Update on my over-rev'ed head...

[veeman]

Looks great, Jake...  Those scotchbrite pads really do work well.  I tried putting mine on a straight die grinder like yours (pictured), but had a heck of a time trying to keep it on course.   It seemed to jump right out of my hands.

Soon after, Harbor_freight (underwriting car projects everywhere...) had a special on their 90 degree air grinder / sander for $14 or something.   Seems much easier to control.  

Kinda like this, although I don't remember mine being 20k rpm (!)...

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=32046

[wyldman]

While they do an excellent job of cleaning up the surface,they don't do a very good job of keeping it straight.Be very gentle,and go slowly,or you can take off too much material.It's not so bad on a cast block,but I'd think twice about using them on an aluminum head.They will leave a very uneven surface,and gasket failure will result.

If you are going to use one,a right angle die grinder is the way to go.

[fspGTD]

veeman: Gotta love harbor freight.    I'm using their $10 straight grinder!  I bought it to polish intake manifold runners and do other stuff with, but haven't had any problems using it for flat surface prep application.  I support it ridigly with both hands and when keep it (only very slightly) "on edge" to keep it from darting around.

However, I have had some practice using it on my custom intake manifold project.  It's the only tool for the job of runner polishing.  The scotchbrite pads work great for welding surface prep too - removing carbon, dirt, oxides.  I found it is slow if not impossible to actually remove any of the metal itself with it.  I found it is much different than sandpaper in this regard.

wyldman: IMO, on a cast iron surface with an ultra-fine pad, there just isn't anything to be worried about; I don't think you could screw it up if you tried!

[wyldman]

It may be the type of scotchbrite disc you are using,it must be quite fine.

Most scotchbrite discs WILL cut metal.You may not see it,because the surface seems so shiny and smooth,but it will leave a vey uneven surface.

Ask any good automotive machinist.They usually see quite a few heads and blocks,and even manifolds,screwed up by scotchbrite discs.Most gsaket manufacturers and engine rebuilding associattions also have service bulletins out recommending not to use scotchbrite discs.

The easiest way to see this is to try it on an old fender,or body panel.Use the disc to shine it up just like you did the block.Then paint it with some gloss black spray paint.Now hold it up to the light,and look at the surface.Is it flat ? Is is smooth ?

[wyldman]

Forgot to add..........The best way to clean any gasket surface is to carefully scrape off the big stuff,then use a fine wire wheel on a die grinder (make sure it is rated for the RPM).

[fspGTD]

The 3 scotchbrite grades I usually see are: medium (brown), fine (red), and extra fine (blue).  Standard abraisives, the manufacturer of the abraisive pads, does not recommend using anything but extra fine with a "light touch" for aluminum gasket sealing surfaces.
Standard Abrasives "Engine Block preparation guide": http://www.sa-motorsports.com/blockdiy/blkdiy.shtm
... and a related thread: http://www.vwdiesel.net/phpBB/viewtopic.php?t=2831

[Master ACiD]

how can one damage metal with a scotch brite? i use a scotchbrite with my air powered die grinder on plastic headlights to get rid of the yellow and it takes probably 15 minutes a light. i couldnt get the scotchbrite to gouge into plastic headlight if i held it in 1 spot for 30 seconds. how could you hurt metal with it?

[wyldman]

how can one damage metal with a scotch brite? i use a scotchbrite with my air powered die grinder on plastic headlights to get rid of the yellow and it takes probably 15 minutes a light. i couldnt get the scotchbrite to gouge into plastic headlight if i held it in 1 spot for 30 seconds. how could you hurt metal with it?

That must be a different kind of scotchbrite.The 3M surface conditioning discs will ruin plastic if you hit it even for a few seconds.

