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September 19, 2010

My Subaru Outback Head Gasket Repair

Don't try this at home.

This could be your Subaru (parts).

I have a 1997 Subaru Outback with about 280,000km on it. It began showing the head gasket failure symptoms so typical of the Subaru boxer 2.5L engine of this series of cars: foaming/bubbling in the coolant (the reservoir actually looked like a boiling kettle when the engine was running), brief random apparent spikes of the temperature gauge, and coolant loss. Much has been written elsewhere about this issue, and there are a few references about the problem and some repair examples at the end of this blog. Known model years affected by this problem are at least 1996-2002, so be aware of it if you are looking at a used Subaru of that age. I decided to do the repair myself, being very inclined to tinkering, foolish enough to attempt it, and also being unwilling to spend about $2500+ for a shop mechanic to do the job.
Edit Oct. 2011: A few people have asked me about the “head gasket sealer in a can” products. There are a few on the market. I actually had tried one of these, Bar’s Leaks, before I did the real repair, with no success. What I’ve seen in other reports is that they simply don’t work on “internal” head gasket leaks such as what this series of Outbacks gets. Furthermore, given how severe the gasket damage tends to be, I don’t have much confidence in them. The gasket replacement job looks to be the only option, if you want to keep the engine. The good news, though, is that you don’t need to remove the engine from the car to do this repair.
Here are some details of the head gasket repair that I did, in case it helps anyone else trying to do the same thing. Note that this is a big job,

and what started out looking like this:

The engine, pre-repair.

The engine, pre-repair.

was looking like this mid-way through the job:

The engine, pre-repair.

parts out, mid-repair

Usual safety and competence caveats apply: this is on the more advanced and complex extreme of car repairs that one could undertake. You might irreparably damage your car, and injury might result, if you get it wrong. If you aren’t reasonably mechanically competent or if you have no experience working on engines or related things, this isn’t a job that you should undertake.
Special tools needed:
1. The Haynes manual for this series of car. It has pictures, all the details about torque specs, procedures for the HG removal and timing belt replacement (a job that you would be foolish to not do while you have this engine apart), and so on. It’s great – just get it. I found with the Haynes manual, I had no need for the official Subaru shop manual. YMMV. Here are Amazon links for the manuals for 1990-1999 and 2000-2006 Subaru’s:

Note that if you buy either manual by clicking on the links at left, I get a small commission. Even better, if you really want to help support a starving author, you can buy my new book Dog Friends. Dogs often ride in Subaru’s :-).

