aschwerin Posted March 13, 2017 Author Share Posted March 13, 2017 Yes, I'm planning on buying the '97-'99. Is that why they look so different than current pistons? There's more of a dish/depression in the piston top. I figured slightly less CR in a single cylinder likely wouldn't hurt the engine any, especially compared to the couple hundred miles I put on it with a single cylinder running at 1/3 the compression of the other cylinders. Wouldn't the CR depend on the thickness of the headgasket? I don't know how much, but I think I replaced the driver side with a .7mm HG (Cometic) while the previous was .5mm? I'm not 100% sure on those numbers. And I don't know how much that changes anything. Its not a big deal to take the pistons out, almost kinda fun, though it looks like I'd have to take off the water pump for #2....and I wouldn't mind saving $100 if its not necessary...but if it is highly recommended...also not a big deal....unless we start throwing in splitting the block and having a machinist bore/hone cylinders. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted March 13, 2017 Share Posted March 13, 2017 Huge difference in compression ratio - 10.6 vs 12.5 or so. You will break one of the other pistons and it will run rough due to that cylinder being about 50-60 psi low. Most of the time the pistons are sold in sets for pretty cheap. Same with the rings. For the little extra work it would be really stupid to not do them all. Do not touch the cylinders!!! GD Quote Link to comment Share on other sites More sharing options...
aschwerin Posted March 13, 2017 Author Share Posted March 13, 2017 I would like to avoid "really stupid". My plan it to measure cylinders, in case it would be good for me to buy oversize pistons/rings (they go up in like .25mm diameters). Would you elaborate on not touching the cylinders? I have an urge to hone them. I'm looking at these on eBay http://www.ebay.com/itm/Fit-97-99-Subaru-Legacy-Impreza-Forester-2-5L-DOHC-Pistons-Rings-Set-EJ25D-/370618892329?fits=Year%3A1997%7CMake%3ASubaru%7CModel%3ALegacy%7CSubmodel%3AOutback%7CEngine+-+Liter_Display%3A2.5L&hash=item564a9b8029:m:mUqeICj_Sx0jT3j8a-D7BgA&vxp=mtr Thanks for the guidance. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted March 13, 2017 Share Posted March 13, 2017 (edited) Do not hone the cylinders. Don't even measure them. Just install a set of 97 to 99 pistons - I may have a used set I can sell you. I can get Japanese rings for you also. It would likely be about $150 shipped for a used set of pistons and new rings. These would be factory pistons and the rings we use on all our builds. 100% of my engines have zero oil consumption. If you like for an additional $80 I'll knurl the piston skirts also. Those aftermarket pistons will slap like crazy - that ebay stuff is Chinese. Read this: http://www.snowvalley.20m.com/bikes/dnthone.htm GD Edited March 13, 2017 by GeneralDisorder Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted March 14, 2017 Share Posted March 14, 2017 Pistons are balanced as a set so installing one piston of a different manufacture can throw off the balance of the engine. Different piston design will also change the compression ratio of that one cylinder which will cause a large power imbalance. Quote Link to comment Share on other sites More sharing options...
aschwerin Posted March 14, 2017 Author Share Posted March 14, 2017 I appreciate your offer GD, still looking around. I was checking with a local muffler shop about borrowing a bore gauge, (though I realize now that all those thoughts were a bit silly since I can still see all the honing marks in the cylinder). Anyhow, they had a Subaru out back with ten EJ25 blocks in it. It seemed we could get together a set of pistons from a 2005 Forester, though one mechanic was sure they were turbo pistons because they had little oil holes in them. There was another potential block that still had the heads on it. They also had a 2.2L still in a car, he thought the valves were bent. The Mizumo pistons on eBay are "genuine NPR", with set of rings is $130 Quote Link to comment Share on other sites More sharing options...
