Alternator belt tension causing cooling issue?

[///M3Mike]

After replacing my radiator, thermostat and housing, hoses, clutch fan with a Volvo fan (and removed the aux fan), and water pump...my coolant is still running close to the 3/4th mark on the gauge.  I believe it's properly bled as I get no bubbles and after sitting overnight, the (OEM with 50% distilled water and a bottle of Royal Purple 'water wetter') coolant is maybe 1/2 above the KALT line.  I'm wondering if the belt running my water pump and alternator might be stretched, or out of whack?  The alternator tension bolt is cranked all the way over and the alternator bushings are fine...no play in them at all.  When I start the car, my alternator light stays on until I rev it to 2-2.5k or so and never comes back on.  My battery checks out fine and my alternator puts out acceptable voltage and passes all the load/no load tests per the Bentley.  The belt is less than a year old after snapping while on the freeway.  I was able to limp it to a friends house without getting into the red zone and got a Napa-sourced belt on there.  I can't find any reference to belt tension in the Bentley or a Google search.  I don't have a belt tension gauge, so I don't even know if the numbers would do me any good, but I was wondering if there was a good 'rule of thumb' for checking it manually.  In my old RX-7, I used to put a straightedge across the pulleys and measure how much it would deflect by pressing on it...usually a couple centimeters.  Am I going about this all wrong?

Oh, and due to neglected maintenance by the PO, it needed new cooling gear anyway, although the old water pump was a metal impeller.  I just like to know the actual no-shit age of stuff like that.

Sorry for rambling.

[tjts1]

Hoses can fail internally where a chunk of the hose can block coolant flow while the outside still looks normal. Try bleeding the cooling system with the front tires pointed uphill. If the belt doesn't look worn and its not making any noise it should be fine. when you press on the belt, it shouldn't deflect more than 1/2" or so.

[Choking Hazard]

Check the actual coolant temp with a candy thermometer.  Baddata caused me to replace all that stuff before I figured out it was the gauge cluster, not the cooling that didn't work right.

[1991 E30 M42]

Check the actual coolant temp with a candy thermometer.  Baddata caused me to replace all that stuff before I figured out it was the gauge cluster, not the cooling that didn't work right.

I had that problem, (well except for the replace everything part because everything was already new) the gauge kept telling me I was running hot when a month prior I had issues keeping my temp up, so i pulled the cluster out and loosened and tightened the ground nut on the back side of the temp gauge

[///M3Mike]

Hoses can fail internally where a chunk of the hose can block coolant flow while the outside still looks normal. ... when you press on the belt, it shouldn't deflect more than 1/2" or so.

all my hoses are new within the last 6 months, and I had them all off when I did the recent water pump r/r.  No internal damage as far as I know.  I think my belt has more than 1/2" of deflection so I may pick up an OEM belt and go from there.  (I also have been meaning to thank you...your threads on the "mess under the intake" and the Volvo fan were inspirations to me )

Check the actual coolant temp with a candy thermometer.  Baddata caused me to replace all that stuff before I figured out it was the gauge cluster, not the cooling that didn't work right.

Hadn't thought of that.  I'll have to check that.  Thanks

I had that problem, (well except for the replace everything part because everything was already new) the gauge kept telling me I was running hot when a month prior I had issues keeping my temp up, so i pulled the cluster out and loosened and tightened the ground nut on the back side of the temp gauge

Hmm....I can get my cluster out in 4 minutes now I think so I'll do that this weekend.  haha.

[DesktopDave]

+1 on the cluster.  Especially if it's a VDO.

I'm good with the cluster too; I did a little dremelling behind the steering trim to make it even easier!

[ecalder]

Also consider getting an oem belt from BMW. Mine was brand new but it was cranked all the way as well and although it felt tight enough I could not have tightened it more even if I had wanted too. The oem belt is smaller giving you more control of the tension. Can't remember who it was on the forum that reccomended that but I think it makes a difference having that extra room. Mines now cranked about half way on the tensioner. The manual said to tighten that to around 8ft-lb and I haven't had any problems.