2. A really good socket set (see also item 3). I actually have 2 sets, a Stanley “Mechanic’s” tool set, which is my “high end” precision set for jobs that really matter, and a cheaper set, one of the low end Mastercraft ones, for less critical work to save wear and tear on the precision set. Both were purchased at Canadian Tire. I used both on this job, the lesser set mainly for all the many fasteners that have to come off, and when I needed extra extensions and so on. (However, I shattered a 10mm socket in the cheap set quite spectacularly trying to remove a camshaft clamp bolt; fortunately the precision set was up to that task, and on inspection, the socket wall thickness is significantly higher on it for the same small sockets. Probably better metal too. Not a big criticism of the cheap set; it was a lot of torque on a small socket, enough to need a breaker bar.)
3. a 14mm 12-point socket. This is needed for the cylinder head attachment “stretch bolts”.  These sockets are somewhat rare but the Stanley set has them.
4. (a) A torque wrench. I have one that is nothing special but you need to be able to measure torque  to about 60 ft-lbs for the cylinder head bolts, and also enough precision and sensitivity to measure 130 in-lbs for the valve cover seal bolts.  I made do with one big Mastercraft torque wrench but the low torque measurements were a bit sketchy with it.
4.  (b)Optional: Some people have said that you also need a torque angle meter. That is for the intermediate and last stages of the cylinder head bolt torquing sequence, wherein you need to be able to accurately do 180 and 90 degree untightening and tightening steps.  I got by without one by carefully watching the angular displacement of the socket handle during the critical rotations and thence estimating the angle, and the job result was fine, but this tool might have helped.
5. Lots of time and patience. Seriously, this is a big job and takes a lot of time.
Minimal parts you’ll need:
1. Subaru or valid OEM multi-layer steel replacement head gaskets. The advice I read was “Don’t use the cheap single layer graphite gaskets that you can get on ebay or elsewhere.”  Nothing at all against e-bay, and I found a good deal on the real gaskets there, just be careful to get the real ones. The genuine ones look like this
Subaru multi-layer steel head gasket
2.  a replacement engine gasket set.  Not the head gaskets; see item 1 about those. You’ll want to replace many of the “soft” gaskets for the valve covers, the intake manifold etc.  I mainly pulled gaskets as needed out of an “Eristic” set I found on ebay, but I didn’t trust the head gaskets or the intake manifold port gaskets that came with it. They looked like they were made from cardboard. Fortunately the original IM gaskets looked OK and I just reused them with no apparent problems afterward. Also, from what I’ve seen elsewhere, the Eristic head gaskets that typically come in such a set will apparently not last even 15,000km in a Subaru boxer, so avoid those. For the work you will be putting into this repair, it’s not worth it to use cheap head gaskets.
3. Anaerobic sealant. You need a small amount of this to seal the 2 outer camshaft cap clamps per head on the aluminum-to-aluminum mating surfaces so that they seal against oil.  NAPA and other parts places carry this stuff.
4. A replacement timing belt. The timing belt is crucial to the operation of the DOHC EJ25 Subaru engine series. If it breaks, catastrophic damage to valves and the engine is likely so get a good name brand timing belt and follow the Haynes instructions exactly for putting it in, after the HG replacement is done and the valve covers are back on. Youtube also hosts many good videos about the procedure. I used a Mitsuboshi belt from
5. (maybe) A replacement timing belt tension adjuster. If you have a 1996 or 1997 you will likely have the old hydraulic tension adjuster. Late in the repair, I noticed the old one had no “spring” to it and the tensioning plunger would not extend much out of its casing, so I had to buy a replacement. It was $233 from a Subaru dealer, the most expensive part in the whole repair. This part is also crucial to the engine, so check it and replace if needed.
6. All the rad hoses. The high temperature from overheating, plus exhaust gases getting into the coolant because of the leak may have deteriorated your hoses and soft gaskets, and you have to take the old ones out for this job anyway, so just replace them; for the cost involved, don’t risk reusing the old ones.
