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Engine Timing Problem

Discussion in 'Mitsubishi Minicab' started by wesleygarrard, Apr 4, 2021.

  1. wesleygarrard

    wesleygarrard New Member

    Hey kids,

    Well, I think I done goofed.

    I was changing the timing belt on my 1993 Mitsubishi Minicab Van with the 12 valve 3G83.
    I followed the Danko engine manual to a T for reinstallation.

    With the belt on, I thought I would just run the engine just for a second to see if it all looked fine.
    Well, my torque wrench must need calibrated because the tensioner moved and the belt skipped a few teeth. I shut it down the second I saw the tensioner move.

    So I redid everything and lined all the marks back up per the manual. Now it is all back together and it just does not seem right. It idles fine and does not seem like it misses or anything.

    Thinking maybe I hit a valve? So I did a compression check and I get 165-170psi on all 3 cylinders. Tested each cylinder 3 times and got the exact same results each time.

    Maybe I averted disaster and did not hit the valves.

    I checked all the alignment marks like 20 times and they seem spot on.

    What else should I be looking for?
     
  2. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    I think you covered it.
     
  3. wesleygarrard

    wesleygarrard New Member

    With such good and consistent compression numbers like that, do you think the valves avoided damage?
    I picked up an endoscope and am going to get a close look at the valves. If the valves are all seated properly, I am going to check the timing marks again. I had heard from someone that sometimes timing belts can be a little off and that my ignition timing may be a little off. This is the first I am hearing of such a thing. Is it possible?
     
  4. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    With the numbers you are getting, I seriously doubt that you had any damage to the valve train. Contacted between the piston and valves is generally catastrophic. So I doubt you have any damage.

    I guess the timing belt could have minor errors in manufacture. But the odds are very low, and any errors would be quite minor. If the cogs on the belt don’t match the slots in the wheels pretty closely, it will just chew them up in short order.

    If you have a compressor I would recommend buying a bleed down tester. It will tell you if the valves are seating, and endoscope will not. If you go with the endoscope you would look for damage to the piston, because it will be much more visible.
     
  5. wesleygarrard

    wesleygarrard New Member

    Leak down is my next test. With the endoscope, I saw no evidence of contact on the pistons. They had no marks or divots and the slight carbon coating from combustion was undisturbed. Everything looked pristine inside. I suppose I could be off a tooth. When I drove it, there did not seem to be a loss in power. It just seems to grumble and vibrate more. Maybe I am off a tooth on the balance shaft? Either way, it is all coming back apart. I will report back with what I find.
     
  6. wesleygarrard

    wesleygarrard New Member

    I did a leak down test and I got under 20% leakage across all three cylinders. Looks like the valves are ok. Now to pull the timing cover and recheck. Maybe I am off a tooth or something. But it seems I have avoided introducing the valves to the piston.
     

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