MEP-002a Injection pump disassembly / repair

[BlackhawkMTP]

Hello,

I know that this has been covered in another post with detailed pictures located here: https://www.steelsoldiers.com/threa...pics-mep-003a.183913/#lg=post-2181690&slide=2 But........

I am having issues getting my injection pump apart on step 4 in the thread linked above. When I try and pry my gear set half away from my injection port half it doesn't seem to want to separate. My question is, is this normal? I don't want to damage this injection pump assemble so any help would be greatly appreciated. I have never disassembled an injection pump before so I am learning as I go. Thanks in advance.

Josh

 

[BlackhawkMTP]

Hello,

I know that this has been covered in another post with detailed pictures located here: https://www.steelsoldiers.com/threa...pics-mep-003a.183913/#lg=post-2181690&slide=2

I am having issues getting my injection pump apart on step 4 in the thread linked above. When I try and pry my gear set half away from my injection port half it doesn't seem to want to separate. My question is, is this normal? I don't want to damage this injection pump assemble so any help would be greatly appreciated. I have never disassembled an injection pump before so I am learning as I go. Thanks in advance.

Josh

Okay I finally got it apart. I had to drive out the center rod / plunger with a punch and rubber hammer. I found a broken thrust washer. I'm guessing I need to call Ambac on Monday and order the orange seal in the thread listed above or a rebuild kit. Mine doesn't look like it's in great shape. Also, I scratched up the brass looking washer when I was separating the gear half / fuel port half. I'm assuming I should order another washer as well. Anything else I should replace while it is apart?

 

[Guyfang]

Hopefully RAY70 pops in here. He seem to be the guy to go to for these pumps.

 

[Guyfang]

I have taken the liberty of re-posting, what Ray posted in your other thread.

So you are having trouble removing the entire assembly out of the housing after removing the throttle lever and the 4 cap screws?
If so, please verify from the ID tag if you have an Ambac M-50 or an American Bosch PSU injection pump.
If you have a PSU there is a large flat head screw sticking out of a boss 90* down from where the throttle arm go in,
That screw has to be removed to get the body out of the housing.
If you have an Ambac M-50 that same boss is still there but is is not drilled and tapped and there is no screw to remove, it should come apart with just the 4 cap screws and throttle lever removed.

 

[Ray70]

What happened?? Did I stick my response in the wrong thread? God, what a dope!
Now to reply to the correct thread!
How badly did you damage the brass washer? Can you sand it flat with a piece of glass and some 220 grit paper?
If it is too far gone you'll have to replace it.
As long as your plunger guide is ok, then you should be good by just replacing the 2 seals on the body, the one on the throttle lever and the delivery valve spacer ( thin orange washer )
If there were any signs of fuel leaking from the throttle lever, the internal seal is probably the culprit.
The throttle assembly is tack welded closed and not meant to be serviced, just replaced, but if you have a tig or mig welder it can be opened up, replace the internal o-ring and tack it shut again, but if not leaking just leave it be.
HOWEVER.... I was recently told by another SS member that Ambac no longer sells to the public as of a few months ago and he had to go to Green Mountain for his rebuild kit.
I'd say call Ambac and see who they say is your nearest authorized dealer, if they won't sell to you.

 

[Mr4btTahoe]

What happened?? Did I stick my response in the wrong thread? God, what a dope!
Now to reply to the correct thread!
How badly did you damage the brass washer? Can you sand it flat with a piece of glass and some 220 grit paper?
If it is too far gone you'll have to replace it.
As long as your plunger guide is ok, then you should be good by just replacing the 2 seals on the body, the one on the throttle lever and the delivery valve spacer ( thin orange washer )
If there were any signs of fuel leaking from the throttle lever, the internal seal is probably the culprit.
The throttle assembly is tack welded closed and not meant to be serviced, just replaced, but if you have a tig or mig welder it can be opened up, replace the internal o-ring and tack it shut again, but if not leaking just leave it be.
HOWEVER.... I was recently told by another SS member that Ambac no longer sells to the public as of a few months ago and he had to go to Green Mountain for his rebuild kit.
I'd say call Ambac and see who they say is your nearest authorized dealer, if they won't sell to you.

