Rebuilt 45 blower knocking on start up

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so i bought a rebuilt blower on ebay from a certified rebuilder..

4 months ago or so

hooked up today and it knocks on engine start, metal on metal sound for 1/2 second, then seems to run fine.

i texted him and he said that sitting for so long may have rusted the lobes knocking it out of time.

1. does this sound accurate?
2. Is it OK to run it as is ?
3. What is worse case scenerio if i do

It is direct drive with #7 love joy. 30 aegis
 

steve_64

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My 56 has a similar knock but it's old and tired. Keeping the filter clean seams to help as does lubricating oil.
 

Cleanworks

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so i bought a rebuilt blower on ebay from a certified rebuilder..

4 months ago or so

hooked up today and it knocks on engine start, metal on metal sound for 1/2 second, then seems to run fine.

i texted him and he said that sitting for so long may have rusted the lobes knocking it out of time.

1. does this sound accurate?
2. Is it OK to run it as is ?
3. What is worse case scenerio if i do

It is direct drive with #7 love joy. 30 aegis
Was it sitting out in the rain? Sounds like a bullshit excuse. Probably a blower he thought was good and didn't need rebuilding. If it's rebuilt to factory specs, it should turn smoothly by hand and shouldn't knock at any speed. Just my opinion.
 

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I turned by hand no less than 40 Revolutions, and it turns by hand fine. nice and smooth

I thought there was gears , like a timing chain, that it could NOT slip.

Not my area of expertise though, why i am asking the Collective
 
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Depends on make. Some have timing issues. If it is not "center-timed" the direction of rotation can allow lobes kissing each other in some situations.

Measure leading and trailing gaps with flat stock.
 

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Lee,
Have not had chance to measure.

Seems only to knock at lo RPM, so I have my lead keep rpms up over 2500.

What are my odds it locks up on me?
 

Cleanworks

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KNOCKING, if that is what you are hearing, is serious, and will get worse at high rpm.

I suspect something else.

Double check.
I wonder if it's vibrating on its mount or maybe physically knocking on something nearby when the engine is at low rpm. Check the clearance between the blower and belt guards or frame structures, etc.
 

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Thanks guys,

to clarify, it ONLY knocks at start up, when rpm 2200 or less.

Running at 2800 there is no knocking during use.
 

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Ron, there is nothing by it.

Come to think of it, the other time I heard it was when I switched to the orange Hytrel? Couplers. 100$ #4. Love joy. They were suppose to last forever, but they were far too ridged. Upon start up they did same thing.

Lee, what I described, It is not a timing issue?

I might have the couplers too close.... I will readjust blower back 1/4” pending feedback.
 
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steve_64

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Was it sitting out in the rain? Sounds like a bullshit excuse. Probably a blower he thought was good and didn't need rebuilding. If it's rebuilt to factory specs, it should turn smoothly by hand and shouldn't knock at any speed. Just my opinion.
When I bought mine I was told the knock started after it seized and a pipe wrench was used to free it up. Just remembered that.
It knocks on start up until it gets to speed but it can knock on shut down too on occasion. Like I said usually when I'm not keeping the filters as clean as I should. When I run things clean and use lubricating oil more often I don't hear it knock.
 
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Knocking is caused by worn bearing and or timing gears, and rarely, warped lobes.

Worn bearings and gears are caused by too little (or too much) oil. Excessive side load (belts too tight) will contribute to this wear.

Warped lobes are caused by excessive heat from prolonged back pressure (vac relief or blocked blower hx), usually in the center, and can be measured with a flat feeler gauge as I said earlier.
 
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Cleanworks

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Knocking is caused by worn bearing and or timing gears, and rarely, warped lobes.

Worn bearings and gears are caused by too little (or too much) oil. Excessive side load (belts too tight) will contribute to this wear.

Warped lobes are caused by excessive heat from prolonged back pressure (vac relief or blocked blower hx), usually in the center, and can be measured with a flat feeler gauge as I said earlier.
If this was really rebuilt by a certified rebuilder, they should take back and replace it.
 

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we moved the blower back a little, making sure coupler did not have any horizontal tension and seem to help. still knows a little on start up. will wd40 and see how that helps

gonna run it till goes...
 
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