to be for the coolant to vaporize? As you say there isn't "suction" only pressure below atmospheric. If you look how low the pressure has to be for the coolant to turn to vapor, it is well below what a centrifugal pump can produce. The pressure cap holds the "suction side above atmospheric, the pressure side can be as high a 46 psi in the block.

That is a torque limiting clutch brake and would be my 1st choice also. There is another "1 piece" that is just a solid disk with friction material on both faces. That one can break off the tabs that slide on the input shaft if "pinched too hard" The torque limiting prevents that from happening by slipping if it gets squeezed too hard, before the tabs break.

Braided line is durable and can take pressure well. Most 1/4" hose, like fuel hose would be less durable. Also the reusable hose ends don't loosen with repeated heat cycles like worm drive clamps can.

There are 2 top tanks, the one closest to the tubes is the tank where the big upper hose goes and the coolant passes down the tubes to the bottom tank/hose. The upper half is the de-aeration tank and is where the cap and where you put coolant in. The 1" line is "bottom fill" line so coolant in the de-aeration can fill the system marmon tank.pdf

The bypass line is use until the T stat is full open to return the coolant back to the pump to allow it to circulate within the block. The bleed line or passage prevent any air from being trapped in the future. Injector copper sleeves can weep a small amount of air into the coolant on start up. the bleed line or passage makes sure it doesn't get trapped in the top of the pump housing. Run a de-aeration tank low, and you can get air into the system. By allowing it to escape, you prevent the pump from being air bound. Take a picture of which lines you are talking about and I will try and tell you the reason for them. In all cases, the outlet of the water pump is directed to the bottom of the block, this makes the outlet of the pump lower than the top of the waterpump housing. That makes the housing an air trap. There are some (tend to be lighter duty engines) where the outlet of the water pump is to the top of the block or cylinder head, these self vent but direct the coldest water to the hottest part on the engine, which isn't great for even cooling. Most modern engines direct the outlet to the bottom of the block.

There are two reasons, for a pipe from the thermostat housing to the pump. One, is a return when the 'stat is closed (bypass), this keeps the coolant circulating. This, however tends to be a larger pipe, and is connected to the inlet side of the pump. Often a small hose or pipe from the pressure side is exactly what I am referring to, a bleeder line to to high point in the block to allow the air to escape. In Larry' s engine the bypass connects back down at the oil-cooler so not directly connected to the waterpump. depending on how the waterpump is situated on the block, the bleeder can be internal or external with a line, in each the reason is the same to eliminate a pocket of air. For the last aprox 50 years, a bottom fill/degassing tank has been used to eliminate air in the cooling system, with vents lines in the upper water rail and in the upper radiator tank. On a 3406 the pumps is low and gear driven, there is a large passage from the T stat housing back down to the pump ~1.5" diameter, when coolant from the degassing tank (where the cap and fill are) is directed to the inlet of the waterpump and the air can escape up the bypass line to the T stat housing (and upper water rail vent line) to the degassing tank. Since the bypass line is vertical from the top of the pump, the air pocket is eliminated. Cummins does it different with the waterpump bolted in a casting on the front of the block, with a small hole through to the main coolant passages in the block to allow air to vent out of the pump recess in the block into the main coolant passages in the block and on to the upper water rail.

No need for "bleeders" all over the block, because there aren't cavities that can trap air all over the block. Block has opening on top to the heads, heads have opening on top to the upper water rail, upper water rail has a vent to the degassing tank on top of the radiator. Yes, we could agree but then we both be wrong, as you say.

really no comparison, when you are looking at older mechanical engines and trying to compare to newer electronic ones. The L-10 topped out at 300 hp mechanical, but was more common at 240hp or 2 hp over an old 6-71! Gear ratio/tire size also makes a big difference. The whole truck has to be spec'd for the job to make the most of any one component.

Worked on Deere engines in river tow boats.

