squealing noise at startup

[RickM]

I have an early 80's model b6100. Months ago when it was much cooler I started my tractor and heard a terrible squealing noise. It scared me and I immediately shut it off. After checking over everything I got my courage up to start it again. I let the glow plugs heat longer this time and it started without any unusual noise and it never happened again until the other day. It was hot /w3tcompact/icons/blush.gif outside and I did my normal start routine when it did it again. This time I fought my instinct and let it run to isolate the sound. The sound is comming from the right side of the engine near the fuel pump. The sound went away after 20-30 seconds. The best way I can describe the sound is like a screeching noise that a belt sometimes makes. It is not my belt however because it is new and tensioned properly. Am I correct to suspect my fuel pump is the culprit to make a noise like that? I can add a conditioner, but since this frightful noise happens so infrequent I'm unsure how to properly diagnose. Any thoughts or comments welcomed.

 

[Gerald]

I would try removing the belt and see if anything it turns is
hard to turn. A new belt can make a noise if it's not the
right width for the pulleys, ie riding too low or too high in
a pulley.
The only noise I have ever heard a fuel pump make is a knocking
noise, but anything is possible.
Gerald

 

[Hawgee]

I would look at the pulleys like Gerald said. You did say it was a older model. You could have enough metal wear on a pulley so as not to mate perfectly to the new belt.
I found a stethascope from Harbor Frieght Tools for less than $5.00 that can really help you isolate the noise. When the noise shows up again, try a large screwdiver against the side of the block with your ear on the end of the plastic handle. Cheap stethascope.

"What is a weed? A plant whose virtues have not yet been discovered."
Ralph Waldo Emerson (1803-1882)

 

[_RaT_]

Rick, not knowing much about this tractor I will make a few assumptions. If you have a clutch then you probably must push it in, in order to start the engine. Doing so will engage the throwout bearing. The throwout bearing releases the clutch pressure from the pressure plate. In doing so it also must spin at the same RPM as the engine. Many times a temporary squeal can be from this bearing. (they get dry of grease or are worn) There are ways to test that. If it is not that, I would certainly suspect the belts as mentioned by the others. I too have never heard of a fuel pump squealing. For fuel pumps its pretty much they work, or they don't work. Rat...

 

[gordon]

I agree with the others possible belt squeal.
If you have never used a stethascope or put a screwdriver to the side of an engine be prepared---it will sound like the moter is getting ready to come apart at any second. Because every little noise is so clear. Try it out on or when the engine is running proper to get a feel for what you will and or should be hearing.
Gordon

 

[Bud]

For a cheap scope get a piece of wooden dowel. Hold your thumb tight on one end and put your thumb in your ear. Put the other end at different places on the engine. The length of the dowel doesn't matter.
Bud

 

[roysallis]

Even though it is a new belt you might try some belt conditioner. Also, are your sure it is tensioned properly? If it is too tight the bearings in the pulley may squeal when the pulley first begins to turn.
I hope you find the problem and it is easy and inexpensive to fix. Let us know what you find.

 

[Anonymous Poster]

I HAD A B6000 LAST YEAR AND HAD TO REPLACE THE BEARING IN THE IDLER PULLEY. (BELT TENSION PULLEY) IT WAS CHEAP AND EASY TO DO. THIS TOOK CARE OF MY SQUEAL.

 

[Keoke]

Rick, if the squeal is ONLY heard at start up, then there is a good chance that it is coming from the belt being to loose for the alternator pulley. To be sure, just unplug the alternator field leads (skinny wires coming out of alt) and see if noise goes away. A cold alt on start up goes to full charge, if it's going to slip a belt, this is when it is most likely to do it.
good luck,
george, keoke

 

[RickM]

Thanks to all those who have lended their thoughts. It has been over 3 weeks now and not another squeal has been heard. The funny thing is I have done nothing except re-examine my belt tension to confirm proper deflection. My tractor has no alternator. The idler pulley and fan/magneto pulley both seem fine. I start my tractor with the hood up now just hoping it will happen again so I can isolate the sound. If dry/worn bearings and and a slipping belt can be ruled out, what is left that might cause such a dreadful noise? Thanks again for any additonal thoughts.

 

[Kelvin]

Good to hear that you're not having any problems.

You say that your tractor has no alternator. There is what I've heard called a "pulse alternator" attached to the back of your fan. I believe that you called it a "fan/magneto". Whatever you call it, that is what charges your battery.

What your tractor doesn't have is a water pump or thermostat (check out all the posts on "thermo-siphon" cooling").

