Diesel engine setup

[rogerthebodger]

Just setting up the diesel engine on my new boat and 2 questions come to mind.

1) setting the timing of the injector pump is done ,according to the manual, stationary , not with the engine running.

Is there a way to check the timing with the engine running in the same way as a petrol engine is set with a strobe light trigged of the injector pulse like the tiny tacho is trigged.

2) The fuel return line is not taken back to the tank as I understand is normal but back to the inlet side of the fuel filter. Is this OK or will it cause some problems.

I do have a fuel flow meter which is supplied with 2 flow sensors feed and return. If there is no return to the tank only the feed id required. Is that correct.

Most of my practical experience is with 4 stroke petrol engines so I don't know what problems may occur.

 

[aluijten]

I'm not sure about the timing bit but not leading the diesel return line to the tank is not wise. The returned diesel can become quite warm after the engine has been running a while. There are three goals for the diesel fed into the fuel pump:

- Being the combustible fluid (obviously)
- Act as lubricant for the pump
- Act as cooling liquid for the pump

It's the last point where your setup might lead to problems.
AFAIK the return line is always led back to the tank (in boats as well as in cars)

Arno

 

[FlyingDutchman]

I have never heard of a devise to check the injection timing with a running engine, but even if it would exist, do you have any data to adjust it to? I mean, do you have a handbook that says the injection timing is 5 degrees before TDC at 1.500 rpm or so?

 

[PCUK]

Timing is set statically.
Return fuel to the tank.

 

[VicS]

There is, according to my car workshop manual, equpment that senses pulses in the fuel pipes as you suggest but that is the limit of my knowledge. Expensive kit for the diesel workshop I suspect!
I have timed one pump (Fiesta 1.6) with a dial gauge but forget all the details. Presumably that is how you are doing it. Didn't make any difference it still smoked

Sometimes the fuel spill back is taken back to the tank but sometimes (MD11 for example and presumably others ) it does go back to the engine mounted filter. My understanding it that the spill back volume is small so the effects on temperature will be minimal.

I guess you are right about the fuel flow meter if just the one sensor is fitted between tank outlet and engine but you will probably have to wire the other sensor up to the meter and leave it measuring nothing. Might be worth contacting the makers for advice.

 

[Twister_Ken]

The return fuel line on my Bukh 10 comes back on the upstream side of the water separator filter. No idea whether that's good practice, but it's been that way for 28 years.

 

[savageseadog]

I actually have the equipment you need. It's made by TI Dieseltune, a pressure sensor is fitted on the injector and triggers a strobe. I think Facom and Snap-on do one and they may work of the vibration sensed from the injector pipe.

 

[DownWest]

The return to the filter makes sense if you have two or more tanks. Otherwise you would have to switch the return as well as the feed. If only one, better to the tank.
Timing is almost always static. With your level of experience leave any pump adjustments to a specialist. Fitting to the engine normally just needs careful lining up of the marks. Unlike a petrol engine you do not need to check timing often (we are talking old tech petrol here? Mod. CPU engines look after themselves) I assume this is academic or do you have a problem?
Andrew
Re. the sensers, only need the return if the feed unit is fitted after the filter where the return is plumbed in.

 

[ShipsWoofy]

[ QUOTE ]
2) The fuel return line is not taken back to the tank as I understand is normal but back to the inlet side of the fuel filter. Is this OK or will it cause some problems.

[/ QUOTE ]

Although this is a small engine (I am presuming an auxiliary) there is surely a chance running the overflow back into the line could build up pressure and also more worryingly could introduce air to the fuel.

I might, nay, am probably worrying too much, but why has it been done this way, how difficult to run some micro-bore to the top of the tank?

 

[VicS]

[ QUOTE ]
there is surely a chance running the overflow back into the line could build up pressure and also more worryingly could introduce air to the fuel.

[/ QUOTE ] No it wont build up any pressure.
The air question is not so much that of introducing air... wheres it getting in?..... but of making it non self bleeding. Modern car diesel engines do not require bleeding after say a filter change, at least neither of the two I have had did. (And only one of them had a priming pump) All that had to be done was wind them over on the starter at full throttle until all the air is vented back to the tank!

