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Andrew's DiySB Rebuild


What color combo should I paint my block / heads / valve covers?  

37 members have voted

  1. 1. What color combo should I paint my block / heads / valve covers?

    • everything SILVER
    • everything RED
    • sb RED / heads SILVER / vc's SILVER
    • sb RED / heads SILVER / vc's RED
    • sb SILVER / heads RED / vc's SILVER
    • sb SILVER / heads RED / vc's RED


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All four pistons are at FPI getting inspected by a certified pro. I wanted to avoid bringing them to work because it's a little less than kosher, but desperate times call for desperate measures. The end of the month/quarter was last week so the higher-ups aren't checking in on things very often. You know, cause it's ok as long as you don't get caught.
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Red typically links to rust. Rust typically links to moisture (coolant). Coolant rust typically links to cracked coolant circuit. Check your heads for that.
- Pro amore Dei et patriam et populum -
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Wondering if measuring overall valve length and diameter might reveal any discrepancies? I've heard/subscribed to the theory that these valves (exhaust mostly) when running too hot tend to deform... almost like an open flower closing slightly. This makes the valve head diameter a tad smaller, and overall valve length a tad longer. The latter is what then reduces precious valve clearance. Then we say hey my valve clearances are getting too tight, and we increase the clearance to get them back into spec.

 

Having the luxury of the valves sitting on your counter might be a nice opportunity to see if any might jump out as being different than the rest.

BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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Red typically links to rust. Rust typically links to moisture (coolant). Coolant rust typically links to cracked coolant circuit. Check your heads for that.

Gee that sounds fun. I'll dig around and see what I can find. They're both red so I'll start by looking in places that would supply coolant to both valves. or into the combustion area.

 

Wondering if measuring overall valve length and diameter might reveal any discrepancies? I've heard/subscribed to the theory that these valves (exhaust mostly) when running too hot tend to deform... almost like an open flower closing slightly. This makes the valve head diameter a tad smaller, and overall valve length a tad longer. The latter is what then reduces precious valve clearance. Then we say hey my valve clearances are getting too tight, and we increase the clearance to get them back into spec.

 

Having the luxury of the valves sitting on your counter might be a nice opportunity to see if any might jump out as being different than the rest.

Checking the overall height will be easy. Also measuring the new valves could help me pair them up with different locations in the heads. Good idea.

 

I wish that was my countertop! Ours is a 30-year old off-white laminate. The slab of marble was my mother-in-law's cutting board, now it's my surface plate. The center area of both sides is flat within 0.003" so its not quite good enough, but getting used anyways.

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Are you replacing all your valves? If so what kind are you getting and from where ?

 

I'm replacing all of the valves with GSC Power-Division nitride coated stainless steel valves. The 36mm intake valves (p/n 2012-8) are made from 21-4n stainless, and the 32mm exhaust valves (p/n 2011-8) are made from 23-8n stainless.

 

I got the intake set off Amazon (actually came from Heuberger Subaru), and the exhaust set from JSC Speed. At the time those were the two cheapest vendors that I could find.

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The valves were in water for a while, when the OP `wet tested' the heads. Could that be the source of surface rust? There doesn't seem to be any other evidence consistent with a HG problem or cracked head, unless pretty much every cylinder has a crack.

 

Any pitting on the valve sealing surfaces, however, is just plain bad. It is hard to imagine how the engine was running without lots of problems with chewed up valves. Is this also surface only, or can you catch a fingernail on the pitting?

 

As for distortion, I think it would be tough to measure valve length accurately, and that might not be a very useful number anyway since the important measurement is the length from the seating surface (midpoint, say) to the stem end. Brand new, the overall length might be a satisfactory surrogate for effective valve length. Eyeballing the remaining valve margin might reveal something. Does it look uniform? Are they all more or less the same (exhaust to exhaust, intake to intake)?

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Last night I inspected the heads for flatness, and I didn't find one single spot where my 0.0015" shim fits.

 

Depending on what you mean by this . . .

Measure flatness by putting your straightedge on TOP of the feeler gauge. Then pull on the gauge. If the straightedge follows the feeler, the gap, if any, is less. Do this in a few different directions, measuring at various points along the straightedge. I don't think you need to go any finer than 1.5 thou, if I am remembering the specs correctly.

 

Myself, I've never had much luck stuffing a 0.0015 feeler gauge under a straightedge. Not with any confidence, anyway.

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The valves were in water for a while, when the OP `wet tested' the heads. Could that be the source of surface rust? There doesn't seem to be any other evidence consistent with a HG problem or cracked head, unless pretty much every cylinder has a crack.

 

Any pitting on the valve sealing surfaces, however, is just plain bad. It is hard to imagine how the engine was running without lots of problems with chewed up valves. Is this also surface only, or can you catch a fingernail on the pitting?

