A New World of Cooling Systems

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A New World of Cooling Systems

MACS Service Report for Feb 2020 • February 5, 2020

This article is excerpted from the MACS Service Report for February 2020 a MACS member-only publication. ©MobileAirCondiitoningSocietyFeb2020.

This month MACS is running a Leap Year membership special to buy one year of MACS membership get one free for all educators. Use the attached form to apply and take advantage of all the great technical resources MACS has to offer. For more information contact: marion@macsw.org

Advanced Cooling System Becoming "Mainstream"

A New World of Cooling Systems

You probably haven’t seen many late-model super-high-performance vehicles in your shop, or even late-model premium European cars (and likely won’t for a number of years to come). So, models with multiple radiators combined with variable-speed electric water pumps will not have appeared and changed your impression of cooling system design. Probably all you may have seen is the computer-controlled variable speed electric water pump, which has been used on hybrids for several years and more recently by BMW (2.0-liter four-cylinder) and Toyota on new Camry models.

But when an advanced cooling system makes its debut on “mainstream” so-called “conventional” gasoline engines, it’s time to really pay attention.

General Motors has begun a changeover to what it calls “Active Thermal Management,” on the base engine in its Silverado pickup. The engine is the 2.7-liter in-line four, which matches in displacement (although not in the number of cylinders) with the 2.7-liter V6 in the Ford F-150.

SAE International has been running a Thermal Management Systems Symposium for a number of years, and it’s been a sign of engineering to come, so MACS staff members have been attending, to be ready for the new technology.

Precision cooling isn’t limited to internal combustion engines. Battery electric vehicle cooling may be even more complex, as high-rate battery pack charging comes into use, but for the present, let’s look at GM’s new cooling system for the 2.7-liter four-cylinder, and how different it will be to service.

The system doesn’t have a thermostat, so if you sud- denly are thinking, “Hey, that’s the part I’ve replaced most in cooling system service over the years, followed by radiator, hoses, belt and water pump.”Well, relax. It has lots of parts.

There’s an electric water pump on the right side of the engine. And as the illustrations show (Figures 8 and 9), there’s a lot of external hoses and piping, but the pump itself, as an electric motor-driven device, does not have a belt wrapped around it. Although the water pump’s electrical control (by the engine computer) means it’s infinitely variable and perhaps more subject to failure, it’s also more accessible for service than the integrated mechanical pumps on some conventional engines. And although the thermostat may be gone, there’s a massive coolant control valve on the left side of the engine (which is actually a combination of two valves).

One valve section is integrated with a hot coolant manifold, which controls the flow to the radiator, a bypass circuit, and engine oil and transmission oil heating or cooling circuits, using one actuator. It’s this valve that not only regulates engine warmup, but is a primary factor in eliminating the need for the thermostat.

The second valve, called a “block valve,” has a sep-

arate actuator that regulates coolant flow for engine block temperature control as well as to the passenger compartment heater.

The valves’ electric actuators both are on a “LIN” (Local Interconnect Network) to the engine computer (Figure 10). A LIN is a relatively simple network. Although the valves are not covered by trouble codes, the system includes trouble-code covered temperature sensors (10 of them) and along with how-it-works descriptions and which and when cool- ant circuits have flow and which don’t, the diagnosis should be straightforward. If the valve assembly has to be replaced, it must go through a learning curve, which is on the factory scan tool menu. At this early stage there are probably no detail parts available, such as an actuator, although eventually we suspect there will be.

We suspect that as active thermal management systems evolve, some of the external hoses and pipes will be passages within the engine, with additional trouble coding to cover the absence of external parts that can be checked by use of infrared guns and hand-feel diagnosis. At this time, we can’t tell what will be necessary to flush such a system. Obviously, its complexity makes it pretty obvious that all the piping, hoses, passages and heat exchangers will make conventional flushing just about impossible. We probably will see scan tool routines that put the system in various modes for partial flushing of each section. Or you may have to make specific disconnections and individually flush the block, head, radiator, heater, etc.

The active system does mean that the system is in a continuous control mode, and if any of those 10 coolant temperature sensors fails, a technician will deal with new problems he has never seen before. Right now, you check a cooling system for cold and warmed up. The 2.7-liter I-4 has up to seven, yes sev- en cooling modes, although not all seven are used every time; it depends on the temperature of engine and transmission components, their oils, coolants and ambient temperature. The system is designed to switch seamlessly between modes, depending on what amount of heating is selected. The engine-cold, heater-off, startup mode (No. 1) is the fastest at warming up the engine. The electric water pump is run at low speed and both valves are in low coolant flow mode, as heated coolant is allowed to stay around the combustion chamber. The low flow through the block helps speed warmup of that area.

If the driver requests heating or turns on the defroster, the water pump may speed up and from here on, through the remaining coolant flow modes, pump rpm is regulated according to engine demand. And the coolant valves are adjusted by the computer, with feedbacks from position sensors at the valves.

-MACS Service Report for Feb. 2020

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The Engineering End of Year Roundup

By ATech Training • February 3, 2025

The automotive industry is an ever-changing landscape of engineering innovation. As always, this atmosphere of change has once again made the attempt to lurch forward. There are multiple changes and challenges coming for automotive technicians in the near future. Some small, some large, and some totally ground-breaking. I won’t be going too far into the technology of some of these innovations as some are not only complicated, but quite difficult to describe. I will, however, do my best. As a round-up of older developments let’s take a look at these technologies from Nissan, Konigsegg and Liquid Piston that seemed far-fetched only a few years ago. Seven or eight years ago Nissans developed a variable compression engine that changed the stroke of the piston as needed to alter the performance characteristics. Thus, aiding both performance and fuel economy. When a change in compression is needed, an actuator motor adjusts the pistons position changing the compression from 14:1 (economy) to 8:1 (performance). This engine is now offered in many of their newer vehicles and will be installed in all of their Nissan Murano SUVs in the 2025 model year. It is an engineering marvel that seemed like magic only seven or eight years ago. The engine has proven itself fairly reliable and Nissan is hoping that it will perform as their new standard looking forward. Of course, their engineers are now on to greater things.

Cylinder Deactivation

By Jeff Bogue • October 25, 2024

What's Old Is New...

Engines of the Future are Already Here!

By Jeff Bogue • December 12, 2023

I have been dreaming about and studying engines and engine performance of cars, trucks, and motorcycles for the better part of 45 years. It’s a hobby. It keeps me busy on cold winter evenings. It’s something that has become a large part of my life and, like playing with dogs, is something I love to do. I have written about engines and the engineering that is involved in them for the last 15 years, and I have always been forward-thinking. When a new engine is being lauded by the manufacturers as the next big thing, I read all about it and report those findings here. In the past, I have written about every one of the engines in this article at one time or another, and each one was glowingly revealed by the engineers with the statement “We can expect these engines in our cars in the next few years”. Well, a few years have passed and now most of these engines ARE in our cars and trucks and should be reaching repair shops and dealerships now. We just haven’t heard that much about them because people, as a general rule, really don’t care that much about which engine is in their car if it gets good gas mileage, is reasonably reliable, and has a little umph to get on the highway. Well, that is not us. We care. We study it. It’s what we do and why you are where you are reading this article. Without further ado, let us look at the “Engines of the Future” that you can buy (and service) now.