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Rear Main Seal

29K views 28 replies 6 participants last post by  psinuse 
#1 · (Edited)
Excuse me for being a noob here but I'm replacing my rear main seal and I have a couple questions. I have taken out my transmission twice now but this is the first time I have taken my engine out. The last time I took my transmission out I replaced the rear main seal, but after I started it up and drove it it started leaking puddles shortly after. In order to install the seal last time I got a PVC endcap and tapped the PVC cap against the rear main seal in order to get it in flushly. The PVC cap is the same exact diameter as the rear main seal so it didn't get stuck on any part of the engine or anything. When I felt that I was done I went ahead and tapped the endcap a little bit harder than usual just to make sure it was in, but I still didn't hit it very hard. I'm just wondering what I did wrong last time? Is there a trick that you are supposed to do in order to have it seat correctly? Also since I pulled the engine out this time instead of the transmission I would like to replace any gaskets and seals that I can. I have ordered the valve cover gaskets, head gaskets, spark plug seals, the little corner plugs in the heads, an O-ring for my oil cooler, and camshaft seals. Are there any other seals or gaskets I could replace while its out? When I take the heads and the valve covers off is there anything I need to watch out for or anything tricky that I might overlook? Has anyone made any mistakes that I should avoid? Also when i was taking out the old rear main seal I looked at the crack where the block comes together around the crank (still looks sealed) but there was some dirt around the crack above and below where the rear main seal seats, is that normal? It definately didn't look like anything new but I'm just making sure. Thank you for all of your help in advance.
P.S. I just tried posting pictures but I guess you can't upload them from your computer it has to be a website?
 
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#3 ·
^^ +1

To further explain that, if the seal is too far in, it blocks a tiny little oil passage which exacerbates a leak. The same thing happens if you use Fuji-bond or any silicone sealer and get too much in there (plugging the hole). It is also possible that the leak from back there could be coming from the oil separator plate. I highly recommend re-sealing that while you have everything apart.

I always just get the complete gasket and seal kit from Subaru. There are a few things you won't end up using (like valve spring keepers and timing cover seals etc.) but it is a good way to have all your bases covered. Welcome Duners usually has a good price on that.
 
#4 ·
Thank you!! Can you see any seals or gaskets I am missing? Since grimmspeed doesn't make any pulleys other thank the crank pulley does anyone have a suggestions on a brand that they have tried or heard of? I know cobb is a good one that a lot of people use, are there any others?
 
#5 ·
OK thanks wagonracer. Does that little spot that the oil passes through have a little bubble when you remove the rear main seal? What kind of sealer should I use? Will any silicone sealer work? I'm assuming that since the question is being ignored or looked over replacing the gaskets for the heads is going to be straightforward and nothing is going to fall out or move without me getting a chance to notice then right? I just don't want to overlook something and make a couple thousand dollar mistake for nothing. Thanks again guys.
 
#7 ·
Does that little spot that the oil passes through have a little bubble when you remove the rear main seal? NO What kind of sealer should I use? FUJI BOND OR SUBARU THREE BONDI'm assuming that since the question is being ignored or looked over replacing the gaskets for the heads is going to be straightforward and nothing is going to fall out or move without me getting a chance to notice then right? I just don't want to overlook something and make a couple thousand dollar mistake for nothing. Thanks again guys.[/QUOTE

Replacing the head gaskets is a HUGE job for a novice, since it entails removing just about everything (intake, exhaust, timing components etc.) The cam gears are a real bi-atch to remove without the right tools or know-how. Torquing the heads along with just about everything else is also critical (keeping the buckets in place when you remove the heads etc.) I highly recommend following the shop manual to a tee and having some experienced help, if this is your first attempt at an engine overhaul.
 
