Geoff Weeks

IDK, I know a neighbor had a problem with a IHC. It was wet lined . Coolant filter and SCA's were the std answer in trucks at that time. He, like many farmers never gave it any thought until there was a problem. Never used SCA's or coolant filters.

I went looking for the causes, not solutions but you bring up good questions. I would add one more, does a dry liner engine have a similar problem as a parent bore? Do either of them have a problem at all? You don't hear much about dry lined engine leaking coolant between the dry liner and block/crankcase. I know it happens with freeze cracks. It would follow that the places in the block that hold the liner would effect the resonance of the liner. So a liner pressed in at the very top and bottom might resonate differently than one with the top press fit is lower in the block. The irony about learning is: the more you know the more questions it brings up! Mostly I hear about it in wet lined engines, but those are often the most powerful engines as well, so the cylinder pressure and piston speed may be a factor? I bet there could be a collage level course on the causes and solutions alone!

Not to muck up Larrys 300 build thread any more I am going to start an new one. 1st I would like to say that I wasn't trying to be disrespectful to anyone (esp Paul) but did want to understand the thinking. I did a deep read on the subject, and found we are both wrong. Liner cavitation has nothing to do with the water pump at all. Not design, not placement on the block, not how well it bleeds itself of air, nor air itself. We were both partially correct and partially wrong. Paul is correct that vaporized coolant, not air, is the cause. It isn't due to flow or pressure however, according to what I have read on the subject. Liner cavitation is caused by high frequency sound wave from the liner itself, cause by the combustion and movement inside the liner. When these high frequency sounds get transferred from the liner into the coolant, they make high and low pressure points in a wave, as the liner resonates. When at the low pressure stage of the wave the coolant can vaporize and when at the high they "burst" back to liquid. This, over time can etch the liner in a tale tail pin hole shape. For this reason, cavitation damage is limited to one plane of the liner, and 90 deg around the liner there will be none, it is all in how the liner resonates. This also explains why it occurs more or less evenly across all liners in the engine without regard to how close or far they are from the water pump. If it were caused by vapor pockets circulating in the coolant, we would expect the damage to be random around the outside of the liner. It is also why some manuals state "with minor cavitation damage, the liner can be reused if turned 90 deg in the block". Centrifugal pumps can not pump air efficiently and even less so with a liquid "head" above the outlet. As stated it is why they are not "self priming". For this reason, there is a way provided to expel air when the outlet is below the top of the impeller housing. Eliminating any trapped air is important, but has no effect on liner cavitation. It can effect the pump itself and other parts of the engine. It is partially why all trucks for over 50 years use a "bottom fill" system (shown in the 300 thread as a Marmon attachment) so the coolant rises from the lowest point in the engine and pushes out the air as level rises. Paul stated "I must have an open mind to learn" and I do, which is why I ask anyone to back up their statements, I can't learn if I don't know the "why". An open mind lead me to a few hours of reading on the subject. I have already apologized to Paul in the 300 thread if I seamed a bit too "confrontational" but I need to understand the "why" of something to be able to retain it. His If you want more info or possibly a better explanation then I can give, do a web search for "causes of liner cavitation in heavy diesel engines" and select the ones Not from some YouTTube, but from engine mfg. To quote Paul " So cavitation occours when the liquid, in this case water, separates into gasses Oxygen and hydrogen in the case of water This happens when the delivery side of the pump isn't restricted enough or supply side is to restricted " It isn't that the coolant separates into Oxygen and Hydrogen or even that the mixture of antifreeze separates at all, but rather that it changes from liquid form to gas form while still being coolant, this happens at the minute scale where the wave caused by the high frequency sound from the liner meets the coolant on the outside of the liner. Much like an ultrasonic cleaner does. It does this while at pressure inside the block. Cummins low flow has a block coolant pressure of ~45psi @2100 rpm! That engine still has liner cavitation issues. It isn't that the flow is restricted in any way, either on the low pressure or high pressure side. Until I read up on it, I never really gave a thought to why it is on one side of the liner and 90 deg it doesn't happen, I knew that to be true, both from reading and pulling liners out of engines, but now I know the "why" and it help me to better understand the problem. Likely more than most want to read or know, but I did put in the time to understand it. The most important point I learned is the "vapor bubble" is both created and destroyed at the liner itself and not the result of being moved about by the circulation of the coolant.

I come up with 67 MPH @ 2100 rpm with 11R22.5 rubber. If your tires are different, then the top speed will be also.

Paul, I did not mean to be insulting, Please accept my apology if anything I wrote came across as such. That was not the intent. I do try to understand what you were saying and square that with the laws of physics as I understand those by the people who taught them to me. I think this is one of a few things we are not going to be able to agree on. I too am willing to let it go.

Yep, nice tool, but hard to justify the cost unless you do a lot of them. All the ones I have done, I did without the puller. Can be a pain to get something small enough to get behind the bearing snap ring.

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.