Rocky
New Member
Posts: 5
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Post by Rocky on Apr 11, 2009 10:21:00 GMT -7
I had my 250 rebuilt a little over a year ago and I only have maybe 10,000 miles on it. When you let up on the gas and you are going down hill blue smoke starts to come out and then when you start going again it stops. I thought maybe the PVC valve was sucking oil in the intake. I changed it and that didn't work but I still thought that had to be the problem and I finally just took the thing out and drove it that way and the problem is still there. Sometimes it doesn't do it. Here is what they did to my motor when it was rebuilt. They change all the valves in the head so it would burn unleaded. They change a sleeve that was cracked in the block and put in all new pistons and of course change the usual things. Please any suggestions and Ideas
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Post by 66gilbert on Apr 11, 2009 13:17:52 GMT -7
Sounds like the valve seals are gone. These are usually like an o-ring type seal and do not seal very well. They ride up high on the stem. As the valve gets pushed down to open they stay up high on the stem and allow oil to get by them and even become brittle and fall off over time. This causes oil to get sucked down the valve guides on deceleration or like going down a hill. I like to use an umbrella type seal they work a lot better and do not fall off as easy. Are you sure they used the hardened valves along with the hardened seats and valve guides for unleaded gas?
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Rocky
New Member
Posts: 5
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Post by Rocky on Apr 11, 2009 15:22:04 GMT -7
They suggested to me that I should buy the unleaded valves I guess I am not sure they must have they suggested it. Would that make any difference with the seals or are they the same? I had a one year warranty but I think i am past that by 3 months.
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Post by riverracer on Apr 27, 2009 19:28:00 GMT -7
If you only get smoke when you back off the throttle it's valve guides not seals, if after you let it sit for a period of time and when you start it up you get a cloud of smoke then it's the seals, or if the exhaust seals are bad you'll get smoke all the time!..
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