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BigAl.NZ · 16-09-2019, 19:09

Hello,

It feels like Dejavu - I am in the situation where I need to bleed my Perkins 4108 again after the engine was starved of fuel.

I have primed with the lift pump the primary filter and fuel comes out. I think my issue now is with the High Pressure pump and exactly which screws need to be opened to bleed it.

There is a good guide here from TAD : http://www.tadiesels.com/assets/docs...20Changing.pdf

But the pictures are blurry and I suspect I have the later model of high pressure pump.

Mine looks like this.

Which screws should I loosen and in what if any order?

rbk · 16-09-2019, 19:26

Can’t see which pump you have but looks like cav from a quick look. Low pressure union into the pump, side bleed screw, governor bleed screw and each injector line. Follow the fuel and tighten each as bubbles stop from low pressure to the injectors. Best to have an electric pump or someone else working the lift pump for the first bit then crank the starter once fuel is to the pump.

rbk · 16-09-2019, 19:28

Bad internet connection got a chance to see your pic. Don’t touch screw 2. Just 1&3 as well as low pressure line in and injectors unions.

**skipperpete** · 16-09-2019, 19:45

Quote:

Originally Posted by BigAl.NZ

Hello,

It feels like Dejavu - I am in the situation where I need to bleed my Perkins 4108 again after the engine was starved of fuel.

I have primed with the lift pump the primary filter and fuel comes out. I think my issue now is with the High Pressure pump and exactly which screws need to be opened to bleed it.

There is a good guide here from TAD : http://www.tadiesels.com/assets/docs...20Changing.pdf

But the pictures are blurry and I suspect I have the later model of high pressure pump.

Mine looks like this.

Which screws should I loosen and in what if any order?

#2 is either the idle screw or max rpm screw so no need to loosen it but #1 and #3 are the governor and case bleed screws. Avoid overtightening the bleed screws, they break easily. In your photo it looks as though the stop control linkage/chain is under a bit of tension, best to make sure the little lever on the pump is happily sitting in the "run" position.
No particular order for bleeding but sometimes it's necessary to spin the engine over with those screws slightly open and let the internal vane pump spit out the air.

BigAl.NZ · 16-09-2019, 20:05

Awesome. I will have another go later in the week. I am a little suspects of things upstream towards the tank since it was a problem with the Racors that stopped for in the first place.

I might fully loosen the nut on the first filter and check that.

BigAl.NZ · 16-09-2019, 23:16

PPS: After servicing the racors, can they just be filled from the top with a jerry can? Refill to the top again?

BigAl.NZ · 16-09-2019, 23:18

Quote:

Originally Posted by rbk

Bad internet connection got a chance to see your pic. Don’t touch screw 2. Just 1&3 as well as low pressure line in and injectors unions.

Where are the low pressure line in and injector unions? Are they in the picture?

**skipperpete** · 17-09-2019, 02:40

Quote:

Originally Posted by BigAl.NZ

Where are the low pressure line in and injector unions? Are they in the picture?

That's a good photo, you managed to capture all the relevant bits. The supply into the pump is the vertical pipe with blue paint on the far rhs that does a u turn. The hp pipes and unions can be seen behind the supply pipe. They are attached to the blackish horizontal extensions that are banjo bolted to the hydraulic rotor head.

BigAl.NZ · 20-09-2019, 15:48

Thanks all. Got motor to go but had to use some Enthanol starter fluid - ran great after that but would not start even after leaving the pre heater on for a few minutes.

Incidentially fuel gushed out screw #3. Hardly came out #1.

rbk · 20-09-2019, 15:54

Usually doesn't come out the governor vent very much, sorry I missed your other post. follow the copper line from the top of the on engine fuel filter to the HP pump, it enters above the HP injector lines. When replacing the on engine filter you can end up pushing air into the HP pump for a bit so cracking that line and getting fuel to the HP pump is a first step, then deal with the HP pump bleed ports.