#8 ·
I appreciate your warning but I have followed the guide to take the transmission on and off a couple times now. As long as i follow instructions and read carefully I should be alright. I already have the engine sitting on a stand. The only thing I have removed so far from the engine that has anything to do with timing is the alternator and a/c belt (because they're connected to the crank pulley). I will definately follow the shop manual and if i have any questions I feel like I can always ask you guys or the mechanic at my shop for anything. I just wanted to know if there was anything not in the shop manual that may catch me by surprise.
 
#9 ·
Just to let everyone know what happened. I replaced all of the gaskets and seals in the engine while it was out of the car and I started it up yesterday. I drove it around the block and everything was great. No more oil leaks! Yay! The car sounded great (I got grimmspeed tgv deletes, and ported and polished manifolds - turbo as well as an ewg.) I started driving the car today and when I started it up the temperature gauge shot way up. I shut the car back off and the coolant resivouir was full (the one on the radiator) but then I looked at the little coolant resivour that is between the radiator and the turbo and it was empty. The coolant from the resivour leads directly into the turbo coolant tank right? So if the system is empty and there is no coolant being drawn then I'm thinking that little pipe is blocked. I also put in a brand new grimmspeed thermostat with the gasket that they gave me (it seemed like a tight fit going into the housing). I also looked at the radiator cap on the turbo coolant tank and it seems like its in ok condition, its a little rusty but its nothing severe looking. Any other ideas? Thanks again for the help with the gasket/seal replacement guys.
 
#11 ·
I figured that was a problem too but why wouldn't it be drawing any of the fluid out of the reserve coolant tank if its empty? I filled it with water (so I could get home) and it was emptying so fast and it still wasnt drawing any coolant. Is that normal with these cars?
 
#12 ·
Meh yeah. They have a habit of being fickle about the cooling system. Just fill the top coolant tank, the one in between the turbo and the radiator. Then squeeze the upper radiator hose fill the tank again repeat. then start the car let it come up to temp to make sure the system is full.
 
#13 ·
ok. I still have to turn on the hot air also when the car is running right? I'm on my way to get some antifreeze now and I'll let you know how it goes. Also I was wondering how the coolant was flowing through the system. It just bugs me that I don't know why it isnt drawing from the tank connected to the radiator... Does your car ever do that?
 
#14 ·
Ok so after I messed with that tube that leads into the main cooling tank I was draining the coolant fluid and noticed that water was still flowing out of the thermastat housing (water because I used water to get home from the gas station since it was leaking). I took the housing off and sure enough my t-stat was leaking at the bottom of the seal. It is a grimmspeed t-stat and I used the gasket they gave me. I went upstairs to get the old gasket that was on my original t-stat and it looked like it was a hair larger than the grimmspeed one. Just to be sure about the "dongle" thing I also installed it the same way that I took the oem one out. the coil looking part went into the engine and the part that had three different "beams" that met in the middle (with the flat face of the dongle) on the outside facing the toward you if you are looking at the engine from the front of the car. Did I install it wrong or was the gasket that I got from grimmspeed just a couple mm too small?
 
#15 ·
Just to let you guys know I took the thermostat and put the OEM Seal on it and it stopped leaking into the housing from the bottom. I filled the entire system with coolant and burped it and then let it idle and the temps were good. Then I drove her around the block and everything was still good. I looked under the car one more time and no leaks. Thank you for the burping technique psinuse. Does anybody know why you torque the headbolts the way you do in these cars? Is it to stretch them and then tighten them or what? Why are they made to stretch anyways?
 
#20 ·
Every motor I have build sans the one that used ARP studs, I torqued the way the factory manual said to. There is a reason for it to be that way and since Subaru has been building cars longer than most of the people on here have been alive I kind of follow there way of doing things.
 
#21 ·
Good point !! I've always thought it helps seat the gasket, and since the block and head are aluminum you want the load distributed evenly. I've done that procedure so many times with success that it's almost a relaxing zen-like exercise.

I also ####ed up an engine (an NA 2.5) using somebody else's short cut instructions. One extra 90 degree turn and the head studs snap ! The different torques for the center bolts, compared to the corners may seem silly, but why question it ?
 
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