Thread: Missing Heat Shield Causing Oil Fouling?

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This is for a 1991 Chevy G10 Van with a 5.7L (350cu.in.) engine.

The engine has been missing at an idle. The warmer it gets the more it misses.

The number 1 and 3 spark plugs are oil fouled.

The spark plug heat shield for the number 1 and 3 plugs is missing. I bought this van 30,000 miles ago. I was told that this engine was new and only had 40,000 miles on it. The guy who sold me the van put the engine in himself.

The engine oil is clean.

I can't help thinking that the missing heat shields have something to do with the missing. Has anyone ever heard of a missing heat shield causing oil fouling and missing?

I have seen where the missing heat shield will cause the plug wire boot to overheat, crack, and allow the wire to short to the manifold. See if you can pull the boot off for an inspection, or watch the engine running at night or in a darkened garage. Look for the wires shorting.

Might cause your miss but not the oil fouling. Might have sucked the intake gasket in may have worn valve guides or seals who knows till you do some tests. You need to do a cylinder leak down and compression test and some exploritory surgery to find the cause. But my experiance with the guy who says its new or I just rebuilt it, is running a cylinder hone and throwing a set of rings in it does not constitute a engine rebuild.

It turns out that the number 1 and 3 spark plug cables were switched. I switched them back and I have noticeably more power. Later on down the road I will take a look at the plugs and see if they are still fouled.

Thanks for your posts.

It turned out that when I bought this van the number 1 and number 3 spark plug cables were switched. I switched them back and now it's running better than ever.