Ah the boxer’s achilles heal. Such a strong and reliable engine, until one day you see little droplets of fluid on the ground. You think, oil? Then when you look underneath the car, you see that it is coolant. A little coolant leak isn’t usually a big deal on most cars. Usually just a worn out hose. However, when that coolant is dripping out of the head, it is a bit more of an involved repair. Particularly on a flat engine.
Make very sure that you correctly diagnose a head gasket leak if you suspect one. Getting a mechanic to verify it can be worth the extra few bucks if you aren’t 100%. As a water pump (which is quite close to the head) could be leaking coolant and appear to be a head gasket leak.
The 2.5l 4 cyl SOHC boxer engines made between ’98 and ’04 are known as being the most problematic for head gasket failure. I have also heard of a lot of cases in the DOHC naturally aspirated and turbo charged engines HG failing and the 2.0l and newer models too. I haven’t heard as much about problems with the H6 engines. The leak usually starts on the left side (drivers side in North America) of the engine.
Unfortunately, I didn’t take a picture of mine when it was leaking to show you what it can look like. You will need to take the splash guard off the bottom of the car to get a clear view. It will appear like some droplets of coolant (or oil) along the line where the head meets the block. Make sure that it isn’t running down the engine from somewhere else. Though it is also possible to have more than one leak (my car had a few). It was a bit like a sick person leaking fluids from different parts of their body.
It is possible to change the head gaskets with the engine in the car and there are a few blogs and videos out there about how to do that. I believe the Haynes Repair Manual also explains that procedure. However, I didn’t do that. There are a lot of reasons I would recommend taking the engine out for this repair. Number one is room, there isn’t much room in that engine bay to remove heads or get a torque wrench in to torque the heads down properly. It will also be a pain in the ass (or more specifically the back) to clean up the engine block .
Pulling the engine seems like a daunting task to anyone who hasn’t done it before (myself included). But it isn’t that bad and will save a lot of time and stress to your back. It is also pretty fun seeing the engine flying out of the car on a hoist. This blog is going to explain the head gasket change with the engine out of the car.
Enough with the introductions. Let’s get your tools ready.
For this job, you will need a lot of them:
3/8″ and 1/2″ ratchets, with lots of metric sockets 8,10,12,17,19,22, pretty much a full set, most of the same sizes of wrenches and lots of different sizes of extensions. Plus a breaker bar with an extra long pipe (the one from your jack will work great) for extra leverage. Lot’s of little stuff, different types of pliers (the long bent ones are super handy), a big phillips screwdriver, different sizes of flat heads, a strap or chain wrench, vice grips, a vice is handy too, pry bars, a ball pein hammer.
A cordless impact wrench or air and an air ratchet, will make things go a lot faster.
Don’t forget the big stuff: jack and jack stands, engine hoist with chains or a leveller, and an engine stand.
The first part of this repair begins the same as my previous post on how to change a timing belt:
https://shagbarkblog.wordpress.com/2015/02/12/how-to-set-timing-on-a-subaru-sohc-ej25/
Except that you stop after you get the drive belts off. But before you disconnect the battery, relieve the fuel pressure by pulling the relay, it is under the steering wheel. The Haynes repair manual describes where to find this. But you will need to take plastic trim off, two plastic body bolts on the door edge of the panel. One metal screw under the steering wheel and pry a few clips off where it meets the other part of the dash and it is off.
Also disconnect the positive terminal of the battery. Then unbolt the bracket that holds the battery in place and remove the battery.
I removed the hood for this job. But I wouldn’t recommend doing that. Instead, I would recommend opening it all the way and attaching it to the ceiling of your garage with some rope, wire or straps. As re-attaching the hood is a pain and it is nice to be able to hang a trouble light off of it while your are working.
Remove the washer fluid bottle. It is just two bolts on the top of the bottle, then pull the plugs to the pumps and the hoses. It is a good idea to drain the bottle first if you can. Otherwise, fluid will start to leak out of the pumps once you pull the hoses. If you quickly pull the bottle out once it is free and tilt is back a bit, that will stop fluid from leaking out and you can just pour off the excess fluid out the top.
The next step is to unbolt and unplug the alternator from the a/c compressor.
Unbolt the tensioner bracket with the power steering pump together. Remove the bolts that attach the power steering line to the shield on the right side of the intake manifold.
