I recently had my wife"s 1999 250 Trailblazer engine rebuilt. I bought it with the piston out of it. My shop said that the clearences were good, so I shouldn't have any problems. That is all the info that they could give me. I mixed my first tank, which is not completely run through at 40:1, gas[img]i/expressions/face-icon-small-blush.gif[/img]il, as recomended by the manual. The oil injector is working properly. The piston (WISECO) is 20 thousands over. That is the only mod. The engine, after running at 3/4 throttle and then when decelerating sometimes "pings" twice before reaching low RPMs again, it also sounds "tinny" 50% of the time when running between acceleration and deceleration. Is this normal, as I still have a high oil content? When I accelerate it sounds good and strong. I have to "feather" the throttle sometimes at midrage to accelerate as it "bogs" down slightly, probaly due to the high oil content. Also when the engine is warmed up, the idle slows slightly. I have about 15 miles or 3 hours on the rebuild. Is this normal? What nioses are normal for this engine? What should I look for?

 

Mine does it, I think its normal.

 

I've heard the Wiesco pistons have a tendendcy to make a "pinging" noise

 

mine did the same thing, so i took it to the dealer. mechanic had one ( '02 ) and showed me it did the same thing. said one noise i was hearing was th rev limiter.[img]i/expressions/face-icon-small-happy.gif[/img]

 

That is a normal noise on the 250's. They all have a pinging,tingy,light knock noise to them. Dont be worried. I have had my 00 from day one and even with all the mods it sounds the same since I bought it. One thing with the 250 is that it dont have a counter balencer and the engine is built lose. So it runs rough and makes noise. It has been the same motor since the 80's so they must be doing something right.