First Post - Introduction - My MEP003 Saga to Date...

[NJ_Toolnut]

As I described above, I inserted the 3/32" drill in the delivery valve orfice and used a ratchet wrench to crank the engine through two revolutions, while using digital calipers to measure the distance between the exposed end of the drill and the lip of the threaded hole in the hydraulic head for the delivery valve holder. I took measurements each 45 degrees (approx.) of crankshaft rotation. I made this group of measurements twice: Once with the control unit in the normal engine off (throttle closed) position and once with the control unit propped wide open with a stick. My measurements had an overall range of 0.015" (measurement error due to awkwardness of measurement situation). I cannot measure any movement of the IP plunger so it must be stuck. Given what I have tried already to free up the plunger, does the IP need to be removed, or are there other tricks I can apply?

As always, thanks for your comments!

Stan

 

[Keith_J]

If you have tapped on the plunger, it is unlikely that just diesel varnish is the problem. So you need to pull the pump.

The plunger turns at half engine speed (1:1 off camshaft) while it strokes to inject fuel. The mechanism which provides for this is probably what has failed. Specifically, the Oldham drive. The good news is this part can be replaced without impacting the timing.

Before you tear off the pump, run through the basic timing method with the brass rod inserted in the side, noting the timing marks on the flywheel. If you align the pump and keep the crankshaft in the same position, the timing on reinstall will be perfect if you reuse all original shims and buttons. It is the stackup of these shims which sets timing, the index of the pump to cam is fairly coarse being limited by the pitch of the gears.

Get the Model 50 service manual from Ambac (online).

 

[NJ_Toolnut]

Thanks, Keith. I really appreciate your advice and frequent feedback.

I printed a copy of the AMBAC manual. Another member sent it by PM to me earlier before I realized it is available in the Wiki.

I would appreciate confirmation that I understand the timing procedure before I pull the pump: From the TM-34, it looks like I need to turn the crankshaft until #1 cylinder (closest to blower wheel) is on compression (after intake valve closes) and then line the port closing mark on the flywheel up with the pointer on the generator adaptor. With the crankshaft at this angular location, I should then be able to slip a 1/8" brass punch into position in the timing hole on the IP housing and the end of the punch will engage the timing slot in the face gear. As long as I engage the punch in the timing slot in the face gear before re-installing the IP, I will have maintained the original timing. Is this correct? There should be no need to change shims or button. Is there an easy way to determine when #1 cylinder is on compression without pulling the front rocker arm cover to observe valve action?

I looked up the part called the Oldham drive (part 26 in Figure 1 in the AMBAC manual). The text in this manual also calls it the plunger guide. If this part turns out to be cracked, broken or worn, how difficult will it be to source a new one? Do they come in a rebuild kit? I will need a rebuild kit in any case, since I will need to separate the hydraulic head from the housing to examine the Oldham drive, so I will need to replace o-rings (not to mention that I need a delivery valve spacer). Who still sells rebuild kits, AMBAC?

Thanks again for hanging in there with me on this,

Stan

 

[Keith_J]

You have the timing procedure understood perfectly. Just go by the flywheel marks, using a mirror and flashlight to see if the notch in the face gear is aligned.

For parts, it would be best to contact a distributor or a local diesel injection service. There may be other items in need or replacement.

 

[NJ_Toolnut]

Thanks, Keith.

The mirror and flashlight idea sounds like another trick learned from experience.

There is a White/Volvo repair shop near me, but I don't know whether they work on injection pumps. Perhaps they can either source any needed parts or suggest who can. I think Cummins bought Onan, so perhaps parts are available from Cummins?

Stan

 

[Keith_J]

I'm certain Cummins has completely divested itself in legacy Onan engines. Ambac has continued to provide parts although the end is near as these engines don't meet emissions requirements. Very low PM but high in NOx.

 

[NJ_Toolnut]

Thanks, Keith.

From my local yellow pages, I found a place in Bangor PA not too far from me called Diesel Systems Inc. "specializing in the rebuilding of all makes of fuel injection pumps & fuel injectors". Perhaps they can get parts. Does AMBAC sell directly to the public?

