D11N governor issue

[Rihpper]

Hello all, we have a D11n #74z00648 with the 3508
Mechanical engine that has I believe a governor issue, the symptoms are lack of power and slow acceleration. We use it it for deep ripping and if you get moving and the rpms up before the ripper is lowered it seems to keep power but once it slows down enough you can feel it lose power and it won’t speed up to full rpm until you raise the ripper. I thought I found the problem and replaced the diaphragm on top of the governor with the cat rebuild kit and it ran great for a month, then same symptoms came back. Replace it again and it ran great for a few days, replaced it a third time it ran good for half a day. Finally I took out the governor diaphragm and put some oil on it and it ran great for a few hours then back to the low power if the engine is under load at low rpm. We have changed fuel filters and the transfer pump, checked fuel rail pressure. Quinn Cat came out and couldn’t help. Any suggestions would be greatly appreciated.

 

[Rihpper]

Does anyone have any ideas of what my next step should be?

 

[Mobilewrench]

This may sound simplistic. But, if you have gone through the governor three times... I would check compression.

 

[Coaldust]

This thread is a lot different than the typical “ my 50 year old neglected backhoe is low on power, please help” thread.

In on page one!

 

[Coaldust]

Holy Cow! Ripper Cat down! Don’t panic! We totally got this.

I would start ruling some other things out before messing with the gov any more. Sounds like you are messing with the AFR control diagram. Which may help temporarily, if you are dealing with a low boost issue.

I’d check and record converter stall speed, boost pressure and take cylinder temp readings, exhaust temp readings and compare to the test specs in the TMI.

Make sure you have full rack travel and not a bunch of worn out linkage.

I would look carefully for a boost leak.

Nige will be along shortly to straighten this mess out.

 

[Mobilewrench]

I beat you to the thread, Coaldust, but I think you beat me in the diagnostic advice. I doubt that it is a boost issue. The n series has two double sets of silicone orings in the adapter between the turbo and intake. The weak link is the paper gasket on the intake and the serious chance of the bolts holding it in place coming out. But, if he spent that quality time with his injection pump; he would have seen that failure.
I am with you on the converter.
Rhipper ? I am a little confused by the original post. You say ripper up.and ripper down. I assume ripper down means fully engaged in the dirt and rock. So if there isn't a load on it with the ripper down; you can still build up rpms and power? But it all fails when you try to go?

 

[Rihpper]

Thank you guys, yes I checked that I have full rack travel. And I’ve already replaced the (very expensive) silicone o-rings on the turbo pressure side. (That’s what’s the guy from Quinn recommended). I haven’t spent much time on the governor, the diagram I’ve changed is a 10 minute job, that I can change with it in the machine, Is there a common internal failure point in them?
Mobilewrench , I meant that if I hit a hard spot in the ground while ripping, if it losses enough rpms it won’t build rpms and power even after I’m through the hard spot. I have to raise the ripper almost completely out of the ground, then it will rev up and I can start over. Basically it probably makes 80% power, if I pull 90% it cuts back to 50% until I reduce the load to 15% then it’s back to 80% if that makes sense.

 

[Nige]

G'day folks.
First question is did the dealer guy who came out to the machine measure the boost pressure.?
I'd like to see some boost numbers first and then start to have a bit of a think about it. Are we chasing a boost leak or a lack of fuel.?

The above aside, the 3500 MUI engines have a convoluted linkage connecting the Woodward governor to the injectors, especially for the left side of the engine (governor is mounted on the right front corner). Those linkages have more joints in them than you can shake a stick at. It might pay to start pulling covers off and taking a good close look for play in the linkages.

When it comes to checking/adjusting the governor itself (and the injector rack linkages) you need a genset engine guy, because most mechanical gensets have 3161 Woodward governors installed, just like this engine. The added complication on this particular engine installation is that it is not designed to run at a constant speed like a genset engine. DO NOT try to make adjustments to the governor.

EDIT: How many operating hours does the engine have on it, both total accumulated hours and hours since the last time it was rebuilt.?

 

[Nige]

This is what you're up against. If that sight does not frighten you then nothing will...........
All that lot has to be correctly adjusted AND with zero play in it before you even get to setting up the injectors.
And we haven't even mentioned the governor yet......
It's not something you can do with a manual. It's more of an art form with a bit of witchcraft thrown in.