 

As for distortion, I think it would be tough to measure valve length accurately, and that might not be a very useful number anyway since the important measurement is the length from the seating surface (midpoint, say) to the stem end. Brand new, the overall length might be a satisfactory surrogate for effective valve length. Eyeballing the remaining valve margin might reveal something. Does it look uniform? Are they all more or less the same (exhaust to exhaust, intake to intake)?

 

The rust color could for sure be from me water testing the heads. I totally forgot I did that. I looked at the gaskets pretty closely and I didn't find anything indicating a leak.

 

I'm going to leave the valves as-is for a day or two to give me time to think, then I'll soda blast them and see if the pitting is really that, or if it's just thin deposits that look like pitting. You can gently catch your finger on them so there's definitely something there. I won't measure the valve length until after they're clean. Right now there's too much grit on the hot side of the valves to be able to get them to sit flat on the surface plate.

 

Depending on what you mean by this . . .

Measure flatness by putting your straightedge on TOP of the feeler gauge. Then pull on the gauge. If the straightedge follows the feeler, the gap, if any, is less. Do this in a few different directions, measuring at various points along the straightedge. I don't think you need to go any finer than 1.5 thou, if I am remembering the specs correctly.

 

Myself, I've never had much luck stuffing a 0.0015" feeler gauge under a straightedge. Not with any confidence, anyway.

I thoroughly checked for flatness in a ton of places (see my inspection sheet pdf) and was very surprised to find not a single gap. Using my flashlight I couldn't even see light, anywhere. I didn't want to believe that the first head was flawlessly flat, so I went back over it again, doing exactly what you mentioned in about 25 places. The shim pulled the straightedge every time. I even checked the shim about 100 times to make sure I wasn't using the 0.015" one by mistake. Using a 0.0005" shim would be borderline-horribly excessive, but that's who I am and I can't help it :rolleyes: Something deep down in me needs to KNOW how flat it is, not just know that it meets the tolerance.

 

The FSM says 0.0014" is acceptable (ME(H4DOTC-59).

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The SB decks check flat within 0.0015, just like the heads.

 

The cylinder bores all measure within 0.001 of each other. My AAAB block looks to be about half of a thousandth (0.0005") away from being an AAAA block. I'm going to measure the cylinders again tomorrow and average everything up before settling on the final numbers.

 

It's really a pain trying to get clear pics of the cross-hatching. There is only very light scoring inside the cylinders in a few places. It's definitely not enough to catch a fingernail on. I'm thinking that I may be able to skip the honing.

 

What's the general opinion about reusing my crank (rod) bearings without taking them out and calculating the clearances? I haven't taken the rods off the crank yet so just using it as-is would save a decent amount of time and effort.

Edited by StkmltS
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further down the cylinder bore, does the cross-hatching change to a more mirror-like finish? I remember finding that in my original SB (about 130K miles) the top part of the bores had nice original cross-hatch and the bottom part of the bores was where all of the wear was hiding.
BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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further down the cylinder bore, does the cross-hatching change to a more mirror-like finish? I remember finding that in my original SB (about 130K miles) the top part of the bores had nice original cross-hatch and the bottom part of the bores was where all of the wear was hiding.

 

I believe these will answer your question.

Without a borescope I don't know how someone could get decent pics down inside the cylinders.

205334122_Cylinder1crosshatching.thumb.jpg.e007feb296c97b409a2ace649765cd47.jpg

374461919_Cylinder2crosshatching.thumb.jpg.b18bf7b42dcdb3a1c94d314134cc1699.jpg

1825503686_Cylinder3crosshatching.thumb.jpg.c92c90e189742442c388864e79af9fff.jpg

777458734_Cylinder4crosshatching.thumb.jpg.6a37916884c3f2331e9acd7b762e3863.jpg

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New rings in old (as in not freshly honed) bores is a well-known recipe for building an oil burner.

 

If you don't take the rods off the crank, how will you clean everything up?

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those cylinder walls (cross-hatching) certainly look a lot better than those in my original sb!
BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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Good pictures! Thanks.

 

The lower end of ring travel -- that line down near the bottom of the bore -- I would try to get a measurement just above and below to figure out how much the bores have worn.

 

Are you going to enter all the measurements into your spreadsheet? I'd be super interested in what you get for oval and taper. With PTW clearances at +- 4 tenths there isn't much room for any of that.

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So, am I to understand that these vertical scorings are strictly on the top and bottom of each cylinder? What is causing these if the rings were just fine? Piston skirts scraping the cylinder walls during piston slap? I am new to all this piston stuff :redface:
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Good pictures! Thanks.

