Problem with a new head..

[MilwaukeeGSX]

Alright I just got done swapping a freshly rebuilt head and everything associated with timing (Except the auto tensioner). I torque everything to spec and set the correct tension on the belt. All timing marks lined up including crank, B/s, oil pump, and both cam gears with the dowel pins pointing up. I even turned the motor by hand like 34534 times and each time, the timing marks lined up without any problems..


The car started beautiful .... she in fact purred, no misfire no leaks.. I drove it around the block and she felt smooth. I then park it for 20 mins, and when I start her back up theres a horrible clanking sound, almost like a bearing or a valve hitting a piston type sound...SO here's what I did...

1..Timing : I rechecked all the timing marks and they all still lined up perfectly.
2..Compression is fine
3..I inspect my auto tensioner and notice that the piston the pushes the bracket upward is snapped in half.... I was like WTF?!!

So could this in fact be my problem? Is the bracket vibrating violently up and down rapidly against whatever is left of the piston? i mean it really does sound like a valve or rod or something.... could I have bent vavles even though all timing parks still line up?

 

[Shaggy_357]

Can't say for sure if you bent valves (at least I can't) since the timing marks still line up, but I would say its a safe bet that broken piston isn't helping anything. I'm sure it's a "no sh*t" situation, but I wouldn't drive it until you got that fixed. And I'm pretty confident that the remnants of the piston would make a horrible noise, and on a side note, make sure you try to find the broken piece. i.e. making sure its not going to get stuck on any of the pulleys, etc.


Eric

 

[Locke]

Did you make sure the tensioner's piston fully contacted the tensioner arm, and that the arm was 0.150"-0.177" from the auto tensioner's body, after you pulled the pin? The auto tensioner could break if the tensioner arm was allowed to flop back and forth against it.

If the timing has not jumped, you are very lucky. Don't start or crank the motor. Replace the auto tensioner, and do another compression test. Good compression will equal good valves.