Linkages like these were in the 3516 MUI engine in the first model 994s. In the dealership we had a couple of guys from the fuel injection shop who would go to site and do the adjustments/settings on every MUI engine that went out after rebuiid (and that was in spite of the fact that every engine was dyno run). I remember one of them telling me that the "settings from the manual" were just a starting point for setting it up in a machine as far as he was concerned, because every machine behaved just a bit different.

One of the difficulties as I recall was to get the left bank of the engine (opposite side to the governor and operated via the cross-shaft) to respond the same way as the right bank.

 

[Nige]

If I understand the OP correctly he gets in a position with the ripper in the dirt where the engine RPM dies (for whatever reason) and will not recover unless he raises the ripper out of the ground. Once the RPM has sufficiently recovered he can drop the hook again.

Question to the OP. When the engine loses RPM with the hook in the ground does it black smoke like a sunamabitch.?

Also how many hours on the injectors and when were they last set/adjusted.?
Hours on turbos.?

 

[Rihpper]

Nige, yes boost was ok when it was making power, I forget the exact Number, 27lbs maybe? When it would lose power it would of course lose boost as well. As far as hours I’m not sure. Meter shows 17k, engine was rebuilt by Empire Cat in 2006.

 

[Rihpper]

.

 

[Rihpper]

 

[Rihpper]

No, there is very little smoke. When it loses power.

 

[Nige]

99W01763 - that's the original engine from when the tractor was built in 1989. If that machine only has 17k on it by now I'll eat my hat.
If it was in Empire's territory in January 2006 it was most likely working in one of the copper mines in Arizona working 24/7 and clocking around 7k hours a year. I'd be surprised if both the machine and the engine are not closing in on (or past) 100k hours by now.
Even if the number of 17k is only since the last rebuild/dyno test by Empire and is a good number that engine ought to be weil tired by now.

27 psi (maybe) of boost doesn't cut it I'm afraid. Can you ask whoever came out to it for a hard number.?
Full load boost spec is 43.3psi and at converter stall (which is how I assume the Quinn tech measured it) the spec is 39.7psi with an absolute minimum of 33.7psi.

I think you are missing a significant slice of boost somewhere.............

 

[Rihpper]

Yes it came from Arizona, and I’m sure it has tons of frame hrs, we had service records from the mine but they got misplaced in a move... I will try and get good boost readings. Thank you!

Edit. I was pretty sure that the boost numbers were within spec...

 

[Nige]

Yes it came from Arizona, and I’m sure it has tons of frame hrs

And the engine is the original S/No, so at least some parts of it must have the same hours as the frame surely.?

 

[Rihpper]

Yeah, I didn’t realize it was the original engine block. So It was actually Holt that came out and they did not record any boost readings. I will try to get it tested again next week. Also, one other thing, if it’s not started for a few days it will smoke white smoke out of the left exhaust just until it warms up. No excessive smoke after it’s warm.

 

[Nige]

Also, one other thing, if it’s not started for a few days it will smoke white smoke out of the left exhaust just until it warms up.

Not unusual. What did I say above regarding the convoluted control linkage from the governor via the cross-shaft to the left side of the engine..?

It sounds to me as though the first thing it needs is: -
1. Injector control linkages (see post #9 above) inspected, joints checked for wear, then correctly adjusted.
2. Injectors set.
And they need doing in that order. There is no point trying to set the injector adjustment until the linkages are correctly set.

My doubt regarding the injectors at the moment with the last time that engine was rebuilt apparently being in 2006 by Empire, and with probably 17k hours on them since that rebuild is that they are fcuked.......... If CORRECT adjustment as above does not sort the smoking issue then you're probably going to be in for 8 injectors @ $700+ each Reman or $1400 each new. FYI a replacement Woodward governor is $14k and there is no Reman option any more. TBH the whole engine is probably ready for rebuild with those hours on it.

You really need to find a good genset fuel injection guy, because this would be right up his street. AFAIK there are still a load of emergency generators around with 3500 MUI engines installed in them.
As I mentioned above setting up that fuel control system is a cross somewhere between an art form & witchcraft. There are two chances of a Cat dealer these days having a technician familar with this setup - Slim & none. And Slim just left town.

 

[Nige]

Forgot to ask. When was the last time that the engine valve and fuel injector adjustments were performed.?