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Thread: No Torque, No Power?

  1. #1

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    No Torque, No Power?

    Hey folks.

    I've got a 4d55 with the upgrade 4d56 head in a 85 Mitsubishi 4x4 pick-up truck.

    Here's the issue.

    From a start or at low RPM's the truck has almost no power, I have to ride the clutch a little to get going. Driving down the road at 2500 rpms it feels okay but I'm not familiar with these trucks so I'm not sure exactly what it should feel like., my gut says it should have more power. I've put in new injectors, a rebuilt pump. Valves are set at .010" cold. I've got a inline electric fuel pump before the fuel filter. It pushes 3lbs (i think) I don't have the tool to set the injection timing perfectly, but with my VW diesel I've done okay by listening for injector knock and then backing the pump off as a way to get it close.

    Any help would be awesome. I'm starting to have a pretty big hole in my wallet over this truck. Ask away if you need clarification. Thanks

    Thorin

  2. #2

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    You sure there's no other issues like hanging calipers, e-brake etc? Maybe timing is off? Theyre non emissions so no cats or anything to plug up. What about turbo? Is it spooling like it should? If it's not spooling it is nothing but a restriction. They don't last long on these trucks before needing a rebuild.

    I'm also curious how that's worked for ya. I've got a 4d55 with a blown h/g. If it's got a bad head I wana do the 4d56 head upgrade. Where'd you get yours? Were there any issues mating it to the block?

  3. #3

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    Are you sure the turbo is spooling up? My waste gate adjustment rod loosened up once and the thing had almost no power.

  4. #4

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    Not sure about the Turbo spooling up correctly. I don't have a boost gauge but pulling off the boost line from the intake to the waste gate actuator at idle there is positive pressure. I wouldn't think that at very low RPMS the turbo would be a big part because it hasn't started spooling, maybe I'm wrong though. If I pull the intake hose and can spin the turbo with my fingers is that a good enough check for the bearings being free? What cost am I looking at for a rebuild if I need one?

    Truck rolls fine so I don't believe that its a mechanical issue with brakes etc. I've checked timing the timing, I'm missing the cam timing mark on the aluminum plate it has been broken off since I've owned the truck, but I can made a pretty good guess by looking at my friends truck. (the pin on the cam is at 12 o-clock right. Any chance that the 4d56 heads have a different timing mark than the 55?

    Latest check reveals that cracking injector lines one at a time #3 cylinder makes very little difference in idle speed. All the others nearly kill the rig. I'm getting good fuel spit from the line so I'm thinking maybe a dead cylinder. Valves or rings. I'm going to do a comp test and leak down test next and go from there.

    About the head it bolts right on no issues. A friend of mine who has a shop out in Oregon ordered the head for me. I'm not sure what his source is. I've heard you can get them on e-bay but also heard poor reviews of the Chinese heads.

  5. #5

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    Turbo boost spools up right at 2500 stock. That means your turbo is working.
    You're engine is not making any power when there's no boost. Compression should be giving you low end. #3 not performing, points to injector or rings. Real interested to see your compression test #'s.

  6. #6

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    So just did my comp. test. #1 cylinder=380 #2 cylinder= 320 #3=200 #4=300. Did a leak down test and it was hard to tell where the pressure was going in the #3 cylinder. Any ideas what the compression should be? in the VW diesels 380 is fine. 300 sounds low to me and 200 is obviously something wrong.

    I guess pull the head and see if I can find anything. What do you folks do as a simple way to check valves. I've always pulled the rocker arms and poured gas in the manifold openings and watched to see how much was leaking out. Is that to crude?