[hillfolk'r]

i know this an old post but some stuff here scared me in a bad way,,, i work in an engine rebuild shop,,,the block guys get scared when theysee us with those schtchbrite discs, they are ok for some things,like valve covers or somethinlike that,very easy to mess somethin up,,i found like 400on up to 1000 grit on a palmsander,with some brakecleen is nice on aluminum,depending on how qwickyou want it cleanwhen i did this on my head,it almost retained the "rainbow" of a freshly milled head,,and use a wire  wheel on cast iron,,,,thats what the rebuilders recommend,,stains dont hurt cast,,,,,,,,NEVER never glassbead ring areas of piston,,just dont bead them at all,,,,use either that cold carb dip,or zip strip/"gasket remover" ,,,,cold dip i have had that discolor pistons,,,,but for my tdi build,,i used zipstrip and wood slivers to clean ring lands,,tootthpicks work ok,,DONT  use any metal utensial on pistons,,,plastic and wood is ok,,,my pistons cleaned up like new,,but it took 4 --5 applications,tooklike 3-4 hours ,,you mcanuse some toothbrushes,but they melt in the zipstrip after a while,,use it to get the heavy stuff off,,,you  do not want to remove any metal from the lands by scraping,,happy building,,70% of engine building is cleaning and prepping,,,a fine wire wheel can be used on aluminum covers and stuff,like seal carriers,,if you are careful and easy on it,,dont  stay in one spot for long,,itll dig a little,,carefulwith the rebuild,and itll runa long time with good power potential

[fspGTD]

The GTD is up and running!!!

Pic of it sitting in grid after its last run at yesterday's autocross:


I was up really late the night before getting it ready to race...


What happened was it sprang a MAJOR fuel leak when a make-shift injector return cap popped off after a high-rpm burst (it wasn't the right cap because I misplaced the one that I was supposed to use, but I will never cut corners with a non stock type cap there again.)  To make a long story short: there was a 4" diesel GEYSER fountaining out of that fuel return nipple with the engine at idle (Can only imagine how hard it must have been spraying diesel at operating RPM!)  When I first popped the hood, it was sopping wet and rained diesel down onto the motor.  EVERYTHING under the hood was drenched with DIESEL.  It was steaming like a radiator boil over, but was actually HOT diesel.  What a mess.  Anyway what I think happened was that some of it got onto the clutch and contaminated it.  It couldn't hold the full boost power.

Here is a shot of the contaminated pressure plate (notice the discoloration):


Everything cleaned up nicely with a die grinder powered scotch brite pad.  It's a racing, sintered copper clutch friction material.  Pretty cool it just cleans up after being contaminated like that.  Here is what it and the flywheel looked like after air-powered scotchbrite cleaning:

That did the trick to get the clutch to hook up like new.

I'm very pleased to report that the performance at the autocross practice yesterday was limited by the driver and not by the car! :lol:

I think it's official: the over-revved head incident has now finally been overcome.  (Hmmm... I might have to start up a new thread next time)  I'm very excited about campaigning this car in the rest of the '06 racing season...  Oh and by the way the engine and freshly rebuilt K24 turbo are just performing superbly.

Next event is August 12-13 at the SCCA National Tour in Packwood, WA.  Wish me luck!  (With only one practice event on this car in two years, I need it.)

[fspGTD]

Oh by the way here are a couple shots from inside the motor concluding the engine prior to the getting the car running again...

pistons installed:


head prepped:

[veeman]

Way to go, Jake!   Looks like the old "drive" is still there, eh?.... staying up until all hours redoing the clutch.  Wow.    

How do you like that four puck clutch?  I've got the same copper / ceramic type six puck in my gasser FSP rabbit and it was a bit "digital" (on/off) until it really got bedded in after some use.

How does the K24 setup you're running compare to the previous turbo?  Driving impressions?  Did you end up raising the boost per the rules?

Great work on the rebuild...looks super clean.   Is that a valve mark I notice in piston #4 in the pic?

[fspGTD]

I haven't done a back to back comparison of the K24 versus Garrett yet, but am very pleased with the current performance of the motor with the K24.

The piston tops were well covered earlier in this thread...
http://vwdiesel.net/phpBB/viewtopic.php?t=406&start=28

4-puck clutch observations are noted here:
http://vwdiesel.net/phpBB/viewtopic.php?t=164

I've got some sort of coolant leak.  I've gotta bust my ass to make the national tour this weekend.  I don't feel particularly well prepared for it...  :?  All my wrenching and tuning time got sucked away from other things last weekend.