Job details and sequence:
0. Park the car in a good covered space with lots of room to work and to place parts that you’ve removed.  Understand that you aren’t going to be able to move the vehicle once you get started, until the job is done (days, if you’re fast and lucky).
1. Disconnect the negative battery cable.
2. Jack up the engine about 2 inches via the following procedure:  (Although one guy has a great video of doing this job without lifting the engine, this is such an easy thing to do and makes the cylinder head removal so much easier that my advice is to just do it.  You can actually only need to do this step when you get to the cylinder head removal stage, but I’m tall and having the engine that little bit higher also was easier on my back for removing the IM and other stuff beforehand.)  Follow what the Haynes manual says. Essentially you need to remove the 2 front engine mount nuts. Note that each of these also has a companion washer between it and the frame. Those are easy to miss (I nearly lost them) because of all the grease and grime that will inevitably be down there, so watch for them. They’ll probably fall off after you take the nuts off.  Also remove the exhaust manifold header bolts (3 on each side).  For lifting,  I found I could just use the tire jack that comes with the car (it can hold 800Kg, which is far more than the weight I estimated was being lifted. Put a square piece of wood under the oil pan at least covering the pan, and a 2×4 between that and the jack just in case the plywood fails (thanks Keith, for that advice).  Centre the jack so that the engine lifts equally on each side. Careful here:  If you cause uneven lifting, the engine and hence the engine mount bolts can move out of alignment with the mounting holes and it will be hard to get the engine back down into place. Also, I wouldn’t lift by more than about 2 inches;  any more than that looked like it might put potentially damaging strain on suspension and drive train components.  Back up the lifting parts with blocks of wood in case the jack or anything else fails. After lifting, my setup looked roughly like this except that I leveled out the blocks and jack with shims a bit.
3. Drain the coolant and remove the radiator. Other online examples show this job being done with the rad in place, but it’s so easy to remove the rad (just 2 easily accessed bolts need to be loosened above the rad) and it gives you so much more working space in front of the engine that I recommend that you remove it. Follow what the Haynes manual says and put a short hose onto the spout off the radiator drain plug so the coolant flows into whatever you are collecting it in, otherwise you’ll have coolant dribbling all over the place.  Remove the radiator hold-down bolts, and all the hoses attached to the rad.  Pull out the rad and put it aside. Note that you don’t need to unbolt the cooling fans. They come out with the rad; just disconnect the electrical cables to them. Finally, tape some protective cardboard or thin plywood in place temporarily at the A/C radiative fins assembly to protect it from e.g. wrench damage during the rest of the repair.
By the way, when you drain the rad, don’t just let the old fluid run into the street or a storm drain. Collect what comes out in a drain pan and take it to a legit disposal/recycling depot. Same for any used oil. The automotive service dept. at my local Canadian Tire store is nice enough to accept the used fluids, so they get my repeat business, but also check e.g. with your local municipal or environmental authorities if you don’t have a similarly helpful business nearby.
Next, the real work begins. You’ll need to remove a lot of parts, so use some masking tape to label everything, especially bolts and hoses, as you take them off. Use a digital camera to record any details that might be significant. See also my detailed pictures of the job. Follow the Haynes manual.
4. Start by removing the generator, and remove its drive belt. Also unbolt the power steering and the A/C compressor and carefully move them aside with their respective hoses in place. DO NOT disconnect the hoses for these.
5. Remove the intake manifold. This is a lot of work. There are many connected hoses and cable connectors, so photo and label them all. Remove the air cleaner too. This will leave your engine exposed looking roughly like this

