Here are photos and some advice about changing the head gaskets in a 1998 Subaru Forester 2.5 DOHC (and below, a 2000 Outback SOHC 2.5 for comparison) without pulling the engine.
See the photo below: a tight engine compartment that makes head removal "difficult" according to the Haynes manual.
I started out thinking that I would use a hoist to remove the engine, but as I only had my one vehicle which was presently not running, I had to rely on friends to help me rent and deliver a hoist and stand. Nobody was available at the time, though, and I live kind of far from the rental company. So after talking to a local mechanic who insisted it could be done by jacking up the engine, I went ahead and tried removing the heads myself without a hoist.
Background which you are free to skip if you just want the nuts-and-bolts: I bought this Subaru in 2009 for $3700 (130k, 5-speed, "S" model) after having it inspected by a shop. The shop did it for free, which I was surprised by, but not once I realized that that's all their "inspection" was good for: nothing!
I should have done more research and then I would have noticed the exhaust smell in the overflow tank. Or the bubbles that appeared there once the engine warmed up. Everything became apparent soon after I had used a radiator flush kit and added fresh coolant. My Check Engine Light appeared within 15 miles of doing this, and the engine ran roughly all of a sudden. I went to autozone and had the CEL diagnosed for free: #1 cylinder misfire.
After some online research, I realized with mounting horror that I likely had a bad head gasket. Chronic problem with the Phase I DOHC EJ25, so I learned. It helped explain the coolant that disappeared every time I drove it, and the CEL. Ok, I told myself, you just made a terrible decision by overpaying for a POS...
I went through the easier options first. I'm going to be honest and say I tried Bar's Head Gasket Fix, the stuff with copper and sodium silicate, and the stuff in a can that looks like brown goop. No dice. So I upped the ante money-wise and bought Thermagasket. It did seem to improve things insofar as the CEL no longer appeared, and the engine ran better; but it still drank coolant and the bubbles in the reservoir were still present. And then a side-effect materialized a day after I used Thermagasket: water pump leak! Apparently not an uncommon side effect of using a chemical head sealer laced with metal particles, especially on an engine with high-mileage parts. At least I removed the hoses going to the heater core before using these "gaskets in a can," thus preventing possible damage/blockage during this experiment in wasting time and money.
Consulting with Thermagasket didn't help, ultimately, so I was left with either paying $1500-$1800 to a mechanic...or, doing it myself. I've replaced a couple head gaskets before, but never on a DOHC Subaru. I hesitated. Thought about it. And then decided to go for it so that I could save $.
These sites helped me to prep, especially Skip's Subaru page (2nd link):
Doing 2.5L Phase I head gasket job myself... - Ultimate Subaru Message Board
Subaru Head Gasket and Clutch Replacement
Timing Belt and Water Pump Replacement - Page 5 - ClubWRX Forum - Subaru Impreza WRX and STi Community and Forums
Good timing belt instructions in pdf format (I printed this out for a reference):
It turned out to be a straightforward job. Not as bad as it sounded at first, but it did take me over a week to complete (including the two days for machine shop work on the heads).
Here is the engine looking down from above with the intake manifold and timing belt removed. You can see the heads are close to the frame rails, and there doesn't look like much room to work with.
Here is a close-up view of the driver side cams with the valve cover removed - again, it's rather tight against the firewall, but everything is accessible with a socket wrench.
One problem I ran into was removing the camshaft sprockets. If you look at the photo above, you can see the hex portion of the cam that makes a convenient place to hold the cam with an adjustable wrench. With the engine in the vehicle, though, there is not much room for a wrench. I was able to use an 8" adjustable and use the frame rails as a stop, but the first cam I tried this with ended up slipping when I applied torque to the sprocket bolt with my 4-foot cheater pipe. Not good. I think you could use a 1" (25 or 26mm) crow-foot wrench with better results, but no one (not even Sears) had such a size in stock, so I was stuck.