If Diesel Systems Inc sounds good on the phone tomorrow, I might trust them to just rebuild the IP, depending on the price, of course. On the other hand, it might be good to just get the parts and do it myself in order to confirm I'm capable of doing it.

Stan

 

[storeman]

I don't have any special tools for use on the IP. Just used drill press and a socket of appropriate size from a socket wrench set to allow the spring to be depressed and afford travel inside the socket.
Jerry

 

[sewerzuk]

Does AMBAC sell directly to the public?

Stan

Yes they do; I have ordered lots of parts directly from them. They even sell complete reman pumps, although prices are a little high IMO

 

[RichardR]

Toolnut,

I believe that you can get all the rebuild parts you need directly from Ambac, but you will find them to be pricey. They will take your credit card and shipping info over the phone so ordering from them is easy, if not cheap.

I rebuilt my IP by replacing only the Oldham Drive (plunger guide) which was broken into several pieces. Ambac sells it for $15 + shipping. The Oldham Drive is designed to break whenever the plunger sticks, to prevent more serious damage.

A proper rebuild requires new gaskets and o-rings, which I believe cost nearly $100 from Ambac. I was able to get by with reusing all the old parts. You will have to decide whether you need new ones after you disassemble your pump and have a look.

Do not be intimidated by what you have heard about IP repair requiring special skills and tools. This particular IP isn't too difficult. You can do it all yourself if you take your time and take care to keep things clean. Be sure to clean the varnish and any dirt from the plunger so that it slides smoothly. The tolerances are very tight but it doesn't require any metal removal, just cleaning with solvent to remove whatever has made the plunger stick. Use clean diesel fuel for assembly lubrication. The TM's are reasonably detailed in how to do it step-by-step.

Good luck,
Richard

 

[storeman]

Anyone know a source (other than AMBEC) for the delivery valve spacer (I put my IPs back together without it since some seem to have it, others dont, and it always seems to be torn up.) Also for the copper gasket in the glow plug ports?
Jerry

 

[NJ_Toolnut]

Thanks, guys. I really appreciate the attention I'm getting here.

If the weather cooperates (003a and its trailer set in the driveway to my workshop due to insufficient room inside), the IP is coming off today. I'll let you know what I discover once I get it apart. As Keith mentioned, I strongly suspect the Oldham drive has broken, but we will see.

storeman,

Thanks for confirming you are able to work on these IPs without special tools. I have a lot of confidence that I can either do the same or else make any tools I determine necessary.

I think I read in one of your posts that you have put an IP back together without using a delivery valve spacer. Did it work OK?

sewerzuk,

Thanks for posting to my thread. It's good to have confirmation I can get what I need directly from AMBAC. I was impressed with your videos, and I've been following your thread about 004 rewiring.

RichardR,

Thanks for posting AMBAC's Oldham drive and rebuild kit prices. I'm surprised they want so much for their rebuild kits. I'll carefully consider the option of using the old o-rings, but if they are in the same kind of shape my delivery valve spacer was in, I will likely decide to replace them.

Stan

 

[Keith_J]

I'm almost certain the o-rings are standard parts. Viton is the material of choice here. A $25 dial/digital caliper and a visit to McMaster-Carr will get you what you need in 3 days.

Stan, the great part about these generators is the ease of removal of the injection pump. Even easier if you have an assistant roll the engine with a breaker bar while looking for the timing marks. Once pulled, cover the opening on the crankcase to keep clean.

These pumps are far easier than the injection pump on a VW ALH TDI engine (1999-2003). Yet they have the same heritage (Bosch) and same injection quantity modulation. Even the M35 A2's injection pump has the same type. The Ambac is the easiest as timing is fixed.

 

[NJ_Toolnut]

Hi gents,

Well, at this point in my examination of this no-start situation, I'm sure that I have a much bigger problem than a non-functional IP, but at least I now know why the IP is not functioning: The camshaft is not turning!

I took off the front rocker arm cover in order to be able to confirm intake valve closure on #1 cylinder (to confirm the PC mark correctly on the flywheel), and based on what I did not see (pushrod, rocker arm and valve stem movement while turning the crankshaft), I removed the access plate on the side of the block just to the left of the IP. (This plate may exist to provide access to the cam in order to run some assessory not included on 003a's). With the access plate removed, I can see the cam. It does not move when I turn the crank via a ratchet wrench. Wow, now we're talkin' about some major wrenchin' to get this baby to run again!