 

The lower end of ring travel -- that line down near the bottom of the bore -- I would try to get a measurement just above and below to figure out how much the bores have worn.

 

Are you going to enter all the measurements into your spreadsheet? I'd be super interested in what you get for oval and taper. With PTW clearances at +- 4 tenths there isn't much room for any of that.

 

Good idea. I'll get above/below measurements tonight.

 

After I measure the cylinders again tonight I'm going to average my data for each location and say "this spot measures 3.91X". Then I'll know taper and out-of-roundness. I'll post all of my numbers after I double-triple check everything to make sure I did it correctly :cool:

 

So, am I to understand that these vertical scorings are strictly on the top and bottom of each cylinder? What is causing these if the rings were just fine? Piston skirts scraping the cylinder walls during piston slap? I am new to all this piston stuff :redface:

 

Yes, scoring is only visible on the top and bottom of each cylinder (top = 0°, not top dead center). That makes sense based on how I understand it. Rods move in and out (linear), but they also move up and down because they're connected to the rotating (circular) crank. A piston only moves in and out, but at the start and end of it's travel it rocks slightly inside the cylinder when the rod changes direction from "in" to "out". I'm guessing that's why the skirts are there in the first place, and I believe that's also the reason why forged pistons are noisy. The forged material expands more (than OEM) when it's hot, so there needs to be a larger-than-OEM gap between the piston and cylinder wall. That extra clearance allows a forged piston to rock more than an OEM piston, so it's noisier and the skirts wear down the cylinders more. Most of the gains from going forged are seen at car meets, not on the street :p

 

Don't be intimidated by your lack of knowledge or experience, just rebuild your motor and be forced to gain a little of both :lol:

That's what I did, and I'm practically already doing AWD burnouts in 3rd gear at highway speeds because my motor is fully (re)built. #BuiltNotBoughtBeeeeeeeeeeeeeyotches

 

Also, vote in my stupid poll thingy at the top of the page. I need help deciding on colors.

Edited by StkmltS
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So, am I to understand that these vertical scorings are strictly on the top and bottom of each cylinder? What is causing these if the rings were just fine? Piston skirts scraping the cylinder walls during piston slap? I am new to all this piston stuff :redface:

 

In the mercedes world these are termed `optical streaks' if you can still see the remnants of the cross hatching under them. They are considered benign. As in, if you see them when you have the head off for rebuild, it is standard practice to leave the short block alone and run it for another 500K ;)

 

If you still had the pistons as they came out of the bores, you may have been able to index those streaks with corresponding marks on the piston skirts. So yes, it is the skirts doing this although there are debates about exactly what causes it.

 

If the streaks are indeed optical, they will come out with the hone.

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Here's a fun story.

 

On my way home from work yesterday the guy behind me at a stop light got out of his truck and came up to my window and said "hey buddy, you're leaking gas pretty bad." 15 miles and three gallons of gas later I pulled into my driveway just as the gas light turned on. Apparently 2005 Suburbans have two fuel lines that cross each other above the gas tank, and they like to rub on each other and wear holes in themselves. I used my borescope to... scope it out... and I decided that I shouldn't take the tank out by myself. It's my parent's car that I'm borrowing while the wagon is down, and my dad usually prefers to have a shop work on his cars than do it himself (or myself).

 

So dad called AAA for a tow, but they won't tow it without written approval from my local fire department. What?!?! So I call the fire depot and the guy has no idea what I'm talking about, he'll call me back. An hour later he calls to tell me there's nothing they can give me, the car is safe to tow if it isn't actively leaking, and it sounds like AAA is being stupid. So I call AAA and convince them that it's not leaking anymore and the fire depot said it's safe to tow. AAA concedes and say's they'll tow it, but I'm not the member so my dad has to call back. Bla bla bla the tow truck ends up showing up and it was the same guy that towed my LGT home this past winter. We hit it off like old friends and got to talking about plumbing, guns, snakes, and spiders (it got buddy-buddy really fast). Anyways, he asked what was going on with the car because he saw the log of our calls to AAA and it's really confusing. He showed me the log because we're best friends now, and it turns out that somehow my dad's initial conversation with AAA gave them the impression that the car needed towed because it was on fire. Ahhhh! The puzzle pieces are starting to come together now. My dad's not old and crotchety (yet) but he's starting to develop the strange ability to tell people the 100% truth, yet still leave them thinking something totally different. It's entertaining to watch sometimes.

 

As soon as I got home I could tell that my wife needed a break from me+LGT, so I didn't mess with the motor last night. It's difficult sometimes, but long-term priorities need attention too. Changing diapers, holding the baby, talking about our feelings... yeesh!

 

My ball hone will be here tomorrow.

Edited by StkmltS
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