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Head Deck Surface - Second Opinion Needed

730 views 5 replies 4 participants last post by  arctic_man 
#1 ·
I did not expect cleaning of the heads to be this hard. I have already spend 3 days on one of them, exhausting all kinds of techniques available to a DIYer - from nails to plastic brushes to (OMG) Scotchbrite pads. I think I may have damaged the surface effectively ruining the entire project... So I need a second opinion.


This is the rear head, the one that was overheating, and therefore the gasket material on it has seriously welded in.

First, even after days of soaking and cleaning, there are still "dots" of the gasket material left. Second, there are "microscratch" spots - the brighter areas of the surface.

Auto part


This one gives me hope. There is a clear casting imperfection, nice and deep, and it still was sealing without any problem judging by the lack of discoloration or black crud filling.

Automotive exhaust Auto part Metal


These two give a better look at the kind of scratching and dark spots.

Tire Arch Architecture Metal

Metal


On the pictures it looks actually worse than in real life. The "light" does not really show anything bad, meaning I could not see any light coming through between the surface and a metal ruler. Granted, there is no guarantee the ruler was precisely straight...

And the bad news is that there is really no material left to machine if I take it to a machine shop - the valves are VERY close to the surface.


My question - does this surface look good enough to seal or no? Just from your experience.
Thanks a lot for your responses!!!

...and happy Thanksgiving, everyone!
 
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#2 ·
NEVER use any sort of ScotchBrite within 1/2 mile of an engine. The aluminum oxide that forms the abrasive factor in one of those pads is as hard as a diamond and lasts (sticks to stuff) forever.

There is no cylinder block deck cutting allowed. The heads can take a .004" cleanup cut. The surfaces do not need to look like off-the-rack factory sparkly - only smooth and true. The slight gasket material on the head surfaces had absolutely nothing to do with "overheating". That gasket material pattern appearance is normal in any engine on earth.

Now that you have used ScotchBrite (not the scraping work) you need to completely disassemble the head, hot tank it, and reassemble after brushing out the oil passages and installing new valve stem oil seals. Each valve lash adjuster, cam follower, and valve must be replaced in the same location it came from.

Ask a head refinishing shop to show you a freshly cut aluminum head surface.
 
#3 ·
NEVER use any sort of ScotchBrite within 1/2 mile of an engine. The aluminum oxide that forms the abrasive factor in one of those pads is as hard as a diamond and lasts (sticks to stuff) forever.
Those green scouring pads from Dollar Tree have oxide aluminium in them?! Wow, I had no idea... Isn't it dangerous to use them even on dishware then?

The slight gasket material on the head surfaces had absolutely nothing to do with "overheating". That gasket material pattern appearance is normal in any engine on earth.
Well, it was not just a pattern - half of the gasket stayed on the head surface.

Now that you have used ScotchBrite (not the scraping work) you need to completely disassemble the head, hot tank it, and reassemble after brushing out the oil passages and installing new valve stem oil seals. Each valve lash adjuster, cam follower, and valve must be replaced in the same location it came from.

Ask a head refinishing shop to show you a freshly cut aluminum head surface.
So you're saying the surface as it is now looks good enough? Are the camshaft bolts reusable (I am paranoid at this point)? Instead of a hot tank, wouldn't it be easier (and even more effective) to pressure wash it (especially oil passages)? Why do I need to see a freshly cut aluminium surface?
 

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#6 ·
I used the controversial 3m roloc discs that you attach to an air tool. Cleaned it up nice and quick. Controversial since they can also leave questionable particles everywhere, and if you aren't careful, you can create low spots.

Food for thought though, I have used the green scrubby pads on a different engine and it is still kicking a year and a half later. Many other auto forums also question it. However, I have found no one that said that the dish pads were the cause of their engine failure. Only speculation.

All that being said, I have used razor blades before. You can also buy a gasket scrapper and use some chemical remover.
 
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