Carbon at exhaust (one port)

[Russell King]

Asking for advice on a L185. I was changing the exhaust manifold (it had rusted and was leaking exhaust at the exhaust pipe flange) and noticed that the rear exhaust port had more carbon build up than the front. The front was fairly clean but the rear had probably 1/8 inch carbon around the edge of the exhaust port.

I should probably just leave it be as it is - runs well, starts well and does not smoke. There is some blow by out of the tube but not too significant.

What would cause the difference in carbon build up. I suspect the injector should be rebuilt or replaced but have no real proof of that.

A new injector is about $60 (if I identified the correct part number).
How much is normally charged to test/rebuild injectors?

 

[North Idaho Wolfman]

Another possibility is that the leak caused it, as it would introduce air at odd intervals.

I would run it a while with the leak fixed and recheck.
It could also just need the valves adjusted.

 

[Russell King]

Thanks, I'll look into the valve clearance.