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Thread: Cylinder leakdown test results/comments

  1. #1

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    Cylinder leakdown test results/comments

    Hello, I have a 1992 mitsu strada RHD from japan. comes with the 4d56T setup. 150,000 kms
    Lately I've been trying to find/determine where my power loss(10-20%) is coming from. I have to drop a gear to climb hills now that over a year ago i wouldn't.

    I do have blow-by, enough that when the engine is idling and i remove the dipstick, it will spray the engine bay.

    I do the usual maintenance oil/fuel/air filter.
    re-re injector nozzles, shop said IP was good at time of injector re-re
    fluids all around are good

    Here's my last weekends fun
    reset valves: they were bang on from last year except for cyl4, .002in high
    done warm, set to .010in

    compression test (440 is a brand new engine)
    done warm
    cyl1 425
    cyl2 415
    cyl3 405
    cyl4 435

    leakdown test
    done last(~ 2 hours after shutdown, was in a heated garage though), so still a warm block
    cyl1 10% no noise, couldn't really tell where any air was coming from
    cyl2 18% noise, air leakage from crankcase (dipstick tube)
    cyl3 18% noise, air leakage from crankcase (dipstick tube), and from intake (a tiny bit)
    cyl4 9% noise, it was coming from the crankcase.


    looking for a little insight. what are the upper most limits to the leakage rate?
    does anyone have results from their engine?
    Am I due for new rings?
    any others comments?

  2. #2



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    Welcome to the site.

    how long ago did you put in the injectors? And how soon after that did you see the loss in power?
    New injectors = smaller holes, tighter springs and slightly less power.
    As for the upper most limits to the leakage rate. These trucks will run with massive blow by and compression loss. But who knows what the stopping point is.
    It would not hurt to put in new rings, a quick hone and barrings.

    Look in the manuals section under 116+ manuals for the diesel books. There might be more in there.
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  3. #3

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    Thanks for the welcome...

    Injectors were done last may and I saw next to no change in performance/fuel mileage etc.
    I had new nozzles put in and the crack pressure reset to whatever the shop knew as std.

    This might help explain my concern for the engine rings.
    another symptom I know the problem to is at cold start (below 0C). my glow plug controller does not operate after starting the engine causing it to smoke (white/grey, not steam) and miss on cylinders until warm enough. I have a manual glowplug switch and can play with that to keep it happy for a couple minutes. But before I put the switch in, the truck would smoke and miss enough to sometimes stall out completely (even with 5W40 syn).

  4. #4



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    White smoke = not enough heat.
    Black smoke = to much fuel.
    No smoke = no fuel
    The glow plug temp sensor or timer might be on the fritz. Thats why it cuts off to soon. It is possible that there is an air leek in the fuel system or you got a load of water. Also in cold weather you can get gelling of fuel. Is the fuel clean looking or cloudy. Cloudy is a bacteria in the fuel often reffed to as diesel fish. They can cause problems when it's bad enough.
    How long has it been loosing power? Fast or long, over time.
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  5. #5

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    the loss of power symptoms came on over time.
    I've never tested the GP temp sensor but have thought of it as a possibility.

    fuel is correct color, no bacteria.
    no water
    I have put clear fuel lines in for inspection to see if I had air in the fuel. I didn't have any air before the IP, but don't recall if I had any after the injectors. would air after the injectors be a concern?
    My fuel filter pump does not stay solid if I pump it up. the pressure will drop off after a few seconds, is that normal?

  6. #6



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    I'm not sure what the pressure relief and check valve should be holding and for how long. Is there any information on this in the manual and source info section. You will find the manuals in 2 places for the IP. 1 under the 216+ manuals and 1 in the UTI books. Take a look through there and see if they cover this. Ya never know but the information is always good to just scan through and store in the old brain for future reference. But since you said it has been over time it might be the IP needs to be checked out. Things might be worn and needing some love.
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  7. #7

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    i have a hunch your head gasket (cyls 2 & 3 is relatively lower than 1 & 4) is failing but have you checked your cooling system too for bubbles?

  8. #8

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    Quote Originally Posted by strada-caster View Post
    the loss of power symptoms came on over time.
    I've never tested the GP temp sensor but have thought of it as a possibility.

    fuel is correct color, no bacteria.
    no water
    I have put clear fuel lines in for inspection to see if I had air in the fuel. I didn't have any air before the IP, but don't recall if I had any after the injectors. would air after the injectors be a concern?
    My fuel filter pump does not stay solid if I pump it up. the pressure will drop off after a few seconds, is that normal?
    got the same situation too (we have the same motor)...priming pump does not get hard even after numerous pumps. yet it pumps fuel. when i replaced the priming pump, it will get hard after about 5 pumps on it. the return line (after the injectors) is plumbed back to the IP via a banjo bolt on the rear of the IP then goes back to the tank. previously i had a loose clamp holding the return line and the engine would cut me off on WOTs.