3406 is over 14L, L-10 is 10 liter, not a fair comparison. L-10 was kinda gutless but it was small and topped out at 300hp in mechanical form and 330 in electronic at the end of its life. It was replaced by the M-11 a "stroked" version, that was electronic from the get-go and that got power up over 400 hp. I had the experience of driving both an L-10 and a 3306 which were a closer comparison, in the same service with the same loads, and I felt the L-10 was slightly better than the 3306, both were 300 hp and the Cat blew the timing gears early in its life, the L10 lasted a lot longer. IIRC I got in the mid 6's for fuel with the L-10, about what my 6.9 did in my service truck! Both Cat and Cummins were pushing these small displacement, mechanical engines as fuel savers, over their large bore engines.

It has nothing to do with pressure, it has to do with an inverted U bend (at the top of the housing) that is above the inlet and outlet. It forms a pocket that holds air. You can have gravity or pressure on the coolant and it still will not cause the air to go below the coolant level to pass out of the pump. If you force the coolant in under pressure, you will compress the air trapped but not eliminate it. A vent line from the top of the housing allows the coolant to push the air out of the housing, gravity is more than enough to do this if there is an outlet at the top. If the outlet to the block was at the high point of the pump housing it would not be needed, but that isn't how this pump is made. By getting the air out of the housing, it makes the pump move coolant more efficiently, and leaves no air bubbles in the coolant to break on contact with the hot block and cause cavitation damage. All engines have some way to vent any air out of "high spots" in the system. Some have a small hole in the thermostat or a place where the stat doesn't seal off so air can pass. Others with Weir-stats, have a vent line to the degassing tank on top of the radiator. Air will not dissolve in coolant, it will always try to be above the coolant, if you provide a trapped area with no outlet with coolant below, it will occupy that space. Having an air bubble trapped in the top of the pump housing is like running a boat propeller 1/2 out of the water!

Yes, that will bleed it. You will notice in the diagram, the coolant "conditioner" is above the pump housing and runs to the thermostat housing.

How did they vent with the new housing? problem with bleeding once, is if the block ever gets drained, you have to do it over. IDK Macks but others sometimes have a internal bleed hole to vent the top of the pump housing.

That is not what I am saying! The inlet to the pump is at 3 O clock, the outlet is at 9 O clock (really closer to 4 and 7 oclock) , and there is no way to get the air out of the top of the water pump housing. Air will be trapped in the housing with no way out. It will cause cavitation. With that 3/4" nipple at the high point air will be pushed out of the waterpump housing. If you plug it there is no way for the air to escape. You'll end up with an air bubble. A bleed line out of the high point will force any air out of the pump housing and eventually to the top tank of the radiator.

Keep in mind you want some way to vent any trapped air at the top of the w/p housing. It doesn't have to be large (3/4") but some way to get the trapped air out. -3 PTFE line would be plenty. If it were mine, I'd cut the tube off and tap for a fitting to reduce to 1/8 NPT and a small breather line to the high point in the cooling system.

As far as Power steering, it depends, on what gear you have. Sheppard takes 10-40 motor oil as per Sheppard. 15w-40 has been the oil of choice until recent engines. Trans depends on what transmission. Look to the manuals, for the last word.

This shows the lower rad connection, through the oil cooler to the center of the waterpump. Yes, you need to vent the scroll to prevent air being trapped, but centrifugal pumps ALWAYS pump from center to outside. Where the outside is connected to the block (top, bottom or side) doesn't change the fact that it is on the pressure side of the pump.

This was the one.

I think you have that backwards, it draws through the oil cooler to the center of the pump, centrifugal pumps always pump from center to outside. The block is on the pressure side of the system. edit: hum the post I was replying to seams to have been deleted?

One looks to be on the pressure side of the pump (new one on top) while the other is on the suction side (lower). Not interchangeable.

There does seam to be something about the last name "Green" no matter how it is spelled, disrupting the SOU speech. I agree with 67Rmodel, it isn't just one side.