Let's Not Overheat This Summer

We know that the BRZ was a leap of faith as Subaru went outside their own all-wheel-drive boundaries and decided to gift us an affordable traditional rear-wheel drive sports cars that were co-developed with Toyota with their respective 86 and Scion FR-S models.  Still even though the BRZ was off to ride into the sunset with the Miata’s and other momentum talent-based driver’s cars, the heart of the vehicle remained Subaru.

Which segways us into the discussion of engine cooling. Now that Memorial Day is over, that holiday is considered to be the official kickoff to summer. This means that Jeeps will remove their tops and doors while drivers stick their legs out. Bikers will be out in full-force lane-splitting and getting mad at everyone for not noticing them fast enough. Most importantly, people are going to be out there overheating in traffic because they are not “car people”. Now another topic we will touch back on another time is the fine line of, can you still be considered an enthusiast even if you don’t know how to wrench? Yes, there are owners who are walking encyclopedias that can tell you every technical spec and origin of the BRZ, but they can’t change their own oil or can’t tell the difference between a Phillips or a flat head. The point being, is that if you want your BRZ or your daily driver to last, at least be aware of the basics. And those basics are:

• How much oil does your motor have?
• Do you have enough power steering fluid?
• Are your battery terminals free of any acidic buildup?
• Are your lug nuts tight and most importantly, what is your tire pressure?
• How is your alignment?
• Is your coolant topped off and do you know how to check it?

 

The last bullet point is the objective of today’s discussion.  Your cooling system and more importantly because we’re entering summer, how to keep your cooling system properly maintained. Because again, the heart of the BRZ, FR-S, and the 86 is a Subaru.

Now do Subarus have inefficient cooling systems? No, not really. It’s actually pretty straightforward and simplistic for the majority of mechanics. You just have to stay on top of things because like all vehicles, Subaru engines are not prone to neglect, and wear and tear. However, the key area of focus is that you’ve got a flat-four engine. Overheating a boxer engine can quickly lead to a series of very expensive and catastrophic repairs *cough head gaskets* if not addressed appropriately. We will discuss how to prevent these issues, and if you’re not experienced behind the wrench, we have the right products that your trusted mechanic can install. But first, let’s talk about how we need to check coolant levels, and what specially we need to look for before you can potentially get the infamous Subaru blown head gaskets. In which case the motor must come out and you’re not going to have a good time.

 

ABOUT THEM GOSH DANG HEAD GASKETS

Now regarding head gaskets, Subaru’s have a natural propensity to consume coolant. It’s just one of those fluids that you need to check on a regular basis to make sure that you are always within the fill range so that now we are officially in the hotter season, your engine has the right amount of coolant in the overfill tank to supplement the radiator if there should be any consumption or loss within the coolant system. Now why does overheating take out your head gaskets? Because aluminum heads if they get hot enough will warp and the mating surface between your heads and your short block will get compromised, and the gaskets can no longer contain pressure, and contain a good seal. Therefore, your coolant will fill your cylinders where coolant will wash through your piston rings, and into your oil. The mixture of oil and coolant is what causes your oil to look like chocolate milk. Your oil loses its lubricating properties, and your BRZ will turn into a smoke show because all the coolant that is pouring into your cylinders as a result of a bad head gasket, will get burned during the combustion process which will cause billowing white smoke.

Aside from your oil looking like chocolate milk, if you remove your oil cap and it looks like a frothy cappuccino buildup under your oil cap, that is also an indicator of bad head gaskets.

Your engine will have to be removed where your mechanic will have to remove your heads. The heads have to be re-decked to ensure a flat mating surface, they must be cleaned up with the valvetrain inspected and re-installed with new head gaskets. And this is why replacing head gaskets is so expensive because it is very labor intensive.

To prevent failed head gaskets, make sure that you never overheat. So, we will discuss upgrades that you can do to your cooling system that not only maximize the cooling efficiency, it is also great preventative maintenance especially if your BRZ, FR-S, or 86 is your daily driver.

 

 

CHECK YOUR COOLANT LEVELS FIRST

The reservoir with the red cap is your coolant overflow tank. If you look down the tank you will see a minimum and maximum coolant level indicator. It is always best to top the overflow reservoir off to the top, then during the summer months, periodically check those levels to make sure that you are not running low.

 

 

NEVER OPEN A HOT RADIATOR CAP

Unless you like multi-degree burns on your hands, arms, and face. This is very dangerous because you have hot boiling coolant that is highly pressurized.

