I replaced the timing belt and its tensioner on my 1991 Civic LX the other day. Everything went well except for setting the tension. I followed the manual but did not understand what the steps I took were doing. On my first attempt to set the tension, the belt was too slack. A muffled rat-a-tat-tat noise, like rubber on plastic, came from the engine compartment when the car was running. Putting my hand on the TB cover as the car ran, I could feel that the noise was in synch with vibrations on the TB cover. I took all apart again and watched how un-smooth the motion of the TB was as I rotated the crankshaft by hand. This is when I realized what the rat-a-tat-tat noise was: It was the TB hitting the TB covers. I concluded I had set the tension wrong.

I studied the tensioner more and experimented with it installed and covers off, so I could see how it moved. I finally got it set, using the manual's directions to loosen its adjusting bolt a half-turn or so, then rotate the crankshaft 3 camshaft teeth, watch for tension on the forward side of the timing belt, then tighten the adjusting bolt. I then rotated the crankshaft a few times and watched for smooth turning of the belt over the sprockets' teeth. Some observations:

-- the aft side of the timing belt became tense //as I tightened the adjusting bolt//, and not before. From studying the slot in the tensioner body, and assuming that the bolt is at the top of the tensioner's slot just before tightening, I can see how the tensioner body would rotate so as to put tension on the belt during this step. What happens when the engine is actually running is another question, though.
-- the tensioner spring was not in tension before I tightened, and I am not so sure it went into tension as I tightened the bolt. I see that tightening the bolt fixes the point where the spring attaches to the tensioner body, or at least it is fixed while one is doing the adjustment. Does more happen (with the tensioner) when the engine is running at a few thousand RPM? For example, does the tensioner move so that the spring extends or compresses and so changes the orientation of the tensioner body?
-- the manual says that the tensioner "is spring loaded to apply proper tension to the belt automatically after making the adjustment [given in the manual]." Does this mean that "auto" adjustment is taking place for the life of the timing belt?
-- does it matter which way the hooks at the ends of the tensioner spring are oriented? It seems to me the difference would be small, and thus there is no warning about this in the manual.

My car is running fine after some 100 miles of suburban and highway driving over several days. I also went to a junkyard and looked at the tensioners on a few of the more intact Hondas. The tensioner springs all seemed to be applying force (that is, the spring was in tension). But the spring hooks are not oriented the way mine are.

The manual's directions do not impress me. It seems to me it's key to watch the aft side of the TB go from slack to reasonably tense when tightening the adjusting bolt.


Photos will soon appear at http://home.earthlink.net/~honda.lioness/id21.html

Comments?

 

Do you have the hole in the tensioner on the peg? It sounds to me like you do not. You need to fully remove the tensioner, put it on that peg, then install the bolt. The spring will then be tight and set the correct tension for you. I know thta is vague, but i hope it helps. Im better at just doing than explaining. Good luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gator88 &raquo;</TD></TR><TR><TD CLASS="quote">Do you have the hole in the tensioner on the peg? It sounds to me like you do not. You need to fully remove the tensioner, put it on that peg, then install the bolt. The spring will then be tight and set the correct tension for you. I know thta is vague, but i hope it helps. Im better at just doing than explaining. Good luck.</TD></TR></TABLE>

Oh god, which hole? The one opposite the hole to which the spring attaches? Peg?

This is a really hard one to explain without photos. I just put the photos up at my web site. See my previous post for the link.

The car is running fine, but maybe, based on what you say, it's safe by only a hair at the moment.