Remove the resonator (black plastic thing) on the right side of the car. You can just flop the power steering pump over into that spot with the lines still attached.
You can do the same thing with the a/c compressor. Remove the bolts attaching it to the block and flop it over into the spot where the battery sat. You might need to remove the throttle cables first.
To remove the throttle cables, loosen the bolts further from you in this picture all the way off. Then slide the cables back and up and out of the brackets. Don’t worry too much about getting them back into the same spot if they are old like mine, they will be pretty well marked with rust.
To remove the wires out of the throttle body, push each pin out of the side, then follow with the wire. Once the cables are free, move them out of the way. First make sure to label which goes where.
Pull off the brake booster hose and the two fuel lines and the vacuum line beside it. Make sure to label their order.
Loosen the hose clamps and pop off the two coolant lines below that run to your heater core. Also remove the air box bracket at the back of the picture. It is attached by two bolts on the transmission. It may be easier to access them underneath the car.
Unplug all of these six connecters and remove the other air box bracket. You will want to bolt the lower part of that bracket back on the block if you choose to use the loop on it to lift the engine out.
Remove the starter motor (sorry didn’t get a great picture), it is probably the easiest one I have ever removed. It is located on the top left side of the transmission. Just unplug/unbolt the two connecters, then unbolt the one nut and the other bolt. That’s it, the starter should now be free to remove and trade with your friends. There is a little bracket with a couple of grounds attached to it, that you will be removing at the same time. Make sure to label it well, so, you remember where it goes.
I think that is about everything on the top, you will need to unbolt the exhaust manifolds underneath the car. You can just leave them hanging. You might also want to drain the oil at this point.
Unless, I am forgetting something, your engine should be free to unbolt from the transmission. If your car has an automatic tranny, you will need to unbolt the drive plate. There is a little rubber cover on the back top right of the engine. Pop that off and rotate the engine around to find and unbolt the attaching bolts. I think that there are eight.
Unbolt the big support that comes down from the firewall to the transmission on the transmission side. Then get your floor jack under the transmission to support it.
Next, get your hoist out and chained onto the engine. I used the lifting loop on the back and one of the a/c compressor bolts with a washer. Don’t put any tension on the chain yet, just have it ready to support the engine.
Remove the nuts and bolts attaching the engine to the transmission. I recall there to be 4 nuts and 4 bolts, including the two that held the starter on. Leaving three of each remaining. I found all of these easier to access from above.
Once those are out, remove the two nuts holding the engine mounts on the cross member.
Double check that there isn’t anything attached between the engine and the car.
Now the fun begins, start to jack up your hoist until the engine mounts are free from the cross member. Then jack up the floor jack so, it is supporting your transmission.
Now you need to separate the engine from the transmission. If you are lucky, you can shake it bit, side to side and it will start to slide out. Doubtful that will be the case, you will probably need to pry it a little bit. Make sure that the engine hoist and floor jack are evenly supporting the engine and transmission respectively.
I just used a long handled pry bar to coax the two apart from each other. Just be careful if you do the same not to damage the engine or transmission. As they are both made out of aluminum, the metal is very soft and easy to gouge.
Once it starts to slide out, you should be able to pull it the rest of the way by forcing the engine towards the front of the car with your hands. I managed to do this by myself. But if you can get help with this, it will be a lot easier.
When it is off the transmission, jack it way up in the air to clear the front of your car and roll the hoist back. Congratulations, you got the engine out of your car!
Time to take a break and celebrate.
After that, the next step is to remove the clutch and flywheel or the drive wheel from the back of the engine. Then get your engine set up on an engine stand and off the hoist.
Notice the paint sprayed across my old pressure plate. The surprises you find when working on a car. This is confirmation that the engine was swapped in my car.
Remove the spark plug wires, if you haven’t already. Make sure to twist side to side until they release easily from the spark plugs.
Next, remove the intake manifold. First the EGR pipe needs to come off, you will need a 22mm wrench for that. Then there are a bunch of 14mm bolts on the two shields and each side of the intake itself. There will be a couple of plugs underneath the intake and two small coolant lines that will need to be detached. Then you can pop the whole thing off as a unit.
Remove the little 10mm bolt and pull out the dipstick. It may take a little wiggling side to side to get it loose. Be patient, you don’t want to bend it. Make sure that you have drained the oil before you do this.
