Engine down, blew out all the oil...

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ppillard

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1997 M1078, 3116

Driving home last night, oil pressure warning lights up on the dash. I pull over immediately. Truck idles fine for the second before I hit the switch and I thought it must be a sensor problem. Looked under the cab and the engine bay is covered with oil.

Now I’m trying to finding the failed hose or whatever it was that leaked the oil. Based on the engine bay and the road behind me, it looks as tho all the oil was dumped very quickly.

driver side of the engine is soaked, passenger side is dry. Is there a common oil pressure failure point on these engines? Any thoughts would be appreciated. I was really hoping to avoid filling her with oil, and firing her up (finding it the messy way).
 

coachgeo

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It seems as tho the air compressor is at the center of the soak area, tho I see no signs of failure. Likely a gasket?
sounds like the small metal oil tube from block to the Governor... but that would be other side of engine though... hmmm.


 
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coachgeo

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with all this going on in the front.... check those driveshafts asap... check your compressor bolts... search the cracked cover threads about this.

what fan/clutch combo did you go with? curious of some vibes from old one is what leads to your present issue..... or present issue is an additional symptom of what caused the fan/clutch to be unhappy
 
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frank8003

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foods for thoughts
 

snowtrac nome

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foods for thoughts
it sounds like the governor pressure line but mine blew out the starter lockout switch this winter it made a big mess
 

Ronmar

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Oil line block to governor or oil line block to compressor, both On drivers side, both would dump a lot of oil quickly. The governor line is right between the block and the governor. The oil line block to governor has been a repeated LMTV failure point possibly caused by excessive vibration...
put more oil in it, crank it over and see what sprays:)
 

Awesomeness

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Oil line block to governor or oil line block to compressor, both On drivers side, both would dump a lot of oil quickly. The governor line is right between the block and the governor. The oil line block to governor has been a repeated LMTV failure point possibly caused by excessive vibration...
put more oil in it, crank it over and see what sprays:)
To be clear, this doesn't usually fail by itself. It usually fails because the rear air compressor bracket comes loose, allowing the vibrations to fatigue the oil line (and sometimes crack the front engine cover housing).

In order words, the oil line cracking is the symptom of a different problem, not a failure point on its own.
 

Kbarnes0

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Wondering,
do these engines build decent pressure during cranking? Could use that start inhibit switch by the fuse panel to allow it to crank and not start. Not sure what the minimum amount of oil is to get to the oil pump pick up.

I haven't used that switch yet, but that's what came to mind. After a bit of brake clean and someone to crank might allow you to pin point without to much mess /oil added.
 

ppillard

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Awesomeness, when I first purchased this truck back in Feb, the water pump failed while driving to Dallas from Michigen. Before I made it to Dallas, the starter nose cone broke. Per your suggestion (thanks), I pulled the driveshafts and had them worked over by a quality shop. As I was leaving Dallas for Denver, the alternator mount bolts broke. I figured then I was still chasing collateral damage from the old driveshafts. Now, this week, I just replaced the fan as the aluminum hub ripped away from clutch (I updated to the newer style metal hub and had to upgrade the clutch to fit as well).

For its part, the truck runs very smooth. I have replaced the tires with new, and while there is a very slight vibration at 47 mph, it is gone by 50.

However, it is clear that the truck has ample sign of this driveline cancer. I’m hoping these are residual weakened components of the previous driveline imbalance and once they all expose themselves she will become reliable...?

Assuming (praying) this latest incident didn’t shred my engine. I was able to pull over and shut her down immediately when the low oil pressure light came on. Time will tell.
 

Ronmar

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To be clear, this doesn't usually fail by itself. It usually fails because the rear air compressor bracket comes loose, allowing the vibrations to fatigue the oil line (and sometimes crack the front engine cover housing).

In order words, the oil line cracking is the symptom of a different problem, not a failure point on its own.
Exactly!
 

Awesomeness

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Awesomeness, when I first purchased this truck back in Feb, the water pump failed while driving to Dallas from Michigen. Before I made it to Dallas, the starter nose cone broke. Per your suggestion (thanks), I pulled the driveshafts and had them worked over by a quality shop. As I was leaving Dallas for Denver, the alternator mount bolts broke. I figured then I was still chasing collateral damage from the old driveshafts. Now, this week, I just replaced the fan as the aluminum hub ripped away from clutch (I updated to the newer style metal hub and had to upgrade the clutch to fit as well).

