Intake manifold and cyl. head full of carbon buildup.

[85Rangerr]

Can someone tell me what this passage goes to? I understand that it's part of the intake. I just bought this 1985 ranger and this is my first time taking apart an engine this far. After removing the intake manifold I found one of these passages is clogged with what I assume is a ton of carbon buildup. It's rock solid. The intake manifold had a lot of this build up too. An explanation of how it gets this clogged would be great. This is the driver's side cylinder head if that helps. The passenger side cylinder head has a lot less buildup. Thanks.

 

[AndyB.]

It’s the port for the EGR valve. Exhaust gases get routed from the cylinder head, through the intake manifold, to the EGR spacer. Under certain operating conditions, this exhaust gas is routed into the intake, since exhaust gases contain no oxygen, they’re inert and just take up space—this decreases temperatures and reduces nitrous emissions.

 

[alwaysFlOoReD]

I'm not familiar with the 2.8, but on older carbed engines that port would lead thru the intake to under the carb to help with warming up the carb on cold starts.

 

[Bill]

I'm not familiar with the 2.8, but on older carbed engines that port would lead thru the intake to under the carb to help with warming up the carb on cold starts.

That's exactly what it's for.