Then unbolt the main coolant line off the top of the block. You can leave the other black line attached. You can leave the main one too, but it is a good idea to replace the o-rings on it.
If you are removing the harmonic balancer by hand, it would have been a good idea to do that in the car. As you can leave the car in gear to put some resistance against you. But if you are using a heavy duty impact wrench, it will be no worries now that the engine is out.
Then remove all of the little bolts holding the timing belt covers on and remove the timing belt as described in the previous article.
Now you should be ready to get the heads off.
First remove the valve covers.
Cool check that out.
Two on each side (painted orange in this case) with the letter ‘s’ on them and two in the middle (no s). It is recommended to replace your head bolts when doing a head gasket. But if you are going to reuse your bolts, make sure that you keep them in order.
It is going to take a lot of gusto to get these bolts loose. So, get out your breaker bar with the long extension on it and your 12 point 14mm socket and get ready to sweat and swear. Careful to make sure the head is supported before you pull all of the bolts out.
Once your heads are off, remove the camshaft sprockets, plastic cover, and camshaft position sensor before sending them off to a machine shop to get them milled. It is a good idea to get the shop to replace the valve stem gaskets, camshaft oil seal and plug at the same time. It didn’t cost me much more at all, I think $40 for both heads. I supplied the gaskets which came in the Fel-Pro MLS head gasket kit I bought.
It is interesting to examine the old gaskets. The one on the left is from the head that was fine and the one on the right is the head that was leaking. Notice how badly that gasket had deteriorated. It was starting to leave little puddles everywhere I went.
If you have a manual transmission in your car, it is a good idea to get the flywheel machined at the same time as the heads. Ohhh shiny.
Also, examine your clutch plate and pressure plate. If either or both are worn at all. Install a new clutch kit. It will be a heck of a lot easier now.
As you can see, mine were both very worn. There wasn’t much material left on the clutch plate and that ring on the pressure plate is a sign of severe wear. There were also some bent fingers.
Also, check for evidence of oil leaks front the back of the engine. It is a good idea to reseal the aluminum plate on the back of the engine (right side of the picture). Careful not to strip the screws when taking them out. If your rear main oil seal doesn’t have any evidence of leaking, it is probably okay to leave in. It is not the easiest thing to replace and I am told they aren’t prone to failure.
Though, with that said. Mine was leaking. But I think that might be because the engine was probably sitting for a long time unused.
The next thing to do is prep your engine block. First scrape away any old gasket material, careful not to gouge the surface, again this is aluminum. Then use coarse emery cloth and a block to get the surface nice and clean and ready for your new head gaskets.
This is a good chance to clean up the heads of your pistons. Just rotate the crankshaft to get each head up to TDC to avoid getting crap in the piston chamber. Then carefully scrape off the carbon and wire brush them clean.
That’s better.
Now it is time to put the new head gaskets and heads on the block. I recommend using a multi-layer steel (MLS) type of head gasket. They aren’t cheep, but they should last as long as your car does. Fel-pro makes a set, they brand Permatorque. But they also make some cheeper quality single layer ones, so make sure you get the right one. Six Star also makes them. But I wasn’t able to find them in Canada. An OEM Subaru HG set will be good quality but the HG are prone to failure after 160k as we know. Cobb also makes really good quality ones but only for the DOHC turbo charged engines.
Check out the pretty periwinkle blue colour Fel-Pro chose for these gaskets.
Once the new HG and head are on. Lightly oil (with clean oil) and hand tighten all the bolts on with the 4 ‘S’ marked bolts on the sides.
The tightening order for this engine is complicated. Your repair manual should explain it in detail. There is also a good video on briansmobile1 on Youtube that explains it.
The rest of the installation is basically the reverse of the removal.
It is recommended to use Subaru coolant and Subaru Cooling System Conditioner. They are supposed to last longer and have less likelihood of future leaks. It didn’t cost much more than any other quality coolant.
Careful when re-installing the engine not to drop it on your head.
Also, it is key to get the engine and transmission at just the right angle and level to each other. They should basically slide back together. If the engine seems to be resisting a lot. It probably isn’t at the right angle. Take your time and don’t rush this part of the job. It is great it you can get someone to help you.
Good luck and feel free to ask me any questions in the comment section.
shagbarkblog 