Re: alfa-digest V7 #555 - White Stuff in Milano Motor

[AlfaNeely@domain.elided]

<< From: Jason Ball <madmac@domain.elided>
 Austin, Texas
 Subject: Cooked Coolant(??) and Kissed Pistons
 
< I'm in the process of pulling my Milano Donor car's heads because I
 <found oil in the coolant........
 
< After much yanking and banging donor motor finally let its 4-5-6 head
< loose.  The inner head stud between the 5 & 6 cylinders was coated with
< crusty white stuff which prevented the head from just sliding off.
< The head gasket however,  pulled right off, completely intact.
< Underneath the head gasket,  I saw that the outside of the piston liners
< were caked with more white crusty stuff.  (cooked coolant????)>>

	The white crusty stuff is corrosion or aluminum "rust."  Clean it out with a
wire brush, scraper, bead blaster or what ever.  Many transmission shops also
have a hot bath for cleaning aluminum transmissions that might work to remove
the corrosion from within the head passages.
	When you go back together consider using the magnesium sacrificial anodes
available commercially.  Basically the magnesium "rusts" or goes into solution
in your coolant before the aluminum does.  Also use new antifreeze with
distilled or deionized or whatever kind of non tap water you want (I do not
want to start the water thread all over again).
 
 
<On the other side of the block,  the 1-2-3 head slid right off to reveal
< carbon coated piston heads with shiny little half moons where the intake
< valves had been kissing the pistons.  I had noticed that the cam timing
< on that 1-2-3 side had been a notch or two off but thought little of it
< because the compression was still good (193-195-190)   After lightly
< scraping away the carbon surrounding the "half moons",  I could detect
< just a hint of an impression that the valves left.
< - ---Should I consider myself  lucky (somewhat) or has there been some
< real damage done here???? >>
	Sounds as if you lucked out.  If it had compression, the valves probably are
not bent.  However, you should disassemble the heads and have the valves
ground and checked for straightness.  Also clean and inspect the pistons
carefully.

<< In Alfa digest 556, "Eric H." <ejham@domain.elided> said in part:
<My belief is this: the valves are only seriously damaged if
<the collision happens when the engine is running or somehow
<turning at high RPMs. Judging from the condition of that
<Milano's timing belt, I think that low RPM collision simply
<stops the cam from turning and makes the timing belt ratchet
<over the stationary pulley. Valve stems aren't butter,
<they're designed to absorb quite a bit of force. >>

	The first Alfa I ever built (after various American V-8 hot rod rebuilds) was
a 1750.  I got the cam timing wrong.  The starter turned the engine with a
pause 4 times then spun quite freely, thank you.  Seems I had bend all four
intake valves.  Once all 4 were bent the engine turned over easily.  The new
pistons were marked, but not hurt.
	This is contrary to Eric's comment in Alfa-digest # 556 that you can only
bend valves when the engine is running.   Of course, the four has a chain cam
drive and the V-6 a belt, but the valves will still bend.

< - ---Should I continue messing with this motor (101K) or should I give up
< on it and rebuild the heads on my original motor? (170K, 185-195PSI and
< leaky valve stem seals)
 
 	Rebuild one and use it while you rebuild the other.  Maybe bore one out to
2800 and build a screamer.  The lower end of the V-6 is quite strong and
should last a long time with proper maintenance. 

Ciao,
Russ Neely
Oklahoma City

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