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Hey Guys, tackling the headgasket job over the next few weeks. Thoughts on other things I should replace while I'm in there?
Thinking:
-Head Bolts? (I've read not required)
-Exhaust/Intake Gaskets
-Valve Cover Gaskets
-Motor Mounts?
Thanks!
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Here is my opinion on head bolts: Many, many people don't do them and seem to get by just fine. But if you understand how the bolt works, and why they are considered one time use, then I would never use them again. Ever.
When you torque those bolts in the X amount of ft. lbs., what you are really doing is slightly stretching that bolt just a little bit. That stretch helps to keep the bolt still, from backing out. So they are officially one time use, but they also are not cheap so make that call yourself.
Rule of thumb on gaskets: if it has been pressed before and gotten hot, it needs to be replaced. Similar issue as before, they are officially one time use, but many people still do. If it were me, I would replace every gasket I touch. You can buy complete head gasket sets. Flat Irons Tuning might be able to help you get one cheap. I've had great luck dealing with them in the past and they have the only complete gasket kit I have ever gotten for engine rebuilds. Plus the price is great. These guys are actually like co-joined with a Subaru dealership so you're not getting some FelPro shit, you're getting OE gaskets.
It's also a really good time to go ahead and replace the plugs and do a full fluid flush.
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Timing belt, for sure. Just because.
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You think I could just replace the belt without the tensioners? Not looking to spend extravagant amounts of money. I replaced the belt and tensioners about 50k miles ago.
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Also, would it be worth replacing the rear main seal? Don't want to cause more trouble than i need to.
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I suggest replacing any gasket that goes into/onto the head, the head studs and spark plugs
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Just do the belt+ tensioner (not water pump, see how pulleys feel) if you want to cheap out, not a huge deal in the grand scheme of things. 50k is still a lot of time and miles for a belt. Peace of mind mostly. If you re-use it, make sure to re-compress it vertically over the course of AT LEAST 5 minutes. Follow the procedure, it's critical.
Leave the rear main seal the hell alone unless its actively leaking. PITA to remove and replace that one (without it leaking afterwards). Cam seals on the other hand are easy and worth doing.
Make sure whatever gasket kit you order includes the half moon gaskets.
Many don't. Part number 11051AA070, I think they're like $5 each from Subaru. x4
I know a local Subaru tech, he says all the techs in his dealership re-use head bolts only once. Best to buy new after that. $11 each x6.
One of my cylinder heads is held on by new bolts, the others are used once. Long story. Almost 30k miles, nothing to report. Head gaskets definitely worth getting new. If they leak, you do the whole job again. Good luck 
Last edited by eurocoffee (2015-09-04 23:01:37)
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Homyality wrote:
Here is my opinion on head bolts: Many, many people don't do them and seem to get by just fine. But if you understand how the bolt works, and why they are considered one time use, then I would never use them again. Ever.
When you torque those bolts in the X amount of ft. lbs., what you are really doing is slightly stretching that bolt just a little bit. That stretch helps to keep the bolt still, from backing out. So they are officially one time use, but they also are not cheap so make that call yourself.
Rule of thumb on gaskets: if it has been pressed before and gotten hot, it needs to be replaced. Similar issue as before, they are officially one time use, but many people still do. If it were me, I would replace every gasket I touch. You can buy complete head gasket sets. Flat Irons Tuning might be able to help you get one cheap. I've had great luck dealing with them in the past and they have the only complete gasket kit I have ever gotten for engine rebuilds. Plus the price is great. These guys are actually like co-joined with a Subaru dealership so you're not getting some FelPro shit, you're getting OE gaskets.
It's also a really good time to go ahead and replace the plugs and do a full fluid flush.
Except if the bolts aren't torque to yield, that little bit of stretching doesn't hurt them at all, and you can reuse them.
