Radiator Fluid in the Oil Pan

Discussion in 'Thumpers' started by Stormrider787, Apr 30, 2019.

  1. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    I have a 2004 yz250f that I just finished rebuilding bot stop and bottom ends. I went to start it and it runs but acting very lean. I noticed that my radiator fluid was going missing extremely fast and checked my oil pan and sure enough I had milk colored oil. Since I just rebuild the whole thing it is possible that any gasket is the source of my leak so I was wondering if there was a diagnostic test to find where the radiator fluid is coming from or if I need to take the shotgun approach and just go back through and replace everything again.
    #1
  2. cyclopathic

    cyclopathic Long timer

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    Most likely head gasket.. or could be pump. Did you torque head as per instructions? (Usually to smaller torque value then higher)? Old head gasket? If gasket you should see bubbles in radiator just start engine without radiator cap good luck.
    #2
  3. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    I don't think it's the head gasket. Its bran new and I don't see bubbles in the radiator when I'm kicking it over. What would be the signs of a bad pump?
    #3
  4. Pwest1

    Pwest1 Adventurer

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    Not sure about yours particularly but usually it is head gasket, inner clutch cover (ktm), or wp shaft seal.

    Also why the rebuild? Could the head be warped now.?
    #4
  5. Blakebird

    Blakebird r-u-n-n-o-f-t

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    :nod

    there's only so many ways coolant and oil can get in each other's space - if it happened in large quantities fast, the head would be the first place I'd look.
    #5
  6. sprouty115

    sprouty115 Long timer Supporter

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    Apologies for the suggestion, but you replaced all the seals and installed them in the correct orientation?
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  7. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    Im a college student who likes practical skills and is trying to get a large base of them. Ive completely rebuilt many small engines but there isn't really money in that unless you can run a shop (not to mention people don't get rid of their broken lawn mowers, they just let them rot outside in their side yard), so Im trying to teach myself dirt bikes from youtube and forums (Youtube University and the School of Hard Knocks). This means that Im okay with messing things up a few times since I view it as the price I pay for dirt bike homeschool. I like to find bikes that are totally trashed and fix them up, knowing full well that Im jumping into the deep end with a minimal idea of how to swim (and then for a real challenge I try and turn a profit).

    I got this bike because some idiot dared their friend to put metal shavings in their oil pan and the bozo did it. He rode it for a few days and put the piston through the cylinder - as in all the way through so it stuck out the side (I could see it!). Consequentially he let it go for $300. I split the cases and cleaned the insides out, put in a new crank, piston, cylinder, and head - so its unlikely that the head is warped.

    I believe that there are only about four ways that they could mix (head gasket, cylinder gasket, pump, and gasket between the cases - feel free to correct this). Im just hoping that I don't have to go all the way back to spilling the cases to fix it so I need to know what I can do to test/look for in finding the problem.

    It has all new seals.
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  8. cyclopathic

    cyclopathic Long timer

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    Bike engines usually have coolant in head, cylinder block and pump only so if it's mixing it's either head gasket or pump seal. Yes there are some additional places you could have coolant in some engines like water oil cooler, etc. So unless you have a hole punched through cylinder, head gasket and WP seal are only 2 places.

    Take spark plugs out, pressurize radiator if coolant in head than it's head gasket if not it's water pump. Also if it is a head gasket you should get a white antifreeze smelling smoke when engine's running coming from pipe. If it's pump you just see coolant going down but not into cylinders.

    Any chance coolant got in before/during rebuilt? Trash left in engine tore up WP seal, eh?

    EDIT: above is only if you have coolant going into cylinders. You won't see it if you have compression and coolant going from oil to coolant passage.

    Any chance head gasket was not fit correctly? You can usually fit head gasket only one way but perhaps in your case it could have been fitted upside down? Have you cleaned the surfaces on head/block? Any chance it was scratched? Warped from overheating?
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  9. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    The head gasket could have gone two ways but one way it was pretty obviously wrong. The head and cylinder were clean. I don't see any bubbles in the radiator when the bike is running. Im getting blue smoke out the tailpipe, which I believe to be due to it running rich (it has a carb issue that Im not worrying about yet). I am getting copious amounts of smoke from the oil dipstick and the crank case breather. This makes me think that the head gasket is good and it may be the water pump.

    Just asking since I just messed with these things, is it possible that it is the gasket between my cases or at the base of my cylinder? If so, how would I know?
    #9
  10. cyclopathic

    cyclopathic Long timer

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    If head gasket is leaking you can have either combustion camera(s) bridged to oil or oil to coolant or coolant to combustion or combination of. If coolant to combustion you would get bubbles in radiator and white/sweet smoke, if blue smoke this is oil.. could be head gasket, oil rings, valve seals or high crankcase pressure.

    Have you looked at bike work manual on head tightening sequence? Torque specs? Order in which bolts to be tightened? Head should be tightened gradually something like all torqued to specific small value in sequence then retightened again to higher value etc.. manual would have specific torque wrench settings to use.

    If not improperly/insufficiently tightened head Could be bad gasket (cheap aftermarket or reused) or warped head. If it is warped it doesn't have to be by much could be by a few thousands. Another possibility is oil/coolant passage connected due corrosion but this is usually on marine engines which use outboard brackish water..
    #10
  11. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    So I just pulled the head gasket and this is what I found. IMG_0736.JPG IMG_4893.JPG IMG_2510.jpg IMG_2509.jpg First the gasket looks to be totally trashed. I don't understand how this could have happened when it was a brand new gasket. Second, It looks like my piston and head were hitting each other, but I wasn't hearing it or feeling it when the bike was running. Any ideas as to my problem/s?
    #11
  12. cyclopathic

    cyclopathic Long timer

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    Wrong/thin gasket? Piston fitted wrong way? Pieces of crap somehow made inside?
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  13. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    Could be the wrong gasket, but then it would have been false advertising. I know it got hot before I realized that my radiator was half full the first time and filled it up, after that I had rubber floating in the radiator fluid. Any idea about the weird wear pattern?
    #13
  14. cyclopathic

    cyclopathic Long timer

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    My 1st impression was that the piston was facing wrong way so valve indentations on piston and head don't match. If you got something sucked in through intake it could have caused it. Were marks on crankshaft and cams aligned correctly? Then check if valves are not bent good luck.
    #14
  15. sprouty115

    sprouty115 Long timer Supporter

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    Piston should have some type of mark cast/stamped on the crown - or is that just two-strokes and BMW Airheads? (might be showing my age...)
    #15
  16. Stormrider787

    Stormrider787 Aspiring Dirt Bike Mechanic

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    The piston is facing the right way but even if it were facing the wrong way, it wouldn't change anything because the piston is hitting the head, not the valves. Timing also wouldn't affect this since timing doesn't change the head location, just the valve position related to the piston. The piston looks like its striking the head. I don't think it was something from the intake since it is so symmetrical, though it could be related to the radiator fluid reacting some weird way in the combustion chamber.

    The stamp just has the bore of the piston on it, which I know is correct since it fits in the cylinder.
    #16