I stepped back before scratching my cam any further, and thought about how to best hold that sprocket...and after much searching online, I found this photo which solved the issue:
This is how to wrap your old t-belt around the sprocket and the crank: Use a vice-grips to pinch off the loose end to make it tight, and you have a strap wrench. At the same time, use the adjustable wrench on the cam so that you now have two devices to hold the sprocket firm.
With the sprockets out, I removed the timing belt covers and the cams, leaving only the heads. I unbolted everything as if I was going to remove the engine (except for the engine-to-trans bolts), and removed the two trans mount bolts in order to prevent stressing the trans when jacking up the engine. I was able to lift either side of the engine about 4-5", which proved adequate to remove the heads.
Here is a photo showing my method - using the specific bolt loosening sequence in the manual, I got all the bolts loose and then removed the upper head bolts first, then unscrewed the lower head bolts until they were no longer threaded into the block. You can't actually remove the lower head bolts because of the frame rails, but you can dislodge the head and then lift it out of the bay with the lower head bolts still in the head (see the lower bolts in the photo). The heads came out very easily this way.
And here is what the block looks like with the heads removed:
I was curious to see the faulty gasket, and here it is - it looks like it failed in exactly the same way that Skip's gasket failed, and also the other online examples I have seen. It's at the bottom of the cylinder, where your oil and coolant is in constant contact with the gasket (even when the engine isn't running). More proof of how important it is to frequently change coolant and oil in order to keep old fluids from eating away at your gaskets. This was the 1+3 (passenger side) head gasket, and the leak is also evidenced by the rust seen in the cylinder in the above photo.
And here is the old gasket compared to the new one - I got this gasket in a $100 kit off ebay, and the new gasket was obviously better constructed than the original. It's easy to see why these things fail when you see the thin material on the OE gasket. (Note made on 5-11-2010: See the end of this post for remarks on purchasing a quality head gasket. Turns out the ebay gasket was junk!)
After cleaning the mating surfaces, I reattached the heads using the same method as before, i.e., inserting the lower head bolts into the head and then lowering it into the vehicle and attaching to the block. Here is the birds-eye view of both the driver and passenger sides with heads attached:
As you can see, there is actually enough room to work with here, which is important since you will need to apply a torque wrench to those head bolts and cam cap bolts. Also, you will need to buy this $10 tool, a torque angle meter. This is an excellent way to achieve the precise torquing procedure these heads require. Also, I used a 3/8" torque wrench for its more compact design, although I think a 1/2" version would also fit into the space between the heads and rails.
I found that my compact digital camera was an invaluable tool to both document the tear-down process for reminding myself later where everything goes, and also to check the timing marks when attaching the t-belt. With the engine in the car, you can't quite see the crank mark nor the side-sprocket marks - but you can set your camera to the macro setting and use it as an "eye" to check your timing marks. Here's how I knew I had the crank marks lined up perfectly:
Once I had everything reassembled I got in, turned the key and she fired right up!
So far, everything seems to be fine and the HG issues have disappeared. Also, the engine runs smoother and more quietly, as I replaced the water pump and the idlers and tensioner. My old water pump was on its last legs and looked a bit crusty with rust. I was interested to see that there wasn't much evidence of the gasket sealers I had tried using at first. But there was some crud built up around the water pump, so I could see how the Thermagasket had affected the pump.
One more tip - be sure to spray PB Blaster on your motor mount nuts a day before you remove them. I stripped out one of mine and spent lots of unneccessary time and money by biking to Sears for a bolt-out kit. It worked thankfully, but what a pain. I really took care removing any bolts or nuts afterward, taking care not to strip anything.
