E30 325i Cambelt tension

[T89 Callan]

Can anyone help me out with a little info here.

I have just changed the cambelt on my E30 325i (while fixing other broken parts).

Now, all of the guides I have read say that the spring on the tensioner automatically tensions the belt but...... the spring is 25 years old and doesn't seem to hold the belt very tight at all, certainly not as tight as every other cambelt I have worked with.

So what is the way to test the tension of the timing belt? I have used the old school engine builder method of tensioning and made it so on the longest run (between the oil pump pulley and the cam pulley) I can just about twist the cambelt by 90 degrees.

Any help?

[TheEnd]

BMW don't have any data on that, as far as they are concerned, a tensioner will sort it out.
I've heard of the 90' twist before as a guide. There are deflection meters about, but with no official data for tension nothing to judge it against.

Are the tensioners expensive? It probably is time to refresh it I imagine, unless there is info on checking it from the point of view of checking tensioners

[chrisr29]

90 degrees on the longest stretch will be about spot on on one of those. In fact, if I rely on the factory tensioner on mine then the belt wines and I have to back it off a little to get it right.

[T89 Callan]

chrisr29 said:

90 degrees on the longest stretch will be about spot on on one of those. In fact, if I rely on the factory tensioner on mine then the belt wines and I have to back it off a little to get it right.

Yeah thats how I have set-it up.

The 90 degree twist seems to work just right on most cars, I'll leave it as is then.