Alts struggling in the cold?

[HardCorps79]

So the weather here has been in the single digits to the 20s the past few days and the M1009 is having a time of it. Problem is, it's taking a good 3-4 tries to get it started (GPs need to be replaced, I'm sure), but they do fine when it's over 30, so, anyway...

Once the truck starts, the belts are squealing like mad and the voltmeter gauge stays in the low green forever. It's taking a good 20-30 minutes and some increased RPMs for it to get up "over the hump" where the belts stop squealing and lock itself in.

When i switch the cab-heater on, it's fine until I put it on full blast. Then the gauge drops and takes another few minutes to recover. Once I'm driving at speed I'm not having any issues, but when I slow down or turn, the gauge drops below the notch and the belts squeal for another 5 seconds or so until it recovers. This problem is persistent even when the truck has been running for over an hour and everything is warm. Never have had this issue in weather over 30* though.

When I turn the fan to anything other than high, it's good 90% of the time, even with slowing, stopping and turning.

Is this normal and just due to the cold, or is there something else I can do. Seems the fan is putting more of a drain on the alts/front battery than it should.
Batteries are fully charged.
Front shows 14.7v, then drops to 13.8 with the fan on high
Rear shows 15.0v

Driver's side alt shows 14.5-14.8
Passenger side alt shows 29.9v

Thoughts and comments appreciated.

(BTW- did notice a bit of belt squealing starting a few weeks ago with temps in the 40s, but only when turning. PS pump/belt? Seems that went away though, and now it's the alts or something. Or I may really have no idea what I'm talking about...)

 

[doghead]

How old are your batteries? Maybe have them tested at an auto parts store? How old are your belts?

The fan only runs on the front battery.

 

[mistaken1]

Adjust the belts?

Mine just started squealing here recently after a cold start. The squeal would come and go as the glow plug relay switched on and off.

Today I adjusted the alternator belts to about a 1/4" to 3/8" deflection at the center of the belt (on the top side where it is easy to reach).

We will see if this eliminates the squealing at start up.

 

[2mtrucks]

Check your V belts. Mine had narrowed enough on the edges that they were too narrow to "bite" on the pulleys. And they were too narrow because the belts were not tight enough in the first place and wore from slippage, which made the problem progressively worse. I roughed up the very polished surfaces of the alt pulleys with sand paper, being careful not to get any grit in the alts and replaced the belts. Problem solved, at least for now.

 

[4bogginchevys]

I have a similiar issue with belt squeeling and such, my belts look good and the reciept shows only 4 months old, i'm going to try belt dressing and keeping a watchful eye on the tension for a while. It is also really cold here and these problems only arrived with the change in season.

 

[Wolf.Dose]

The alts have a power output of max. 1.4 kW (1.9 hp). This is something. If the belt tension is low, they make noise. So check the tesion of your V-belts or better just replace them.
Wolf

 

[HardCorps79]

Belts don't really show any signs of wear, but i don't know how old they are. Will have to change them out first chance I get and tighten them up. Any quick tips on this? Potential pitfalls?

4boggin- glad to hear I'm not the only one who's had belt squeal in the cold.

Batteries should be good. I'm going to recondition them/desulfate 'em when I can get a 48-hour period where I don't need the truck. (daily driver, so I'll be rollin' in the wife's mini-van) and see if that helps.

How do you adjust the "deflection"? That's a new one for me.

Thanks, guys.

 

[4bogginchevys]

One other thing that just came to mind is, I too have to try 2 sometimes 3 times cycling the plugs while trying to start the truck (ya ya, thier bad). The volt guage never shows in the yellow for me though, at first startup it's even a little in the red and then drops as it "catches up" eventually relaxing to just above the little mark that I believe is where it should run. Before I put new alts in the truck it would be in the yellow.....then eventually go up to the green.

 

[91W350]

Its an old automotive term to measure belt tightness. Some applications actually specified a weght to be hung in the middle between two pulleys. You measure the difference between no weight and the weight pulling the belt down. Most guys just press with a tool or their thumb to get an idea how tight the belts are. The problem with saying 3/8ths of an inch is one guy will measure that with gentle pressure on his thumb and the next guy will use a tool and apply 30 pounds to the belt.

 

[acmunro]

I'm with the other guys as far as the belts go. They can be tight and still squeel. They get old hard, glazed, and worn skinny. I would recommend quality replacement belts - I usually get mine from NAPA their brand is usually manufactured by Gates. The thing to watch out for when installing belts is pulley misalignment. I have a civilian 6.2 truck I had to grind the spacer between the alternator and the cylinder head to make it quit burning belts off. Also remember to check the tension of the new belts after running the truck for awhile. Good luck

 

[avengeusa]

I'm with the other guys as far as the belts go. They can be tight and still squeel. They get old hard, glazed, and worn skinny. I would recommend quality replacement belts - I usually get mine from NAPA their brand is usually manufactured by Gates. The thing to watch out for when installing belts is pulley misalignment. I have a civilian 6.2 truck I had to grind the spacer between the alternator and the cylinder head to make it quit burning belts off. Also remember to check the tension of the new belts after running the truck for awhile. Good luck

Bingo!


