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Old 03-05-2010, 10:31 PM   #1
petrakov08
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Default Injector and piston/cylinder wall clean up question?

I'm doing the head gaskets on my 98RS and needless to say after I took the heads off I discovered a mess...



How should I go about cleaning the cylinder walls and the top of the pistons safely? (I won't be tearing down the block any further)

Also as long as my intake manifold is out will it benefit me at all to put wrx injectors in? I could get them practically free but will I see any gains? Possibly with a tune?

Thanks
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Old 03-06-2010, 02:53 AM   #2
reddevil
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Rotate the pistons to the outside, and just carefully wire bruss/pick the carbon off. Carefully scrape the block face clean. Use that copper spray stuff on the block, heads, and gaskets when reassembling. Should be fine.
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Old 03-06-2010, 10:54 AM   #3
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brake cleaner
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Old 03-06-2010, 03:13 PM   #4
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Quote:
Originally Posted by arghx7 View Post
brake cleaner

Can I use brake cleaner on a microfiber rag to clean the cylinder wall?
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Old 03-06-2010, 03:15 PM   #5
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make sure to oil the cylinder with a *slight* coat before you go back together
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Old 03-06-2010, 05:44 PM   #6
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Quote:
Originally Posted by modaddict View Post
make sure to oil the cylinder with a *slight* coat before you go back together

Yeah, after cleaning, rotate piston back, clean cylinder out with CLEAN rag and solvent, then oil cylinder walls. Once all 4 are done, rotate, rotate, rotate.... You might want to then wipe out the cylinders again and repeat if you see ANY crap materialize....
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Old 03-06-2010, 07:53 PM   #7
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Quote:
Originally Posted by reddevil View Post
Yeah, after cleaning, rotate piston back, clean cylinder out with CLEAN rag and solvent, then oil cylinder walls. Once all 4 are done, rotate, rotate, rotate.... You might want to then wipe out the cylinders again and repeat if you see ANY crap materialize....
Thanks, what type of solvent should I use? I hear brake cleaner can be used
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Old 03-06-2010, 10:24 PM   #8
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when the head gaskets fail on these things does the coolant leak into the cylinder, or does the coolant get into the oil?
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Old 03-06-2010, 10:33 PM   #9
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Quote:
Originally Posted by reddevil View Post
Yeah, after cleaning, rotate piston back, clean cylinder out with CLEAN rag and solvent, then oil cylinder walls. Once all 4 are done, rotate, rotate, rotate.... You might want to then wipe out the cylinders again and repeat if you see ANY crap materialize....
while it certainly couldn't hurt to go through that regimen, that's not necessary as long as you crank the motor over to build oil pressure before actually starting it

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Originally Posted by petrakov08 View Post
Can I use brake cleaner on a microfiber rag to clean the cylinder wall?
sure. you're not going to hurt it. just make sure everything is clean before re assembly.
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Old 03-07-2010, 10:45 AM   #10
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Quote:
Originally Posted by arghx7 View Post
while it certainly couldn't hurt to go through that regimen, that's not necessary as long as you crank the motor over to build oil pressure before actually starting it



sure. you're not going to hurt it. just make sure everything is clean before re assembly.

what does cleaning the cylinder walls have to do with oil pressure prior to startup?
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Old 03-07-2010, 01:23 PM   #11
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Oil pressure prior to startup has to do with getting that oil film back that he just wiped off.
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Old 03-07-2010, 02:38 PM   #12
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[quote=arghx7;29980189]while it certainly couldn't hurt to go through that regimen, that's not necessary as long as you crank the motor over to build oil pressure before actually starting it

So what you're saying is once the heads are back on I should crank over the motor by a hand so it lubricates the cylinders before I actually start it up?
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Old 03-07-2010, 02:56 PM   #13
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We beat this to death a couple of months ago. Due to how slowly the starter spins the motor and how long it takes to pull up a prime on the oil pump at starter-speed (you can't get the oil pump to pump at all by hand), it's easier on the engine to just start it. The total number of revolutions before full pressure is achieved is MUCH less if you just start it.
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Old 03-07-2010, 03:16 PM   #14
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I guess I missed that conversation willaty. Thanks for correcting me.
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Old 03-07-2010, 03:20 PM   #15
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Quote:
Originally Posted by ihadmail View Post
I guess I missed that conversation willaty. Thanks for correcting me.
NP. I had been among those who thought that spinning the engine on the starter until you get oil pressure, then firing it was the most gentle way to do it. When someone posted the math to calculate the revolutions, and then I timed priming it with the starter vs just starting it, it takes sooooooo long to prime it with the starter that you spin it many more revolutions.
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Old 03-07-2010, 08:30 PM   #16
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Quote:
Originally Posted by williaty View Post
NP. I had been among those who thought that spinning the engine on the starter until you get oil pressure, then firing it was the most gentle way to do it. When someone posted the math to calculate the revolutions, and then I timed priming it with the starter vs just starting it, it takes sooooooo long to prime it with the starter that you spin it many more revolutions.
So what you're saying is that cranking it over by hand to get the oil pump going is useless? Just start it up once the engine is back in?
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Old 03-07-2010, 08:35 PM   #17
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Quote:
Originally Posted by petrakov08 View Post
So what you're saying is that cranking it over by hand to get the oil pump going is useless? Just start it up once the engine is back in?
Yes. Even though the oil pump is positive displacement, when it's full of air (and even if you "pack" it with oil after install, it'll all just run into the sump in a minute or two), you can't spin it fast enough by hand to get it to pull oil out of the pan. So your only other two options are to spin it on the starter without letting the engine fire or just start the engine. It turns out that the engine revolves fewer times if you just start it than if you just spin it on the starter due to how much faster it'll idle than the starter motor turns it.
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Old 03-07-2010, 09:37 PM   #18
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But doesn't force come into play if you just start it on assembly lube only, or in this case very very minimal residual oil? Cobb's startup instruction that came with their blocks back in the day said to turn it over with the plugs removed and fuel pump disconnected until oil pressure builds.

EDIT: I understand the total piston travel with no oil is less if you just start it up, but the force on the bearings and the heat generated will be much lower turning it over on just the starter.
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Old 03-07-2010, 10:34 PM   #19
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The majority of the forces on the bearing at part throttle are the g-loads from reversing the direction of the piston. That's the same no matter what's powering the engine.
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