Alternator Problem

[snagmaster62]

I have been experiencing a annoying problem with my LB1914 alternator. The bottom bolt that secures the alternator to the engine continually shears off during short periods of running the tractor (10-15 minutes). I spoke to a couple of dealers about this and arrived at a reasonable suggestion to go to a harden bolt #8 versus what I was purchasing at a local home improvement chain. This unfortunately did not resolve the problem since the #8 shear off as well. The best I can tell is that the alternator has developed an excessive amount of vibration that is wreaking havick on the bolts that secure the unit to the engine. I have a new alternator on order for the tune of $115 hoping that this will resolve the issue. Has anyone every experience this or see this in the field? Other than a new alternator I can't think of anything else to try.

 

[depratt_equip]

Never seen this before, but I am wondering how the alternator rotates with the belt off? Is it pretty wobbly? How old of a unit do you have? The alternator you should be getting will be an updated one but you will have to change out some brackets along with a new belt.

 

[Elvis3054]

Have you checked the top bracket for cracks? The only other time I have had something like this happen was on my daughters Jeep, When the bearings went bad and wiped out the bolts.

 

[IH3444]

I have run into this type of problem before, just not on a Mahindra. My solution, after many a frustrating replacement failures, is to just go to a larger bolt, and if possible find a top quality allen head fastener. There are bolts harder than grade 8. Yea, they use them in submarines, so try ebay for a super alloy larger bolt. Hopefully this will help with your problem, and you don't have to tap any larger holes into the engine block. Don't forget, just because a bolt says it's grade 8, doesn't mean that it is. As a EIT, frsh out of school, I was asigned to the mechanical test lab, where I pull tested many a sample. I pull tested the bolts for the M1A1 tanks, which kept the treads onto the track rails. Yes they were marked, but the tank treads kept flying off the tanks. Not good! Especially in battle! Thank god, Uncle Sam has mil specs, that many people love to make fun off, and ridicule, because their life is not on the line if the equipment fails. I would approach many a hardware offered at grade 5, and grade 8, a bit wary. It could be good, it might not be the grade advertised. For this, I would search out a top quality bolt, and go up a size if the space allows it. Hopefully it will just be drilling out a few holes. Think of me when you put that drill to that brand new $115 alternator. /forums/images/graemlins/grin.gif

 

[PILOON]

I would locate an aviation supply house and request an AN or better still MS bolt of the size you need.

They are available in just about any length and diam as well as fine and coarse thread.

The MS series is about equivilant to grade 12 (try cutting one with a hacksaw).

Van Dusan Aircraft supplies is one source.

 

[IH3444]

Good idea. That hardware has to be certified for aviation use. Those bolt which were breaking on the M1A1 treads were traced to the supplier, and then back to,...............are you ready? CHINA! This was back in the late 80's. Hmmmmmm.................Chinese steel tractors..........6 month warranty. I'm getting the picture now, it's becomming clear. 82hp Chinese Perkins engine..........right! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[snagmaster62]

Jon, I removed the belt from the alternator last night to check to see how the alternator spins. First thing I noticed was that the pulley is a split pulley with the back portion firmly in place and the front half of the pulley has freedom to move around the bolt that attaches it to the alternator. The alternator itself seems to spin without a wobble but does not spin freely like a car alternator. As you try to spin it, it's freedom to spin about an 1/8 of a turn freely then gets harder to turn for about another 1/8 of a turn. This cycle of repeats itself for the full 360 degree of rotation. I briefly looked at the shop manual and I am thinking that this is by design since as I understood it there are magnetic poles that are attached inside this outer spinning cowl. If this is true I am wondering if somehow the alternator lost one of the magnets and has caused the unit to be out of balance went running.
The unit is a 2003. Would the installation of a new alternator require the retrofit that you were talking about? Thanks for your help and advice.

 

[snagmaster62]

I did check, based on your advise, the upper bracket that is used to adjust belt tension. I did not find any cracks or damage but certainly was worth checking.

 

[snagmaster62]

IH3444 and PILOON, thank you for the educaton on high quality/hardness bolts. I am thinking that along with the new alternator I should get a bolt from Koiti as well since they should have everything spec. properly. If this is not successful I will go shopping for aircraft bolts.

 

[ToadHill]

If the unit begins to bind after only 1/8 turn, chances are you have a bearing going bad. Take the unit to a automotive shop and have them spin it on the test stand. A vibration may only show up when the tension from the belt is applyed. If that is the probllem, a bearing replacement is a lot less expensive then a new alternator.

 

[depratt_equip]

You will get resistance about every 1/8 turn or so, like you said this is the magnets and the design of this little alternator. Your tractor should have the new style alternator I believe. Something must be broken inside and causing a vibration though…. Have you got your new one yet?

 

[snagmaster62]

Jon, my local dealer in VA did not have the alternator in stock. Still waiting to pickup when it comes in from Koiti's distribution center.

 

[tractorhill]

I have one in stock if you need it.
Will ship ups

 

[snagmaster62]

Received the new alternator for the tune of $184. Installed and the tractor humms like a champ. No vibration or noise that was experienced with the previous that would end up shear of the mounting bolt. In comparing the old versus the new I believe that I identified the problem. The pully is made up of two halfs that are pinned together by a spring pin (no sure of the proper terminology) The pin either broke or worked its way out, which allow the outmost half of the pulley to rotate freely instead of spinning true with the alternator shaft. I believe this caused all of the excessive vibration due to an out of balance situation. I am going to see about getting it re-pinned and will use as a spare if I have any future issues with the alternator. What a difference it makes to have the luxury of comparing a problematic part to one that is new.

 

[MotorSeven]

Snag,

Thanks for posting the follow-up. It may help one of us down the road if something similar happens.

RD

 

[KiotiJohn]

Yes, thank you for posting the follow up. It always helps others to know the outcomes of posted problems.

I'm glad you got it fixed. It must make you feel much much better.
John