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  1. #1

    retorquing head on msx150

    boy, this is weird. i was out with the ski last week cruising the river when back at the dock i noticed a little extra smoke in the exhaust, not oil smoke but water vapor smoke. i checked the coolant level and it was down a little bit and there was some darkness to it as well. oil level was fine with no water at all, no milkshake.

    so i called and left a message for jay over at atlantic power sports. he returned my call within an hour and we chatted about the problem. i'll tell you, i should have been dealing with him all along. nice guy to talk to and he seems to definitely has these motors down. he told me to do a couple tests: check for coolant flow and do a leakdown. ok, simple enough.

    well the coolant was flowing so no water pump problems. unfortunately i was having a real hard time with the leakdown. i was pretty much guessing where tdc was since there is no markings anywhere and its next to impossible to rotate the motor w/o the starter. best thing i could do was get it close with the starter and grab the cam chain with a rag and channel locks and slowly work the engine around while measuring the depth of the piston. even with that the best pressure i could get into the chamber was about 60 psi before the piston shot to bdc and of course a geyser of oil would shoot up from the intake side cam chain hole all over everything. thats got to be the cruelest joke when they designed that engine. happened to me also when doing the valve lash. right in the service manual it says "rapidly tap the start button to rotate engine". so tap, tap, tap, big eruption of oil all over everything. ha ha, real funny.

    anyway, so no bubbles in the coolant with 60 psi so doesn't seem like there's any serious damage to the head gasket. in the service manual the picture of the head gasket looks to be a mls type and that style is very durable. just for the hey of it, i decided to put my torque wrench on the head studs again and all but two were moving with just 30 ft/lbs of torque. now when i did the lash at about 15 hrs, i had checked the head studs and all the nuts would rotate when i hit them with 30 ft/lbs. i retorqued the head back then and now with about 37 hrs, i have the same problem. this time after retorquing, i marked the studs and nuts to see if they are rotating.

    so the only conclusion i can come up with is that since i'm losing torque on the head studs, i could have been lifting the head some and that could be why i lost some coolant and there is some dark discoloration to it. does that seem plausible? and why is the torque being lost on the studs anyway? i'm just hoping the studs aren't over streched from all this retorquing.

    sorry for the long winded post, had to get it out.

  2. #2

    Join Date
    Oct 2006
    Beaver Falls, PA
    Hot exhaust cold water you will see some white out the tail pipe when you get the exhaust hot enough. Not to worry one of my boats has over 200 hrs and still does it. As far as coolant discoloring keep an eye on it some will occure just from time but if it gets black or real dark time for an oil cooler it must be broken.

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