803 Bogs Down and dies at 85% Load

[Guyfang]

This is what I put my money on for the reason for the broken rocker.

I just got a mail from someone who used to do QA/QC on reset assets here in Germany. He said he saw several times, engines with this type of damage due to shock loading. In a facility that shall remain unnamed, work done by a major defense contractor that shall remain unnamed, this problem cropped up at least 4 times in less then a year. He was sent to check out the problem. It seems that the largly untrained work force, was doing a Pre- inspection of units, to determine what needed to be done. And a load test is performed when the gen set is ready for shipment. the personnel there shock l0oaded the gen sets, to "test" the overload relay, and to "insure reliability". The quotation marks are his, not mine.

Its possible I guess. Worth keeping in mind. Shock loading is something I have never liked, done rarely, and only lightly over loaded.

For what its worth.

 

[Demoh]

So you are saying this about the reason for the rocker and not the reason for the valve kissing the piston right?

 

[Guyfang]

Yes, the rocker arm.

 

[Demoh]

Yes, the rocker arm.

That being said, what do you and/or experts that were to perform the loading, what would be a safe step for loading up a generator to 100%? is 2000watt resolution too big of a jump when going from 0-10k? Reason why I am asking is the swift-e that I have involves a whole lot more switch toggles to work at 1kw resolution instead of going down the line of 2kw switches. The "simultaneously turning 2kw off while turning 1kw on" in order to go up by 1kw gets annoying. But if its an annoyance that I need to deal with then I would deal with it.

 

[USAMilRet]

Problem just cropped up. I was working on the piston rings right now and the TM indicates that the 2nd ring goes in with the inside notch facing up. The ring though says that the notch goes down if you follow the ring manufactures marking of the ring with the word TOP on it. I am going to see if I can get a better resolution from another TM.

Resolved: Will just use the manual. Does not matter what they look like (if they are the right ones) but the only fit in one grove each.

 

[jamawieb]

Also remember that there are mistakes in the TM so don't always trust them but 99% of the time they are correct. Just wanted to throw that out there.

 

[USAMilRet]

Well, due to yesterdays fiasco with the rings in the nr 2 piston, I decided to pull the remainder of the pistons to see if my suspicions about the rings were correct. Well, they were, As you can see in the following photos, the ring openings are nowhere near where they are supposed to be. The first ring (oil ring) is supposed to offset 45 degrees from the piston pin, while the second ring opening is supposed to be 90 degrees from the first (oil ring) opening or 135 degrees from the piston pin. The third ring opening is supposed to be 90 deg forward of the 2nd ring opening which is 90 deg forward of the 1st ring opening which is 45 deg offset from the piston pin.

This is what I was provided with today for my amusement.

 

[USAMilRet]

Piston Number 3



Piston Number 1



Piston Number 4. At least they had the decency to offset the oil ring about 120 degrees.




Rod Bearings:

 

[USAMilRet]

The ever present TDC that I like to maintain every time I have to remove or install a component.






I decided to partially pull the cam shaft so that I could take some measurements. Had to pull the Governor assembly first and that was rather easy. Wish I took some pics. What I found is that this thing is fresh out of a box. If I opened a new box with a cam shaft in it, these are the specs that it would have. Everything in spot on or within .001in of spec max.



Finally something starting to look up.

Pictures of the crank shaft through the piston sleeves.





After cleaning the head:

 

[USAMilRet]

Piston rings:

Cleaning the pistons and rods.
​

 

[USAMilRet]

This is the number three piston before it is cleaned. Notice anyting here about the piston? All the clues have led us here to the answer to the puzzle. At least I hope this is the answer.



I am telling you that all the clues are right here. You just have to see or not see them.

My ring slot cleaning tool from years ago. Part of it seems to be missing....



Checking piston specs which are just as spot on as the cam shaft measurements. Another good sign.

 

[justacitizen]

i don't think those bearings are as good as you think. "sorry" i swear i can see yellow metal in at least one. i don't think this was a pristine new engine as you think it was but no matter as it will be as new as you want to make it. i think the cam looks like it has some hours on it too but i agree it doesn't need to be replaced.

 

[USAMilRet]

Some of the measuring tools used.




Rings cleaned up and ready for re-installation. Notice the different cuts on the rings and also the markings "TOP" for installation assistance.






The completed piston, clean and ready to be re-installed.




I have decided at this point that given the specs of the cam shaft, crank shaft (measurements I could get), and the piston measurements...….these three items being within specs and almost exactly on spec satisfies me that I do not have to tear this down any further than where it is now.

 

[USAMilRet]

i don't think those bearings are as good as you think. "sorry" i swear i can see yellow metal in at least one. i don't think this was a pristine new engine as you think it was but no matter as it will be as new as you want to make it. i think the cam looks like it has some hours on it too but i agree it doesn't need to be replaced.

There are two spots that I can start to see copper. And I do believe that you are correct and that these bearings were never replaced because they sure have more than 15 hours on them, but I can believe the 212 original hours. The specs on the cam shaft, crank shaft, pistons are all almost exactly spot on. No wear. I can not explain the bearings but I have a suspicion that I have to investigate further to determine if it is of consequence.

 

[justacitizen]

yea who knows what was put in it. i don't think 212 hours would wear the bearings like that either and bearing wear would support the low oil pressure problem. have you pulled a main bearing for inspection? also have you disassembled and checked the oil pump for wear?

 

[USAMilRet]

yea who knows what was put in it. i don't think 212 hours would wear the bearings like that either and bearing wear would support the low oil pressure problem. have you pulled a main bearing for inspection? also have you disassembled and checked the oil pump for wear?

i do not have the ability to remove the main bearings because of lack or certain tools and I`d have to pulll the engine from the generator. I do not have a means of removing (lifting them) out.

Visual inspection of the cam bearings, from what I could see, indicated no abnormal wear seen or felt.

 

[USAMilRet]

What I can say is that if the bearings were worn, it would show during the backlash chech of the cam/crank shafts. Backlash is also within specs.

 

[DieselAddict]

Did you check the ring gap?

 

[USAMilRet]

There are many gaps. Are you speaking of the gap in the piston for the rings (measured) (those are all .080, .070, and .156 in respectively), the gap as shown here?

https://www.aa1car.com/library/ring_end_gap.htm

.......which leads to where to put the ring on the piston for measurement....

If the gap between the ring ends, then no, on my today list because I have to find the correct spot.

 

[justacitizen]

incorrect info so deleted it