Contessa 32 with Bukh DV20: valve clearance question

[svTazling]

Greetings all

I am the usually-proud owner of a CO32 with the original Bukh DV20 still running. I hope that is classic enough for this forum

I've been tinkering cautiously with the engine lately, trying to find out why one cylinder starts far more willingly than the other (which joins in 30 or more seconds later). One thing I checked right away was the valve adjustment. The Workshop Manual calls for .01 inch for the inlet and .012 for the exhaust. When I checked them, the clearance was about twice that -- .02 at least, all round.

I thought "Aha!" and corrected the clearances; after reassembly, started the engine. It still started hard, with one cylinder leading by half a minute or more. Worse than that, it was now tremendously noisy with major valve clatter. I killed it quick and sat down to think.

The manual is unambiguous. There is no room for misunderstanding. It says .01 inch and .012 inch. And yet my valve clearances were double that.

I am not expert in diesel engines. Can anyone tell me whether there is any *reason* why a previous owner or mechanic would have deliberately defied the manual and set such a generous clearance? is there a reason why the correct setting should be noisier than an apparently wrong setting?

To those who say "oh chuck the thing and repower already," believe me I have been considering that option, but it's awfully expensive for the moment, I'm exploring the "keep it running a few more years" option.

thanks in advance for any light you can shed

 

[Tranona]

Welcome to the forum.

It is better to post this sort of question on the PBO forum where more people look and have knowledge of Bukh engines.

Would also suggest you call the guys at Bukh UK in Poole. They are very helpful and know everything there is to know about the engines.

 

[jerrytug]

Double-check if the valves clearances should be set with the engine hot or cold. Check the decompressors are not interfering in any way. And welcome to the forum

 

[Poignard]

Did you check the clearances again after you tigtened the locknuts? The thread on the adjusters is quite a coarse, loosely cut thread and when the locknut is tightened the clearance will increase because the tappet is pulled towards the nut.

 

[oldharry]

Are you sure you set the tappets with the engine at tdc on the power stroke. It's easy to get that wrong, and they would be well adrift if you did it on the wrong stroke. It's not exceptional for valves to be a long way drift on an old engine if they have not been serviced for a long time.
E
The non starting cylinder: is there a lot of white s moke before the cylinder fires? Suspect low compression due to eg broken piston ring, or damaged valve seat. Most likely though, the injector needs cleaning. Run a dose of injector cleaner through - that sorted a non cold starting cylinder on my van. Does it do it just on cold or on warm start too? If just on cold then injector is the first thing to check. Get both drawn and checked. If one is dodgy chances r the other needs checking