The prestress is to increase the average stress in the bolt so that the variable loading doesn't cross over into compression/low stress, which causes more damage to the metal microstructure and cause a fatigue failure. It also prevents backing out, but you can achieve that at much lower loads- the "real" reason is to prevent fatigue failures, either in the fasteners, or in the part surfaces.
The reason people reuse them is because Subaru doesn't require them to be replaced.
if it's apart, I'd replace all the gaskets and rubber parts - do the cold weather fix, PVC system, etc.
Last edited by bentmettle (2015-09-05 12:17:41)
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Re seal the breather plate to the right of the rear main and new oring or Subaru 3 bond on the left side wrist pin cover plate. All seals cam and crank seals, vcg's all timing stuff. Order a head set and timing kit from six star. Top quality stuff.
Don't sweat the bolts unless they get necked down from rust. They hold up just fine and won't sour your job. Spend the extra $150 on slotted rotors or something. Plugs wires all the goodies . Your the one to directly benifit from all of it.
Set the valves to 8&12 on a 2.5i nice n quiet
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I definitely wouldn't spend money on slotted rotors either...
I've seen too many horror stories from people not replacing head bolts. Do it right the first time.
As to torque to yield bolts, you are correct. Those are true one time replacements. However, when you factor in rust, vibration, heat, etc. etc., you wouldn't catch me dead reusing old head bolts in anything. That being said, in a vehicle like ours, if they had only seen a few hours or something and you had to pull the engine again, well, that's a different story. But that is not the OPs case.
I am a big fan of preparing for a worst case scenario. Will the bolts probably be fine? Maybe. Probably. Sure. But what if?
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Cool thanks a lot for all your help! I think I will go with new head bolts. The way I'm looking at it now is that I'm not spending 2500 t have it done at a shop so I can spend a little more for new parts
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just catching up to this thread. You're making a wise choice. Keep in mind, combustion chamber heat (it's a turbo, mind you) has likely altered the temper of the bolts over all of the miles. To what degree? DNK. But the torque specs of the bolts was based off of fresh ones. And ANY bolt, stud etc. that has you tighten to a torque, then a specified turn further should be considered to be TTY unless you know the specific tensile strength of the fastener, the give of the fastened, etc. IOW, the design specs. For a big job like a top end rebuild or for safety based parts, it's better to be safe than sorry.
And regards to slotted rotors...save your money. Slight loss of performance (slots reduce swept area and rotor mass while venting non-existent pad outgassing) for a bit of bling = wasted $$$$
Last edited by Scargo (2015-09-06 21:26:32)
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Hey, since you said you'd be doing this over the next few weeks and it's only been a couple, I figure I'd chime in and make myself useful around here.
I just did exactly what you're doing/thinking of doing. Like Homyality said, Flat Irons Tuning is a great resource, but I ended up ordering almost everything from Amazon. They have the master gasket kit for a good price that will cover just about every gasket you'll need. Header, headgasket, throttle body, IACV, valve cover, cam oil seals, rear main seal, etc, etc. They even have the gaskets you'd need to replace if you were to go all out and split the block. I did not do that. Nor did I do new head bolts. If I ever have to do it again, I'll probably replace them, but I didn't find it necessary this time around. Nor did I do the rear main seal. I wanted to, but was running out of time and I couldn't get the flywheel to stay still so I could unbolt it.
I also got a full timing belt kit, which included all the pulleys. If you go this route, keep in mind that new timing belt kits will have an idler pulley that requires either a longer or shorter bolt. I forget which. You can find info about it if you research.
I also took the opportunity to get silicone radiator hoses and a lightweight crank pulley. I went with Mishimoto (matches my aluminum rad) and Grimmspeed, respectively.
A few random tips: Try to stay as organized as possible. I used little plastic cups and a sharpie to keep track of bolts, but even still I have a few left over... I think I know what they go to though... so hopefully the pistons don't fall out.
I did everything outside because my parents' garage is too small. I would recommend doing it inside if you have the space. Trying to finish up your train of thought (work wise) outside at 10pm getting eaten up by mosquitos isn't fun.
