Volts momentarily low, then rise upon starting, only after car wash

[Jonathan]

I've only seen my car do this twice, and both times were in the past few weeks. The only consistency I know of is that it happened both times right after a car wash.

I try my best not to hose down anywhere near or right into the engine bay (from above). I recall a few years ago when I didn't know that was a no-no, I got the engine pretty wet and one of my spark plug wire caps was wet and the car chugged or misfired for a bit until I got it dried out.

What I noticed this time around, was where I would start the car, and the volts would be low, say around the 8 volt mark or so. Engine would be on for a couple/few seconds only, and you could watch the needle come back up to normal, which for me reads a bit over the 13 volt mark. From then on it is fine and right where it always is. Car never stalled or chugged or anything, it was purely visual seeing the gauge move when sitting in the drivers seat.

Anyone ever seen this on their car, or could suggest something I might need to look into?

[cybercusp]

My car did the same thing a few weeks ago. It had been sitting in the rain..volts stayed low for about a minute then came up to normal. I'm thinking the belt may have been slipping with the moisture, then heated to normal operating temperature which drove off the moisture. I haven't seen a problem with it before or since.

[Bitsyncmaster]

Agree it's probably a wet belt but you should not be as low as 8 volts even with a dead alternator. How old is your battery? Does your starter crank the engine slowly?

[Jonathan]

Ok, I just refreshed my memory on where the "8" is on the volt markings. It was likely more in that tick between 13 and 8, rather than all the way down to 8. It caught my eye as it was moving so not 100% sure where it started. Not to mention I don't exactly see some of my gauges all that well with where my head is stuck up in the roof, plus what the steering wheel is blocking or the top edge of the binnacle.

My belts were probably a bit wet. And maybe borderline loose perhaps. They look like they could be tightened up slightly as at times they look like they wobble. What's that rule of thumb again? If you press relatively firmly on it, it should deflect a 1/2 inch? I would bet mine deflect more than that. I remember having a hard time by myself trying to get it right good and tight the last time I moved something. Needed a third hand if I remember correctly... Any tips or tricks on belt tightening by yourself??

[sdg3205]

Jonathan,

Definitely a loose belt. I used a jack with a piece of wood as a buffer to gently push up on the alternator and hold it there while i tighten.

Got the idea for Steve Rice. Works great, just go slowly and check tension constantly.

[Bitsyncmaster]

Install the "turn buckle" bracket that is shown in another thread. One man operation to tighten the belt.

[Kenny_Z]

Any tips or tricks on belt tightening by yourself??

http://dmctalk.org/showthread.php?3186-Adjusting-alternator-tension

There's a list from Farrar in that thread that will get you everything you need. It'll make changing a belt on the side of the road with a hot muffler in your face much less painful.

[stevedmc]

Jonathan,

Definitely a loose belt. I used a jack with a piece of wood as a buffer to gently push up on the alternator and hold it there while i tighten.

Got the idea for Steve Rice. Works great, just go slowly and check tension constantly.

The jack trick works but Steve Rice prefers Farrar's alternator mount/tensioner. I had an alternator belt pop in Kentucky a few weeks ago. I pulled over, took a pee, changed the belt, and 20 minutes later I was back on the road. It would have taken a few minutes longer using the jack method.

[David T]

A good test to see if the belt is too loose is to see if you can turn the alternator with your hands WITH THE MOTOR OFF!!!!!! Won't tell you if the belt is too tight, that you can tell by trying to deflect the belt. Or you just tighten it up till you can't turn the alternator. You an also have a glazed belt or a belt that is the wrong size. If it is running on the bottom of the VEE, hitting the bottom of the pulley, you have the wrong size belt. The VEE belt is ONLY supposed to ride on the sides of the V. If you see any of the cords showing the belt is no good.
David Teitelbaum

[Dangermouse]

My car did the same factor a couple of several weeks ago. It had been seated in the rainfall..volts remained low for about a instant then came up to regular. I'm considering the buckle may have been falling with the wetness, then warmed to regular managing heat range which forced off the wetness. I haven't seen a issue with it before or since.

Either very bad english, or very clever bot. I vote #2

[Elvis]

Is the belt squeeling sometimes when cold ? Then -> loose.



If it needs a few seconds to get the voltage up it could also be some water on the brushes of
the alternator or you have a bad bulb in the dash.

The old/simple alternators would work without a bulb if they are revved up to a high speed, then they
keep themselves working.