pitting

[munkee]

The question I have pertains to a 3.0 vulcan intake but I was hoping some of those who have pulled apart an engine would be able to help. I was cleaning the intake off of my 88 gl's blown motor and I noticed a bunch of pits in the bottom of it. It looks like someone took a chipping hammer and tapped all over. Could particles or carbon in the oil have caused this? I thought at first it was from being set down on the work bench, but some of the marks are up in areas that wouldn't make contact. Has anyone seen this before or know what it's from?

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"It's not just the speed, it's how well you handle it."

 

[smokesho]

where exactly are these oxidized areas ????

 

[munkee]

Ummmmm, looking at the lower intake manifold from the bottom, there are 3 square intake tubes on each side and a thin round rail that runs down the middle. In between the square tubes are round shrouds that bolts run through. The edges of three of the four shrouds and the edges of all six tubes have a high concentration of dents where they match up with the head. Not on the gasket face though. The rail also has dents on it as does the rest of the square tubing. I apologize if this is confusing, I have a scanner but I can't figure out how to post pics online. Thank you for your help.

 

[smokesho]

well. hmmmmmm. it is tough to guess without seeing. however. it could be pitting from oxidization i suppose. if more moisture was in the plenum than normal, i suppose if it had a chance to sit and eat away over time. and the air rushing through would keep the surface clean, so that you couldn't see all the evidence.

maybe i just missed it, but is the metal alloy, or steel/iron. it is the aluminum isn't it???? if so, sometimes it's harder to tell if it has oxidized. have you seen any white powdery stuff?????

 

[munkee]

It is aluminum. Maybe it would be more helpful if you knew that the engine ran very hot before it died. (Hot enough to melt the fuel rails and melt down the #5 cylinder!) It had a cracked block (which is another long story entirely) so there was also water in the oil for a short time. The intake was heavily coated with oil though so there wasn't any indication of oxidization. A friend of mine is coming over to show me how to scan pics onto the net so I will try to post those later. Thank you for the interest.

 

[smokesho]

well. in speculation..... the pitting could partially be because of the heat.....alluminum does this when it gets to hot sometimes. and you said there was water in the oil. if the water was able to get at these areas directly it could be part of the problem. how deep and big is the pitting ? cause if it's not too big something along those lines makes sense.