Broken camshaft MEP003a

[Dirtykurt]

New guy here, I do a lot of research on this site and always seem to get help just by reading. This time however I had to join as a member to ask a question that I just can't find a definite answer to.
My sitiation is:
My uncle ran "our" generator out of fuel, being I am the only "mechanic" that will touch it out of our group it basically sat for three years air locked.
Last week I went out to the hunting camp to get it going and found no fuel coming out of the injection pump. I pulled it and had it repaired. the guy told me something in the pump was jammed and when I cranked the engine it pretty much destroyed the pump. Luckily he had spare parts and got it fixed. Yesterday I replaced the pump and couldn't get fuel out of all ports. I also noticed that the rockers on #2 cylinder wasn't moving. Figured I had a broken camshaft so I removed the pump and sure enough, it's sheared right at the gear that drives the pump. I found a replace the cam online.
My first question here is:
Will I have to change the button on the injection pump to match the new camshaft?
eyeryting I read in the manuel says "only if the block is changed".
Second question:
what caused the cam to break? Frozen injection pump??
if anyone out there knows please help.
Thanks again and hopefully one day I can help someone here.

 

[Keith_J]

The cam change shouldn't require timing adjustment since it is precision machined. But if th old cam was worn significantly and a new pump timed to it, then you might have an issue with a new cam. It would cause timing to be advanced. I would put a dial indicator on the injection pump pad (mag base) and measure cam lobe height on the old one and compare it to the new. That will show you if you need to change timing buttons.

Cams break on the 003As because it is a long, whippy noodle that also drives the governor at the tail end. Torsional vibration stress. Don't know if Onan addressed it in the later camshaft designs.

be sure to check all pushrods for damage as diesels don't like open valves when Pistons reach top dead center.

 

[Dirtykurt]

The cam change shouldn't require timing adjustment since it is precision machined. But if th old cam was worn significantly and a new pump timed to it, then you might have an issue with a new cam. It would cause timing to be advanced. I would put a dial indicator on the injection pump pad (mag base) and measure cam lobe height on the old one and compare it to the new. That will show you if you need to change timing buttons.

Cams break on the 003As because it is a long, whippy noodle that also drives the governor at the tail end. Torsional vibration stress. Don't know if Onan addressed it in the later camshaft designs.

be sure to check all pushrods for damage as diesels don't like open valves when Pistons reach top dead center.

I am still using the original pump and the original timing button. The guy at he injector shop assured me that the parts he changed would not affect the timing button. As far as a dial indicator on the broken shaft, I doubt it would give me accurate measurements being that the lobe I need to check is on a part of the cam which is only being supported by one bearing. I will mic the two cams lobes and compare them before installing the new cam.
Bent valves.... Fingers crossed. I guess I should look into that. Would airing up the cylinders be the easiest way to insure the valves are seating?
I really hope this goes well, I am sure I can work my way through button issues but I have never done it before. Thanks for the response.

 

[Keith_J]

With bent pushrods, valve lash is way off. Pull the valve covers and compare. Besides, you have to pull each pushrods to swap the camshaft. That and the tappets. Just roll them on a flat plate.

 

[LuckyDog]

I might suggest that when you get it back together with the new cam shaft, do the flow timing check in the TM. Easier and maybe more accurate than the dial indicator.

TM 5-6115-585-34 Page 7-38

h. Adjust/Time on Equipment.


(1) Time the injection pump to the engine by using the proper thickness timing button between pump plunger and tappet (see figure 7-3 3).
Use method 2 if the dimensions are lost, and old pump is being timed, or when replacing either the camshaft or crankshaft:
The procedure says start with a #12 button, but just use your old button. Based on where the marks line up when the flow stops, you will know if you need to change the button and by how much.

That is the procedure I used and it worked well for me.

 

[Dirtykurt]

I might suggest that when you get it back together with the new cam shaft, do the flow timing check in the TM. Easier and maybe more accurate than the dial indicator.

TM 5-6115-585-34 Page 7-38

h. Adjust/Time on Equipment.


(1) Time the injection pump to the engine by using the proper thickness timing button between pump plunger and tappet (see figure 7-3 3).
Use method 2 if the dimensions are lost, and old pump is being timed, or when replacing either the camshaft or crankshaft:
The procedure says start with a #12 button, but just use your old button. Based on where the marks line up when the flow stops, you will know if you need to change the button and by how much.

That is the procedure I used and it worked well for me.

LuckyDog,
Pardon my ignorance but can you post a link to this TM being I am having absolutely ZERO luck finding it. I am sure its right in my face but I am honestly not seeing it. Thanks for the reply.

 

[LuckyDog]

Follow the link in my signature to the Wiki (MEP 002A and 003A).

Second post is by Speddmon. In his signature is links to all the TM's for the MEP002A and 003A.

That is the easiest. There is also forums from the main forum page that have all kinds of TM's.

 

[Dirtykurt]

Follow the link in my signature to the Wiki (MEP 002A and 003A).

Second post is by Speddmon. In his signature is links to all the TM's for the MEP002A and 003A.

That is the easiest. There is also forums from the main forum page that have all kinds of TM's.

