Should I be scared of taking my Volvo Penta 2003 injector pumps apart?

[Wotname]

Originally Posted by roland stockham

Givent that you seem confused by the basic parts terminology I would say no The injectors, one per cylinder, distribute high pressure fuel by spraying it into the cylinders. They must meter the correct amount in the right spay pattern to ge the engine to run smoothly and evenly. ...............

I think you will find the injectors do not meter the correct amount of fuel at all, rather that is the job of the injector pump in the engine under discussion.

[Wotname]

This thread reminds me of...

Those who are saying it can't be done need to get out of the way of those who are already dong it.

For the particular job as described by the OP, I suggest you have a go and you will soon know if you can do it or not. Others have been successful and therefore you might also be. It will depend on your learning ability and adaptability to developing new skills.

If you fail (and there is no shame in that), you can still take it the shop.

[Swizzle Stick]

Originally Posted by roland stockham

Givent that you seem confused by the basic parts terminology I would say no The injectors, one per cylinder, distribute high pressure fuel by spraying it into the cylinders. They must meter the correct amount in the right spay pattern to ge the engine to run smoothly and evenly. Cleaning them and replacing the seals between the injector and the fuel lines is a DIY job. Servicing them is not. The high pressure pump, one per engine, controls engine speed and creates the fuel pressure the injectors need. They are super sensitive to even the smallest grit particles which will rite off the pump (that's also why you have multiple filters on the fuel lines) They are serviced in a clean shop. By clean I mean clean as in like a hospital surgery, dust proof room, filtered air, everyone in paper suits and hair nets etc. So no, not DIY

I appreciate your advice about cleanliness Ronald but the Penta 2003 fuel system is not configured as you described.

My system has - in order of flow direction:
- two fuel tanks with an outlet selector valve for port or starboard tank selection.
- one CAV fuel filter.
- one mechanically driven diaphragm "lift pump" to provide low pressure feed to the suction side of the injection pumps. The lift pump is gravity fed and always has a flooded suction because it is mounted below the fuel tank level. I just replaced this pump because it had a small leak. This section of the system no longer leaks.
- one secondary fuel filter on the pressure side of the lift pump.
- three high pressure cam driven positive displacement high pressure injector pumps (Bosch) Penta part number 840594. On inspection, I'd say the timing of the pumps is adjusted by the shim height where they mount on the engine and the stroke length (which determines the output per stroke) is determined by the thickness of the adjusting washer inside the mechanism. Someone please correct me if I'm wrong here.
- low pressure hose distribution lines daisy chaining the low pressure sides of the three pumps to the common fuel return line to the tanks. I've replaced the aluminium sealing washers on the banjos but I still see a leak - which I suspect is coming from the HP pump outlet nozzle and perhaps also the swaged hose fittings on the banjos. I will rebuild these hoses just to make sure they are not also leaking. They've been painted over so it's hard to gauge their condition.
- selector valve to return fuel to the correct tank.
- three injectors (one per cylinder) fed from dedicated injection pumps. These are not leaking externally so I don't plan to do anything to them.

I perhaps should have framed my question a little more clearly:
1. I'm a chemical engineer and have had a fair bit to do with pumps - but not this particular pump.
2. If I understand the exploded view diagram of the pump correctly, it would appear to be trivial to unscrew the top of the pump, replace the O-ring and put it back together.
3. The guy at the engine shop tried to talk me out of it.
4. I thought I'd ask for additional advice from people who are familiar with this particular Bosch injector pump - and even better - someone who has taken one apart and put it back together successfully.

[Wotname]

Originally Posted by Swizzle Stick

.......

I perhaps should have framed my question a little more clearly:
1. I'm a chemical engineer and have had a fair bit to do with pumps - but not this particular pump.
2. If I understand the exploded view diagram of the pump correctly, it would appear to be trivial to unscrew the top of the pump, replace the O-ring and put it back together.
3. The guy at the engine shop tried to talk me out of it.
4. I thought I'd ask for additional advice from people who are familiar with this particular Bosch injector pump - and even better - someone who has taken one apart and put it back together successfully.

Welcome aboard CF, Swizzle Stick.

I guess half the posters align with the guy at the engine shop .

Given this additional information about yourself and reading the lines of your two posts I am more convinced you don't need further advice however it is always prudent to ask!

