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1991 Deville / 1989 BMW 635csi
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896 Posts
Discussion Starter #1 (Edited)
HT4100 valve train pics *PICS ARE POSTED!!*

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As of 7pm on november 15, i removed my front and rear valve covers to paint them the matching color of my cadillac, Royal Blue Flake. I found that the front of the engine is carbony, while the rear looks brand new. The milage is only 94,000 miles (152,000 kilometers).
 

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1985 Fleetwood S&S Funeral Coack
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49 Posts
Clean 'em and paint 'em. Seems fairly normal. More frequent oil changes and using synthetic oil or Rotella can help, but if you look at the cover at the front of the car, you'll see the reason. If I was sitting on top of a catalytic converter and exhaust manifold, my butt would be a little toastier too. I don't have numbers to prove it, but I'd be willing to be that the valve train there is about 40 degrees warmer on average than the other side of the engine. The aluminum block and valve covers shed heat wonderfully well and prevent any coking or sludging from engine heat, but EXHAUST heat is another story. Moving my beast out of the garage for a short run usually has the front valve cover too hot to touch, and the other is still cool enough to work near.
 

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510 Posts
Absolutely perfectly normal.

What little "varnish" or deposits are there are perfectly fine and will hurt absolutely nothing.

The difference in the appearance of the two sides is not due to temperature or location differences on the engine or in the engine compartment nor due to the proximity to the catalyst or the exhaust manifolds.

Why the difference then, you ask??

Look at the PCV system. Clean air is pulled into the engine into the right hand/rear/clearner valve cover from the air cleaner. The left hand/front/more deposited cover is where all the foul air ends up and is pulled from the engine by engine vaccum thru the PCV valve. Since the natural flow of cleaning air thru the engine starts at the right/rear cover, flows thru the crankcase and then to the left/front cover the "dirtiest" air will always be in the left/front cover by design so you will always see more deposits there. Just the nature of the beast. Any engine will always show up cleaner on the side the clean air enters the PCV system and dirtiest where the PCV vapors exit the engine thru the PCV valve.

Put the covers back on and drive it and forget about it. The deposits you see are absolutely harmless.
 
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