My 2003 w/108k miles on the clock is suffering from low idle oil pressure, crappy compression (125/110/123/125). Time to rebuild.

I am making up a parts list, considering going to o/s pistons, doing the sprintex supercharger upgrade kit.

Couple of items that I need some help with - any rebuilders out there? I have built several engines - but all of them Audi / Mazda. Never a Mini. Not afraid of any of the work, just unfamiliar with the finer points.

1) Shop manual and bentley both suggest replacing the M8 and M10 bolts that hold the block together - is this necessary? Cant find a 'kit' online - if they really need to be replaced, anyone selling the 20 bolt kit?

2) Same resources suggest replacing the spark plug tubes - but cant find a tool online. I figure I would grab them out with a blind slide hammer puller - any reason they cant be reused if in good shape? Hold with some loctite 518 (same as used to put the block together?)

3) Assuming the mild power upgrade of the sprintex s/c, any reason to swap out the stock pistons? I scoped them, and I am assuming they are in good shape, and if not I will replace anyway.

4) I am assuming my cylinder 2 has a combo of bad rings (all of them are prob bad, getting replaced anyway) and at least one burned exhaust valve. I dont feel a burning desire to spend more money on this rebuild, but assuming the radial play is within spec, any compelling reason to replace the stock valve guides? Replace the stock exhaust valves?

Thanks in advance! I really appreciate your input!

 

From what I have gathered our mahle pistons are pretty beefy. I have to upgrade my injectors and retune my car. This is what happens when you over cook the pistons from running lean without detonation.

 

Oh and I had 125/120/130/65 psi compression and 289k miles. The busted piston is cylinder #4. Everything else checked out, no cylinder wall wear, bearings were all worn out but no wear on the main or rod journals.
i haven't read yet that I need to replace the main crank journal bolts. If they are stretch bolts then I would but if they are not then I'll probably reuse given they are in good shape. So far the only bolts I'm planning on replacing are my head and camshaft sprocket bolts.

 

Impressive malfunction. Reminds me of my first TT - leaned out, BT+BFI upgrade - didnt quite have the fuel map correct...

Decided to replace the block bolts anyway - I *hate* drilling out grade 8 bolts when the break. Still curious about the other items tho.

I have the entire rebuild down to about $1300.00, which includes all bearings, rear main seal, bolts, rod bolts, piston rings, head gasket[+0.3mm], intake/exh gasket, valve seals, guides, machining head flat, at least two exhaust valves, orings, oil filter gasket, timing chain cover gasket, etc.
If the bores measure too large, I will add ~$450 for a piston/ring set at +.5mm and boring out the block.
I am reading about the positives of the Valeo single mass conversion flywheel benefits, so throw another $350 in there for parts on that which includes a new clutch / throw out bearing / flywheel / hardware.

 

I was doing my rebuild this time last year, and honestly don't remember if I replaced those bolts, pretty sure I did replace them, I replaced everything I could think of that needed it or may be close to needing it. My rebuild thread.
2) Did not replace spark plug tubes, only the gaskets
3) stock pistons probably fine (my guess is you could just replace the rings and be fine)
4) Since you're there, and its fairly simple, I'd replace the guides. Also inspect the head around the spark plugs closely, mine had cracks in every cylinder.......

Good luck,

I look forward to updates,

Nik