Do let us know what you decide to do and the results if you end up doing it yourself.

[Compass790]

Whilst I can't tell you about your particular pump our yanmar has a Bosch/Zexel pump very similar.
Everybody told me not to touch it except a retired diesel tech I had used to pop test an injector I had put a new nozzle in.. He told me it's not rocket science to rebuild them & encouraged me to have a go. I stripped it, replaced the delivery valve & plunger & barrel. Took me a couple of goes to get the assembly right but I had no choice as I didn't want to pay the $630 the diesel place wanted.
Just be clean & careful but I'm in the no worries replacing the o-ring on the holder camp.

[sandy stone]

Originally Posted by kenbo

Ronald,
No offense but you are the one who is confused. Inline HP pumps have one pump per cylinder or injector. You are describing a rotary HP pump. Different design and much less complex.

Yep, a lot of advice here from people who clearly are not the least bit familiar with this particular engine.

[DougR]

“- three high pressure cam driven positive displacement high pressure injector pumps (Bosch) Penta part number 840594. On inspection, I'd say the timing of the pumps is adjusted by the shim height where they mount on the engine and the stroke length (which determines the output per stroke) is determined by the thickness of the adjusting washer inside the mechanism. Someone please correct me if I'm wrong here.”

Your estimation of the pump action is pretty close......

There’s a plunger sliding up and down in a cylinder that constitutes the main component of the pump. The area above the plunger acts as the pump chamber, and fuel is fed into this chamber thru a port in the side of the cylinder wall. As the plunger is driven up by the cam it begins to compress the fuel above it, driving the fuel back out the fill port until the upper edge of the plunger passes the opening of the fill port. At this point, “port closure”, fuel begins to compress and is driven out to the injector.


As you noted, the start of injection timing is controlled by the thickness of the shim pack positioned under the pump mounting flange, because thicker shims move the fill port position further from the cam shaft, but the injection amount is not controlled by adjusting washers.

The physical stroke length is always constant, as it’s controlled by the cam lobe dimensions, but the EFFECTIVE stroke length varies and that controls the injection volume.

Below the top edge of the plunger, and a little way down the plunger wall, there is a helix ground into the wall of the plunger. This helix (spiral) grind opens access to the top of the plunger. So when the plunger is going up and port closure occurs, injection begins and continues for as long as the port is closed. However continuing plunger motion causes the helix to uncover the port and fuel which was being compressed above the piston now flows down the helix grind and back out the fill port, stopping injection. The volume of injection is determined by the length of distance between the plunger top and the helix, and this distance can be varied by rotation of the plunger.

So the governor and it’s linkage control the rotation of the plunger in response to operator demand and the rotation position determines the length of time the port is closed and fuel is injecting.

Probably a completely confusing explanation, but you can google it and get a better understanding......

[DougR]

Here’s a short photographic essay to give you an idea of what to expect if you end up having to replace the delivery valve retainer O rings. The engine here is a VP 2030 model (Perkins 103-10), so it’s not the same as your MD2003, but close enough that the differences are minimal. As you see, this injection pump contains all three plungers instead of one plunger per pump as on your engine.

I had the pump out of the block, but I put it back in as it’s easier to hold and work with when it’s secured in the block. In your case, if you can do the work while the pump is mounted in the block, then there are no worries about tearing gaskets/shims, dropping stuff in the block opening, etc.
As you can see this is a Nippon Denso pump, but all of these pumps are based on, licensed, copied from Bosch and they are all similar....

-First two photos- pump and it’s location on the engine. Timing shims under the pump flange are not shown...
- Delivery valve retainer unscrewed until the O ring is visible..clean up paint chips at this time.
- Delivery valve retainer removed and lying on the pump body... delivery valve spring sitting in its place...it won’t go flying anywhere
- Delivery valve and it’s components laid out in their positions. For your purposes it’s not even necessary to remove them from the pump body. From my recollection the 2003 pump has a few more parts above the spring, but it’s nothing that will give you any problems. Just keep them in order. On this engine the mounting angle of the pump body causes the delivery valve to drop down out of the center of the opening when reassembling, so feed the end of the spring into the retainer and lift it up to the center of the opening when starting to screw in the retainer. I don’t recall that’s it’s any problem with your engine...

As you can see, this is a job that any one-eyed mechanic who knows which end of a screw driver to grab can accomplish...even I did it! Now let’s see if I can load the photos.....