**Update made on 5-11-2010: I made a mistake in this whole repair by installing an "evergreen" head gasket which came with my cheap Ebay head gasket kit. It looked fine to me at the time, but 15,000 miles later I received a call from the next owner who said this Forester had bad head gaskets again! I can't be sure, but I think it was the cheap gasket itself that was at fault. My reasoning? Well, I had the heads cleaned up at a machine shop so I feel certain they were not the problem. The engine head mating surfaces were flat according to my straight edge. So now, when I'm in the middle of doing yet another HG replacement on a different Subaru 2.5 DOHC, I happened to research the Ebay head gaskets and found many people who experienced failures after installing them, particularly the brand Evergreen. Some people even had them fail within a few hundred miles. This time I went with more expensive Felpro gaskets. Going to the dealer is the best thing to do though, and at this time they are charging about $50 apiece. Don't skimp on the HGs after doing all this work!
**Update 5-23-2010: In case you were wondering if this same repair is possible for other Subarus, I changed the head gaskets on a 1999 Outback wagon with the engine in the vehicle. I bought the car with the heads off and everything disassembled; the owner said his mechanic quit halfway thru the work due to losing his building lease. I put it back together and noticed that the mechanic had removed the intake manifold mount bolts and then left it sitting on top of the engine for ease of re-installation. Saves some time in the reassembly phase.
If anyone has questions, feel free to contact me. No doubt these engines are easier to work on when on a stand, but it was also quite simple to do this work in-vehicle.
And now, I can get back to using my Forester for its intended purpose - taking me to places like this!
This month I bought a 2000 Outback 2.5 SOHC with blown head gaskets and a noisy timing belt. I got a good deal on it ($1700) and decided to fix it myself, with the experience I had with the '98 Forester (and a couple other late-90s Outbacks).
I was curious to see how the newer SOHC engine differed from the older DOHCs. In general, everything is easier about the SOHC. The great news is that 2 major steps can be skipped with the SOHC: You don't need to remove the camshaft sprockets (which always seems to give people trouble), and therefore you don't have to disassemble the lifters nor camshafts either.
Also, the timing belt is MUCH easier to install on the SOHC. None of that counting-of-teeth to properly set it - just eyeball the 3 timing marks and slip on the belt.
I'll add some photos here to show how to remove the head gaskets on the 2000 Outback:
This is the engine compartment, very tight along the sides near the heads.
This is a look at the passenger side valve cover. This is lots easier to deal with than the DOHC because the spark plugs can be accessed easier.
Here's the passenger side showing the head removed, with the engine mating surface cleaned up. I use scotch brite and acetone.
Here's the technique I used for installing the head. It comes out easy enough by unbolting the motor mounts and transmission mounts, then jacking up the oil pan about 5 inches, then swinging the engine from one side to another to create more space to access the head bolts. (If your rear main seal is leaking oil, best to remove engine to replace seal, otherwise changing the gaskets in-car is preferable for me.)
For re-installing (especially without a helper - I did the entire job alone), I used rubber bands to keep the lower head bolts in place. This worked, even though it's a bit of a challenge to lower the head into place without scuffing either the gasket or head mating surface. But it can be done, and you can use the tubes that stick out of the engine to hang the head on while you're threading the first bolt (I threaded the top center bolt first to secure the head).
Here is the top view of the passenger side head after it's installed. Plenty of room to torque the head bolts!
A few tips about the SOHC:
- Again, you don't need to remove the camshaft sprockets
- Removing the intake manifold is easier than the DOHC because of fewer connections to undo. It only took about 15 minutes to remove it once I got to that point.
- Make sure to line your radiator with a sheet of cardboard to protect against dings
- The only gaskets you'll need to complete the job are head gaskets (I used Felpro 26415 PT), intake manifold and exhaust manifold gaskets, and valve cover gasket set. You can also change your oil pump gasket, and main seal but if they're not leaking I'd say leave them be..
- If you have an auto transmission, the Haynes manual says you need to get a chain wrench to hold the crank while you undo the crankshaft bolt. Not necessary! Underneath the air filter housing is a "window" on the top of the transmission housing covered by a removable piece of rubber about 3x3 inches. Take off the rubber cover, and you'll be able to see the flywheel with holes in it. Stick a sturdy screwdriver into a hole in the flywheel and you can then undo/install the crank bolt without the engine turning.
