Scary, almost killed my 3B...

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Sep 2, 2007
Longmont, CO

So I get in the car after a long happy hour and I think I hear a funny noise at low RPM, sorta like an intermittent whirring. It goes away when you touch the gas so I didn't think anything of it...

Drop a friend off and hop on the highway. As I accelerate up the ramp the Filter light goes on; this is very weird as I just emptied the thing a week ago. It goes off for a while only to come on again. Now I'm thinking this is too weird that I heard a funny new noise AND my filter light is acting up.

Looking around the dash for clues I notice the temperature gauge is at the 3/4 mark! utoh!: pulled right over. I've never seen it that high before (usually hangs out at 1/3). I'd just repaired, last weekend, a radiator leak so I was carrying a gallon of coolant "just in case", so I thought maybe I sprung a new leak and lost some coolant. I figured that if I was low I could remove the cap without too much trouble, so I sacrificed my shirt and took the cap off; almost no pressure. When I added coolant, I was surprised that it only took ~1/2 gallon; thats what it "usually" drinks when I top it off (the overflow tank seems to suck it out until theres 1/2 gallon of free space), so it didn't look like I was leaking.

... which is when I noticed the belt nearly hanging off my alternator!!! Somehow it managed to vibrate itself loose; the noise I heard when I got in the car was the belt just starting to slip. I didn't have any wrenches, so I beat it back into good tension with a tire iron and the jack as a hammer, and made it the rest of the way home at 1/3 on the temp gauge.

Close one!

Heres the question though; why did the filter light come on? I did check if it needed a drain when I got home; nothing came out.
Because of the loose belt, the alternator probably was not charging properly.....?
And AFAIK that may cause the lights to show?
Because of the loose belt, the alternator probably was not charging properly.....?
And AFAIK that may cause the lights to show?

My alternator is worn and the filter light comes on as the voltage drops below around 12V... This would be my guess for your problem as well....
Notice that the filter light comes on when you turn the key on, but haven't engaged the starter? Thats because the light grounds back thru the alternator when it is not operating. A basic design feature, it tells you the alternator is not charging and your filter light is working, think of it as a twofer, two bits of info for the wiring of one.
Hey. I wanna filter light too. :crybaby:

Users who are viewing this thread

Top Bottom