Engine Carbon Or Oil Deposits On Block?

chapters707

Member
Jul 13, 2014
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Hello all, I am in the midst of replacing my 4.6 motor on my 96 with a new one I purchased online. (The new one isn't off a '96, it was manufactured in '99 and doesn't have pi heads so I'm thinking it might be off an explorer or something.)I have the old one pulled and am preparing the new one to be dropped in.

When I got the new motor I noticed a lot of heavy black build up, primarily on the block itself around the pulleys. It is a very thick black substance that feels kind of moist to the touch. I cleaned a lot of it off with a wire brush and when cleaned it kind of crumbles up into tiny pieces that just look like dirt.

So my question is does this sound like carbon build up or burned up oil or something else? My old engine had a very thin black coating on it but nothing like this. The heads look quite clean so I'm thinking it isn't a bad valve cover gasket.

I'm replacing a few gaskets (exhaust manifold, intake manifold, oil pan) before installing the new motor because I would like this thing to be leak free once it's installed.

If anyone has had a similar experience or has insight to offer on this subject please let me know.
 
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Neuron

Mustang Master
Nov 6, 2016
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Its usually oil seepage/slow leak that attracts dirt and crud to build up, also usually easy to clean off leaving the underneath clean. Carbon buildup is usually harder to clean off, kinda like baked on paint. Clean it off and watch the area, probably OK though as long as there is no leakage trail from the area.
 

chapters707

Member
Jul 13, 2014
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0
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Okay definitely sounds like the oil then. It comes off pretty easily but it's just almost impossible trying to get to hard to reach areas. Thinking about taking a pressure washer to it when I have the engine on a hoist, any thoughts on that idea? Is it safe?
 

Neuron

Mustang Master
Nov 6, 2016
756
149
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That high pressure water can get in the wrong places real easy. Water can easily force itself past seals at that pressure and create havoc with electronics. Get some spray degeaser from the store and just use a hose.