[Bycrick]

Back in the thread, there was a comment about aluminum crush washers on some of the fuel fittings. A long time ago, on a Volvo MD11C, I had endless problems with the engine running for "a while" and then stopping. Bleeding the fuel system would fix the problem, until the next time. My Volvo mechanic just said "Oh, yeah. That always happens." He explained that the aluminum washers can corrode and cause tiny air leaks. He replaced them all with copper washers and the problem never recurred.

[Swizzle Stick]

Well, I went down to the boat this morning and did the job and I'm pleased to say it worked. I did all three pumps and there are no leaks. Boy am I glad not to smell diesel now every time I go below!

I will now describe what I did in more detail with the aid of some photos.

1. I took off all the low pressure hoses.



2. I screwed a banjo bolt back into the lower outlet to stop debris falling into the pump when I unscrewed the high pressure connections.

Plug Bolt In.jpg Views: 109 Size: 419.7 KB ID: 219122" style="margin: 2px" />

3. I unscrewed the HP compression fitting on the outlet pipe then unscrewed the nozzle, being careful not to allow paint or other crap to fall into the pump. A photo of the nozzle is shown below. I had previously bought three O-rings (item 8) and three "gaskets" (item 9, probably better described as a copper or brass washer). The pieces shown on the towel came off with the nozzle. As expected, the O-rings were well past their prime so I binned them, cleaned everything up with WD40 and put on the three new O-rings.



4. The pieces shown below stayed inside the pump. All three "gaskets" looked clean and in perfect condition so I left them in there and didn't replace them with the new ones I bought for 60c each.



5. I rebuilt the low pressure daisy chain hoses. I cut the swaged fittings off the banjos with a Dremel and sanded all the paint off the banjos so it didn't interfere with the seals, or chip off and get into the pumps. I bought a short length of 1/4" ID fuel hose, cut it into two short lengths and clamped it onto the barbed fittings on the banjos to complete the two new hoses. I replaced all the aluminium sealing washers and re-assembled everything.



I really appreciate the excellent (and prompt) advice I received from some people on this forum as it gave me the confidence to tackle the task and complete it successfully. There are some champion boat owners on this forum. Cheers!

Next cab off the rank - tuning the engine in a valiant attempt to make my clunky old diesel run like a non-clunky new diesel. I'll start a separate thread about that shortly if one doesn't already exist. I'll check.

[Wotname]

Good job and thanks for the update!.

You may have already replaced the pipe clamp (shown in first picture but missing in the last picture) but if you haven't, don't forget to do so. These clamps are important on injector pipes.

[Compass790]

Well done,
I would have said you are better off replacing the copper washers or at least annealing them. They work harden but it's not leaking so who cares?
I did the same as you with the Yanmar crimped fuel line as they wanted $135 for a short bit of fuel hose.
Its a real joy conquering diesel leaks for sure

[Swizzle Stick]

Originally Posted by Compass790

Well done,
I would have said you are better off replacing the copper washers or at least annealing them. They work harden but it's not leaking so who cares?
I did the same as you with the Yanmar crimped fuel line as they wanted $135 for a short bit of fuel hose.
Its a real joy conquering diesel leaks for sure

That's a good point Compass790.

I wonder if fuel could slightly bypass internally (high side to low side) without leaking externally and reduce the delivery pressure if those washers are not actually as perfect as they look.

Maybe I'll take the pumps apart again and replace the washers

[Wotname]

Originally Posted by Swizzle Stick

..........
I wonder if fuel could slightly bypass internally (high side to low side) without leaking externally and reduce the delivery pressure if those washers are not actually as perfect as they look.

........

Unlikely - IMO.

[Compass790]

Originally Posted by Swizzle Stick

That's a good point Compass790.

I wonder if fuel could slightly bypass internally (high side to low side) without leaking externally and reduce the delivery pressure if those washers are not actually as perfect as they look.

Maybe I'll take the pumps apart again and replace the washers

Well it looks like the washers seal the delivery valve & delivery v/v holder from the plunger & barrel so I'd say it's possible for a leak path if they weren't good. There should be a torque setting for the delivery valve holder ( the part with the o-ring ) so you get the pressure on those washers right.
Doubt it will fix your white smoke problems but I hope you prove me wrong