I wonder what happened? Has anyone ever broken a cam? A cam gear or crank gear? Could cam or crank end play have somehow become so excessive as to have prevented the cam and crank gears from meshing? I'm really floored! It looks like the lobes on the part of the cam I can see are no longer centered under the tappets for the #2 cylinder.

I guess I need to go back to the TM-34 to see where to go from here...looks like I will need to separate the engine from the generator in order to get the access I need to remove the cam and tappets. Maybe then I can determine what broke and what it will take to fix it.

Best regards,

Stan

Please let me know your thoughts regarding this situation.

Stan

 

[RichardR]

Stan,
Sorry for the situation with the broken cam. Certainly more of a problem than whatever you might have had with the IP. I haven't ever experienced a broken cam, but I know that other folks have had that problem on similarly designed Onan engines such as the DJC or JC. If I recall correctly, they have found the camshaft broken near the driving gear at the front of the engine.

Do a search on SmokStak. That's where I recall reading about it. I believe it is repairable with a replacement cam, but the whole process didn't sound easy. You can probably get replacement parts fairly easily since Onan made a lot of these engines and many of the parts are interchangeable, even among the military and civilian versions. However, you will have to decide whether it's worth your time and effort to dig into it.
Richard

 

[NJ_Toolnut]

Thanks, Richard.

I'm going to tear it down, determine what happened and what else it may have damaged, then go from there. If the cam is broken, it must be up front near the gear since none of the valve train moves.

Stan

 

[Keith_J]

Thanks, Richard.

I'm going to tear it down, determine what happened and what else it may have damaged, then go from there. If the cam is broken, it must be up front near the gear since none of the valve train moves.

Stan

Check pushrods. All diesels are interference and if the camshaft broke near the drive gear, chances are one or more valves were open causing piston to valve contact. Being a flat head OHV with flat-top pistons, the valves should be fine, the pushrods take the abuse.

 

[NJ_Toolnut]

Thanks, Keith.

I did not know all diesels are interference, but it makes sense given their high compression ratios compared to gas engines. I did know some gas engines are interference, like Subaru boxer engines. From what I can currently observe (admittedly very little) upper valve train appears undamaged. Once I get the pushrods out, I'll roll them on a surface plate to confirm straightness.

I got the shrouds and blower housing off yesterday afternoon. Today I'll concentrate on removing the blower wheel and gear cover.

Quirky note: The top bolt holding the grille to the blower housing must be removed before the blower housing will come off. This bolt threads into a hole in the oil cooler frame. I wasted a lot of time trying to remove the blower housing before discovering this bolt was holding it on. There is now a handwritten note in my copy of the TM-12 about this quirk.

Thanks again for hanging in there with me though this saga. I've got a long way to go before this unit will run again. If the cam must be replaced (as I suspect), I will need to find a replacement, make sure cam bearing clearance is correct, correctly set cam end play and cam/crank gear lash, etc, etc...It looks like I will have to separate engine from generator and rig it off the trailer in order to remove/inspect/replace tappets--this task alone will require considerable thought and effort.

As always, I greatly appreciate all your comments and recommendations.

Stan

 

[storeman]

storeman,

Thanks for confirming you are able to work on these IPs without special tools. I have a lot of confidence that I can either do the same or else make any tools I determine necessary.

I think I read in one of your posts that you have put an IP back together without using a delivery valve spacer. Did it work OK?

sewerzuk,

I don't know how differently the engine in question would have run with the delivery valve spacer, but it does run without it. Seems as I recall in one of the TMs that you replace spacer IF present, implying that some don't have them. I tried to make a couple but chickened out for lack of knowledge of correct material and thickness (and purpose for that matter) As I said, the ones I've seen are all torn up. Good luck. Let me know if you need a short block.
Jerry

 

[NJ_Toolnut]

Thanks, Jerry.

Sounds like the delivery valve spacer is not critical. I wonder why AMBAC designed the delivery valve this way. Maybe it's a buffer, kind of like the recoil buffer in some firearms.

You have a PM regarding the short block.

Stan