Thats sad if they no longer sell to the public. I still get emails from them all the time and have direct contact info for the sales person I dealt with.

To the OP... if you indeed have an Ambac M-50 pump and the screws and throttle lever are out, it may just take some work. Mine was stuck pretty good. Soak the whole pump in diesel fuel or wd-40.. then using a soft faced hammer, tap it upwards from the bottom and out of the housing. If I remember correctly, I had to work a thin putty knife in between the lip of the pump and the housing and carefully pry it up as I worked around it.. then tapped it out. It was a bit of work to get it apart. It shouldn't take a 4lb sledge to get it loose.. but it will take some fiddling. Lol

 

[Mr4btTahoe]

Just to verify, Ambac is still selling to the public.

 

[Ray70]

That's good news, thank you for verifying that!

 

[BlackhawkMTP]

What happened?? Did I stick my response in the wrong thread? God, what a dope!
Now to reply to the correct thread!
How badly did you damage the brass washer? Can you sand it flat with a piece of glass and some 220 grit paper?
If it is too far gone you'll have to replace it.
As long as your plunger guide is ok, then you should be good by just replacing the 2 seals on the body, the one on the throttle lever and the delivery valve spacer ( thin orange washer )
If there were any signs of fuel leaking from the throttle lever, the internal seal is probably the culprit.
The throttle assembly is tack welded closed and not meant to be serviced, just replaced, but if you have a tig or mig welder it can be opened up, replace the internal o-ring and tack it shut again, but if not leaking just leave it be.
HOWEVER.... I was recently told by another SS member that Ambac no longer sells to the public as of a few months ago and he had to go to Green Mountain for his rebuild kit.
I'd say call Ambac and see who they say is your nearest authorized dealer, if they won't sell to you.

Hey Ray,

I was flying yesterday so I was unable to respond. I have the American Bosch pump best that I can tell. I don't see the set screw you are referring to but I do see the boss. I might be able to sand the Brass washer smooth where it is acceptable. I will have to look at it again today. I bought a new plunger guide and got it in the mail yesterday. I called a local Ambac yesterday and they referred me to a parts distributor in my local area. I should get the rebuild kit today with the seals. I don't see any evidence of fuel leaking from the Throttle lever. I am going to clean the parts the best I and try and get this thing back together. I will let you know how it goes.

Josh

 

[BlackhawkMTP]

Thats sad if they no longer sell to the public. I still get emails from them all the time and have direct contact info for the sales person I dealt with.

To the OP... if you indeed have an Ambac M-50 pump and the screws and throttle lever are out, it may just take some work. Mine was stuck pretty good. Soak the whole pump in diesel fuel or wd-40.. then using a soft faced hammer, tap it upwards from the bottom and out of the housing. If I remember correctly, I had to work a thin putty knife in between the lip of the pump and the housing and carefully pry it up as I worked around it.. then tapped it out. It was a bit of work to get it apart. It shouldn't take a 4lb sledge to get it loose.. but it will take some fiddling. Lol

I was having an issue getting the internal components apart. The guide pin was gummed up and I just tapped it out with a punch and rubber hammer. I took off the 1 inch cap screw, small spring, and metering valve and seal and put the punch in there and tapped it out.

 

[Ray70]

Hi Josh, you should be good to go. You have an Ambac m50 not the American Bosch PSU ( Thank God!)
You should have a blue ID tag on the side.
The PSU has a black tag. It also does not use a plunger guide, it uses a drive pin drilled through the plunger, that is the pump's biggest downfall. When frozen, the pin will break the plunger right at the hole where the drive pin goes through.
Luckily, you have the better Ambac M-50 pump!

 

[BlackhawkMTP]

Hi Josh, you should be good to go. You have an Ambac m50 not the American Bosch PSU ( Thank God!)
You should have a blue ID tag on the side.
The PSU has a black tag. It also does not use a plunger guide, it uses a drive pin drilled through the plunger, that is the pump's biggest downfall. When frozen, the pin will break the plunger right at the hole where the drive pin goes through.
Luckily, you have the better Ambac M-50 pump!

