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-   -   Perkins 4108 High Pressure Pump Bleed (https://www.cruisersforum.com/forums/f54/perkins-4108-high-pressure-pump-bleed-223966.html)

BigAl.NZ 16-09-2019 19:09

Perkins 4108 High Pressure Pump Bleed
 
1 Attachment(s)
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 : https://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

Re: Perkins 4108 High Pressure Pump Bleed
 
Canít 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

Re: Perkins 4108 High Pressure Pump Bleed
 
Bad internet connection got a chance to see your pic. Donít touch screw 2. Just 1&3 as well as low pressure line in and injectors unions.

skipperpete 16-09-2019 19:45

Re: Perkins 4108 High Pressure Pump Bleed
 
Quote:

Originally Posted by BigAl.NZ (Post 2978264)
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 : https://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

Re: Perkins 4108 High Pressure Pump Bleed
 
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

Re: Perkins 4108 High Pressure Pump Bleed
 
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

Re: Perkins 4108 High Pressure Pump Bleed
 
Quote:

Originally Posted by rbk (Post 2978270)
Bad internet connection got a chance to see your pic. Donít 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

Re: Perkins 4108 High Pressure Pump Bleed
 
Quote:

Originally Posted by BigAl.NZ (Post 2978362)
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

Re: Perkins 4108 High Pressure Pump Bleed
 
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

Re: Perkins 4108 High Pressure Pump Bleed
 
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.

rbk 20-09-2019 15:56

Re: Perkins 4108 High Pressure Pump Bleed
 
Also try using wd40 rather than ether IF you need some help starting, but you really shouldn't need anything. You will ruin your engine with ether.:danger:

rbk 20-09-2019 15:58

Re: Perkins 4108 High Pressure Pump Bleed
 
Your low pressure inlet is the furthest copper line on the right in your picture.

BigAl.NZ 20-09-2019 15:59

Re: Perkins 4108 High Pressure Pump Bleed
 
Quote:

Originally Posted by rbk (Post 2980898)
Also try using wd40 rather than ether IF you need some help starting, but you really shouldn't need anything. You will ruin your engine with ether.:danger:

Awsome - more great learning.

BigAl.NZ 20-09-2019 16:01

Re: Perkins 4108 High Pressure Pump Bleed
 
1 Attachment(s)
With the green arrow?

skipperpete 20-09-2019 18:25

Re: Perkins 4108 High Pressure Pump Bleed
 
1 Attachment(s)
Try and avoid the ether based starting aerosols, they can do harm unless it's done in subzero temperatureAttachment 200260


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