For its part, the truck runs very smooth. I have replaced the tires with new, and while there is a very slight vibration at 47 mph, it is gone by 50.

However, it is clear that the truck has ample sign of this driveline cancer. I’m hoping these are residual weakened components of the previous driveline imbalance and once they all expose themselves she will become reliable...?

Assuming (praying) this latest incident didn’t shred my engine. I was able to pull over and shut her down immediately when the low oil pressure light came on. Time will tell.
Man, that's brutal. It's crazy how similarly these stories go down... I was right in your shoes several years ago.

I know it sucks, but I would check the driveshafts and u-joints again. You shouldn't have mysterious residual issues that just haven't been discovered yet. If you're still breaking things, something is still wrong, or is wrong again. In one of the Army's engineering reports, soon after fixing a bad driveshaft they discovered the problem had reoccurred, though to a smaller extent.

The nature of the driveline (e.g. geometry, RPM, forces, etc.) is operating very close to its limits. By switching to the heavier duty shafts and u-joints ("D" stamping on the data plate), they helped pull back from those limits a little more. However, the system is not going to tolerate as many issues as a driveline that has a lot more margin, so perhaps just a single thing being wrong (e.g. u-joint cap not getting grease, a little wear, etc.) could push it over the edge... and then it seems to be a cascading effect that one issue worsens the next (e.g. works the u-joint cap bolts loose), and that worsens the next (e.g. increased slip joint play), and it builds quickly until things get destroyed.

My truck felt like it was running ok when I destroyed the engine. You may not be able to tell. Empirically, this happens to enough people that it must not be super obvious.
 

ppillard

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Evergreen, CO
OK, here's the plan:
1. Pull the oil pan and inspect the crank journals to determine if further work on the engine is even worthwhile. If journals fail inspection, search for replacement engine.
2. If journals are ok, replace oil pan, pour in some oil, crank engine with inhibit switch engaged to confirm location of leak. Order replacement parts.
3. Pull driveshafts and take to be re inspected, balanced, and be sure to have the splines checked.
 

Reworked LMTV

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Man, that's brutal. It's crazy how similarly these stories go down... I was right in your shoes several years ago.

I know it sucks, but I would check the driveshafts and u-joints again. You shouldn't have mysterious residual issues that just haven't been discovered yet. If you're still breaking things, something is still wrong, or is wrong again. In one of the Army's engineering reports, soon after fixing a bad driveshaft they discovered the problem had reoccurred, though to a smaller extent.

The nature of the driveline (e.g. geometry, RPM, forces, etc.) is operating very close to its limits. By switching to the heavier duty shafts and u-joints ("D" stamping on the data plate), they helped pull back from those limits a little more. However, the system is not going to tolerate as many issues as a driveline that has a lot more margin, so perhaps just a single thing being wrong (e.g. u-joint cap not getting grease, a little wear, etc.) could push it over the edge... and then it seems to be a cascading effect that one issue worsens the next (e.g. works the u-joint cap bolts loose), and that worsens the next (e.g. increased slip joint play), and it builds quickly until things get destroyed.

My truck felt like it was running ok when I destroyed the engine. You may not be able to tell. Empirically, this happens to enough people that it must not be super obvious.
It's the driveline domino effect. It makes sense. The resonating / rotating forces continues like jack hammer until something extinguishes the force. Things that resonate at or around the frequency of the oscillation will receive almost the full force. So, in testing, we need to detect forces at the common failure points. I think the air cab may disconnect us a bit.

I just got driveshafts back from the shop. 2 were good, one was way off.
 
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ppillard

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Location
Evergreen, CO
By 'residual issues' I mean that accessories, bolts and such were weakened/loosened beneath spec while the vibe was present, and thus still ready to fail even tho the offending vibration was removed from the scenario, albeit at a much later time. Those components are no longer torqued to spec and rated for the strain of service duty. That's what I'm calling collateral (long term) damage of the initial vibration.
 
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