For some reason the links I try to click on don't work. I don't know if its a problem with my computer or the site. Is there anywhere else I could get step by directions with pics to do this flow timing?

 

[Dirtykurt]

For some reason the links I try to click on don't work. I don't know if its a problem with my computer or the site. Is there anywhere else I could get step by directions with pics to do this flow timing?

Found it, I never said I was good with computers. haha
Thanks, Luckydog

 

[Dirtykurt]

I am still fighting this demon. Here is a quick run down of what I have going on. I have replaced the broken camshaft, had the injection pump rebuilt, had all injectors tested, (which one was stuck open and repaired). this is my issue... I flow timed the pump as advised and found that it is actually closing late which could easily be fixed with another button however I cant seem to find one. My injection guy, lets call him Joe, tells me that it should still operate with the button we have in it and honestly it does seem to run "pretty good" but the issue I am having is no matter how I try to adjust the governor I cant seem to get it to run without hunting unless I raise the engine speed above 68-70 hertz, this is with and without a load. I have tried every combination of adjustments with Zero success. The generator never had this issue prior to the broken camshaft issue. It always ran smoothly and governed itself well. I actually pulled the front of the engine off today and checked the governor balls to look for flat spots, checked the "dish where the balls ride" foe wear, checked for unusual wear on the fork, everything looks to be in good shape. If I manually hold the throttle lever the generator runs fine and stops hunting. I guess my question here is Could it be that the button in the pump has the flow time so out of wack that it is causing this issue? Any and all opinions will be well used.

I might suggest that when you get it back together with the new cam shaft, do the flow timing check in the TM. Easier and maybe more accurate than the dial indicator.

TM 5-6115-585-34 Page 7-38

h. Adjust/Time on Equipment.


(1) Time the injection pump to the engine by using the proper thickness timing button between pump plunger and tappet (see figure 7-3 3).
Use method 2 if the dimensions are lost, and old pump is being timed, or when replacing either the camshaft or crankshaft:
The procedure says start with a #12 button, but just use your old button. Based on where the marks line up when the flow stops, you will know if you need to change the button and by how much.

That is the procedure I used and it worked well for me.

 

[gimpyrobb]

Do you know what button? I have some.

 

[Dirtykurt]

I would have to check my notes but i do know its the thickest one on the chart.

 

[gimpyrobb]

Let me know.

 

[Dirtykurt]

Code 16 or S according to the chart. If I did my calculations correct.

 

[Ray70]

If all else fails, ebay usually has tons of timing buttons for sale. Try searching Ambac timing button. Can also try Onan timing button as well as MEP-002 timing button etc. I see a 16/S on there, too bad its $59 when other sizes are like $14! You can probably buy direct from Ambac too, that's where I have bought other pump parts from, cheaper than on-line.

 

[Dirtykurt]

I found a complete set on eBay for like 110$. I will be more than happy to buy them if that solves my issue. Does anyone know if this could be causing my hunting issue? I forgot to mention in my earlier post that when I apply a moderate load it bogs the engine down to around 52 cycles. It seems to be starving for fuel. I don't know if the smaller button is causing this too. Any advise?

 

[Ray70]

I can't say for sure if the timing button is causing the hunting/droop problem, but I would definitely suggest correcting the timing button first, then go back and revisit the governor adjustment, if the hunting and excess droop still exists. My feeling is that if you are late on the timing there is a very good chance that is causing your problem. Either way you will need to readjust the governor after you get it timed correctly.

 

[Dirtykurt]

Ok.... Got new timing button in #16. My flow time is much better but still a couple degrees late. I did run it for a few minutes and it performed much better, I did not run it for long being it was getting late and I needed to get home. My question is now that being the pump is not original to the engine and the largest button available is still late on port closing , could I remove a shim between the motor and pump to get more "push" on the button? I know the book says that the shins should not be removed unless the block is changed but.....
what do you guys feel about this? Also if I do remove one is there any way to check backlash on the pump/cam gear? I don't want to cause myself anymore trouble. Or should I just leave well enough alone? I will run it more when I get a chance to make it back to the camp and see how it does, I'd just like some input before I get there. Thanks agin for any info you guys can bring to me.

I can't say for sure if the timing button is causing the hunting/droop problem, but I would definitely suggest correcting the timing button first, then go back and revisit the governor adjustment, if the hunting and excess droop still exists. My feeling is that if you are late on the timing there is a very good chance that is causing your problem. Either way you will need to readjust the governor after you get it timed correctly.

 

[Keith_J]

Shims on the block to pump mounting face are for gear engagement, not time. What I would do is check gear engagement with the grease paint used to set pinion-ring gear alignment and look for residual grease paint in the valleys and crests of the gears. Just bolt the pump up and turn over by hand with glow plugs removed.

If you don't have enough clearance, the injection pump will wear out plus you can put too much stress on the cam, causing it to break. Too much clearance and you risk worn gears...and of course late timing.

 

[Dirtykurt]

Very late update but... I fought the hunting issue for awhile, everything has pointed to a governor issue so I rigged up and electronic governor on it and it’s been doing great! Now I seem to have an oil leak somewhere. Fun fun. Thanks for any and all help from you guys in the past.