Listen to this guy, I build alternators and see this all the time, tighten the belts, make sure they are in good condition and are from a quality manufacturer, and be sure the pulleys are aligned, this is more common than one would think

 

[mistaken1]

Its an old automotive term to measure belt tightness. Some applications actually specified a weght to be hung in the middle between two pulleys. You measure the difference between no weight and the weight pulling the belt down. Most guys just press with a tool or their thumb to get an idea how tight the belts are. The problem with saying 3/8ths of an inch is one guy will measure that with gentle pressure on his thumb and the next guy will use a tool and apply 30 pounds to the belt.

I am sure there is a specification somewhere on what the proper belt tension is but with it warming up to 15 degrees yesterday and I was dressed from hauling wood I tightened the belts up without bothering to set at the computer before hand and search for the spec.

I just used my thumb but have no real idea what weight/force I am applying. I guess it is more of a relative thing, where I was getting 3/4" or so of movement before adjusting I am now getting 3/8" using the same basic 'rule of thumb'.

 

[91W350]

That is what I do, use my thumb to depress the belts. Over the years you develop a "that's tight enough" feel. If it slips at that tension, the pulleys are glazed or worn, the belts are worn or soaked with lubricant of some sort or that driven accessory has an issue. I have seen belts cranked down tight enough to ruin seals and bearings on belt driven accessories. I have a buddy that thinks a belt dressing can is a cure all, how did I ever get by without buying that stuff Glen

 

[acesneights1]

Well, the real problem is Gates Belt company. It is a little known fact and only us old farts will remember but Gates used to make what was known as "8" series belts. These belts were 7/16 thick and it was a **** good belt. In fact a Gates 8 series belt would usually outlast the engine. Of course the problem with that is Gates a no maka no money so what did they do ?? Discontinue them and took the 7 series which was a 3/8 belt and made it 13/32 and told everyone"this will work fine, we beefed it up" BS. Pretty much all 6.2s end up with premature belt wear and squealing sounds including the civilian models. Gates does make a heavy duty Alt Belt for the civilian version known as a 5725 IIRC. Have not had my CUCV long enough to see if that belt fits either alt or if a similiar belt is availible. I can tell you this has been a problem for a long time which is why alot of 6.2 owners get frustrated and connvert to a serp belt which GM later did. I just changed the belts on my CUCV because they were squealing and the D/S alt had the orginal 7/6 belt on and it didn't look that bad. The pass side alt had a 7 series gates and it was shredded. I will probably down the road lose the extra alt and change to a serp belt. I have contemplated changing the truck to 12V single alt but keeping the 24v starter and using a series parrallel switch off an old Mack.

 

[mistaken1]

http://test.steelsoldiers.com/images/editor/attach.gif

That is what I do, use my thumb to depress the belts. Over the years you develop a "that's tight enough" feel. If it slips at that tension, the pulleys are glazed or worn, the belts are worn or soaked with lubricant of some sort or that driven accessory has an issue. I have seen belts cranked down tight enough to ruin seals and bearings on belt driven accessories. I have a buddy that thinks a belt dressing can is a cure all, how did I ever get by without buying that stuff Glen

According to the TM it is 146 Lbs when new and 67 Lbs when old (or new belt ran for 15 minutes).

There is this handy dandy gauge:
Krikit V-Belt Tension Gauge (91107)

Automotive V-belt Tension Gauge (91107) : HVAC Maintenance & Supplies, (LOW Prices)

Perhaps someday I will spend the money on one and check the calibration of my belt thumb....

 

[91W350]

Wow! I am disappointed.... my tried and true thumb guage is only worth 20 bucks....

Thanks for the link, I am not sure I ever actually saw one of those tools.

 

[combatmech]

This problem seems to be going around. As with my starting problem, while driving and the heater fan on high, headlights on, I get a faint gen1 light that goes away when I turn the fan down. The belts also squeel a little during acceleration, and then goes away after reaching a cruise speed.

 

[Wolf.Dose]

I like to add this, maybe some people do not like to hear / read this.
It is about the live time of V-belts.
I found out (the hard, expensive way) that the alt mounts as stock are not the very best for alinement. For the left alt I had to cut the mount and move it about 5 mm forward and change the angle by about 5 to 6 degree. The right one was even worse. After the modification and propper reweldding the parts together the V-belt makes no more problem since about 4 years. Change is not necessary beside the tension to the left alt normally is supposed to be to low. No squeaks, no wear, just perfect in line. You can see that on the attached photo. The pic is taken with the engine running at idle. If you check the belt for the left alt propperly you will see it.
Beware of slightly rusty pulleys! the eat your belts before the pullys are polished again!
Wolf

 

[acesneights1]

The problem is you can no longer get 7/16 thick belts and that is what these were designed for.

 

[chgofiveo]

Bingo!


Listen to this guy, I build alternators and see this all the time, tighten the belts, make sure they are in good condition and are from a quality manufacturer, and be sure the pulleys are aligned, this is more common than one would think

You sound like an alt expert...I have never heard of cold weather causing alt problems...have you? The only problems i have seen are belt and allignment problems... i thought if an alt was bad, it was bad...never saw one come and go...Whats your feelings?