Mystery fuzz

Ok,, so I have been sorting out this new (to me) 1835dp, which has run pretty well so far. Today,, as I was getting it ready for winter storage, and I notice this strange fuzz around the #3 plug wire boot. So I pulled the wire off, and found a wad of this white and black stuff all around the plug. Then I pulled the #4 wire and found the same thing. Ok,, so I check the #1 and #2 plug wires and found no fuzz. The only thing that the left bank has that the right side does not, is the CHT sensor on the #3 cylinder. Now I am guessing that either the fan has ingested something that is effectively insulating the 1-2 cylinder cylinder head, or, there is something I don't know about, (that such a substance should be there) ??? Anyone have an idea ?? Here is a photo,, that ball of fiber seems like carpet padding,, but it has not melted, as far as I can tell.
Thanks, Catmandu

Any mice do-do?

Nothing noticed so far. The engine has the really nice origonal vw tins on it, so I hesitate to start unbolting them. I may find myself a boroscope, and see what I can see with that. Catmandu

if its mice they may be eating your interior seats, floor padding and such. they can get thru a 1/2" hole.

I found a mouse nest inside my fan shroud that would have blocked cooling on the 3-4 side.

Yep, you've got mice in residence. No doubt about it.

They're so cute! (Hope you don't have young kids)

That's what they do - make their little nests in unlikely places like air cleaners, vent and heater spaces, and most anywhere that you think they can't possibly get into.

I've got a 4 acre field behind my barns, one barn of which I use for cars. The field is a hotbed of mouse and they get cold and want to be inside to make baby meeses.

It's a continual lookout for signs of mice and what you've got there is signs of mice.

They don't care about sprays or deterrents. I think maybe they like those.

Set traps inside the car and anywhere else you can. Give them some peanut butter or some cheese and they'll come eat it, or try to. Check your traps frequently cause the dead little suckers start stinking pretty quickly.

They love my wife's car and it frustrates her comically. Sometimes they make a nest in my diesel truck air cleaner but as soon as I start the truck up they disapear along with all sign of them. A Cummins gobbles a LOT of air (and mice). Must seem like the end-of-the-world hurricane.........for about a second. :)

If you have a good shop vacuum it shouldn't be much trouble to suck out the nesting, or just reach in and pull it out. The mice won't bite you but they'll probably talk about how mean you are.

Thanks all,,, sounds like the most plausible explanation. The engine sat for a long time before I bought it. If a mouse was still in it when I fired it up,, well,, it's a barbequed mouse now !! I will extract all the foreign fuzz and put it away till spring !!
Cheers,, Catmandu