Grrrr...small timing belt problem

boise-nic · Post by **boise-nic** » Tue Feb 23, 2010 8:11 pm

Well I thought my new motor was just about perfect. It started on the first catch, runs great, everything works. I was just about ready to shut the hood and start dedicating my time to the other end of the truck...putting the bed back on, hooking up tail lights etc...

Just one last thing I wanted to double check was the timing belt tension. What I discovered is the belt has moved over to the valve cover side by a small amount so that it isn't centered in the middle of the cam gears. What could cause this? The tension on the belt seemed perfect. I've done a timing belt job probably a dozen times between me and my friends. The only other thread on the internet I've come across which discusses this says the problem is the tensioner is not putting pressure evenly on the belt, making it walk to a side. I don't recall it doing this when I took it off a while ago though. I can see the side of the belt is flaking off like eraser shavings. Something is making the belt "walk" to the side of the cam gear. Wondering what else could make this happen. Any ideas???

lsr mike · Post by **lsr mike** » Wed Feb 24, 2010 8:07 am

bad bearing in the tensioner, or the tensioner is cocked sideways. all the other parts are locked in place (Cam(s), Crank, Oil Pump).

boise-nic · Post by **boise-nic** » Fri Feb 26, 2010 1:33 pm

lsr mike wrote:bad bearing in the tensioner, or the tensioner is cocked sideways. all the other parts are locked in place (Cam(s), Crank, Oil Pump).

Doing some internet research, most people have this problem when the pivot for the tensioner pulley is worn down and it doesn't sit perfectly sqaure anymore. It applies uneven pressure causing the belt to walk over to the side. Strange how this would happen. The pivot doesn't really see much movement over the life of the motor so for it to wear out to the point of getting loose tollerance doesn't make sense.
I'm wondering instead if there is some crud keeping the parts from sitting flush with each other. It wouldn't take much mis-alignment of the parts to get the belt to not sit center of the cam. That seems more plausable to me. Before I go buy a new tensioner pulley, bracket, and pivot, I think I'll try wire wheeling the crap out of the parts and just see if that solved it.

One nice thing about the truck vs the dsm...working on the timing belt is SO much easier. I hated doing the belt in the talon but in the truck...its a half hour job.

StellarDOHC · Post by **StellarDOHC** » Mon Mar 01, 2010 1:07 am

Gotta love it when the engine is facing the "right" way haha

boise-nic · Post by **boise-nic** » Tue Mar 02, 2010 1:32 am

StellarDOHC wrote:Gotta love it when the engine is facing the "right" way haha

Yeah man, its not just the timing belt, its everything. I have so much better access to the front end, the turbo and the intake mani.

Oh, I found what was causing the mis-alignment...part of it was me being forgetful and not putting on a metal guard-shield thing. I don't know the correct name for it so that what I'm calling it. The large cast iron bracket the holds both the idler and tensioner pulley never sat flush, like it was missing something. Looking at the back half of it, I see an outline stain of what looked like a gasket. Well, looking thru the manual, I found the missing shield and put it on...

Here is the shield I am talking about...

Here's what it was doing without it...

You can see what looks like eraser shaving on the wearing side of the belt...

And here is the difference once I put the shield on properly and ran it for about 5 minutes...

Ya learn something every day I guess...

boise-nic · Post by **boise-nic** » Tue Mar 02, 2010 1:58 am

Funny story follow up...

I had accidentally timed it 180 deg. out of time when I put the belt back on...(down pins pointed down not up). Taking off the tensioner to fix it, the belt came off the exhaust cam gear and rotated back a few teeth, no problem, the crank is halfway up/down so the valves cant hit the pistons anyways. I go to rotate the crank over by hand into position and my wrench won't move...like REALLY REALLY wont move the crank.

WTF!? Did I really jam up the valves and pistons? What was I missing, I was sure there was enough room on the pistons to clear the valves...F!@# did I just ruin a brand new head?

In short...I had it in gear. Not used to having a driveshaft LOL!