Exhaust or inlet valve on Bukh engine

[Rafiki]

Just got to the boat intending to adjust tappets. Although I have the valve clearances I don't know which order the exhaust and inlet valves are in, looking from the flywheel end. Could anyone help, then I can complete this job. Apologies for being so unprepared! Regards, Andrew It is a DV20.

 

[Poignard]

Just got to the boat intending to adjust tappets. Although I have the valve clearances I don't know which order the exhaust and inlet valves are in, looking from the flywheel end. Could anyone help, then I can complete this job. Apologies for being so unprepared! Regards, Andrew

On a BUKH DV10 the inlet valve is forward and the exhaust is aft, i.e. nearest the exhaust pipe

 

[boguing]

Look at the inlet and exhaust manifolds. Which valve is which is then apparent.

 

[Rafiki]

Ours is a DV20 is it the same?

 

[Poignard]

Ours is a DV20 is it the same?

I'm almost certain it's the other way round on the DV20 but 'almost certain' is no better than 'don't know', so best wait for a DV20 owner to respond!

 

[VicS]

I think you will actually find that the middle two are the inlets and the end two are the exhausts.

however the workshop manual is http://www.motoren.ath.cx/download.php?filename=bukh/DV10_DV20_Workshop_Manual.pdf

 

[oldharry]

Just checked, and the manual does not specify which is which! However, the decompression lever works on the exhaust valves, so it should be easy to identify them by looking at the decompressor mechanism in the rocker cover.

 

[Rafiki]

Thanks guys - I finally decided that all the evidence pointed to the outside ends being exhaust and the two inside ones being inlet. Strange that neither the handbook nor the manual says which is which despite giving the adjustment gaps.

Regards

 

[Poignard]

Just checked, and the manual does not specify which is which! However, the decompression lever works on the exhaust valves, so it should be easy to identify them by looking at the decompressor mechanism in the rocker cover.

Oh yes - I was going to say that - only I never thought of it

 

[oldharry]

Thanks guys - I finally decided that all the evidence pointed to the outside ends being exhaust and the two inside ones being inlet. Strange that neither the handbook nor the manual says which is which despite giving the adjustment gaps.

Regards

Yes that looks right to me too, from the diagrams in the manual: there is only one centrally placed inlet port, while IIRC there are 2 exhaust ports, which suggests the inlet manifold goes to the 2 central valves, while the exhausts have their own ports at each end of the outlet manifold side of the head. But the decompressor position will confirm it.

Dont forget to bring the flywheel to near TDC on the cylinder you are working on - i.e. with both valves closed, and not in the 'rocking' position where the exhaust has just closed and the inlet is about to open. TDC will be about half a turn of the flywheel after the inlet valve closes, and you should be feeling the compression as you come up to it.

 

[VicS]

there is only one centrally placed inlet port,

That is what I was looking at.
I did not think about the de-compressors but although only one is shown in the diagram you can see that the other will fit at the opposite end of the cover.

 

[unclebraddah]

I constanly readjust my valves and can never get the decompress lever adjusted properly by the manual. I generally just have to do a trial and error about five times. Any tips on the decompress adjustment?