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+--- Thread: SHO Boom (/showthread.php?tid=5705)
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- ViPER1313 - 04-30-2007
After I redid the top end and started it up, the knock was still present (it was the first time I had started the car since I had it towed in the first post.) I revved the motor past 4k RPM and once again the car would stop knocking and start again intermittently. When I stopped the car though, there was smoke and the nice smell of burnt rubber coming from the back side of the timing belt (defiantly not oil.) When I started the car the next morning, it knocked 2 or 3 times on startup and hasn't knocked since (have only run it for 5 or 10 minutes since.)
I'm guessing the tensioner is on its way out - when that video was taken the car was running smoothly, but you could hear a little bit of a knock coming from the belt every time it gained and lost tension between the cam gears. Depending on the rotation of the engine, I can move the belt approximately 3/4in either up or down between the cam gears or it is completely taught.
There were also a few chunks out of the backside of the belt and a nice wear spot on the back of the top timing cover where I assume the belt was hitting it. My guess is that as the car warms up the tensioner looses tension intermittently and causes the rear cams to be seriously out of time with the crank, causing a loss of power and a knock where the belt hits the cover. At this point its the only thing I can think of :?
- ScottyB - 05-01-2007
sounds like a solid guess, i'd give it a shot
- PDenbigh - 05-01-2007
Is the tensioner spring loaded or oil-pressure loaded?
- ViPER1313 - 05-01-2007
spring
- ViPER1313 - 05-01-2007
OK, now I'm doubting the timing belt. It doesn't seem to have any more slack or skip a tooth when it starts to knock, and the noise is not coming from the belt itself. I'm at the end with this car.
- CaptainHenreh - 05-01-2007
What did you "re-do" on the top end?
- ViPER1313 - 05-01-2007
Checked all valve clearances and replaced the injectors / butterfly valves.
- .RJ - 05-01-2007
Do you have a long screwdriver or something similar you can use to pinpoint the noise? Just throwing parts at it wont solve many problems.
- ViPER1313 - 05-01-2007
the problem is getting it to do it consistently enough to actually pinpoint the noise.
- ViPER1313 - 05-02-2007
I'm putting this out there as a feeler - not 100% sure yet what I want to do, but I would appreciate it if you posted this around.
<!-- m --><a class="postlink" href="http://www.mmsports.org/forum/viewtopic.php?t=6132">http://www.mmsports.org/forum/viewtopic.php?t=6132</a><!-- m --> - post this around if you wouldn't mind
- WRXtranceformed - 05-02-2007
Wow man, I know how much you love that car. Maybe just buy a junkyard motor and put it in? You've got a lot invested in that which you'll never get back out unless you part the car out. That's the route I would go in your case if you're really going to sell it. Part what you can and sell the car with stock parts.