M1151A1 engine shaking

[#Rickey_Bobby2252017]

I need help y’all. I’m in the Georgia National Guard as a 91B wheeled vehicle mechanic. We have an M1151a1 in the shop. The engine is shaking violently, and cannot figure out what the problem is. We’ve already checked the fluids, belts, pulleys, engine mounts, etc. any help would be greatly appreciated.

 

[TOBASH]

Harmonic Balancer failure?

Flex plate lost a balance weight?

Crank shaft failure.

Piston or push rod failure.

Thanks to you and your brothers and sisters for your service.

 

[DREDnot]

Is it misfiring? Is it chugging or have a pulsing feel when you hold your hand near the exhaust pipe outlet?
More than likely a clogged injector or two but strange things like tobash mentions do happen.
Mine had a broken alternator bolt that allowed the alternator to vibrate so bad that it was blurry to look at but it sounds like yours is worse than that(whole engine jumping)?

 

[Retiredwarhorses]

Have your maint officer call my shop...assuming It’s a Warrant Officer If it’s a Maint Unit.

 

[#Rickey_Bobby2252017]

Harmonic Balancer failure?

Flex plate lost a balance weight?

Crank shaft failure.

Piston or push rod failure.

Thanks to you and your brothers and sisters for your service.

It’s my pleasure. Thank you for your support. I will check all of those to see. I’ll get back with you when we run some tests. Thanks again!!

 

[#Rickey_Bobby2252017]

Is it misfiring? Is it chugging or have a pulsing feel when you hold your hand near the exhaust pipe outlet?
More than likely a clogged injector or two but strange things like tobash mentions do happen.
Mine had a broken alternator bolt that allowed the alternator to vibrate so bad that it was blurry to look at but it sounds like yours is worse than that(whole engine jumping)?

All the bolts are present , and in good condition. It feels more like the harmonic balancer, but I could be wrong. When looking at the engine, the whole thing is jumping/vibrating. So much so, that even the exhaust and tranny are vibrating like crazy. I checked the engine mounts and trans mount to ensure they were tight. It does have any surging, or misfire type sounds or antics.

 

[#Rickey_Bobby2252017]

All the bolts are present , and in good condition. It feels more like the harmonic balancer, but I could be wrong. When looking at the engine, the whole thing is jumping/vibrating. So much so, that even the exhaust and tranny are vibrating like crazy. I checked the engine mounts and trans mount to ensure they were tight. It does not have any surging, or misfire type sounds or antics.

 

[TOBASH]

Retired War Horses is a respected member of this forum. He restores these vehicles and has great experience.

He offered to help you, and as such I would accept his offer and call him.

PM him to get his number, or PM me and I will give it to you. ( I don't post numbers on the Internet.)

If I was a betting man, I would go all in on harmonic balancer. They cause severe vibration issues when they fail. It is rare to have a failure but it does occur. Severe vibrations usually have to do with balance. Only a few things affect balance. Harmonic balancer, crankshaft loss of balance due to catastrophic issues like cracks and bearings, flywheel off balance, broken rod.

IMHO.

Call RWH, because he is solid in knowledge and knowhow. You can view his website at www.RetiredWarHorses.com

Please post what your issue was. I for one am curious.

 

[DREDnot]

Retiredwarhorses is the best resource.
That notwithstanding...some of my comments will be to make sure we all know exactly what you are describing. One mans bad vibration might be another mans misfire. So it sounds like the engine is running smooth on all cylinders from your verification. So the slipped harmonic balancer is most likely.

I have seen a missing/loose torque converter bolts act in a similar fashion. So that may be worth a look see.

When you say the motor and trans mounts are tight, Did you just check for loose nuts and bolts? or did you get in there with a pry bar to verify that the rubber hasn't separated from the metal?
A bad mount usually looks just like a good one visually. The vibration could have caused the mounts to separate later so there could be multiple issues.

Ive had more than one jeep that had the slipped harmonic balancer and separated motor mounts. Felt like a new vehicle when both got replaced.