Engine Cover Paint Cracking/Flaking/Peeling
Joined: Jan 2003
Posts: 2,184
Likes: 95
From: Granville OH
The valve cover is cast aluminum. The thermal expansion coefficient of aluminum is almost twice that of steel. In other words, every time you go from a cold to a hot engine, the valve cover gets bigger. The surface of the valve cover grows too - almost twice as much as a steel valve cover.
The paint's thermal expansion coefficient is much less. I don't know what it is, but it's likely less than steel. Therefore the more heat cycles the valve cover undergoes, the more prone it is to have the paint peel off. The greater the extremes in temperature the faster this happens as well.
There's nothing wrong with the cover. Most aluminum valve covers aren't even painted and they look pretty bad years later. Honda chose to make the S2000 look sharp with the hood up, and that's the price you pay.
The paint's thermal expansion coefficient is much less. I don't know what it is, but it's likely less than steel. Therefore the more heat cycles the valve cover undergoes, the more prone it is to have the paint peel off. The greater the extremes in temperature the faster this happens as well.
There's nothing wrong with the cover. Most aluminum valve covers aren't even painted and they look pretty bad years later. Honda chose to make the S2000 look sharp with the hood up, and that's the price you pay.
Registered User
Joined: Oct 2014
Posts: 335
Likes: 2
The valve cover is cast aluminum. The thermal expansion coefficient of aluminum is almost twice that of steel. In other words, every time you go from a cold to a hot engine, the valve cover gets bigger. The surface of the valve cover grows too - almost twice as much as a steel valve cover.
The paint's thermal expansion coefficient is much less. I don't know what it is, but it's likely less than steel. Therefore the more heat cycles the valve cover undergoes, the more prone it is to have the paint peel off. The greater the extremes in temperature the faster this happens as well.
There's nothing wrong with the cover. Most aluminum valve covers aren't even painted and they look pretty bad years later. Honda chose to make the S2000 look sharp with the hood up, and that's the price you pay.
The paint's thermal expansion coefficient is much less. I don't know what it is, but it's likely less than steel. Therefore the more heat cycles the valve cover undergoes, the more prone it is to have the paint peel off. The greater the extremes in temperature the faster this happens as well.
There's nothing wrong with the cover. Most aluminum valve covers aren't even painted and they look pretty bad years later. Honda chose to make the S2000 look sharp with the hood up, and that's the price you pay.
Good point
Joined: Jan 2003
Posts: 2,184
Likes: 95
From: Granville OH
Originally Posted by redlineracing
Never heard of this prob.My 03 with 100k looks great.Maybe someone repainted your cover with the wrong kind of paint. \rlr Carolina
Joined: Oct 2019
Posts: 30
Likes: 0
The valve cover is cast aluminum. The thermal expansion coefficient of aluminum is almost twice that of steel. In other words, every time you go from a cold to a hot engine, the valve cover gets bigger. The surface of the valve cover grows too - almost twice as much as a steel valve cover.
The paint's thermal expansion coefficient is much less. I don't know what it is, but it's likely less than steel. Therefore the more heat cycles the valve cover undergoes, the more prone it is to have the paint peel off. The greater the extremes in temperature the faster this happens as well.
There's nothing wrong with the cover. Most aluminum valve covers aren't even painted and they look pretty bad years later. Honda chose to make the S2000 look sharp with the hood up, and that's the price you pay.
The paint's thermal expansion coefficient is much less. I don't know what it is, but it's likely less than steel. Therefore the more heat cycles the valve cover undergoes, the more prone it is to have the paint peel off. The greater the extremes in temperature the faster this happens as well.
There's nothing wrong with the cover. Most aluminum valve covers aren't even painted and they look pretty bad years later. Honda chose to make the S2000 look sharp with the hood up, and that's the price you pay.
Last edited by analogbubbles; Jul 20, 2020 at 09:45 PM.
Registered User
Joined: Jun 2018
Posts: 714
Likes: 158
This is all a mute argument
The valve cover is painted. Any oil that has gotten on it will cause paint failure.
The only way you are getting a non flaking PAINTED valve cover is to use a catalyzed urethane as a top coat. So your regular off the shelf clear coats will fail too. You need a top coat that has chemical resistance.
No OEM valve cover coating will stand up to solvent/chemicals. So you options are catalyzed urethane (2k clear gloss/matte) or powder coating.
You can sneeze the wrong way and make an OEM cover flake.
Passing a car up because of a flaking valve cover. LOL as another poster said, it's what's inside that matters.
The valve cover is painted. Any oil that has gotten on it will cause paint failure.
The only way you are getting a non flaking PAINTED valve cover is to use a catalyzed urethane as a top coat. So your regular off the shelf clear coats will fail too. You need a top coat that has chemical resistance.
No OEM valve cover coating will stand up to solvent/chemicals. So you options are catalyzed urethane (2k clear gloss/matte) or powder coating.
You can sneeze the wrong way and make an OEM cover flake.
Passing a car up because of a flaking valve cover. LOL as another poster said, it's what's inside that matters.
Registered User
Joined: Jan 2007
Posts: 250
Likes: 43
From: Peoria, Illinois
Failing paint on a portion of the engine that you can't put your hand on after driving shouldn't be a surprise and DEFINITELY shouldn't steer somebody away from an otherwise fine car. It's paint, it can fail anywhere on the car, probably more so where it's cooking every time you start your vehicle.
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Joined: Jan 2007
Posts: 250
Likes: 43
From: Peoria, Illinois
Yeah, this is my thinking also. I'd take a 80k car with a pristine valve cover over a 60k car with flaking paint; the 80k car has had fewer heat cycles and fewer cold starts, which is where most engine wear happens. Probably been stored in a climate controlled garage too. Valve cover condition can tell you more than the odometer
WHAT?!
Please explain this, nothing of which you just said made any type of sense. A valve cover with flaking paint tells you absolutely NOTHING about a cars engine health. How did you come to the conclusion that the car with more miles has been started and driven less frequently than the car with fewer miles?! How did you come to the conclusion that a car that has 80k miles on it...must have been stored in a climate controlled garage?!