Cam Belt Retensioning

[Volhv]

I changed the cam belt and rollers this summer, used a Gates belt.
Tensioning method was the water pump pulley spin, and 90 degree twist where the idler is. I have a 86, so no autotensioner.

The thing is, I have not driven the car since, but only ran it every 1-2 weeks for about 20 minutes. Upon checking the water pump pulley today, I noticed It can be easily spun with 2 finger, yet last week when I ran it, there was positive engagement. Can the belt have stretched so much in so little time and with so little use?



Any advice or insight?

Thanks!

[HondaDustR]

A brand new belt will stretch a bit rather quickly, which is why initial tension for a new belt is higher than for a worn in belt and also why the first retension interval is only 1500 miles. I usually tension a brand new belt tighter so that the water pump pulley is moveable with one hand but difficult to do so without a firm grip and a bit of force. Also keep in mind the temperature of the engine block. The factory specification is to tension when the engine is "cold", about 20 deg C/68 deg F. If you are much colder than that, esp below freezing, err slightly on the loose side so that the belt doesn't tighten up too much once the block expands at full temp and burn out the water pump bearing. Opposite goes if you tension when the block hasn't cooled down from running, but no use doing that when you can wait for it to cool. What you could do if it's freezing where you are is get the tension close enough and run the engine to get the block up to around 20 deg, then check the tension.

Temperature does make a difference. It will vary quite a bit on a warm engine versus a frozen one, which is why the manual gives an ambient temp for tensioning. A properly tensioned belt will feel loose when the engine is very cold.

[Volhv]

Good point about the temperature.
It is quite cold right now over here. I was going to run it, and see if it tightens up, but to my annoyance I found the battery to be flat. What I also wanted to see was if there is enough tension for the water pump to spin.