Back pressure in intake manifold? (1 Viewer)

[fixit1404]

I just transplanted a 1982 3b into my 40 series.
330000km. Seems to power along and run well.
However, I hear and feel a thumping in the intake hose in time with the firing of each cylinder. It seems to puff air out even as it draws it in.
My exhaust is the stock sizing for the B engine taken out and is somewhat restrictive. I have the stock intake hardware in place.
Is there something going on with the engine that I should be worrying about?
Thanks for any insights for a novice.

 

[buschmaster86]

thirst ting that comes to my mind is a exhaust valve that does not close off properly

 

[fixit1404]

Thanks. (I think
If that is the case how can I verify it and can it be fixed without pulling the head apart?

 

[buschmaster86]

blow compressed air thru glowplugholes and listen but also before that turn the crank bolt to closed intake valve position for the cylinder you put compressed air in.

Sounds more difficult then it is, the free downloadable engine manual is going to help you realy much if you use it also.

 

[gerg]

You could check the tollerances in the rocker assembly to see it its too tight and maybe preventing the intake valve from closing, but the same thing your experiencing happend to me when my head gasket blew. Do a compression check and if you find two cylinders are low, its because they now communicate with each other where the gasket blew out. I bet its hard to start even after its warmed up when you let it sit for 10 minutes or so.

 

[fixit1404]

Thanks guys. I appreciate the suggestions and will begin my investigations, based on your comments.
Any other ideas will also be entertained!