    hth

  9. #9

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    Quote Originally Posted by camoit View Post
    I'm not sure what the pressure relief and check valve should be holding and for how long. Is there any information on this in the manual and source info section. You will find the manuals in 2 places for the IP. 1 under the 216+ manuals and 1 in the UTI books. Take a look through there and see if they cover this. Ya never know but the information is always good to just scan through and store in the old brain for future reference. But since you said it has been over time it might be the IP needs to be checked out. Things might be worn and needing some love.
    I've read through pretty much everything I have on the truck, I'm sure you guys have too.
    I know the IP is lifting the fuel to itself at a good rate (installed an inline fuel pump to see if any change happened, nothing...) although I don't know what pressure the IP is putting out and if it can hold it long enough (something like 2200psi to crack the injectors). if it couldn't hold that pressure long enough, the atomization would be bad. i DON'T THINK THIS IS THE CASE THOUGH, I don't have any symptoms leading me to think unburnt fuel.

  10. #10

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    Quote Originally Posted by miked50 View Post
    got the same situation too (we have the same motor)...priming pump does not get hard even after numerous pumps. yet it pumps fuel. when i replaced the priming pump, it will get hard after about 5 pumps on it. the return line (after the injectors) is plumbed back to the IP via a banjo bolt on the rear of the IP then goes back to the tank. previously i had a loose clamp holding the return line and the engine would cut me off on WOTs.

    hth
    I've also been thinking the head gasket...but I have no hard evidence other than a hunch. I was hoping to find leakage between two cylinders (i never checked this while I was doing the test, i'll kick myself for being a noobie). the leakage test I performed is pointing towards the rings if anything.

    I will have to recheck my return lines..i know its not in the greatest of shape.

    the fuel primer pump: I know people have replaced them because the o-ring sealing face was rusted and letting air in the lines, or there was a crack around the inlet/outlet and letting air in, I don't see those problems with mine (and no air in the lines after the primer pump...)

  11. #11

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    Quote Originally Posted by miked50 View Post
    i have a hunch your head gasket (cyls 2 & 3 is relatively lower than 1 & 4) is failing but have you checked your cooling system too for bubbles?
    forgot to say, yes I have checked for bubbles in the coolant. there are none...

  12. #12

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    Quote Originally Posted by strada-caster View Post
    Here's my last weekends fun
    reset valves: they were bang on from last year except for cyl4, .002in high
    done warm, set to .010in

    compression test (440 is a brand new engine)
    done warm
    cyl1 425
    cyl2 415
    cyl3 405
    cyl4 435

    leakdown test
    done last(~ 2 hours after shutdown, was in a heated garage though), so still a warm block
    cyl1 10% no noise, couldn't really tell where any air was coming from
    cyl2 18% noise, air leakage from crankcase (dipstick tube)
    cyl3 18% noise, air leakage from crankcase (dipstick tube), and from intake (a tiny bit)
    cyl4 9% noise, it was coming from the crankcase.
    wondering also if you changed also your timing belts. or you may want to recheck the timing too.

    btw, i set the valve clearance on my motor at 0.25 mm (HOT)....

    carbon buildup on the valves may be preventing a full seal even when hot.

    hth

  13. #13

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    I did the timing belts, water pump, tensioners, front seals routine last april.
    I set the belt timing to the 7 ATDC i believe it states on the underside of the hood, and got my IP timing checked at a shop afterwards.

    If there was carbon buildup on the valves, would I not have found that during the leakdown test? it seams like cyl3 might have some buildup on the intake. Are you talking buildup on the sealing faces? or on the stems above the sealing faces?

  14. #14

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    carbon buildup on the valve seats especially on exhaust valves. i also use 2 stroke oil (2T) on the fuel system....somehow works as a decarbonizer as well as prolonging the IP lifespan.

  15. #15

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    i forgot to tell you also that the last time i did the head gasket, i found a vertical scratch on the cylinder liner #2 which is the most probable cause of the engine's blow-by. remaining 3 cylinders were clean.

    maybe it's not with the power source. it could be with the drivetrain. have you checked your clutch or A/T? or the brakes (dragging)?

  16. #16

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    i've read lots on the 2-stroke additive, looks like something good to do, although I haven't done it yet.

    I'm going to do my brakes shortly. I have the squeal from the front pads. and i know the rear shoes are nearing their end.

    I also have a growl from somewhere in the driveline. I think my steady bearing rubber housing (along the 2 piece rear driveshaft) is going again. although this just started happening, so I don't think it's part of my problem.

  17. #17

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    any update s-caster on your strada? solved the power issues already?

  18. #18

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    did the front brakes this weekend, rears will be done shortly as I was waiting on the hardware pieces.

    driveline growling noise is most likely my rear brakes as the steady bearing on the driveshaft seems ok.

    motor has not been touched, no new diagnosis there, my sister was in town for the last 5 days...

    I've been having great weather here in thunder bay, I started the truck up midday in 15C. The truck still coughed and farted once the glowplug cycle stopped early(manual glowplug switch made it idle correctly). I was not expecting that in such warm weather, and the truck never did that in such warm weather last summer...whatever it is, it seems to be getting worse.

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