Bleeding' diesel

[fudd]

Changed the filters on the engine after putting hydraulic fluid in it instead of oil. Clever eh! Thought I'd change fuel filters at the same time. Now I've realised that the first filter is higher than the tank. I can't seem to get the fuel through. Is there a secret? It's a HW3. Any tips welcome.

Edited August 13, 2012 by fudd

[Arthur Brown]

Is there a mechanical pump that can be manually operated?

[fudd]

Is there a mechanical pump that can be manually operated?

 

Hi Arthur.

 

There's a lever on the lift pump and I've frantically worked it but nothing happens. I can feel air pressure building up at the second filter after the pump. But I still don't get any at the first filter.

[Arthur Brown]

You maybe cannot bleed the system as a whole, bleed it bit by bit.

 

In general (I don't know your engine) Slacken something (a union or a bleed valve) just after the lift pump. The operate the pump til the flow has no bubbles. Tighten that union and open the next available point and pump the lift pump til the next place floes clear. Read the instructions (if any) about bleeding the injector pump. After the injector pump is full of fuel it may start on cranking -better if you can decompress)

[fudd]

Ok. Thanks. I'll do that tomorrow.

Steve P

[Roger Gunkel]

I had a similar problem after changing a fuel filter, because the take off end of the fuel piipe in the tank, was lower than the filter, so when I disconnected it, all the fuel in the pipe drained back into the tank as I had forgotten to close the valve at the tank. When I reconnected the pipe to the filter, the pump was sucking air.

 

I cured it by sucking fuel back up the pipe after first attaching a piece of clear plastic tube over the disconnected end, so I could avoid getting it in my mouth. Once the fuel was back in the pipe, I closed the shut off valve to stop it draining back again, then reattached the pipe to the first filter. The system primed via the manual lever on the lift pump, bleeding at each bleed screw from the filter to the injectors. Many modern engines though have self bleeding pumps, so once the pipe before the filter is full, you will hear a gurgling noise from the pump when the key is turned to the pre starter position. This will stop when the air has been bled, or with a non self bleeding system it's back to the individual bleed screws and manual pumping.

 

Roger

[fudd]

I had a similar problem after changing a fuel filter, because the take off end of the fuel piipe in the tank, was lower than the filter, so when I disconnected it, all the fuel in the pipe drained back into the tank as I had forgotten to close the valve at the tank. When I reconnected the pipe to the filter, the pump was sucking air.

 

I cured it by sucking fuel back up the pipe after first attaching a piece of clear plastic tube over the disconnected end, so I could avoid getting it in my mouth. Once the fuel was back in the pipe, I closed the shut off valve to stop it draining back again, then reattached the pipe to the first filter. The system primed via the manual lever on the lift pump, bleeding at each bleed screw from the filter to the injectors. Many modern engines though have self bleeding pumps, so once the pipe before the filter is full, you will hear a gurgling noise from the pump when the key is turned to the pre starter position. This will stop when the air has been bled, or with a non self bleeding system it's back to the individual bleed screws and manual pumping.

 

Roger

 

Thanks Roger. I think I may do the same if the other method doesn't work. I will fill the filters with a funnel and suck - blow the fuel round and then try the lift pump hobby.

Thanks all. Steve P

[Arthur Brown]

I've even seen tanks pressurised to lift fuel a little, BUT 1/ you are chancing the tan's pressure limit, and 2/ diesel will not go up a pipe unless there is a way out for the air.

[dmr]

It can take a surprisingly large amount of pumping on the priming leaver before any fuel comes through. Did you give up too soon?

I usually break into the fuel line after the lift pump and divert that into a suitable bottle (health and safety please forgive me), then just keep on pumping till the fuel flows. It takes so long my fingers hurt. The first fuel filter is only slightly higher than the fuel tank but the lift pump is maybe 20 to 30cm higher.

 

............Dave

[fudd]

Thanks again for the advice everyone.

I ended up pumping the tank up with my compressor. It still took about ten solid minutes of trying to start it but at least I know how to do it now. Plus I had some local advice from our local engineer.

Steve P

[alan_fincher]

With some mechanical fuel pumps, including those on certain big Listers, you can waggle the lever back and forward, think you are feeling resistance, and hence that you must be pumping fuel.

 

The reality may be that you are not pushing it hard enough, and hence moving it through the part of the arc where it actually pumps.

 

If doing it correctly, you can expect to meet a considerable amount of resistance. If you don't feel a considerable amount of resistance, it is possible you may not be doing it correctly............

 

 

 

 

 

........... but please don't ask me how I learned this !

Edited August 14, 2012 by alan_fincher

[Tony Brooks]

With some mechanical fuel pumps, including those on certain big Listers, you can waggle the lever back and forward, think you are feeling resistance, and hence that you must be pumping fuel.

 

The reality may be that you are not pushing it hard enough, and hence moving it through the part of the arc where it actually pumps.

 

If doing it correctly, you can expect to meet a considerable amount of resistance. If you don't feel a considerable amount of resistance, it is possible you may not be doing it correctly............

 

 

 

 

 

........... but please don't ask me how I learned this !

 

 

Also the engine just may have stopped with the pump lever on the peak of the eccentric. This gives a lot of free play on the priming lever and not much "pumping" movement. Solution - revolve the engine one turn.