Combat Troop Needs Help

[cowboy832]

I am deployed to Iraq for Operation Iraqi Freedom. I am a gunner on an m-1114 hmmwv(hummer) with a 6.5 turbo diesel. The engine has a terrible knocking sound(detonation?) and considerable loss of power. It doesn't smoke, and seems to run fine except for the noise and loss of power. My maintenance support team has no clue what it may be. They have allready replaced the injector pump and all the injectors to no avail. They ordered another set of injectors, but I have my doubts that they will fix the problem. I was thinking it might be the timing, but I really don't know. I asked the mechanics about the timing, and appareantly they dont have any way to check it, and don't know how even if they did :confused: . What do you guys think could be the problem? My life, and the lives of my crew are on the line in a substandard truck...Thanks for any help. :cool:
Sgt. Rob Kight
U.S. Army
Camp War Eagle, Iraq

[More Power]

Some years ago I visited a local diesel garage, and saw a truck in the bay that was producing a loud and disturbing knocking sound. It sounded to me like a main or rod bearing had a major problem.

The owner came over and scarily revved the engine several times, and the knocking went away for about 5-10 seconds, then returned.

On closer inspection, they determined that an injector was leaking fuel between injection cycles, which produced the knock.

You can determine whether you have an injector with a similar problem by loosening one injector fuel line fitting at a time, till you either discover the bad injector or eliminate all eight injectors as the cause. This is like pulling spark plug wires to find a bad plug. The injector can't "pop" when the fuel line is loosened.

MP

[ 07-01-2004, 06:49 AM: Message edited by: More Power ]

[cudaaa]

Going with MorePower If you crack each injector line untill fuel comes out one at a time with the engine running and the knock goes away try a new injector. If the knock is still there after that the problem is internal possibly rod bearing or piston pin. Hope this helps.

Thank you and everyone over there! Thanks again cudaaa

[rjschoolcraft]

If it's not the injectors, it could be the timeing, as you surmised.

You could loosen the pump and rotate it (1 mm = about 2 deg) to passenger side (to retard timing). Tighten every thing down and start it to see if that helped. If it gets worse go the other way a little. Be careful. Too much advance will be very bad!

[moondoggie]

Good Day!

1. Does your Hummer have a DS-2 (mechanical) or DS-4 (electronic) IP (injection pump)? This could affect future advice we can give.

2. To add to Ron's input: Retarding the timing as he described won't (I don't think) adversely affect anything except power. If you go too far, you'll probably start to see lots of white smoke that won't clear up until it's at full operating temp.

An opposite example of what I'm describing: My daughter's 89 pickup was smoking white on start-up. I know you shouldn't do this, but I loosened the IP & advanced it a couple degrees. The white smoke is gone & no adverse symptoms at all. I know I should have it properly timed & will someday, but sometimes (like when they're shooting at you) you just need the quick fix.

I would guess that this would work regardless if you have mechanical or electronic IP.

2. Don't believe the press: Most of us back home are four-square behind you folks & what you're doing - dxxx proud, in fact!

Blessings!

Brian Johnson, #5044

[morgan]

I don't know all the differences between the civilian GM truck 6.5 and the military Humvee, but I know that broken vacuum pump might cause similar symptoms.

My bro-in-law and cousin just got back from Fallujah a few months ago with the 82nd Airborne. Kimberly Hampton's funeral was held in my church. We are praying for all of you and that your equipment will service you well!! That is some nasty sand they got over there.

God Speed. Please let us know how things go with your mission and your truck.

[cowboy832]

I will have to check all the sugestions out in the morning when the mortars stop falling on us. After I re-read my post, I realized that I forgot to mention that when the engine is under load, like accelerating, the knocking sound kinda fades away, then fades back. I don't know if that helps with the diagnosis or not?...Thanks for the support.
Sgt. Rob Kight
U.S. Army
Camp War Eagle Iraq

[Dewey Faircloth]

My grand son is a Marine,and is near you.
Pray for all the TROOPS daily.
Sound like you have a bad injector.

WE SUPPORT OUR TROOPS!!!!!

[tom.mcinerney]

Sgt Rob Kight--
Try to have all the injectors checked IN PLACE as suggested by MorePower/Cudaaa above. {At least, check until problem found/fixed!}.

If you need to replace one or more injectors, keep in mind that a smallish bit of sand in an injector can make it develop the leaking issue described above. The troubleshooting test of cracking loose the injectors is, in contrast, relatively risk-free, since hi-pressure fuel will push any contaminants out. It's damn near impossible to swap an injection pump without risk of contamination; care can make an injector swap do-able.

Thanks, and good luck to you.

[whatnot]

If it has a vacuum pump, try pulling the accessory belt and starting the engine. If the noise is gone then it is probably a bad vacuum pump. (or other belt driven accessories)

[G. Gearloose]

Also check the rubber isolated crank pully..it makes a racket when it fails

B-safe , wish you all best - and thanks!

Cowboy, whats the address to send your unit some goodies?

[ 06-30-2004, 05:23 AM: Message edited by: G. Gearloose ]

[cowboy832]

G. Gearloose,
My address is:
Sgt. Rob Kight
C.Co 1-12 Cav 1CD
Unit # 90004
APO AE 09373

The U.S. Postal service won't allow anyone to mail anything to a deployed military unit without a specific persons name in the address anymore for security reasons.

[moondoggie]

Good Day!

cowboy832: Were we able to help? Is there anything else we can do?

I don't want to interrupt your busy time, but if you have a few moments, please let us know.

Blessings!

Brian Johnson, #5044

[Eric Selinger]

Cowboy,

Check the flexplate! I bet it's cracked all the way aroung the bolts. see if you can remove the dust shield and shake it back and forth.


I hated that sand.. :cool: