CAV engine filter; where do all the pipes go.

[pcatterall]

Not near the boat and wanting to tackle the fuel supply business next time I go ( France)
in connection with my questions in another thread.

I'm trying remember where all the fuel pipes go in my old CAV engine filter.
There are 4 connecters ( 2 in 2 out) and they are all in use.

On one side
I in from the fuel pump and 1 out to the cold start device.

On the other side (and difficult to see because the connections are right up against the heat exchanger).
1 out to the high pressure side and ( a mystery) 1 in from somewhere. I should have followed it through when I was there but didn't have my mirror handy then forgot.
Can anyone suggest where it may go to?

This is a perkins 4108. The fuel return goes to a banjo connection on top of the filter then out again to the tank.
The 'mystery' pipe 'set off' in the same direction of the pipe to the high pressure side and then the pipes became jumbled and I couldn't track them.
These 2 pipes are all rigid copper and bent in most mysterious ways, one of my concerns is that should one 'fail' when far from home it would be sensible to have the means to effect a repair.
Any advice please?

 

[neil1967]

There are actually 2 fuel returns, one from the hp pump and one from the injectors. On my 4108 the return from the injectors is fed into the bleed valve on the CAV, whereas the return from the pump goes into the 'proper' port on the CAV.

I am enjoying your questions and the responses, as they mirror my current situation!

Regards

Neil

 

[pcatterall]

Thanks Neil, thats a good start!! Your set up sounds just like mine. I guess that the pipe to the HP side and the return from there are not under great pressure and could be made from a flexible material or (if not) then from thick walled soft copper which could be 'encouraged' to find a way through all the other pipes and things.
I must take note of all the fitting sizes.
Now we are far from home it seems much more important to either have spares on board or to have the equipment and knowledge to fabricate something.
Thanks again

 

[Roberto]

Same engine, does this picture help ?


The braided hose up front coming from the bleed screw is the fuel return to the tank, on the right the IN from the lift pump and the out to the thermostart. I do not have a picture of the hidden half of the filter

 

[pcatterall]

Cheers Roberto!
Neil has identified the 'mystery' feed as another return. This means that there are two returns coming into the filter ( one from the injectors) and one from the High pressure pump. These both then exit the filter from the top connector to return to the tank.
We had a lengthy recent thread about the need for the returns to go back via the filter.
Thanks

 

[neil1967]

I'm no expert, but I believe that the original pipe work on the engine is steel. I suspect that this is because copper pipes might work harden (and hence become brittle) with the vibration - happy to be corrected by a metallurgist guru though.

Neil

 

[pcatterall]

Neil, I believe that you are right, they DO look like steel. Assuming that they are begs the question about finding/fitting replacements if and when they fail.

I recall having to replace a section of that pipe ( nearer the injectors ) on another Perkins. I did locate a part ( Diperk I think) but it was a struggle to fit it and some of the other pipes look even more difficult without removing manifolds and such.

 

[Roberto]

Neil, I believe that you are right, they DO look like steel. Assuming that they are begs the question about finding/fitting replacements if and when they fail.

I recall having to replace a section of that pipe ( nearer the injectors ) on another Perkins. I did locate a part ( Diperk I think) but it was a struggle to fit it and some of the other pipes look even more difficult without removing manifolds and such.

when I had to service the injection pump, the mechanic guy after having disconnected all the pipes one by one, he left them all at their place, without taking them away from the engine

it does not help if you need to replace one pipe of course, but in case you need to replace/service some elements they are connected to, it may be worth remembering