Diesel fuel pipe leaks???

[stav]

Last season suffered with diesel bug. Have ended up taking the fuel system to pieces a number of times and fitting an extra filter. Seems ok so far this season..... Except when fuel is low the engine will lose revs then pick up again or die but start. It will do a combination of these things then run fine. I motored 7 hours last week and all ok. Then lost revs etc came along side a boat toped up with diesel and carried on for another hour. Checked the next morning and whilst looking at the breather pipe for the tank found a weep on the electric fuel pump. Redid this joint with hermatite gold. Filled up with diesel and motored about 15 hours and home all fine. Next day filled up with diesel and went for a sail, motoring back to the mooring and the revs dropped and it stalled, did this twice and then ran fine and got back on the mooring.

Is meramtite gold a problem. other choices open to me where hermatite red or PTFE tape. I am also going to do something with the breather pipe as the retrun from the engine tees in to it.

I have put a spanner on all the joints just to check for tightness.

Any suggestions welcome.

It is 3 cylinder 27hp westebeke engine. 10yrs old but ashore for five years after it was used for the first season.

thanks. /forums/images/graemlins/confused.gif

 

[oldharry]

You should not be using any sealant on diesel joints. hermatite breaks up and clogs the system - possibly the cause of your trouble. Hermetite red is a known engine killer used on oil joints, as it can block the oil feed altogether. PTFE can do the same. If you can not make the old joint fuel proof, then you have to replace the sealing component - usually an olive on the pipe, or a copper washer. If it still leaks then the seating has to be replaced, which is a PITA because that usually means replacing the component itself.

Overtightening to try to stop leaks will damage the seatings anyway.

 

[Csail]

I reckon it sounds like air getting into the fuel system.

 

[gandy]

The makers claim that Hylomar is OK for Diesel fuel connections, although as others say no sealant should really be necessary. I must admit that we had trouble with one banjo a couple of years ago, and that's been OK since I gave it a touch of Hylomar.

 

[Malish]

If you want to use a sealant then have a look at the anaeerobic products made by hylomar for fuel systems:
http://www.hylomar.us/anaerobic.shtml

 

[bogman]

is there a problem with teeing the breather line into the injector return..mine is like that and I've always been a little concerned.

 

[stav]

thanks for the suggestions, I have been and bought some hylomar. However, went down yesterday and it started and ran very sweetly??? Will see what happens but as things occur will clean and re do the joints but might add hylomar gasket seal as necessary. I can appreciate about not over tightening connections but did spend time with my father when I was younger helping him, he was a plumber, so I am careful about just nipping things tight. Thanks again, but I can see a winter job coming on already!

 

[oldharry]

" is there a problem with teeing the breather line into the injector return"

Dont see why there should be. The injector pressure is very high so there is no chance of air leaking back into the HP system, and the spill return line is low pressure so will not force air back into the injection system. Self bleeding injection systems have to be connected back to the tank, so usually do go via the injector return in automotive practice.