  7. #7

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    Does anyone know, what parts are compatible from the 4d55-4d56. I'm finding plenty or parts gasket kits, head bolts, etc for the 4d56, not so much for the 55. Also they seem way cheaper. How about the pistons or piston liners? is the 2.5l just a stroked 2.3 with a different crank. Looks like I'm going to need to go through the whole lower end. How about opinions on using a cylinder liner verses using oversized pistons. Any tips to help source parts would be great. Anyone used the Chinese e-bay rebuild kits that come with new pistons and liners? I'm skeptical but seems like the price is right. Thanks

  8. #8

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    I'm not sure. I plan to build power with my truck but those are the only rebuild kits I can find too. I've done alot of research for these engines and yielded minimal results. It's possible to make the truck powerful. The trick will be keeping it cool rather than building it. Internally the engine is pretty sound and will handle up to about 400 ft lbs of tq if i remember right and it's well balanced (but balancing it better never hurts). Just use quality parts. Try to keep the original parts. I'll end up finding out what the dealer carries when I tear into my engine. The weakness is the 21:1 compression paired with a non intercooled turbo for this engine, more external issues. It's harder finding 4d56 parts sinde theyre EU or AU or JP only. I've gota go to EUebay to find any parts for them. Then you've got the issue of not many have swapped things over between them since they're from different areas.
    The 4d56 uses the same bore as the 4d55 but it's just stroked. However I'm unsure if you can swap a 4d56 bottom end and head onto a 4d55 block. I know the head can be done with minor issues. It's a roller rocker and doesn't warp as badly as the 4d55 heads. If it's possible to put the bottom end in I'll end up doing it and lowering the compression and upping the boost with a bigger garret or turbonetics turbo. I think knowing a good machinest will be the trick to making the engine work right.
    The person you want to chime in his username is 4D55 performance. He's done alot to these trucks but doesn't log on much.

  9. #9

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    Found a good shop to do my machining, and am pulling the engine to do a full tear down rebuild.

    Today as I was pulling the engine out of the truck I noticed that the turbo bushing seemed pretty loose. (sticking my finger in the intake I could wiggle the propeller) Got me wondering about rebuilding it or maybe if there is a bigger/better turbo that could bolt up with out to much fabrication that might be something to consider. What has anyone else used as upgrades and how did it go? I hear that these stock ones don't tend to told up all that well.

    Thanks.

  10. #10


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    you can try rebuilding the turbo, you can get a bushing kits for them. I did a T3 many years ago and the turbo lasted 5-6 years of heavy driving for $35.00. No idea where you can get them as the machine shop I used to deal with got it for me.

  11. #11

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    Sounds like a good thing to try. I've never opened up a turbo. Probably not to many little piece in there to get lost? What are there any other wear parts that you replaced at that time?

  12. #12

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    Personally I like your other idea. That's what I plan to do. Get a better, bigger turbo.

  13. #13

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    You can get any parts that you need for the 4D56 from Canada. I have had great service from http://www.maxoverdrive.ca/

  14. #14



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    I was told the turbo off the first Dodge Cummins engines is the best fit for the small Mitsu engines. They were to small for the Cummins but made a nice upgrade on these little diesels.
    Members come and members go, But the board keeps track of them.
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    The MightyRam50 site is sponsored in part by On Site Concrete Inc.

  15. #15

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    Quote Originally Posted by cdalejef View Post
    You can get any parts that you need for the 4D56 from Canada. I have had great service from http://www.maxoverdrive.ca/
    Some of their Pajero parts seem to be the same but for the most part I don't see everything I'll need for the engine I'm doing.

  16. #16

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    Quote Originally Posted by recian View Post
    Some of their Pajero parts seem to be the same but for the most part I don't see everything I'll need for the engine I'm doing.
    They carry tons of 4D56 stuff, I have bought everything I've needed including a brand new 4D56 crate engine. What they list on their site is just a fraction of what the carry.

  17. #17

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    Boring the block is always better if the liners aren't worn too bad. I do not trust those ebay kits. And as far as rings , the hastings chrome moly are the only way too go! Your kit is on its way ! Here is one member that takes advice well!! LOL.

  18. #18

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    Mike, what does your preferred rebuild kit consist of ?
    And what price tag for same?
    I'm looking at a freshened motor by year end.

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