AD41P Loss of power

1joeycheng

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Apr 3, 2012
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Good day all. I'm having trouble getting to full power on my AD41P. I've read through posts others have put up on the subject and I'm still hitting a wall. To date...new turbo with less than 100 hrs, turbo rotation visually confirmed at idle, overhauled fuel injectors, "anti smoke" pin on fuel pump is totally free, diaphragm from boost to fuel pump in good condition, new filters air and fuel (all), new fuel hoses.
In "no load" condition achieving 4k rpm is no problem, at sea I cannot get above 2450 rpm. I definitely do not hear the turbo spooling up when underway. From one of the Youtube sites I saw my same engine in no load condition brought up to 4k rpm and I could defintiely hear the turbo, when I do that at home with the boat onthe trailer I don't hear that sweet whine of funtcitoning turbo. I'm at a loss. I beginning to lean toward a compression issue (sigh).
Any ideas? All constructive contributions are really appreciated
 

Scott Danforth

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welcome aboard

what is your boost pressure? before and after the CAC
 

1joeycheng

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Apr 3, 2012
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Hi Scott and thanks for the welcome.

Unfortunately I have no gauges for boost / CAC - yet. I did pull the cover off of the CAC (water side) and saw no sedimentation or obstruction of any kind. The cooler was cleaned during the same time period as the turbo replacement so I guess no surprise there. I was looking at the engine to try and determine a good location for the gauges in question. It looks like there are some plugs on the intake manifold that I could drill and tap to accommodate a gauge but I really didn't see a good location for the inlet to the CAC. Any ideas?
Many thanks.
 

alldodge

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Have a look in these areas, not sure if they can be used or not

41AP.jpg
 

Scott Danforth

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To diagnose diesel issues, you need to take boost pressure at the end of the elbow before the CAC and at the intake manifold.

I would also pull the plug (item 20) and get EGT

You also need to take fuel pressure readings at both the lift pump supplying the main pump as well as the return line.

Most likely your down on boost and your EGT is up.
 

1joeycheng

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Apr 3, 2012
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Thanks for the schematic Scott. Seems funny that the items you mentioned weren't part of the original installation and I agree that these gauges should be installed, even just the EGT would tell you much about overall engine performance. I also agree with your suspicion of low boost and high EGT, now I'm trying to figure out what may be bringing this situation about. I don't see a good way to perform a compression test as there are no indicator cocks on the head. Others have mentioned a potential problem with the fuel pump but after reviewing the schematic for the pump the only fuel limiting device that I can see is the anti-smoke device (pos 4 in drawing). Well first things first. Time to get gauges installed.
Thanks again for the helpful advice. Bosch VE Injector Pump.jpg
 

Scott Danforth

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boost pressure is taken off of the plugs in the CAC (item 11)

EGT is a probe in the exhaust pipe (a test pipe is needed)

compression is taken by removing the injectors.

fuel restriction and back pressure is measured at the fuel lines.
 

bigbrownbuku

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Sep 17, 2004
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The crossover pipe from the turbo to aftercooler is very easy to remove (1 v clamp) and aluminium so a 1/8 pipe tapped hole for boost measurement is easy to create.
The heater plugs in the intake are straight pipe. I have sourced adaptors from greenline in the past. take a plug with you for reference.
 

1joeycheng

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Apr 3, 2012
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Thank you guys for the pointers. I apologize for the delayed response; I'm trying to take care of this between jobs that are taking me out of state. I did speak with a local VP Tech. After reading the report from the outfit that overhauled the injectors he noted that one of the injectors had signs of erosion; this he said is a problem that started in the injection pump and recommended that I remove that and send it in for overhaul. I'm in that process now.
 

Magnus W

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May 16, 2015
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Also, confirm that the engine gets fuel. There might be a blockage in the line somewhere, not an uncommon problem here in Sweden "thanks" to the bio-additives because they degrade and give bacteria/algea and nice place to grow.
 

QBhoy

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Hi
Could be a number of things...
When you are achieving 2k rpm and throttle full open, is there a load of black smoke from the exhaust ?
If there is, I'd suggest it isn't a fueling problem and points towards a boost problem.
If there isn't, it would point towards a fueling problem.
 

QBhoy

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I have a load of experience on the larger TAMD61 model and not too familiar with the 41, but does it have an actuator on the turbo ? Can't think of it does or not. That could be an issue too.
 

QBhoy

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Air filter clean ? Probably pointing out the obvious here. Try running without it. As mentioned, a good indication of what is going on is often told by the exhaust and what's coming out it.
 

1joeycheng

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Apr 3, 2012
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Hello Q and thanks for the suggestions. I recently had the fuel pump rebuilt. I had to make an appointment with the VP shop that does my engine work for install/timing and unfortunately that won't be until May - that time of the year here in So Cal.
 
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