bukh dv20 running problems

[stevd]

Hello all,

I have ran into some difficulty with my Bukh. When the engine is cold it runs fine and starts without any issues. Once it has warmed up it is a different story.

After around 30 minutes of running from cold, the engine will some times stall when it returns to idle from running at high revs. If it doesn't stall it runs at a lower than normal rpm and refuses to increase speed when the throttle is opened. If the engine hasn't been running too long, say 10 minutes or so, sometimes the rpm will increase but it does take a lot longer to do so. It is as if when this happens it isn't getting the fuel it requires.

So far I have done the following;

Fuel filter is clean, although I haven't checked on the gauze on the lift pump yet but I will do next time.
Fuel pick up pipe is clear
There is no vacuum being created in the tank, breathers are clear and to be sure I have ran with the filler cap removed.
There is no air in the diesel system.

My first thoughts are with the cooling system, I haven't removed the water inlet pipe to the block yet as I didn't have the correct allen key for it, but I did run a flexible sink cleaner wire through the pipe and there didn't seem to be any restrictions there.

I removed the thermostat completely, although it does seem to be functioning correctly. I did pour in some water into the thermostat housing and it didn't clear as quickly as I would have expected it to. So I am now going t buy some rydlyme to see if that clears up any blockages.

could an overheating engine cause these issues, or should I start looking at the fuel rack and governor on the injector pump ( which was rebuilt 18 months ago anyway).

I have even changed the oil (clutching at straws)

Why would the engine behave like this when it is warmed up?

Any ideas?

Many thanks

 

[vyv_cox]

Years ago I had a similar problem with an old single cylinder Yanmar. It stopped several times when hot, once in a flat calm in the middle of the Irish Sea. When I removed the cylinder head I found that some coolant passages were totally blocked by a mixture of salt and carbon. Cleaning them out seemed to solve the problem, although I also reset the tappets and did a few other simple sorting jobs. Your Rydlyme treatment may well solve it.

 

[Champagne Murphy]

Have you called Bukh? Maybe a routine issue

 

[stevd]

Rydlyme is on order, could only find it on ebay and £15 a liter. I have also managed to pick up a tub of fernox DS40 for a tenner from the local plumb shop.

I will probably remove the exhaust manifold and give it a long soak, but for the block itself, I can't circulate it through the engine so easily as the boat is still in the water and the exhaust outlet is in a stupid place. Should i run the engine up to hot, drain off the water from the block and then run from a bucket of the rydlyme solution, and leave it to soak for a few hours? Will I get the same effect?

 

[dolphin]

i have had the similar problem - the engine run only on low RPM and on high revolution the engine temp get up and the RPM get down
once the RPM are reduced the engine was working normal ! during the investigation found, plugged with debris cooling inlet (overboard valve)
after cleaning everything from the valve to the engine strainer the engine work without problem

 

[VicS]

Rydlyme is on order, could only find it on ebay and £15 a liter. I have also managed to pick up a tub of fernox DS40 for a tenner from the local plumb shop.

DS 40 is citric acid based Probably good for removing iron oxide from heating systems . It will have to be circulatedwarmr if not hot as it will be very slow acting if cold

DS 3 is sulphamic acid based, a stronger acid than citric acid, possibly better for descaling ( in fact sold as a general purpose descaler) and being stronger should be faster reacting. Ideally warmed up a bit if not hot although it'll work in the cold slowly.

Not sure quite what Rydlyme is although almost ceratainly hydrochloric acid based but buffered to reduce the aggressiveness of HCl.

 

[stevd]

This evening I removed the exhaust manifold which was quite badly clogged with deposits. I cleaned this up with the ds40 in a bucket. I also cleaned the ports on the cylinder head at the opening.

After i put it all back together the engine ran fine without issues for an hour. I decided to try shut the engine down and resart her, but unfortunately it would start but it wouldn't idle correctly. So I am getting a bit closer.

I haven't worked out a way to circulate the ds40 or rydlyme solution yet with the boat still in the water. Are the main areas of furring up the exhaust ports from the cylinder head and the water inlet on the front of the engine?

Also the water ports from the cylinder head to exhaust manifold, are they straight through? Basically if I keep chipping away at the deposits in the cylinder head with a screw driver will this be enough or is there a bend in the water channel? Just thinking if I can't get a solution to circulate the fluid around.