- All the bolt sizes are the same as with the DOHC
Let me know if you have any questions.
UPDATE 9-2012: What happens when your timing belt breaks in the Subaru 2.5 SOHC engine
So this summer presented a new twist on head gasket repair. I bought a 2002 Outback from a man who had the unfortunate experience of having his timing belt fail within a few months of owning the car. Apparently the timing belt tensioner sheared off, though just how this happened wasn't explained. From what I could piece together it seems the man's wife was trying repeatedly to start the car after the engine quit on her while out for a drive. There was no compression in any of the cylinders, indicating damage to the valves.
There was a chance of even more damage to the pistons or cylinders, but this was unlikely given the way these interference engines are designed to fail. When the timing belt breaks, the pistons will collide with the valves which are weaker and bend. But the pistons and other lower engine parts are made to survive such a failure.
I removed the heads and $525 later, I had a pair of like-new heads with 16 shiny valves (the guides turned out to be OK) and new cam seals. The machinist didn't seemed too thrilled about Subaru's many subtle variations on the same head design and the price it took to restore them was indeed considerably more than for a 350 Chevy.
See these photos which show the bent valves and the marks on the pistons where the collisions took place. Some mechanics might wish to grind the impact points on the pistons but I didn't notice anything severe enough to warrant the operation. The cylinder walls appeared normal so I counted myself lucky and went about with reassembly.
I used Fel Pro head gaskets (Part # 26415 PT). In the spring of 2012, Fel Pro announced that they'd arrived at a more durable design and had an updated version of this gasket. It's an MLS (multi-layer steel) gasket that is superior to Subaru's original head gasket, a single-ply design with a black coating that's become infamous for failure.
I gashed one of my Fel Pro gaskets on installation ($50 mistake), so after some choice obscenities, I needed a new head gasket to ensure a solid repair. I went to the Subaru dealer curious about what they would sell me as a replacement. What I got was Subaru part #11044AA633 which turned out to be a single-ply design head gasket. Is this the latest improved design that best combats head gasket failure? I couldn't get a good answer online so I returned the part and went with a new Fel Pro instead.
One person I talked to about Subaru head gaskets recommended the brand Six Star, and research showed that some shops in the Northwest swear by this brand. They cost about the same as Fel Pro but I can't attest to which one is better. Generally speaking, the success of a head gasket replacement relies equally on the mechanic's attention to detail as much as the actual head gasket.
The reassembly process was just as described above for the Outback SOHC. Although, with the rebuilt cylinder heads, I did need to adjust the valves upon reinstallatiion. But this was easy (and far easier than adjusting valves in the DOHC). I installed a new tensioner and the bolt threads needed tapping to remove the broken old tensioner bolt. New idlers and water pump and T-belt completed the job.
UPDATE 1-2014: Comparing removal of EJ25 SOHC engine for head gasket replacement vs. leaving the engine in the car
In late 2012 I bought a 2002 Subaru Impreza Outback Sport with 149,000 miles on it. It had bad head gaskets so I decided to remove the engine from the car to see how it stacked up time-wise and work-wise to doing the same repair with the engine in the vehicle.
It was not too hard to remove the engine, with the most time consuming issue being the separating from the auto transmission bell housing. It was more expense because I had to rent an engine hoist, but it was of course easier to change the head gaskets. It was more work in the end to remove the engine instead of leaving it in the vehicle. But many people probably remove these engines faster than I did. It's really a toss-up for me but I think I will leave the engine in the car next time.
I've kept this Impreza for a year of driving and put 20K miles on it without any issues or leaks. I replaced the original head gaskets with Fel Pro head gaskets (Part # 26415 PT), which I would use again without hesitation.