aschwerin Posted March 14, 2017 Author Share Posted March 14, 2017 So looking at Nippon's Piston Buyer's Guide http://www.gjparts.com/products/pistons&rings/NPR2008Book_catalog.pdf The '97-99 piston (11-787) will put the top .1mm further into the cylinder heads, the similar '00 - '08 piston (11-788) .7mm shorter of the cylinder heads. ( I currently have 11-789.) The 787 puts my valves 2.2mm further into the piston top - maybe that means it becomes an interference engine?? 2.9mm closer with the 788. (Assuming I am reading the chart correctly, pg. 227 and 260). The 787 also has 2mm shorter wrist pins, shouldn't be significant as long as I get ones to match the 787. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted March 14, 2017 Share Posted March 14, 2017 It was already an interference engine with the 96 pistons. And yes it will be interference with the 97 to 99 pistons as well. This isn't important if it's put together correctly as EJ timing belts don't break unless (again) you do something really stupid or use cheap components. Trust me on this - you want factory used pistons with skirt knurling and Japanese rings. I've been through this hundreds of times. Literally. Hundreds.... yeah. Bore guage is a waste of time. The bores are tapered, hour glassed, and probably a bit ovaled. None of this matters *in practice* They are factory sized because no one would buy oversized pistons from the dealer for 96 specific and there is no aftermarket on those. You can tell by that alone - also it's obvious the fellow that built it didn't have two brain cells to rub together or he would have not used 96 flat top pistons. What matters is fitting the pistons nice and tight, and new rings. And NOT HONING. You're way, way, way over thinking this situation. I've already done the decades of experience for you here. Just put it together the way I tell you and everything will be ok. Trust me don't buy the aftermarket pistons they will slap like MAD in those used bores. It's a waste of money. Skirt knurling is the way to prevent that and keep the pistons square in the bore and the oil consumption under control. GD Quote Link to comment Share on other sites More sharing options...
aschwerin Posted March 18, 2017 Author Share Posted March 18, 2017 Well the hardest thing about this whole project is getting off the 4mm hex bolts on the oil separator plate. I'm guessing the builder put some strong loctite on them. Its been years since I've stripped a bolt. The little oil ring gasket in the oil pump was in fine shape, and I don't have any records that it was changed when the Frankenmotor was built (most seals were replaced). Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted March 18, 2017 Share Posted March 18, 2017 You have to hit them with a punch. Sometimes you just have to drill the heads off with a left hand bit. Those are the dealer replacement screws for the updated metal separator plate. I never use those. I just use regular 10mm hex head bolts. GD Quote Link to comment Share on other sites More sharing options...
aschwerin Posted March 18, 2017 Author Share Posted March 18, 2017 I used Fairtax's tip I found in a forum search: Used an angle grinder/dremel to make a slot in each head, then used the manual impact driver and a 2 lb hammer while the wife pushed the other side of the engine. Got 'em. All that's left is to pull 3 more wrist pins/pistons, and start ordering parts. I'll replace with hex heads, those allen screws are just silly. By the way, I got involved on this forum doing a search for the builder of the car, he was on here but doesn't seem to be active much anymore, jboymechanic. Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 9, 2017 Author Share Posted April 9, 2017 I've just about got it back together. I replaced a lot of parts, going for a 100,000 mile repair. Does anybody recognize this bolt? Its not the camshaft pulleys, they have hex bolts. Hopefully its not even from the car, but its on my workbench Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 9, 2017 Share Posted April 9, 2017 Subaru didn't use anything like that, but who knows if someone replaced a damaged bolt with that sometime in the past. Either way, probably not important if it wasn't obvious there was a bolt missing when you put it back together. Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 10, 2017 Author Share Posted April 10, 2017 Hmm, doesn't start very well. Takes a bit of cranking, and then it sputters as the RPMs jump between 3k and 1k, and dies within about a 5 seconds. I'm pretty confident in everything except the crankshaft position sensor. The wires broke, and I did some soldering, but there's about a 40% chance I have the two wires switched. It was a pretty rough fit, and I'd like to know the CPS could cause that much problem at startup before I try switching them (a fair chance I would have to order new crimps/connector). Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 10, 2017 Author Share Posted April 10, 2017 With much more effort, I managed to flash a check engine code...P0335 Crankshaft Position Sensor A Circuit So I'll see if I can switch those wires. I'll also check and make sure I pulled the wire I had holding the timing belt tensioner closed... Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 10, 2017 Author Share Posted April 10, 2017 I switched the CPS wires and now it kinda half starts up to 500 rpm, and as soon as I release the key from Start it dies. I tried disconnecting the CPS and it wouldn't start at all. The last two partial starts had a kinda knock before dying, so I'm just going to quit trying to start it before I ruin my rebuild. The manual clearly says it should start without much effort So I guess I'll try to redo the CPS wires? And if that doesn't work, I can't imagine much else but the timing...and I've done the timing belt a few times...it really should be good...lines, not arrows... Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 10, 2017 Share Posted April 10, 2017 If you pulled a code for the crank sensor then it's either wiring or the sensor is bad. It happens sometimes. I would find a used sensor and harness pigtail from the junk yard. Alternatively there are some injector harnesses out there that match the crank sensor also. So what all did you do on your rebuild? GD Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 10, 2017 Author Share Posted April 10, 2017 Pulled most evrything apart except splitting the case, I spent many hours just cleaning everything I took apart: -Side clearance of connecting rods checked from underneath, on the wider side of normal, but well within service limits. No movement felt on other axes. -Replaced pistons with '97 model Teikens and NPR rings. I know, I'll get piston slap, but that's the least of my worries right now. I may regret it down the road...or I'll just picture them belly slapping into a nice pool of oil with each stroke... - checked and lapped all valves...ground heads flat using the glass and wet/dry sandpaper method...replaced valve oil seals - rocker arm measurements all good...replaced all HLAs that showed any wear... - Cometic Frankenmotor headgaskets - cleaned oil pan (the inside), oil pump, etc. replaced gaskets/seals, kindofa waste really, shoulda just left the oil pump on - new clutch and pressure plate. Though they only had 30,000 miles on them, the clutch was unevenly worn and pressure plate had worn and bent fingers. I think the holder springs were missing off the release bearing? It would have been kinda loose in there...also put the new sleeve on, really needed it....and new rear main oil seal - new timing belt, oil seals, and pulleys/sprockets. Those parts also had 30,000 miles on them. A friend figures that since the timing belt covers weren't on, those things all wore a LOT faster. So I bought new timing belt covers. - replaced intake/exhaust gaskets...cleaned everything well...lots of miscellaneous... I figure about $600 in parts and $700 and rising in my labor (my labor is a much lower rate than shop labor...but I'm slower...and generally do a better job...can't say that yet about this job!) Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 11, 2017 Share Posted April 11, 2017 Nice. Glad you got the right pistons in there. We just use the EJ257 gaskets but that does up the compression a little. I don't like using the thicker head gaskets because that was the problem with the design all along - they were too thick allowing cylinder wall movement. A friend did his 98 25D with Cometic's (standard thickness for 25D) and ARP head studs and it only lasted 30k and blew the HG's out again. GD Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 11, 2017 Share Posted April 11, 2017 It has a MAF sensor doesn't it? Intake hose loose, or the big hose for the IAC is loose maybe. Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 11, 2017 Author Share Posted April 11, 2017 Yes, it has the MAF. I sprayed near it with compressed air before re-installing. Had sprayed it with cleaner back before I tore engine apart. Funny, it wouldn't start at all until I saw the intake wasn't back on the throttle body...at least that was an easy problem to solve... I've checked over, big hose is on. I checked around, the IAC was buzzing/humming, but searches said this was normal for a time after car was turned off. I'll triple-check the air system. I think I can get the CPS wires and connector from a nearby junk car, tomorrow. Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 11, 2017 Author Share Posted April 11, 2017 I got a CPS connector from nearby, worked like a charm, started on the first crank. Thanks everybody! I'm going to follow the manual's break-in instructions, so it'll be a little time until I take it for a real test drive. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 12, 2017 Share Posted April 12, 2017 You want to run it medium hard - 3/4 throttle right off the bat. Cylinder pressure seats the rings. After 200 miles hammer on it. GD Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 13, 2017 Author Share Posted April 13, 2017 So its definitely improved. Smoother running sound, and smoother power. And I thought power was good, if not great. We have some good hills around here, so I a lot of good throttle uphill and engine braking downhill. Then I drove my 2.2L again, and it has slightly more power than the rebuilt 2.5L Frankenmotor.... Up a steep hill, I can easily accelerate (1/2 throttle) in 3rd gear at 40 mph with the 2.2L....the 2.5L barely accelerates at 3/4 throttle... I'll go another couple hundred miles to seat the rings and do another compression check... I was expecting some noticeable power from the rebuild...it'll also be good to see the mpg after a full tank of gas. And I'll check some more Torque measurements. Quote Link to comment Share on other sites More sharing options...
aschwerin Posted April 24, 2017 Author Share Posted April 24, 2017 I've driven it around 150 miles and did a compression check: #1 215 #2 221 #3 212 #4 210 So that looks pretty good. Here are the numbers from before the job: #1,2,3, have 228, 235, 242 psi not respectively. #4 cylinder has 68 psi (and when I checked this a year ago #4 had like 150 or so) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.