 

 

 

The normal coolant temperature range when your vehicle is at regular running temps, with a correct-working thermostat along with the rest of the cooling components such as the water pump working as it should, will be between 185-195°F. When your engine starts getting warmer and your gauge wants to start climbing, it will start around 210°F. When you are overheating you are 230°F+ to 240 and beyond. At that point there is so much pressure buildup something is about to give out. It will usually be your radiator cap, or a hose will let go, shooting hot boiling coolant everywhere. NEVER remove your radiator cap if your engine is hot, if you just got done driving it, and even if the radiator cap is warm to the touch, it is still pressurized so coolant will still exit leaving a mess and a loss of coolant. Making sure that your coolant is topped off at the radiator cap fill spout when your engine is cold is always the right way to do. Take this moment to upgrade to an upgraded radiator cap that has a higher boiling point:

Radium Radiator Cap Type A 1.3 BAR Universal

 

CLICK HERE FOR ALL RADIATOR CAPS

 

Now regarding hoses, this is another common fail point in Subaru boxer engines. Now failed coolant hoses are mainly common after years of use, and countless heat cycles. It is a common wear-and-tear item that you will need to replace eventually. The OEM hoses are made of rubber with internally woven fibers. What happens is during every heat cycle, naturally the heat will cause expansion. Over time, mileage, and the elements, those fibers in the rubber will break apart, causing more expansion in the hose. Eventually, the hose will tear at the clamps, or it could even burst at the highest expanding point.

The fix? Silicone hoses.

Mishimoto Radiator Hose Kit Blue 2013-2021 BRZ/FR-S/86

 

This kit from Mishimoto for example, features multi-layered reinforced silicone construction that is stronger, and won’t expand under pressure like conventional rubber hoses will. These examples are more heat resistant and will outlast your OEM hoses for better cooling efficiency.

 

CLICK HERE FOR ALL RADIATOR HOSES

 

At some point, your OEM radiator will fail you. It is inevitable. The reason is the same reason why 95% of OEM radiators fail on every other make and model, and that is because of the plastic upper and lower tanks. Just like your radiator hoses, the radiator plastic tanks will experience lots of pressure and heat cycles. Eventually a hairline crack will surface, and you will lose coolant. Now another OEM radiator replacement will be fine, but you will experience cracking again especially if you try to save money by getting a cheaper eBay or Amazon unit. The right fix is an all-aluminum unit.

Mishimoto Performance Radiator 2013-2021 BRZ/FR-S/86

An all-aluminum unit will not crack under pressure when compared to a stock radiator. Additionally all-aluminum radiators provide better cooling performance due to the increase in core thickness. This is a must-have especially if you track your BRZ since your engine will live in the upper-RPM range for long periods of time. All aluminum radiators will be the last radiator you’ll need to get.

 

CLICK HERE FOR ALL RADIATORS

 

Always remember, whether if you replace your radiator or your coolant hoses, or anything where you must drain your coolant, make sure that you take the small step to replace your thermostat. Failing thermostats are common. If you have a failed thermostat then it could prevent coolant from circulating your engine’s block which would cause overheating. If you have no coolant leaks and your coolant levels are good, then this is a good indicator of a failed thermostat. Also, a failed thermostat could be stuck open which would prevent your engine from reaching optimal cooling temperatures because it allows coolant to flow through the engine right off the bat, so if you’re commuting on the highway, your coolant temps will hang in the 155-165°F range. And the temps would then quickly rise when coming to a stop with no air movement going through the radiator. A way to tell is if your temp needle is lower than the usual spot.

A thermostat’s function is to allow the coolant to remain in the radiator, and when the engine reaches a certain temperature (usually around 168°F), the thermostat will open and allow coolant to flow from the radiator and through the engine’s water jackets and passages throughout the block. Replacing your thermostat while doing any cooling upgrade such as hoses or a radiator makes for great preventative maintenance.

Mishimoto Racing Thermostat 2013-2021 BRZ/FR-S/86

 

A COOLANT FLUSH EVERY 50K MILES IS ALSO A GREAT IDEA

Mishimoto Liquid Chill Synthetic Engine Coolant Universal

Yes, you need to flush your coolant every 5 years or 50k miles generally. There are metal deposits, rust, a bad overall mixture, and chemical buildup. Now the Mishimoto stuff pictured above is approved to use in your BRZ/FR-S/86, but when it comes to coolant, the general rule is that you always must use OEM coolant because they are made using certain chemicals and have different PH levels that won’t eat away at your seals, gaskets, plastics, or cause metal corrosion.

Flushing your coolant is draining your coolant from the radiator, while getting a garden hose and running it up top on your radiator fill area and flush until you no longer see nothing but clear water draining.

 

 

 

REMEMBER KIDS

Summertime is the best time to do any upgrades to your cooling system, because during winter, coolant system components are just as susceptible to failure as coolant hoses (OEM mainly) will become hardened and will crack. Doing all of the coolant mods in the summer is easier and will not only provide better cooling protection and efficiency, but you will be prepared when that cold weather comes back in late October.