3406E plugging breather on side of the block. Anyone done it ??

I do believe there is a block off kit for that. I was not aware that there was a pressure sensor for that on the older cats. I'm no expert. Hopefully someone else comes along to answer.

Try searching it here. I know it's been talked about

 

The 1lw I had started blowing oil out of factory vent port on side of block at a very rapid rate. Top 3406 mechanic at cat dealership truck engine shop instructed me to buy valve cover with vent tube and plug original hole with cap the appropriate size with rubber plug that expands as you tighten it. Ran it several years after that with no issues and no other needed alterations.

 

I think the sensor you are referring to is your atmospheric pressure sensor. Not related to blow by tube.

 

No modification of any kind no. In my case the way I understood it engine had came to a point of creating enough crankcase pressure to push oil out of factory location. Mechanic said bad design location plug it and keep going. After doing so had zero issues.

 

I don't remember the size exactly definitely thinking bigger than inch. Maybe inch and a half. I would call a cat shop and ask. Anyone there who has been around for awhile would know what is needed I would think. Or just measure the hole get one as close as you can find and hope for the best.