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Author Topic: What causes loss of power?  (Read 5052 times)
eagle19952
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« Reply #30 on: May 27, 2012, 10:27:15 AM »

Block the wheels.Use BIG blocks.
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Mike in GA
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« Reply #31 on: May 27, 2012, 12:08:08 PM »

Scott-
      I don't remember anyone suggesting this, but a cracked exhaust manifold will put you down on power, and sometimes they are difficult to detect, at least the small cracks. On many DDs the manifold will have a tendency to crack at the frontmost bolt area nearest the fuel pump, secondary filter etc.
Robs the turbo to boost, etc.
     This actually happened to me, and I went along that way several weeks before someone heard me backing up and thought he heard that funny noise.
     Just FWIW
Mike in GA
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belfert
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« Reply #32 on: May 27, 2012, 12:56:59 PM »

Block the wheels.Use BIG blocks.

I suggest the big black chocks designed for big vehicles.  About $10 each from a truck parts place.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #33 on: May 27, 2012, 01:31:54 PM »

If you need chocks then go buy them. I am not suggesting extra safety is bad. I would think park brake on and transmission in park and some wood chocks would be plenty. The store bought ones look nice and if you need them for other things spend the money. For this test and by reading your posts you may want to save the money and make your own.

John
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John Riddle
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bevans6
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« Reply #34 on: May 27, 2012, 01:56:05 PM »

I think the fundamental reasons (given it worked before, doesn't work now, and nothing was done to change the rack or the governor settings) for lack of power is lack of air or fuel.  Lack of air would result in black smoke, but there is no smoke.  Lack of fuel would result in no smoke for a given amount of air, so I would continue to look for what is restricting fuel flow.  I would, at this point, be measuring fuel pressure, pulling out and replacing (probably not trying to clean) the screen filters in each injector base, and if that didn't change anything pulling and testing each injector for fuel quantity per stroke.  And never ever putting anything other than diesel in it (just my opinion, that and two bucks will get you a cup of coffee...)

72 mph is around 2200 rpm in an MC-X with 3.7 diff and 12R-22.5 tires, so that's what I would expect with a normal 2200 rpm governed speed.  It should get there no problem, and go faster if you turn up the governed speed.  If it can't make that, then I agree you have a loss of power, fwiw.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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Larry B
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« Reply #35 on: May 27, 2012, 07:06:00 PM »

Hello Scott--- After reading Brians post saying your problem is fuel shortage have you considered that your tank pick up tube might be partly plugged with some residue from your bad bio fuel mix that you taked about in a previous post? A while back I suspected I had a pick up tube problem. I removed fuel, tank filler connection and fuel sender. With a light and a long inspection mirror I could follow pick up tube in tank. The tube goes down wall, across floor (16 to 18") up an inch or so and through a hole in the baffle plate. After that I do not know.where it goes. This design makes a low spot for things to settle (thick residue).Your unit and mine are both MCI and close to same year. There is a good chance your tank is same design.  You could check this with a temporary pick up tube. Check fuel pressure reading now with guage at secondary filter at 1200 rpm say. Rig up a tempory pick up tube with a piece of fuel hose through tank fill and connected to pump suction line outside tank. Reprime engine and start. Check fuel pressure at secondary filter again at SAME rpm as before. If your pressure reading is higher than before or if throttle response is better, you might have a partly plugged pick up tube. Take it for a drive and see if is any better. Wire up hose so can't come out. Stuff rag around hose. wire rag so can't go in tank.
     Larry B
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Scott Bennett
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« Reply #36 on: May 28, 2012, 06:59:43 AM »

Brian, thanks for the info on governed speed. Will be checking RPM this week and posting results.

Larry, I have already blown the lines of the entire fuel system out with 120 psi of compressed air backward from filters to tank (filters removed). Didnt make any difference. I think I'm getting to governed speed but it's slow getting there. Injector screens could be an issue I suppose. But my first checks will be air stop skinner, RPM, and throttle assembly. From there I start thinking rack readjustment Or injector screens. Where do I plumb in a fuel pressure gauge?


