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Discussion Starter · #1 ·
I pulled the head off my 1990 900 turbo.

1st thing I notice - cylinder #1 is full of coolant.

The headgasket has blue sealings not the orange of the factory gaskets I've seen and installed in the past. Is this a replacement or standard fit? The car only has about 250 000km.

I removed the coolant from cylinder 1.

I notice there is some pretty bad corrosion that has occured in this cylinder. It appears like a slightly rough silver coloured surface on the cylinder wall. This scared the **** out of me! :eek:

I really don't want to pull the bottom end and be honing... I was thinking of using some 1000 grit sandpaper and making a new cross-hatching pattern.

There is barely detectable ridging.
 

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I'd be honing it. That sounds pretty knackered. What about the bottom of the bore? It will be just as bad, but you'll never reach it from the top with the piston in.
 

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I think i'd have to see pictures to say for sure, but you might want to take a paper towel and some carburetor cleaner and see if that does the trick. Most times i do head gaskets i spend about 30 minutes cleaning cylinders: twice with carb cleaner/paper towels, once with ATF/paper towels, and then once more with carb cleaner and a paper towel (4 cleanings per cylinder total).
If you see any pitting from the rust after all that, then definitely hone...if not, it's your call but i wouldn't bother.
 

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Discussion Starter · #4 ·
What about some "heavy duty gasket remover"? I just don't want it to dissolve my block too...

It is only on cylinder #1 and only at the top 2/3 of the stroke or so, there is one slightly large patch and a couple small dots, pencil eraser size. The big one is perhaps the area of a quarter but more ovoid. I am guessing this occured over the time period from March - July when the car was sitting waiting for me to do the headgasket, as all of this surface area was covered in perhaps 50mL of light-colored coolant (or "green ****" as I will now forever call it).

Cyl's 2, 3, 4 are beautiful and I can see my reflection in them...

I'm taking my camera tomorrow hopefully it not too bad... :confused: I need this car on the road!!
 

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In that case I'd think you can just clean them. How long has it been sitting like that? Get it clean and smooth and let it work itself out once its running again.
 

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Discussion Starter · #6 ·
I guess it occured from the presence of the coolant when the engine was immobile, which was from April until yesterday... the engine is in the position where all four pistons are at the same level.
 

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I wouldn't let it cause you too much concern then. Just clean it up real good. I don't think that coolant is going to do much harm to those bores.
 

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When you have cleaned up the bore, run some oil around the side of the piston, this will release the piston rings if they have rusted into the piston grooves.
 

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Discussion Starter · #9 ·
Here are a few pics of before I did anything to the bore. The little pits are gone now with some 800 grit. The big one (lowest one) however I can still feel it after a fair amount of 800 grit sanding. I did some cleaning with some ether, now pistons nice and clean. Still I am not sure. I might continue with the sandpaper a bit...

Click to enlarge:



 
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