Honda HRC216K3 Engine cylinder head question

Chris Parman said:

Hello All:

I have a Honda HRC216K3 Engine cylinder head that has developed unleaded fuel residue both on the intake valve and the valve chamber. My question is how to remove the unleaded fuel residue. Any tips are appreciated and suggestions. I have attached a few pictures to this post.

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Auto Doc's said:

I have seen this exact same coating when a customer had diesel mixed in a fuel can.

I ended up using Chemtool B-12 carburetor spray to finally cut through that stuff.

Diesel fuel requires much high combustion pressure and temperature to ignite, if not what you end up with is a sticky polymer like this.

The other possibility is extremely old fuel that has oxidized from sitting for years, then been used.

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