engine with intake manifold removed

engine with intake manifold removed

Note that I removed the IM and associated parts completely from the engine, per some of my pictures. In hindsight I could have just folded it back towards the dashboard; that might have saved me disconnecting the throttle and cruise control cables and some other stuff, but removal does make for a clearer work area at the engine, and saves potential kinking and wear and tear on some of the hoses and cables. So despite the extra work, maybe the full removal is worth it. Cover the IM ports with cardboard or something else per the photo, to prevent anything from falling in to the engine.
6. Remove the crankshaft bolt and pulley. You’ll need e.g. the “starter trick” to get the crankshaft bolt free. Google on it, but basically you need to disconnect the fuel pump and spark plugs, put a 22mm socket on the bolt and trap the socket wrench with a breaker bar against the floor, then very briefly crank the starter. That will free the bolt, but do it carefully. Just turn the ignition key to “start” very briefly and turn it off. If that fails to break the bolt free, try again, still hitting “start” very briefly. This took me 2 tries on the starter, but after that, the crankshaft bolt was loosened enough that it could be removed with finger strength alone. I repeat: make sure that you have disconnected the fuel pump (access port is behind the back seat) before you try the starter trick.
7. Follow the Haynes instructions and remove the timing belt outer covers, and then the timing belt. You’ll probably need to loosen the timing belt tension adjuster mounting bolts and maybe also remove the pulley on the passenger side to get the belt off. Make sure you take photos of the “before” state. carefully.
8. Now you are ready to head toward the heads. I suggest working on one head at a time, through to completion of the HG replacement and close up, so that critical parts are not exposed to damage for long, and to have the smallest pile of parts on your garage floor :-). Put a drain pan under the cylinder head area because oil and coolant will seep out when you get the valve cover off. Use a good 10mm socket to remove the valve cover bolts and pull off the valve cover.  Be careful to keep track of the gaskets as this assembly comes off. I replaced many of the rubber (probably viton) gaskets.
9. Take pictures of the camshafts in position so you can reference them for the re-assembly, then remove the camshaft caps. The bolts on these are in tight, and you will need a good quality 10mm socket; a cheap one I used first actually shattered.
10. Carefully remove the intake and exhaust camshafts. Take care to keep each cap with the appropriate camshaft in the original position.
11. Now you are ready to remove the head gasket bolts. Rest up. This is hard work, lots of torque, and you’ll likely want a breaker bar. Use the 14mm 12-point socket.  Follow the reverse of the assembly torque sequence per e.g. the Haynes manual.
12.  At this point, the head will probably pull off sideways. If not, gently tap it sideways with e.g. a rubber mallet.  This should expose the head gaskets, which will likely pull away easily. Clean all the mating engine and head surfaces before putting the new gasket in. I used a hardwood shim to scrape the surfaces clean rather than use something that might scratch the aluminum.
13.  Once the surfaces are clean, place the new gasket in place on the dowels on the engine. Be very careful with the gasket orientation; the upper oil inflow port and lower oil out-take ports must line up with the corresponding gasketing surfaces.  Check this; I got it wrong once. Oil the cylinder head bolts lightly with engine oil before you put them back in. This really helps the re-torquing go more smoothly and precisely.
Before I put the heads back on, I also replaced the spark plugs while I had the heads on my garage floor. That makes getting the plugs in a whole lot easier. Also, this is a stage at which you can check if the head sealing surfaces are still flat. In my case, I just laid a big steel reference straight edge across each head surface corner to corner  for both diagonals, and also side to side in a few places. The surfaces for both heads seemed flat.  Maybe I was lucky to catch the HG problem before severe overheating and warping happened. If you have warped heads, you’ll need to visit a machinist to get them machined flat, or maybe get new heads.
14. Proceed with carefully putting the head in place and torquing the bolts. Follow the Haynes manual exactly; I don’t have anything to add here.
15. Now put all those many parts back in, in sequence.  Watch your labels, and refer to your pictures as needed, plus mine  if they are any help. Good luck!
Many more pictures taken during my head gasket replacement job are here.
1. A great summary of the Subaru head gasket problems for various engine model years.
2. A HowTo for the same job on a Subaru Forester, with pictures.
3. Edit 2011 03 23: a user on noted that the following video links are no longer accessible on Youtube. If you know of working links or other good references, please let me know and I’ll post them.
A great youtube video series that will really show you the extent of what is needed to do this big repair job
Part 1.
Part 2.
Thanks to Keith, Vince, Garth, and Hugh for help and moral support along the way, and also to various other people who wandered by my backyard garage while I was doing the work to offer encouragement. And special thanks to Dee for putting up with me while I was working on this job.
Sept. 23, 2010   Several days after the repair, after some highway driving followed by stop and start low speed city driving tests, none of the original symptoms are present. No more foaming or bubbles in the coolant, and no overheating. No detectable oil or coolant loss. Engine is running great. This was an apparently successful head gasket replacement job.
March 23, 2011  6 months and several thousand km later, engine is running fine. No overheating and no coolant loss. As an added bonus, I’ve found that the engine now loses no discernible amount of oil over thousands of km of driving. Maybe that is the result of replacing a lot of the “soft” gaskets and seals during the repair too. Pretty good for 285,000 km on the car.
October 5, 2011 > 1 year later, the engine is still running fine. No coolant leaks and no oil loss.
October 9, 2014 Well, 4 years later, I am happy to report that the ole ’97 Subaru Outback is still running great. No oil loss between oil changes, and no overheating.

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