Get a 5 quart container of the oil of your choice, you'll need some for lubricating the cams and head bolts and few other things, then you can use the rest for your engine. Somehow I ended up a quart or two low after driving a few miles, so maybe get some extra to top off with.
Get a couple jugs of the Subaru coolant. You'll for sure use one, then you'll use the other for all the coolant leaks you have. I'm kidding, but if I did it over again, I'd check ALL the coolant lines, especially near the turbo, three or four times before putting the engine back in. I THINK stock setups take just the 1 Gallon Coolant + 1 Gallon Water. I think my radiator is bigger than usual though, so I had to use extra.
Don't undo any AC lines and vent all that freon into the atmosphere. I'd like to take this opportunity to apologize to all of your grandchildren for the damage I've done to the ozone.
Also, the TGV's and Intake Manifold can come off as one piece. Don't kill yourself for hours trying to take the Intake Manifold off on it's own first. Oh, that reminds me, now is a good time to paint any engine parts you want to paint. Spray, do some work, spray, do some more work, etc. It works out great. I did my IM and valve covers black.
I think that's it. I hope my Pro-Tips help. Or maybe you know what you're doing. I wish I knew what I was doing at the time. Good luck, Ascott!
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Thanks guys! Progress report. Have the motor back together and and about to put it in the bay this evening. A few things I did:
-Resurface and tank heads (Machinist said he took off .006" which would explain the leaking headgasket!)
-Installed with new head bolts
-Bought the gasket set from Flatirons and replaced as many as I could see
-Replaced timing belt, tensioners, and pulleys
Hope all goes well today. Timing seems to be good as I've spun the crank a few times without interference. That head bolt tightening procedure is pretty ridiculous but I think I got it down. Hoping for the best on start up over the next few days. Fingers crossed.
Any other things I should double check before turning the key?
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The oil level? Good luck!
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Well, got her back together and she seems to be running smooth so far. Pretty excited about that.
One thing I noticed was the the clutch seemed a bit stiffer after reassembly. Any reason why this would be? Still functions fine.
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Could be slightly misaligned. Did you use an alignment tool?
ascott430 wrote:
Well, got her back together and she seems to be running smooth so far. Pretty excited about that.
One thing I noticed was the the clutch seemed a bit stiffer after reassembly. Any reason why this would be? Still functions fine.
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Sorry, should have been more specific. I didnt remove the clutch from the motor so it stayed assembled. I'm assuming you don't need an alignment tool when mating the transmission and motor? Otherwise how would you get it out haha.
I've read that you can bleed the system and that might make it a little better. It seems to be softening up a small amount so maybe it just needs to "break" in...
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I just had my head gaskets replaced at an incompetent shop and suddenly the AC doesn't run cold. I will return if there is a chance that they didn't hook something back up but would prefer to go to a good mechanic if it is coincidence. Advice?
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Head Bolts - There seem to be differing thoughts. If you have original "Subaru" head bolts you can reuse them. The Subaru mechanics do this. However it seems that if you have "aftermarket" head bolts you should replace them. So has anyone reused aftermarket Head Bolts and if so what was/is your experience? Did they result in head gasket leaks requiring gasket replacement?
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I finally decided to go get a set of Head Bolts from the local Subaru dealer. They turned out to cost less than I expected and less than the Fel-Pro bolts I purchased at NAPA which turned out, although labeled as made in the USA, to be defective. There was something wrong with the threads as the bolts required effort to thread in where the Subaru and Chinese bolts I have could be threaded by hand or very light wrench effort. Presently awaiting a reply from Fel-Pro regarding a refund.
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I'm fixing to have this done as well. I bought my car with at least one blown head gasket. I think I'm going to have the turbo inlet hose replaced when this is being done. Of course getting the timing belt, tensioner, idler pulleys, water pump, drive belts, spark plugs, and as many vacuum hoses as possible replaced as well.
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