Intake Valve Pitting
Intake Valve Pitting Bought a set of heads off of ebay, heads themselves look ok, seats look decent, maybe worn but no pitting, and guide clearance checks out.
almost every intake valve had this horrible pitting on the heads of the valves. they don't look like deposits of any kind, and i couldn't imagine they were cast this poorly. the bottom of the heads are actually fine and look nothing like this. valve faces are also worn, very slightly concave.
What say ye, ls1tech? what could have caused this, and are these still usable?
almost every intake valve had this horrible pitting on the heads of the valves. they don't look like deposits of any kind, and i couldn't imagine they were cast this poorly. the bottom of the heads are actually fine and look nothing like this. valve faces are also worn, very slightly concave.
What say ye, ls1tech? what could have caused this, and are these still usable?
someone also mentioned that chlorine can cause the stainless steel to pit. I'm sure other chemicals can as well. wonder if something corrosive would be the cause? if so, how did it did it get in there?
On The Tree
Joined: Sep 2016
Posts: 103
Likes: 18
I'd go with this. Looks like they were rusted horribly, then wire wheel'd to clean them up. No matter what happened to them, the way that pitting run up into the transition to the stem........I wouldn't run them in the cheapest "I don't care about it" build one could dream up.
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I'd go with this. Looks like they were rusted horribly, then wire wheel'd to clean them up. No matter what happened to them, the way that pitting run up into the transition to the stem........I wouldn't run them in the cheapest "I don't care about it" build one could dream up.
there's no corossion on the stems. It all starts right at the filet and is all over the head. Some are worse than others.
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Verdad Gallardo On The Tree
Joined: Sep 2016
Posts: 103
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i didn't mean up on the stem, just right up on the curve where the head transitions into the stem. That's a very high stress area and those are pretty chewed up right in that curve. I'd junk them and if you're on a budget find some better factory replacements or go with like a rev brand or something. No way I'd run those.
i didn't mean up on the stem, just right up on the curve where the head transitions into the stem. That's a very high stress area and those are pretty chewed up right in that curve. I'd junk them and if you're on a budget find some better factory replacements or go with like a rev brand or something. No way I'd run those.
my response was in line with finding an answer as to why they pitted. I don't believe it was from water sitting in the ports, unless it was saltwater. Even then... there was no rust on the valves. Just carbon and varnish, like i said. Unless the previous owner cleaned them up and used them.
WELL i guess LLLosing it and my other associate have the best theories as to why stainless intake valves would pit like this.
Thanks anyway.
The question is... chloride from what? Did some idiot pour bleach in the intake ports, lol?
12 Second Club
Joined: Aug 2014
Posts: 205
Likes: 26
From: Houston, Texas
You can have a build up of chlorides simply from the environment, due to where the crevice sealing surface is and the carbon build up mentioned I suspect that the gasoline/ethanol sulfate salts concentrated these contain chlorides. These under deposit chlorides accelerated the corrosion of the stainless material. I see these types of things in chemical plants all the time. Under deposit corrosion is what created the severity of this corrosion. I would bet those heads sat for a while.
There are all sorts of things that they put in gasoline besides the pure hydrocarbons. 
You can have a build up of chlorides simply from the environment, due to where the crevice sealing surface is and the carbon build up mentioned I suspect that the gasoline/ethanol sulfate salts concentrated these contain chlorides. These under deposit chlorides accelerated the corrosion of the stainless material. I see these types of things in chemical plants all the time. Under deposit corrosion is what created the severity of this corrosion. I would bet those heads sat for a while.
dimpled for moar CFM's of uurrrflow.
TECH Addict
Joined: Dec 2017
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The cheeeep stock valves are better than some aftermarket trash out there