After 39 years in the auto repair business and 31 years as an owner, I’ve had the opportunity to read many articles pertaining to the technical side of repairing automobiles. I’ve also had the opportunity to write many articles relating to shop management. But, this is my first opportunity to write a technical article.
As a shop owner who specializes in the repair of Japanese vehicles, I thought I’d share some tips on Subarus. I started my Subaru experience in 1979 working at a Subaru/Mazda dealership in Southern California. I can assure you that in 1979 Subaru was not the most sought after car by consumers. For example, we sold about 125 new Mazdas each month but approximately only 10-15 Subarus per month. Fast-forward 33 years and it’s quite a different landscape for Subaru, which posted sales of almost 30,000 vehicles in May 2012, up 48% over the previous year’s number.
Subarus, like many other nameplates, have common problems, one of which I’ll discuss in this article. Head gasket failure has been something Subaru has struggled with to some extent since the 1980s. There are many thoughts as to why head gasket failure on Subaru has continued. My theory is that there is a horizontally opposed engine with an aluminum block and aluminum cylinder heads, two metals that tend to move around more than the traditional cast-iron block and aluminum heads found on most Japanese cars. A poorly designed head gasket material also fuels the problem.
There are some other issues that relate to premature head gasket failure. Excessive corrosion has led Subaru to add more ground straps to the car on the later models. The discovery of voltage in the cooling system is believed to contribute to gaskets getting corroded and failing. Although Subaru did have a service campaign that helped pay for the repairs for some Subaru owners, the program has pretty much gone by the wayside at this point.
The head gasket failures are found in a couple of different configurations, the most common of which is the external oil leaks at the back of the cylinder head, generally most prevalent on the left head or driver’s side.
The second type is the external coolant leak, the coolant leak most common on the driver’s side, as well. Generally, it starts with the oil leaks, then progresses to the coolant leaking too. I consider the oil leaks to be of concern, but when we see coolant leaking, the need for repair is more urgent. We generally inspect the heads for the leaks, and then discuss with our customer the severity of the leaks. In many cases, you can monitor the leaks for a period of time before the repairs are classified necessary or urgent.
The final type of failure is the internal gasket failure that will produce the classic coolant loss and overheating. We see many shops try a variety of repairs, including thermostat, radiator and water pump replacement, only to leave the customer with money spent on repair bills that didn’t solve the problem.
The best way to check for an internal head gasket failure on a Subaru is to check for hydrocarbons in the cooling system. You can carefully insert the probe from your smog machine in the radiator (don’t let the coolant touch the probe). The reading will be more accurate with the engine fully warmed up. If the HC levels are above 10 ppm, the head gaskets are leaking internally into the cooling system.
The final topic I would like to discuss before we get into the repair is cost and how to approach the job. We’ve performed this repair more than 400 times, and although each job is unique, the cost for this job varies, depending on how the job is approached and the area of the country where the job is being done. I’ve heard quotes of $1,200–$3,200. I also hear people trying to do the repair without taking the engine out of the car, which, in my opinion, is not the correct way. (We will discuss the reasons as we proceed with the repair.)
I would guess that 20% of the head gasket jobs we perform were done at another shop not that long ago — long enough to get out of warranty, but not long enough to warrant the cost of the “discounted repair.” We also see many shops, including the dealer, try to just repair one side, only to have the other side fail within a few months.
The other issues we see are when the customer gets the head gasket replaced, only to have other seals leak soon afterward, that should have been replaced in the first place. This repair should not be approached with the mindset of “how cheap can it be done?” but rather, “what’s the best way to efficiently repair the vehicle so the job will last?” and “let’s deal with all possible issues that are somewhat related at the same time.” That said, most jobs require head gaskets, a water pump, a timing belt, drive belts, thermostat, idler pulleys, a timing belt tensioner, tune-related parts and machine shop cost. In our area, $2,220–$2,500 is the normal price range.