Universal M25 fuel bleed

[LeslieTroyer]

I've upgraded my M25 to include the bleed valve that was on the later engines. I've read that some folks also use the bleed plug on the secondary fuel filter (mostly only if they change that filter). My question is if I should replace that bleed screw with another "knurled" knob type valve???

Thoughts?
Thanks

 

[Stu Jackson]

Les, don't bother. When I do that secondary I have to almost completely remove that screw to get the air out. By "almost completely remove" I mean it is actually out but I;m holding it there with the socket/screwdriver so I can easily reinsert it without starting all over again. That "knurled knob" won't work there anyway. I have a fuel pump shutoff toggle switch right next to it down there to minimize spillage.

 

[LeslieTroyer]

Thanks Stu - I'll wire a switch in - that "screw" is difficult to get to - I'll practice with various extensions & tool ends to find the best combination. I have a nagging feeling I still have air - I got it started after changing the primary and adding the knurled knob valve - but when I came back a week later it didn't start, and had to run the bleed cycle again (extended cranking with raw water off)- then it started. I let it run for >30 minutes at various RPM's (I was calibrating the Tach). I'll be going up tonight and see if I have a problem - but wanted to cover my bases --

I haven't yet changed the secondary filter, its on my to do list for a month or two out. I am also going to change the primary filter, the DHAL was just too messy to deal with. I don't like having a pint of diesel to dispose of. I've purchased a Racor Snap to replace it. I can get the snap modules cheaper than buying a Racor filter for my DHAL. The filter is under the forward portion of port settee, so I don't have to worry about it being in the engine compartment and heat shields...

Les

 

[Stu Jackson]

extended cranking with raw water off

Not sure I understand. To bleed I turn on the ingition to get the fuel pump to run, then open the knurled knob for a bit, close it to confirm the slower ticking of the fuel pump and I'm done. No engine start required.

 

[LeslieTroyer]

after running the fuel pump for >10 minutes - close the knurled valve - and try and start the engine - it was taking longer than normal to start - so I shut off the intake to the raw water to prevent the muffler from overflowing - and continued to crank a bit longer - once it started I open the raw water intake.

The valve on the muffler looks like it hasn't been opened in 33yrs. I'm afraid of breaking the valve off the muffler drain if I try to open it.

 

[LeslieTroyer]

Just got to the boat and it started just like it did before all bleeding. I'm happy

 

[NICK1951]

A few thoughts,
1. An electronic fuel pump turned to ignition will not fill muffler or pistons.
2. Most racors are for a pull fuel system. Your Catalina 36 Dahl is a push system designed for electronic pumps.
3. Bleed primary Dahl by loosening nut to secondary filter turn on ignition watch for diesel.
4. Open bleed screw on secondary filter, then bleed. Then start engine. I have not needed to crack injectors.
5. Check site secondary housing has broken many times and needs to be replaced.
Nick

 

[LeslieTroyer]

A few thoughts,
1. An electronic fuel pump turned to ignition will not fill muffler or pistons.

No one suggested muffler would fill with fuel. Raw water is the issue when cranking for extended periods

2. Most racors are for a pull fuel system. Your Catalina 36 Dahl is a push system designed for electronic pumps

My Dahl is installed as a pull

3. Bleed primary Dahl by loosening nut to secondary filter turn on ignition watch for diesel.
4. Open bleed screw on secondary filter, then bleed. Then start engine. I have not needed to crack injectors.

After the bleed screw update I can bleed the Dahl by cracking the knurled valve and letting fuel and air return to the tank. I've not cracked open the lines to the injectors.

5. Check site secondary housing has broken many times and needs to be replaced.
Nick

Mine isn't broken but will keep it in mind if I develop a problem.

I suspect that the extended cranking was because I got air into the high pressure pump when installing the knurled valve.

Thanks for responding.