 

[vyv_cox]

Is the boat in a marina? If you have a supply of water via hosepipe you could remove the hose from the manifold and connect the hosepipe to it to cool the exhaust system. Then take the discharge from the engine at the thermostat housing to a bucket and the feed to the seawater pump from the same. Don't turn on the hosepipe tap until the engine is running and be gentle with it, too much could back-flood the engine. Put your rydlyme solution in the bucket and run the engine for a while, keeping an eye on the temperature.

However, i remember reading a post from Cliff, who cleaned up the same engine using cold phosphoric acid by simply filling it up through the thermostat housing. You could probably find it with a search, or try a PM.

 

[stevd]

I have cleaned out all of the waterways, but I am still having the problem. I am now suspecting the high pressure pump.

As soon as the engine is up to working temperature it has this issues. Any ideas why the high pressure pump would be effected differently once warmed.

Last night I removed the pump as I thought maybe something was effecting the rack, but it ran freely and smoothly. Also the yolk which controls the rack was returning back into place.

Any ideas? As I am starting to run out of them now.

Many thanks

 

[Champagne Murphy]

It's a very long shot, but have you checked that there is clearance on the decompression levers in the rocker box? I had a problem starting, but conceivable if there was heat expansion..........?
Perhaps check the tappets asnwell while there.

 

[H4B]

Hello all,

I have ran into some difficulty with my Bukh. When the engine is cold it runs fine and starts without any issues. Once it has warmed up it is a different story.

After around 30 minutes of running from cold, the engine will some times stall when it returns to idle from running at high revs. If it doesn't stall it runs at a lower than normal rpm and refuses to increase speed when the throttle is opened. If the engine hasn't been running too long, say 10 minutes or so, sometimes the rpm will increase but it does take a lot longer to do so. It is as if when this happens it isn't getting the fuel it requires.

So far I have done the following;

Fuel filter is clean, although I haven't checked on the gauze on the lift pump yet but I will do next time.
Fuel pick up pipe is clear
There is no vacuum being created in the tank, breathers are clear and to be sure I have ran with the filler cap removed.
There is no air in the diesel system.

My first thoughts are with the cooling system, I haven't removed the water inlet pipe to the block yet as I didn't have the correct allen key for it, but I did run a flexible sink cleaner wire through the pipe and there didn't seem to be any restrictions there.

I removed the thermostat completely, although it does seem to be functioning correctly. I did pour in some water into the thermostat housing and it didn't clear as quickly as I would have expected it to. So I am now going t buy some rydlyme to see if that clears up any blockages.

could an overheating engine cause these issues, or should I start looking at the fuel rack and governor on the injector pump ( which was rebuilt 18 months ago anyway).

I have even changed the oil (clutching at straws)

Why would the engine behave like this when it is warmed up?

Any ideas?

Many thanks

Sounds very similar to a problem I had some years ago. It was eventually solved by getting the injector pump serviced at a Diesil injection specialist . It doesn't need much in there to be out of line or a little worn or the tiniest piece of crud to up set things. This action rectified my problem and it has not recurred in 6? Years.

 

[Hostage]

The symtoms of the problem are almost identical to those I had at a time. The trouble was traced to the gauze in the lift pump. Its very fine and takes very little sediment to reduce the flow.
you have probably checked it but thought I would mention it.

 

[tnard]

Hi Steve,
Just wondering if you found a solution to your problem regarding low revs.
Cheers, Tom

 

[stevd]

Hi Tom,

I seem to remember it being a faulty injector in the end. If you are having a similar prooblem to the engine cutting out when warm, get your injectors cheked by a diesel specialist. Should only cost around a fiver to check an injector. But running problems can be a caused by numerous things, I would start by checking the basics first.

What are your symptoms?

 

[davidmh]

I remember talking to the Buhk guys at Poole a long time ago and I am sure they said do not use rydliyme on the Buhk engine as it can damage the wet liner seals.
Another Buhk service guy always takes the gauze filter out of the lift pump as he said it blocked the flow it was better just to change the fuel filter regularly.
David MH

 

[singlehanded]

Hi Steve, I am having the identical problems you had in that the engine cuts out after running for 3 hours happily at 2200rpm. I have almost identified the problem as a tired lift pump. Did you change your pump or what did you do to overcome the problem?

 

[Bilgediver]

Any ideas?

Many thanks
[/QUOTE]


Had that in a boat at our marina and fooled the owner for ages. Took of the cover of the lift pump and found the wee plastic filter was completely full of debris that had come through two filters. Wiped it clean and job done.