 

[rogerthebodger]

Thanks guys

On refitting the injector pump after servicing by "expert" the timing needed to be setup again and I did this by setting the crank angle to the manual setting and moving the injector pump to squrt the fuel to injector no 1 by disconnecting the pipe. I felt this a bit crude and thought there must be a better way.

Vic I would love to know your dial indicator method

The fuel return on my previous boat (a Perkins engine) did go back to the single tank but this engine, a Tempest/Layland, was piped back to the engine mounted fuel filter when I gat the engine as VicS and others indicated.

As I have fitted a second filter with change over valves I will either pipe it back to the tank or to both filters.

I have 3 seperate fuel tanks feeding a single main engine (Tempest) and small ferymann AC generator, if I feed the return back to the tanks as I was going to do I had designed and made a double 3 way valve to switch the feed and returns at the same time.

If I now just return to filter inlet I do not need the double valve and the return fuel flow sensor and as such the fuel flow could be replaced with a much simpler (cheaper) device

 

[rogerthebodger]

The workshop manual makes this comment

"The air bleed point located on the head of the forward facing filter element is connected to the fuel injector leak-off pipe and provides continuous air bleeding of the filter during operation "

This seems to agree with your comment above and may be the way to go.

 

[earlybird]

I have read that returning fuel to the feed line is poor practice on account of heating of the fuel. When I installed a Vetus, Mitsubishi, engine, I tried test running it with the return fed to a jam jar. I was very surprised at the high flow rate, far in excess of the engine demand, which terminated that run very quickly. On that basis the fuel would get quite warm by being rapidly reciculated. Incidentally, it was a self-bleeding system, Bosch IIRC. Do self-bleeding systems have this high spill rate?

 

[VicS]

[ QUOTE ]
Vic I would love to know your dial indicator method

[/ QUOTE ] It was the method described in the manual for that engine and Bosch (IIRC) pump. It was a long time ago and I no longer have the manual. It involved removing a plug from the end of the pump and inserting a dial gauge, presumably to bear on the end of the pump plunger and noting the reading change when the engine was turned between some specified positions. The pump was rotated on its mountings until the correct reading was obtained. I think it was something that was necessary if the pump was removed but I was just checking it because I could. In fact I found it did need adjusting but the adjustment did nothing for the smoke levels

There is a similar procedure described in the Peugeot manual for a Lucas pump but the access plug on that is on the top of the pump and special fittings are needed to link the dial gauge to the pump.

As far as i can see the crankshaft, camshaft and injection pump drive sprocket can all be set up using marks on the engine but this pump timing is the final adjustment of the pump itself, relative to the other settings I suppose. It always struck me as odd that it was not all pre-set and fixed in manufacture.

 

[Spyro]

Return line on old single cylinder Yanmars go back to the inlet side of the engine mounted filter.

 

[rogerthebodger]

Looks like a pump specific method and as you said the pump you adjusted was a Bosch and the pump on my Tempest is a Simms so not the same.

The motor runs OK now so I must have the setting OK. Will only really tell once in the water and I put it under load.

Thanks again Vic for all your help.

 

[oldharry]

"The motor runs OK now so I must have the setting OK"

Sorry, no. The engine will start and run off load quite happily with the pump setting quite a long way adrift. On load you may find power loss, over heating or increased diesel knock which will eventually damage the piston, and increased fuel consumption.

Like a petrol engine the point at which the fuel ignites is critical to within a fraction of a degree of the rotation of the crankshaft; guessing it is not acceptable and results in poor performance and possible engine damage.

I do not have the setup procedure for a Simms pump, but you really do need to get the timing right. I guess the reason the Bosch and Lucas pumps (both of which I have set timing on) had adjustable rather than preset timing was because they were used on a wide range of engines both turbo and non turbo, therefore needed different timing settings. The acceptable measurement range for timing these pumps was very narrow, and even with a good dial indicator it was quite difficult to get the timing within the specified limits.