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DT466 Question

7K views 18 replies 8 participants last post by  bpogue 
#1 ·
The last week or so I have noticed my 4700 is definitely down on power when pulling loads. Max boost is only about 9 pounds now. It used to max out at 22 or so, and pull 17 or 18 on a regular basis. I went through a tank of fuel and changed the fuel filter. I checked the air filter and cleaned it (thought it didn't really need anything). I can't find any obvious boost leaks anywhere. The truck sounds fine while driving. I do have to watch the EGTs more carefully now. The only thing I found is a small exhaust leak on the outlet of the turbo. I broke the bolt on the clamp so I will have to replace the clamp to fix it. But since the leak is after the turbo, I don't see how it could really affect anything. No obvious fuel leaks. I haven't done anything recently to the truck, except change the oil. I don't really see any smoke like it is really being overfueld, but it is hard to really see what is coming out from under the truck while driving. Does anyone have any ideas of what to check next?
 
#3 ·
If its a 96 I believe that would be an electronic engine so no cut off solenoid. Are you reading the boost pressures from the ecm or a manual gauge? If you are using a manual gauge check what the ecm sees. Its kinda stupid but if the ecm sees no boost it will not let you build any boost. Also check fuel pressure and for any codes. (Im assuming this is an electronic engine if now forget every thing I just said I dont work on many trucks that old)
 
#5 ·
Avez-vous vérifié la ligne de carburant pour la restriction dans là ? Un jour ou l'autre la ligne de carburant peut arriver enflent et limitent le flux et causent la question.

Je suis assez sûr que c'est un moteur Mech si cela assez facile de définir exactement le cupirt. vous allready change le filtre de carburant.

Vérifiez le levier coupé dans là pour vous l'assurer déplaçant correctement si se déplacent seulement partiellement que pourquoi vous limitez le carburant.


Did you check the fuel line for restriction in there ? sometime the fuel line can get swell up and restrict the flow and cause the issue.

I am pretty sure this is a Mech engine so it pretty easy to pinpoint the cupirt. you allready change fuel filter.

Check the shut off lever in there to make sure it moving properly if only move partway that why you are restricting the fuel.

Merci,Marc
 
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#6 ·
Yes it is a mechanical engine first of all. It sounds like that may make it a little easier. I will go through the fuel lines and look for any issues. I have never had the tank off and checked it before. Looking in it through the fill hole, it looks good. But I can only see a small part of the tank that way.
 
#7 ·
What exactly does the aneroid do, anyway? I know where it is and I have made the fuel plate adjustment there, but have never really understood what I am doing and how it affects the truck.
 
#8 ·
Ce que l'aneroid fait est le contrôle le taux de carburant s'il n'y a aucune augmentation font pression sur l'aneroid limitera le voyage de support de carburant jusqu'à ce que l'augmentation soit en haut alors l'aneroid ouvrira le support de carburant alot plus (le seul temps il ignorera l'aneroid est pendant la période de départ qu'il déplacera au post-ion de Max {certains le feront})

What the aneroid do is control the fuel rate if there is no boost pressure the aneroid will limit the fuel rack travel until the boost is up then the aneroid will open up the fuel rack alot more ( the only time it will override the aneroid is during starting period it will move to max postion { some will do that })

Merci,Marc
 
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#9 · (Edited)
A pinched/cut boost line to the aneroid, or a blown diaphram will really kill the power. No boost or diaphram= no fuel= no power.

And, as Marc suggested, check the fuel pressure.

Also, when there is no secondary air filter, just a single one, you should NEVER clean one. Replace only. To high of a risk to blow a hole in one and dust the engine. Can and will destroy an engine in short order. Seen it happen twice. Once in a truck and the other in a self-propelled field sprayer. The sprayer had less than 1000 hrs on it when it got dusted and overhauled. $4500 f-up, over a $50 filter.
 
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#10 ·
Where exactly is the diaphragm? I removed the aneroid and checked the fuel plate, but did not see anything that looks like a diaphragm. Do I have to take it apart? I do see a set of bolts on the end, facing the firewall? What should I look for? I guess a hole would be obvious if I saw it.

Hoefully tomorrow the clamp will be in to fix the exhaust leak at the turbo outlet. The smoke in the cab is really getting annoying.
 
#12 ·
What kind of pressure should I expect, assuming I can find a proper gauge? If not, I guess I will take it apart tonight.
 
#14 ·
So it's kind of like a cylinder leak down tester. Just hooks up different?
 
#18 ·
I think I might be on to something. I took the AFC housing off and blew into the diaphragm( I know, not a real test). It seemed fine. So I took the cover off and looked at it. It all looks good. I put it back together and started checking for boost leaks again. As I was taking off the plastic stiffener on the 90 degree fitting where the air goes into the top of the engine, part of it went into the rubber. I'm not sure if I broke it, or if it was already broken. Just for kicks, I duct taped it up some and went for a drive. I got more boost today than before and I can still hear it leaking pretty bad. I also fixed the exhaust leak today, so now I can hear better. The dealer has the replacement piece. I will swap it out tomorrow and see what happens. Maybe that is it.
 
#19 ·
Fixed

I got her fixed today. It was a boost leak, I just couldn't find it easily because it was inside the hard plastic cover on top of the engine. Boost is back where it ought to be, 22 or 23 psi. EGT's are down about 300 degrees. And the power is back. Thank you for those who tried to help me.

Now time to advance the timing.
 
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