Differens In T-belt Deflection

[Caribbeandude]

Just changed my t-belt on my '96 pathfinder.

 

When starting I noticed that the belt was put on wrong (arrows on the belt pointing to the back of the car and not to the front) and after counting the teeth between the camshaft pulleys it was of one teeth. Now the car was running good but was slow in the beginning of the acceleration and than out of nowhere i feel the car goes faster (like a turbo kicking in).

Somebody told me ones that people put the t-belt of one teeth so the car is faster in top gear.

 

I put the new t-belt on according the 96 Pathfinder manual, everything looks good all aligned and the right count of teeth. After 2 turns clockwise still all good the only thing is, during the 2 turns the deflection of the belt is different each time. After the 2 turns (engine to TDC No 1, and all aligned at timing marks) the deflection is good again.

Same thing after repeated the '2 turns clockwise' like 2 times more.

 

Is this normal or is there something wrong?

Edited August 17, 2007 by Caribbeandude

[projekz]

I want a 69 Pathfinder... It's got to be the sexiest Pathfinder around

[mws]

Yes, it is normal. No worries.

 

Oh, you wanna know why? It has to do with the camshafts and valves. When the cam is at a position where it is opening or closing a valve, the force of the cam spring is applying strong torsional force to the cam. If the left is trying to rotate CCW and the right is trying to rotate CW, the belt will appear tighter than it really is - but there will be more slack in the lower runs. If left is trying to rotate CW while right is trying to rotate CCW, belt will seem looser between them, and the lowers tighter.

 

Check at TDC per the instructions and all is good.

[Marooncobra]

One possible reason for the incorrect way of fiiting the belt is that Timing belts when new are multi directional. It is only once they have been used i.e. engine running, that they then become uni directional. The arrow is to help identify which way the belt was fitted once you remove it and you are going to reuse the belt.

 

As for being out of alignment by one tooth I suspect that this is down to the mechanic/DIY man incorrectly fitting the belt. You didn't metion if it was between the cams or the crankshaft where the teeth are out of alignment (between cams 40 teeth, between cam and crankshaft 43). If it is between the cams then that would mean one cam is correct and the other would be out. This would give you an imballance in engine timing as the two cams control 3 cylinders each. If it is between the cam and crank then depending on what the difference was (42 teeth or 44 teeth) it would advance or retard the valve timing by approx 5-6 degrees. Feasible that you would get a power band at a specific rev range but as I suggested earlier sounds like the mechanic/DIY man didn't fit it correctly.

 

With regard to the tension, you will get a bit of difference in the tension as you turn the belt over. It is new and settling in. I tend to turn it over for about 5 minutes to settle it in and then measure the difflection.

 

Hope it helps.

[Caribbeandude]

Ok cool, so no worries when i am going to start the engine.

The difference in teeth was between the cams, it was 39 and not 40.

 

I experienced, its a common thing that mechanics here on the

island do things wrong, also at the only one Nissan dealer we have.

Luckily i can hold a wrench myself (and my copy of a official garage

manual 4 the '96 Nissan Pathfinder is a great help 2 me)

 

Now everything is good to go.

 

Thanks people