Rebuilding a Bosch high pressure CP3 fuel pump

[AdamG]

My Bosch high pressure CP3 fuel pump was leaking slightly so I bought a seal kit F00N201973.



There are several variants of the CP3 pump so some of the seals are not used.

First I stripped the pump down. There are six bolts holding the steel pump body to the aluminium back plate. As I did not plan to touch the high pressure side it is vital to keep all dirt out. The high pressure part consists of three pistons that compress the fuel and achieve this by very tight tolerances.

Once I had stipped and cleaned the low pressure side I began reassemble.

First the pressure relief valve oring



Next the fuel temperature sensor. There was no copper washer in the kit for this so I had to reuse the old one. I also put the large oring on the raised circular machining to the right of the sensor. (not shown in the photo)



Next the orings for the quantity control valve.



Next the seals that seal the high and low pressure sides. I put some silicone lubricant on these to help reassembly



Then bolted the six bolts up

 

[josh8loop]

I have a quick question for you all. I have a 2005 E320 CDI(USA version) and my injector pump has developed a leak either on the low pressure fuel inlet or low pressure return to the tank. I will be looking into which one is leaking shortly here in a few minutes. My question is whether or not the rebuild kit mentioned above will work for my particular injection pump or not? while it may not help me with my leak now I might as well be prepared if I should need any future rebuild parts. Any thoughts?

 

[mersum1es]

ask 'kni', he has made the job too...
http://www.benzworld.org/forums/w21...cedes-e320-cdi-high-pressure.html#post7082362

 

[josh8loop]

ask 'kni', he has made the job too...
http://www.benzworld.org/forums/w21...cedes-e320-cdi-high-pressure.html#post7082362

Yes, I will good idea-Thank you!

 

[josh8loop]

ask 'kni', he has made the job too...
http://www.benzworld.org/forums/w21...cedes-e320-cdi-high-pressure.html#post7082362

I chatted back and forth with Kni. He was extremely helpful and offered some tips and tricks to me on the procedure as it was fresh in his mind. I asked him if there were any other seals he wished he would have had. He mentioned the shaft seal didn't come in the kit. There is a bit of confusion here about where and how many shaft seals though. Looks like there may be a shaft seal between the high and low pump sections, and perhaps between the aluminum section and the part that mates to the engine. Can anyone confirm this?

 

[josh8loop]

My Bosch high pressure CP3 fuel pump was leaking slightly so I bought a seal kit F00N201973.

View attachment 16805

There are several variants of the CP3 pump so some of the seals are not used.

First I stripped the pump down. There are six bolts holding the steel pump body to the aluminium back plate. As I did not plan to touch the high pressure side it is vital to keep all dirt out. The high pressure part consists of three pistons that compress the fuel and achieve this by very tight tolerances.

Once I had stipped and cleaned the low pressure side I began reassemble.

First the pressure relief valve oring

View attachment 16806

Next the fuel temperature sensor. There was no copper washer in the kit for this so I had to reuse the old one. I also put the large oring on the raised circular machining to the right of the sensor. (not shown in the photo)

View attachment 16807

Next the orings for the quantity control valve.

View attachment 16808

Next the seals that seal the high and low pressure sides. I put some silicone lubricant on these to help reassembly

View attachment 16809

Then bolted the six bolts up

Hi there,

I am having some slight leaking with my injection pump(low pressure inlet and outlet side only right now) and have been reading about the pump and pump internals. I am familiar with VW TDI injection pumps and have rebuilt one on my current vehicle in the past with success. I figure I might as well get a rebuilt kit for this car and have it on hand just in case I need it. No sense in being stranded and forced to pay for a new injection pump when I can have a rebuild kit on hand and do it at my leisure.

I know it's been a while since you did yours, but it doesn't look like the kit contains all the seals. I ran into the same situation on my TDI pump rebuild. It almost looks like there are two shaft seals that aren't included. One that goes between the high and low pump pressure sides, and one that seals the shaft between the engine and aluminum low pressure pump side. Not sure if you remember or can confirm this? Thanks!

Josh

 

[northernsoul]

Hi,
An older post but a may as well use this as start a new one.
Simple question really regarding the bosch CP3.

On the pressure relief valve should there be any piping attached?
Any help appreciated.
Thanks

And by the way thanks for the original post. It should prove very helpful.

 

[josh8loop]

Hi,
An older post but a may as well use this as start a new one.
Simple question really regarding the bosch CP3.

On the pressure relief valve should there be any piping attached?
Any help appreciated.
Thanks

And by the way thanks for the original post. It should prove very helpful.

Nope, no piping attached to the over pressure relief valve. That way there is a tell-tale if there is a serious injection pump failure.

 

[josh8loop]

Nope, no piping attached to the over pressure relief valve. That way there is a tell-tale if there is a serious injection pump failure.

I was kinda right, and kinda wrong on this answer. Let me correct myself now that I have a better understanding of the over pressure relief valve. I was right in the fact that the over pressure relief valve located on the bottom side of the CP3 pump does not have any lines attached to it, but I was wrong about it's function. It actually regulates the internal low pressure circuit pressure to about 4.5 bar. See this information:

https://www.google.com/url?sa=i&rct...KzvMjYxDY3raz3Og&ust=1459631461392566&cad=rjt


..

 

[Diesel315]

Here are the seal pn's (for pump number 0445010091--05 E320 CDI, in my case)
Has anybody actually changed any shaft seals ?
No clue if this is done with just pump removed or more messy.

 

[josh8loop]

Here are the seal pn's (for pump number 0445010091--05 E320 CDI, in my case)
Has anybody actually changed any shaft seals ?
No clue if this is done with just pump removed or more messy.

I've not done my HP pump seals yet just have it on the shelf if needed. I purchased a complete re-seal kit from a UK seller that was pretty comprehensive and looks to contain all shaft seals. I do know however that to get the internal shaft seals the pump needs to be taken apart. Actually when your doing a re-seal of the pump, the shaft seals should be done as well since they have been known to either leak internally creating fuel pressure regulation issues, or leak overboard making a mess all over the engine.

 

[Diesel315]

Josh8--I did same thing, have the pump and shaft seal kit on shelf.
Hope you need to do it first and post some pics : )
I suspect the shaft seals could be a pain, after all, they keep 20k+PSI inside the pump.

 

[mersum1es]

Deffo no, high pressure is only between piston and delivery valve... body pressure is few bars....

 

[Diesel315]

Ahhh, I understand now. Tks for the info!