 

[BlackhawkMTP]

I think I have the PSU

 

[BlackhawkMTP]

Hi Josh, you should be good to go. You have an Ambac m50 not the American Bosch PSU ( Thank God!)
You should have a blue ID tag on the side.
The PSU has a black tag. It also does not use a plunger guide, it uses a drive pin drilled through the plunger, that is the pump's biggest downfall. When frozen, the pin will break the plunger right at the hole where the drive pin goes through.
Luckily, you have the better Ambac M-50 pump!

The pump that I have uses a plunger guide. It was broken when I took it apart.

 

[Ray70]

Wow, nope. Looks like you may have yet another version I have never seen.
That appears to be a M50 built before American Bosch became Ambac.
Interesting that AMERICAN Bosch was from ITALY !
Early on the PSU pump ( as seen in the TM exploded diagrams ) were used by JR Hollingsworth.
At some point, I believe in the early 80's American Bosch became Ambac and the PSU pump design changed a little and became the M50.
The changes included: a new plunger that uses the plunger guide, changes to the drive gear to accomodate the plunger guide, a thinner brass shim to accomodate a slightly thicker gear, a different cup and the " Jeesus" clips to attach the button spacer to the plunger and the large flat head screw was removed from the main body.
I don't know the specifics as far as timing of the model change and name change, but what you have appears to be a pump built early in the M50, prior to the Ambac name change! Definitely an interesting find.
If you want, post up a couple pics of the internals, which I'm guessing will match the M50 diagram attached here, not the PSU diagram found in the TM.

 

[BlackhawkMTP]

Wow, nope. Looks like you may have yet another version I have never seen.
That appears to be a M50 built before American Bosch became Ambac.
Interesting that AMERICAN Bosch was from ITALY !
Early on the PSU pump ( as seen in the TM exploded diagrams ) were used by JR Hollingsworth.
At some point, I believe in the early 80's American Bosch became Ambac and the PSU pump design changed a little and became the M50.
The changes included: a new plunger that uses the plunger guide, changes to the drive gear to accomodate the plunger guide, a thinner brass shim to accomodate a slightly thicker gear, a different cup and the " Jeesus" clips to attach the button spacer to the plunger and the large flat head screw was removed from the main body.
I don't know the specifics as far as timing of the model change and name change, but what you have appears to be a pump built early in the M50, prior to the Ambac name change! Definitely an interesting find.
If you want, post up a couple pics of the internals, which I'm guessing will match the M50 diagram attached here, not the PSU diagram found in the TM.

I thought it was interesting that American Bosch was made in Italy as well. The internals are identical to the Ambac 50 model. The generator this pump came off of is a 1983 model. I think the hardest part of this rebuild for me is going to be getting the spring compressed where I can put in the split cone washers. I might have to see if I can borrow my neighbors vise because I don't have one at my new house yet. Thanks for the education and help!

 

[Ray70]

A little trick on compressing the spring.... I use a 5/8" deep socket with a slot about 1/2" wide cut down the side ( use a cut-off wheel or grinder ) then use a large C-clamp or a large vise and the socket to compress the spring. The hole cut in the side gives room to get in there with a small pick to get the 2 little 1/2 circle clips out. Use a magnetic pick if possible.

 

[BlackhawkMTP]

A little trick on compressing the spring.... I use a 5/8" deep socket with a slot about 1/2" wide cut down the side ( use a cut-off wheel or grinder ) then use a large C-clamp or a large vise and the socket to compress the spring. The hole cut in the side gives room to get in there with a small pick to get the 2 little 1/2 circle clips out. Use a magnetic pick if possible.

Great idea! I will try that!

 

[BlackhawkMTP]

I am going to install the rebuilt injection pump today. Do I need to do anything as far as timing goes? I have read that if you line up "PC" mark to ensure that the number one cylinder is top dead center. Not sure exactly what I need to do to make sure that it runs properly.

 

[Ray70]

Assuming this is the original pump for this machine and it sounds like you took it out without setting at #1 PC first?
If so, yes get the motor to PC on #1 compression stroke and put the 1/8" drill bit onto the hole in the pump to align the gear and slap it back in.
Remember the o-ring around the body that seals to the block and make sure the original shims are reused.
That should get it done. If in doubt you can perform the static timing test, but generally not needed if it's the original pump going back in.