White Smoke no joke

[noswellplease]

I have lived with a Beta 25 HP engine that produces excessive white smoke or water vapour in the exhaust. The engine is just 4 years old and starts up no problem from cold and will then run in a satisfactory manner (bar the smoke). However if the engine is running for say 1 hour and the revs are brought down to slow speed then the engine will cut out. This problem only occurs when engine has been running for a time or pushed a little, from cold the problem does not manifest itself. I spoke to Beta about it and one thing they said related to the fuel return pipe which in my case goes back to the 1st fuel filter. They seem to think it should go back to the tank and this could somehow casuse the problem. Now I'm no engine expert but I can't see how this might be the case? or am I missing something.
Of course to make the arrangement they suggest will of course necessitate tank removal altering etc. The way the engine is now it basically could not be relied on to safely manoeuvre my boat in a marina, so I have been curtailed in my trips this Summer.
I have checked the fuel filters and replaced, all seem ok
I have checked impellor and its ok. The exhaust water is only luke warm and a good flow, no overheating seems to be present. The engine sounds smooth but I guess something further needs to be checked but what? Could the fuel return pipe really be the root of the problems. Also there is a fair amount of unburned diesel in the exhaust which is there all the time.
Any suggestions as to what I should do next? A mechanic has looked at it without sorting out the problem. Assistance much appreciated on this one, its gone on too long!

 

[jfkal]

White Smoke

Are you able to establish whether if it is steam or smoke? In the later case there may be an injector spray pattern problem leading to unburnt fuel. Or indeed if there is back pressure in the return line the surplus diesel may find its way into the cylinder somehow. Where exactly does your return line lead to, before the first filter, after first filter? Is there a check valve preventing the fuel to push back via first filter to the tank? The setup is indeed odd as the amount of return fuel is substantial and should be lead back into the tank.

 

[sabray]

Return line goes to the tank direct. IThe fuel has already been through the filter. Is this a new problem or has it always been an issue?

 

[noswellplease]

White smoke

Return line leads to base of first filter where there is a connection. I have been told that this arrangement is ok for some engines and not for others. Perhaps I could remove this flexible pipe from the filter and just funnel into another container for a short trial to see if matters improved. I guess the return pipe in a proper arrangement should be lead to the top of the fuel tank and not the bottom? or does that matter. Thank you for suggestions.

 

[Jenaline IV]

Is the return going into the bleed valve? If so then i can see why it would cause problems. This may have dislodged krud and water at the base of the filter into the fuel line. See if removing this line changes things but I would be suspect of the injectors and the filter having been damaged if this is the case.

 

[oldharry]

As the engineer said, some engines can have the fuel return going back to the filter, but best practice is to return it to the tank. Engines vary considerably the amount of fuel used to pressurise and open the injector, and any back pressure on the return line is going to affect the operation of the injectors, possibly sufficiently to stop the engine when the throttle is closed. Beta obviously consider their engines will be affected this way.

If Beta suggest returning the fuel to the tank, then do it. Your suggestion of a temporary 'lash up' to try it sounds perfectly OK for short term.

 

[vyv_cox]

If Beta suggest returning the fuel to the tank, then do it. Your suggestion of a temporary 'lash up' to try it sounds perfectly OK for short term.

Before I had read to the bottom of the thread this was going to be my suggestion. You could either use a 5 litre bottle for the return fuel, although this would require careful monitoring, or you could run a small hose right through to the fuel filler cap if this can be arranged without introducing further problems.

For the future it will be best to take the return line to the top of the tank to avoid back-pressure in this line, which may be the root of the problem you are experiencing.

 

[steve28]

the cutting out problem could be the throttle cable, i have seen them when the idle spped has been sett on the cable and not the stop, the engine is fine when its cold but after the engine and compartment has warmed up the cable has more give allowing the speed to drop below tickover.

hope that explains what i mean.

Steve

 

[PetiteFleur]

I also have the 25hp Beta. When fitted 5 years ago I also fitted a new plastic tank which had the facility for the fuel return to go straight to the tank which is how I fitted it. All new fuel lines as well. Never had any problems like you have. I suggest you feed the return back to the tank - assuming it's a steel tank, can you tap a thread in the top for a compression fitting with sealant, there should not be any pressure to speak of so may work well.
The only problem I had after installation was a minor air leak somewhere in the fuel line which kept stopping the engine. Only found after phoning Beta engineer(I was in Holland at the time) who suggested tightening all the connections which cured the problem. Another time the throttle cable came undone at the engine end so only idled - easily cured with a Nyloc nut.

 

[njthake]

The white smoke and oily exhaust all point to low compression. Do you know the history of this engine? Have you had it from new? It is not unheard of for new engines to be supplied with the wrong thickness head gasket.
It could also be low compression due to a bent connecting rod. Has it ever had water ingestion or a head gasket failure repaired?

The cutting out on idle when hot would also point to this but only if the pump has thermostatically controlled fuel. The enrichment by the fuel pump (choke ) at low temp would help overcome low compression. When hot and leaned off it would stall.

The bleed off pipe from the injectors only returns what was high-pressure fuel that has crept past the injector and is now low pressure. They were always returned to the tank to remove air and cool the fuel. It is possible to get a circuit of air between the filter and the pump/injectors not clearing itself.

The fact that the engine starts and runs evenly from cold is the only reason to destroy my theory on low compression. Does the start up sequence mirror the start up on other Beta 25hp? I think it would need a longer spin if the compression was low. Is there any unevenness? Is it quieter than other engines? Is it smoother running?

Sorry to be vague but in my view you need someone familiar with the Beta 25hp to listen to the start up sequence and running of this engine before you take anything major apart.

Nick

 

[jfkal]

The obvious

Yep. Try the obvious first. As there seem to be a plausible cause and Beta also recommends it give your test a try. Mine goes back to the bottom of the tank which was fine with the old engine. The new one is not happy with that as fuel leaks back when I change the filter for example. This also defeats the fuel shutoff valve which is only in the feed. So I had to install one in the return line as well. Not a good solution though.

Return line leads to base of first filter where there is a connection. I have been told that this arrangement is ok for some engines and not for others. Perhaps I could remove this flexible pipe from the filter and just funnel into another container for a short trial to see if matters improved. I guess the return pipe in a proper arrangement should be lead to the top of the fuel tank and not the bottom? or does that matter. Thank you for suggestions.

 

[noswellplease]

White smoke

Many thanks for all the suggestions. For the record the engine is just 4 y.o. from new and although I had the same problem last season I kind of struggled along with it. As suggested I will try taking the fuel return to a make shift holding bottle and see if that elliminates the problem. If the problem persists then I think I will get another engineer to check it out and see what they come up with. Although I feel competent enough to change filters bleed air from fuel lines etc I don't want to get involved with injectors or any adjustments to them, or any more involved mechanics. If I have any good new developments I'll post on here and let you all know I get on . Again many thanks for suggestions and assistance.

 

[snooks]

I'm sorry to say I have a horrible feeling of déjà vu here, we had a very similar sort of thing happen to us...you can read our blog postings about it here:

The first time....
The second time...

The good news is that it could be air in the system. The bad news is you have to find it.

I moved our primary fuel filter so I could access it easily. I moved it to the top of the fuel tank....unfortunately when the fuel is low in the take the engine has to pump fuel up hill to the filter, and the first time we had a damaged washer in the top of our primary fuel filter which was leaking air.

Have you by any chance moved your primary filter recently?

Have you fully bled the fuel system from filter to returns? You shouldn't have to bleed it after the injectors, but another mechanic did and it seemed to sort out our problem....until our head gasket went

If the fuel isn't being pumped through the high pressure side of the fuel system in enough volume then this could cause your one of your injectors to be working at less than 100%, so you could not be burning all of the fuel in the combustion process. (how one engineer explained it to me)

Are you getting or have you had any sort of hydraulicing (dunno how to spell that) i.e. when you go to start the engine all you hear /feel is a big bad thud. if you've looked at the engine it will turnover then come to a big hard stop. If yes start to worry a little as the weakest part of the engine is the head gasket

 

[snooks]

I don't want to get involved with injectors or any adjustments to them, or any more involved mechanics.

I didn't want to either, but you can't always get what you want.

One bit of advice, If you do get a mechanic to come down, look over their shoulder, and ask questions. I did and I learnt more than I ever did on a diesel engine course....Fingers crossed it's just air in the system

Just had a thought

If you do have an air leak after the injector (so from the injector to the fuel return) this could be introducing air back into your fuel system at the primary fuel filter...where did you say it attaches? and what does air do?

 

[noswellplease]

White smoke

Thanks for your blog Snooks, appears a bit similar but hoping it just an air leak or something silly and basic. Hope to have a chance to look at the problem again in the next couple of days and will post hopefully positive news on here. Thanks again everyone.

 

[michael11]

we have a beta 35 , problems similar to yours early part of last year (our first) and lots of others probs too , after changing filters cleaning tank m6 diesel bug application things settled down, then at the end of the season engine cut out but restarted again, on lower revs it was fine but incresed revs in wanted to stop. got to the berth ok . decided it was a filter problem so changed primary filter for the trip to where we were lifting out, this is where we had the same symptons as you, quite bit of white smoke when the engine had warmed up.

New season changed filters again, not a sign of smoke all year engine never missed a beat. Conclusion i must have bean in a rush to get the boat to where we were lifting out and the seals were not properly seated on the fiter when i changed it.

i think that the return not going to the tank is not right (double negative ). but as discussed above that can be simulated with a can .

while experiencing problems in that first summer i ran the engine from a can at the side of the engine bypassing the tank, primary filter and all its pipe. A plastic pipe from can to inlet for engine filter. this enabled me to get to the start of the RTI race and confirm there was nothing seriously wrong with fuel pump / injectors or engine.


Good Luck

 

[Gumpy]

Couple of thoughts on a beta fuel system.
Practically the system is almost self bleeding, on my beta 10 there is way more fuel going back up the return line than the engine uses. If this goes back to the filter any air in the system will just circulate, if it goes back to the tank the air will be lost.
Secondly on my genset ( beta 12 ) the fuel line goes back to the water trap this is not a problem per-se as I just bleed it every so often, however after a couple of hours running the filter and fuel going to the engine are quite hot due to the recirculating fuel this could affect combustion but I haven't noticed anything bad as yet.