Installing valve in water line from head to heater core

Hard to see the turbo and manifold on a full dressed 6.7 stuffed in under the cab of an M2, plus air cleaner is right in the way….but it LOOKS like the turbo is centered on the manifold…more on that as soon as I get one in here with the air cleaner removed.

 

These are the three different Exhaust Manifolds on our buses. Most of them take the one on the upper left.

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I admit that language of mine there might not have been the clearest thing I ever asked; I was just observing that the 12 valve manifold has the turbo flange centered between cylinders 3 & 4; on the common rails the turbo flange is between cylinders 4 & 5 and thus the runners from cylinders 1 and 2 are longer than those of the other 4 cylinders, allowing the exhaust gasses from cylinders 1 and 2 more room to expand and cool before being merged together than the other runners have. I never had a 12 valve but I thought from other discussions that the high temps in the back cylinders were at least in part due to the redesigned exhaust manifold, but I probably misunderstood.

It looks like the manifolds BigPapa posted also have the turbo flanges between either 3 & 4 (like the 12 valve) or between 4 & 5 (like the CRD) assuming the turbo is located beneath the manifold, however, mwilson's comment on Monday about the turbos being at the front leaves me wondering...

Only trying to understand a bit more, particularly because the heater hose tap is between cylinders 4 & 5, and not farther back. You can't really learn this stuff from the design decisions made at the factory because while they are trying to make the cooling work, the only thing they are trying to optimize is the bottom line.

 

I understand the rear cylinder temps to be from the way coolant flows around the cylinders so the coolant is already hotter when it gets to the back of the block. The cooling issues, and rear freeze plug issues, occur at high power and high rpms which is more common, stock for stock, with a HPCR.

I am not sure the longer runner makes too much of a difference in reality, thou it certainly does make one on paper. Most of the expansion occurs as the exhaust gasses exit the head into the manifold. From there its a relatively constant volume, as there is additional gasses being injected into the manifold at each of the other cylinders. We do get the hottest readings for EGT's on the manifold near 5/6, but the readings between 2/3 really aren't that much different.

A centered turbo will have the most balanced flow, but under most operating conditions I don't think there is much of an appreciable difference.

I know that early on it was thought that 1-4 dumped into the front divider and only 5-6 into the rear, but even with the rear turbo design it's a 3/3 setup.

 

In my experience with trucks the turbo placement is more from a design standpoint, not performance. They move it to and fro depending on what else needs room on that side of the engine, where the optimum exhaust placement is for the chassis, etc..

For example, Cat 3406 engines typically offered three exhaust manifold / turbo configurations for truck use.
High mount, mid mount and low mount. Paccar used one, Freightliner used one and back in the day Ford LTL models had yet another. Ford clocked the Cat one flywheel bolt hole to the right so all right side components were closer to the truck frame. This allowed more room on the left for the drivers feet and other components.
If we order a Cat reman engine right now it will usually come dressed as a high mount as those are the most common components turned in on core engines. Then we have to use existing components from the removed engine to make it fit. I can’t imagine that it affects the engine at all.

High mount..

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For those wondering why that engine is a lot of money…

That is a 2WS Cat Reman new content engine. Block, crank and cylinder head are new, not remanufactured.

Any comparable engine including Cummins and Detroit up to that emissions tier can be turned for core credit. EPA is happy with that as it is a one for one swap and the core engine will be destroyed to satisfy the EPA rules. You can not remove a newer tier engine and go backwards.

 

For those wishing to put in a bypass for the heater core, why couldn't you add a "T" fitting with the feeding the core and put a valve on the straight though feed. This way, it's a straight shot for the flow to go, thus still allowing a small amount to continue to flow through the heater core. Then when you need heat, close the valve for full flow through the heater core. Just trying to think about how it flows and the hard right turn wouldn't allow full flow unless valve would be shut. Just thinking out loud about another option to look at. If it wouldn't work, no harm putting down for others to learn from. I remember when there were heater control valves the were operated by a cable from the HVAC control panel. They would get stiff from corrosion here on the East coast!

 

You could use two T's in the line - one in the supply and one in the return. Put a ball valve in the supply line to the core, and one in the bypass line. Then the returns from both will go through the second T and back to the water pump. No need for valves in the return line.

 

Ok, took a minute to fetch some graphics…again this is on my 2020 truck. Your results may differ…but they shouldn’t..

Number 11 below is the turbo coolant drain..

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Now for the EGR cooler lines…Number 16 is the EGR Coolant return line. Note that both the heater return line and the turbo drain line connect to Number 16.

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My conclusion…you can close the heater feed line (the line from the cylinder head) off and not hurt the coolant flow at all.

 

You fellows talking about tees and two valves are complicating things. The valve I referenced is all you need. When it's open, flow is through the heater core as it normally is. When you close it, the heater core is bypassed and coolant flow to the engine is normal. If you want to put it in the hoses, you're talking about four hose clamps. With tees and two valves you're talking 6-8 or more.

 

Exactly. Do just like Freightliner does and shut the line off that comes out of the cylinder head. That’s all that is needed.

 

That would work just fine. In fact, that provides the exact same functionality as the 4-port valves discussed above by BigPapa and myself, only more parts.

Seriously, just go with one of the 4-port valve assemblies. It will be much simpler, and if you go with the electric version, you can control it with a switch from inside the cab. Plus, it automatically prevents both valves being accidentally closed at the same time.

 

Swap an old Tier X engine for a brand new Tier X engine? (That's what I would do just on principle.) That type of swap not even as effective as the Obama-era Cash-for-clunkers charade.

Doesn't the EPA also permit replacing a given engine with a newer emission tier engine (i.e., Tier X+n) like California is pushing?

 

Thanks for the pics, I see what you're saying for the 2020 engines.

The 2004's didn't have either an EGR coolant circuit (luckily) or a turbo coolant circuit (bummer). The only additional external circuit I can think of is the heater core.

Looking at it as if it were an electric circuit, which somewhat models the circulating coolant flow: Because the heater core is run in parallel with the back portion of the block, blocking the flow through the heater core would increase the overall coolant circuit resistance to flow. I'm talking the total flow: through the block, through the radiator, through the water pump and thermostat, and everything else. (Just like putting a second resistor in parallel with a first resistor reduces the overall resistance of the combination, and taking the second resistor out increases the overall resistance). And with all things being otherwise equal (an extremely unlikely condition), that would reduce the total coolant circulation rate in the system as a whole, which would intuitively raise the temperature of the whole system (same ambient temp, same heat load, same thermostat restriction, etc.). However, if the heater core flow is blocked off, and the total flow decreases to where temps began to creep up, the thermostat would dynamically respond and automatically compensate to increase coolant flow to maintain its set temp. At least up until the thermostat is wide open...

Edit: This is all just "theory" and might not have any basis in reality!

 

I believe it has basis in reality. Many of the freeze plug issues I’ve heard of are at high cylinder pressure (rpm/power production) and low coolant flow (thermostat not fully open 207° for the 190° tstat). So total flow certainly plays a part in cooling system pressure.