Blackness ‘neath the Valve Cover

[lothian]

2000 Honda Accord
148k

I removed the valve covers from an Accord’s J30A1–first time they’ve been off. Take a gander at the images below. The front bank looks remarkably good for a near 20yo/150k valve train. The rear bank, however, is completely black with carbon.

My initial presumption is, the carbon coating is related to the PCV. And, perhaps what I see is 1) normal for the “PCV-side” valve train with respect to the age/mileage; and/or 2) evidence of poor PCV maintenance.

But I’m just speculating.

Thoughts? Opinions?

Front bank:

Rear bank:

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Topic

[Richard Kirshy]

That type of discoloration can be caused by temperature.
Being you state the rear is more noticeably discolored.
This would fall in line with temperature, being the rear has less air flow around it.

Just my thought here, but both banks appear to be quite darkened.
Granted the rear more so.
How often do you do oil changes?

I can tell you from experience I do mine @ 3 months / 3,000 miles for the last 17 years and both heads on my engine look like this.

This head is covered by the intake manifold so it receives less air flow.
Which is one reason for my 3 / 3 oil changes.

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[lothian]

Oil change with full synthetic at ~5k for the past decade. Prior to that, conventional oil at ~3k.

So you think the carbon is an effect of heat. Interesting notion…

[Richard Kirshy]

It is hard to pinpoint exactly what the cause is in your case.
But some are:
High oil temperatures.
PCV fault.
Oil additive package.
Frequency of oil changes.
Air flow.
I have rerouted my PCV lines so that each bank draws equally and installed a catch can inline.

[Author]

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