One Idea: I don't know what kind of a draw that the "alternator or fan/magneto" has on startup, but it may be that your battery is more fully charged now than it was a few weeks ago. You may try a start attempt without pre-heat so that you run your battery down a bit. Then pre-heat and start the engine to see if it squeals when you start it up. In any event, make a mental note of the battery condition the next time you hear it squeal.

Kelvin

 

[Kelvin]

I decided to go to the shop manual and look up the alternator answer (to have or not to have...).

My shop manual covers the B5100 (D&E), B6100 (D,E, HST-E & HST-D)and the B7100 (D,E, HST-E & HST-D). The following statements come from the manual:

Cooling system (All Models):
All engines are liquid cooled and use a thermo-siphon cooling type cooling system. Note that the cooling fan (1-fig.34) is mounted on alternator. Recommended pressure rating for radiator cap is 88.25 kPa (13 psi). Recommended fan belt deflectioin under a load of 98 N (22 lbs) applied mid-point between fan pulley and tension pulley should be 10mm (25/64 inch). Relocate tension pulley to obtain desired belt tension.

Electrical System: Anternator (All models):
Alternator is mounted on water outlet and drives cooling fan. Refer to figure... Alternator should produce 14 volts maximum with a minimum charging current of 8 1/2 amperes at alternator speed of 4250 rpm.

Hope this helps clear up any confusion.

 

[RickM]

Hi Kelvin,
Thanks for your input. I am aware that my tractor uses the thermo-siphon cooling system. I keep my radiator and screen washed out religiously. Like you I opened up my operators manual, but found it calls my charging device a generator. I also have a copy of the electrical schematic provided by my dealer from his shop manuals at it calls my charging device an AC dynamo. My B6100 is of early '80's vintage. I used to know the difference between an alternator and a generator, but I can't seem to recall what is is now. I'm not sure if dynamo is synonymous with generator. I'm not sure why I used the term magneto, except it is what sprang to mind while I was posting. Seems I'm not sure about a lot these days /w3tcompact/icons/crazy.gif!

 

[Kelvin]

Hi RickM,
I guess that I found it a little hard to believe that if the SHOP manual calls the charging device an "alternator", that the OPERATOR'S manual would call it a "generator" but sure enough, mine does too (it took a long time to find it but finally found it on the wiring schematic in the back of the manual).

I too have a hard time recalling the difference between a generator and an alternator. There's room for error here, but I vaguely recall that a generator produces DC current and an alternator produces AC current (and converts it to DC). Nonetheless, I do remember that a generator is huge relative to the size of an alternator. I would therefore guess that we have an alternator on our B6100s and B7100s (my B7100 is a late '70s or possibly an early '80s model).

Anyone else is welcome to join in on this conversation and solve the "generator vs alternator" mystery.

PS I notice from your attached picture that you appear to not have a ROPS. Kubota dealers sell them relatively cheap (below $200 then add tax & shipping) and they are pretty easy to install (with two helpers).

 

[Bird]

Fellows, I can usually do my own troubleshooting and repairing of charging systems, but darned if I'd know how to explain the differences in them. One thing I never forgot was a sales meeting, when alternators first came out on cars, in which the instructor told the mechanics, "I know a lot of you are used to shorting across the terminals on a generator to see if you get a spark to tell whether it's working. Well, you can do that to an alternator, too, and if you get a spark you know it was working before you did that."

My shop manual for the B2710 says the charging system "consists of a AC dynamo and a regulator. The dynamo is an 8-8 pole rotating magnet type generator. It is simple in construction, consisting of a stator and rotor. The rotor is made up of eight permanent magnet pole pieces assembled on a shaft and rotates on the center of the stator around which eight electromagnetic coils are provided for. This dynamo produces higher voltage in slow speed rotation, and charges electric current to the battery during engine idling." I think (not sure) that the B7100 was the same.

Bird

 

[scruffy]

Kelvin, you are 100% correct on your AC=Alternator, and DC=Generator output. You can use an Alternator direct production of A.C. Current, of course you will want to regulate that output to a usable storage medium, ie the battery. (A little off the subject) By using waterpresure through a hose, downhill from a springbox, you can direct it a 'propeller' if you will, connected to an alternator and produce A.C. current as an alternate energy source. By running it to deep cycle batteries, you can power your home 24 hours a day. Cheap energy! it can also be hooked to a windmill for the same effect, although less continuous.

 

[TomG]

I remember letting a bar of hand soap rub on the fan belt of a car to make the belt squeal go away (That doesn't cure a problem of course). However, that might be a way of eliminating belts as a source of the squeal if it starts happening regularly.