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Scott & Heather
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« Reply #37 on: May 28, 2012, 07:03:14 AM »

Mike, a cracked
Manifold is something I would see soot buildup from right? Should see soot all around the leak? I do have a small exhaust leak on my elbow joint that is likely 1/16 of an inch. Tiny but it blows out enough to soot the area. But this leak has always been there without this much power loss in the past. Anyway you guys have given me some excellent advice and things I try so I'll get busy and post the results. Thank you so
Much for the help
On this guys.


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Scott & Heather
1984 MCI9 6V92-turbo with 9 inch roof raise & conversion in progress.
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lostagain
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« Reply #38 on: May 28, 2012, 07:06:00 AM »

You can easily screw a press. gauge into a spare port on top of the secondary fuel filter. That will be under fuel press. downstream of the pump.

JC
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JC
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« Reply #39 on: May 28, 2012, 07:59:16 AM »

You mean the port with a brass fitting and you unscrew a brass cap to get to the fitting? I use that port to prime. What was it for? And did you say it will measure fuel pressure between the filters and the motor?


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Scott & Heather
1984 MCI9 6V92-turbo with 9 inch roof raise & conversion in progress.
http://www.scottmichaelbennett.com/p/our-bus.html
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« Reply #40 on: May 28, 2012, 08:03:26 AM »

Yes and yes. That will tell you the fuel pressure. Make sure you put it on the secondary filter, between the pump and the heads. Putting it on the primary filter would show you a vacuum.

JC
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JC
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Scott Bennett
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« Reply #41 on: May 28, 2012, 08:38:28 AM »

Yes and yes. That will tell you the fuel pressure. Make sure you put it on the secondary filter, between the pump and the heads. Putting it on the primary filter would show you a vacuum.

JC

Oh dear. That would definitely confuse me.


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Scott & Heather
1984 MCI9 6V92-turbo with 9 inch roof raise & conversion in progress.
http://www.scottmichaelbennett.com/p/our-bus.html
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thomasinnv
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« Reply #42 on: May 28, 2012, 12:54:34 PM »

Scott, I would highly doubt a cracked exhaust. Low boost (caused by a cracked exhaust) would show black smoke under throttle. Since you say you have no smoke, you are dealing with a lack of fuel, not lack of air. Lack of air will cause excessive smoke, period. You need to figure out why you are not getting full fuel. Start with Cliff's suggestions. These mechanical engines are pretty simple...air plus fuel equals bang bang.
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There are three kinds of people in this world....those that make things happen, those that watch things happen, and those that just wonder what the heck is happening. Which one are you?

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Scott Bennett
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« Reply #43 on: May 28, 2012, 01:53:00 PM »

My sentiments exactly! Love the "air and fuel and bang bang". Classic :-D


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Scott & Heather
1984 MCI9 6V92-turbo with 9 inch roof raise & conversion in progress.
http://www.scottmichaelbennett.com/p/our-bus.html
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Scott Bennett
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« Reply #44 on: May 30, 2012, 03:48:39 PM »

Here's a video of my startup and throttle push. Seems to go up to RPM and drop fine....I think. Notice the rough running at the very beginning followed by a brief "burp" and then runs smooth and no smoke? Weird. Never used to do that. Undecided

http://www.youtube.com/embed/zzRnI25nYmw
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Scott & Heather
1984 MCI9 6V92-turbo with 9 inch roof raise & conversion in progress.
http://www.scottmichaelbennett.com/p/our-bus.html
˙ǝɯoɔlǝʍ suoıʇɐuop ˙snq ʍǝu ɐ pǝǝu ʎlqɐqoɹd ll,ǝʍ 'sıɥʇ pɐǝɹ uɐɔ noʎ ɟı
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