Diesel fuel return line

[Leighb]

I am having a new Beta 20 engine installed.
The Installation instructions state that "The fuel return (leak off) pipe must loop down to be level with the bottom of the tank before it enters the top of the tank. This prevents fuel ‘drain down’."

The engineer says that this is unnecessary, and that it would not be a problem.
The previous installation did not have this arrangement.

The top of the tank is below the engine beds so well below the return pipe.
Should I insist that he follows the advice from Beta?

 

[doug748]

The top of the tank is below the engine beds so well below the return pipe.
Should I insist that he follows the advice from Beta?

If I understand it correctly, your engineer is correct. The unused fuel will fall back into the tank anyway.
I have the same engine, and should have a loop. I don't think I included one, no problems so far.
PS
Thinking about it, my tank is well above the engine, so the return comes in low and then up to the top on the tank. There is no loop as such.

 

[PCUK]

They don't make these recommendations for fun! Without the loop your fuel could drain back from the pump if it is above fuel level, not fail to return.

 

[dam747iam]

fuel return

when i fitted my beta the return pipe was not low enough and caused all sorts of problems the main one being symptoms of fuel drain back, after i rerouted pipe below level of tank i had no more problems, so betas advice is correct.

 

[Leighb]

Thanks that seems clear!

What exactly are the symptoms of fuel drain back? Poor Starting? Or something else?

 

[daveyw]

I just tee'd my return into the supply. Tank is higher than engine. No problems 6 years on.

 

[Leighb]

I just tee'd my return into the supply. Tank is higher than engine. No problems 6 years on.

Beta specifically warn against this practice. "It is very important that the excess fuel from the injectors is fed back to the fuel tank and not back to any point in the supply line. This will help prevent air getting into the system."

Another contra which I read elsewhere is that the returning fuel is hot and this is better returned to the tank rather than the engine supply.

 

[Latestarter1]

They don't make these recommendations for fun! Without the loop your fuel could drain back from the pump if it is above fuel level, not fail to return.

PCUK you are spot on!

Countless installation surveys on I still see 90% of engine issues down to people not RTFM (READING THE ******* MANUAL)

The fact the know nothing yard numpty, he is certainly NOT an engineer. To come out with such brainless advice on somthing so simple would have me questioning the whole installation done by him. Remember the poster here who had a recently installed engine seize and getting all bent out of shape over who was going to pay for repair as warranty was rejected, all due to poorly thought out and executed exhaust system.

The reason that tank return needs to be immersed is to prevent air working its way back up the return line causing hard starting and white smoke when engine not run for a period of time.

As to putting return into feed.........

Read the terms and conditions of your warranty unless you install engine to comply with installation manual, you have no warranty.

Believe me does not just apply to little puddle jumper motors, I looked at a new Scania last year which was wrecked due to a failure to RTFM. Numpties in this case went bust to escape liability.

As you probably gather I feel stongly about this.

 

[ianj99]

PCUK you are spot on!


The reason that tank return needs to be immersed is to prevent air working its way back up the return line causing hard starting and white smoke when engine not run for a period of time.
As you probably gather I feel stongly about this.

I think you have highlighted why some owners are plagued with air in the system.
Possibly even why the previous owners of my boat had starting problems, although I'm told the 4108 was only hard to start wheh hot. (tanks are lower than the filter head by a good 6inches)

I'll be putting that loop in the return pipe this weekend whilst polishing the fuel

 

[dutyhog]

didn't spot this in instructions

I didn't spot this in instructions for our Beta 28, now in place for four years. But I see it is in the latest version downloaded from Beta's website. The tank is in the bilge, and the return pipe just goes to the top of the tank, about level with the bottom of the engine. This is exactly the same pipe as for the previous engine, installed in 1976. All has worked well with both engines. So do I really need a deep loop? It wont be hard to put in one, but it could catch on things and burst.

 

[mattnj]

why compromise on something that is so simple to do and specifically mentioned in the manual, do it properly and have a trouble free engine for many years, no question

 

[trapezeartist]

Rules are for the guidance of wise men, and the obedience of fools. Which one are you?

 

[ianj99]

Upward loop alternative.

I discovered my engine return line uses an alternative approach to prevent air entering.

The pipe from the return outlet at the engine mounted filter loops upwards for a few inches before descending to the top of the tank. Ie the top of the loop is about 4" above the return outlet.

So although fuel may drain out from the top of the loop to the tank, it will still remain in the pipe on the filter side of the loop, hence no air can enter.

So I'll leave well alone...

 

[coopec]

Re: didn't spot this in instructions

The information in this thread is most helpful and since my tanks are level with the engine I most certainly will be looping the return line down below the level of the tank.

I have just found a supplier of 10mm Diesel Fuel tube (US Coast Guard approved J1527) at a price of $13/meter. Since I need about 7 meters that is a significant saving over the $18.95/mt charged by other firms.

My thoughts have now turned to the return line; what ID should the return line be and I suppose the line should also be J1527?

Would appreciate your advice.

 

[Rivers & creeks]

Re: didn't spot this in instructions

Same ID as the feed, depending on revs up to 80% of the drawn fuel can be returned to the tank. Another reason for never teeing back into the feed line because you want the diesel cooling the injectors.

 

[coopec]

Re: didn't spot this in instructions

Thanks Colvic.
The returned fuel will go to the same tank it was drawn from as well.