Problem with new BDS 871 blower rotor issue
 

Need what you think about that rotor issue, the casse is in perfect condition inside, it is like the rotor tuch them a litle together until making this.
I dont speak english very well but i have talk by phone with Tim at BDS and they wont honor the warranty and want to charge me 2500$ to repair because he tell me this was cause by backfire but this engine never backfiring. The blower was only 60h since it is new. The wear is identical on each blower lobe an in my opinion this is a too tight rotor timing problem and not a backfiring problem because of the wear is strait an identical on each lobe.
The only problem i having last summer is i ran out of fuel on boost due to a fuel pump problem other than that i never had any problem so another time i dont think this was the cause of that rotor wear.

Thanks for any help.

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how much are you over driving the blower?i have seen that on larger blowers with a lot of overdrive.also,are you running carb or fuel injection?

I am runing carb dual 850 quick fuel marine, the blower is 5% underdrive at 10lbs boost

looks like improper clearance to me..

do you have the same swipe marks on the backside of the lobes? Meaning, you have the swipe marks on the rotor tips but where's the corresponding swipe marks in the valley of the lobe? That will tell you a lot IMHO.

That is what i think because the wear is there on each lobe of the rotors and the inside of the case still like new without any sing of wear or scuffing. I am just disapointed that the shop who made this blower wont admit the real cause of the problem and wont respect is warranty on a brand new product.

with that being said,their has to be contact and if it is not rubbing the case i believe it must be contacting the inside of the rotor lobe.if you see that i think rotor timing might be the issue.maybe they forgot to lock tite the rotor bolts.

Wich bolt you are talking? The one that bolt the gear to rotors? Or the bolt pin we can see in the pics?

Slowly turning over the blower can you hear any sounds of rotor contact? Re-timing the blowers is quite easy if that's what has to be done. You can either shim one of the gears or machine the backside of the other, your call.

I've rebuilt my own and also a few B&M 420's which are almost the same (not a helical rotor). My gears are machined, the B&M's was timed with shims. I think guys are afraid to work with them because companies like Blower Shop etc. charge a lot of money to do it. The bearings and seals can all be ordered at your local Napa. The only thing I don't get involved in is stripping them but then again, that's only because I haven't had the chance to do it yet.
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yes i mean the bolts for the gears.

[QUOTE=Panther;4405585]Slowly turning over the blower can you hear any sounds of rotor contact? Re

How do you time them?
Feeler gauge each side of the rotor and adjust to be equal?
Shim til lobes hit on one side, shim til they hit on the other, then split the difference?

very hard to tell from those pictures. I dont know if you are thinking that rotors would put those marks in each rotor because they pass each other or not but if you look at panthers photo and you can see how the rotors mate up to one and other and if the rotors were scraping each other you would have two sets of marks in each rotor not one. From your picture you cant see marks in the concave portion of the rotor if you keep turning the blower do you eventually see marks on the inside of the rotor? If not it is definitely a rotor to case problem.

You turn the rotors until they're at the closest contact and then, with feeler ribbons, you check the tolerance. I wanna say it was .003 - .005 clearance but don't quote me on that. If you are too loose it wont seal, too tight they'll swipe. Don Hampton gave me the tolerances when I did mine several years ago and I can't find them. Another thing that needs to be checked is the gear backlash.

Here's a great step-by-step I found on the interweb... http://www.hotrod.com/how-to/engine/...n-8-17-blower/

If you're simply wanting to re-seal and re-bearing the blower, a lot of the clearance steps aren't necessary because nothing you're replacing will change the rotor timing unless you're installing new gears for example. I've done a half dozen now and the process was pretty easy in my opinion.

Nice link, thanks.

The wear is not totaly in the center tip of the lob, it is where the two lobe start to cross one in the other at the closes point when it start to cross overlaping the other lobe. It is hard to explain but if you take the time you will see what i talk about in the pics

I understand what you are saying and i am getting old and maybe all the scars from restripping them damn things is blocking my mind but to me the marks dont line up for which side of the teflon the marks are on. I was wondering if you could do a test for me if the motor is out of the boat. If it is i am sure you have spun the blower by hand and there are no tight spots while it is sitting on the bench. Try this sit it back on the motor and spin it by hand with no belt Then put the nuts on just finger tight and spin it and see if there are any tight spots then torque it down as you did when you put it on the motor and see if there are any tight spots Then let us know

Sorry i cant do the test, the blower is at BDS for warranty claim since octobre 2015 and today i dont know when i will get it due to bad service from her. This blower was brand new at the start of the summer, this is a stage 2 BDS 871 without teflon strip, ran it for max aprox 60h and thats is the result...

sorry for all your issues hope they get you squared away. I meant the black strip running down rotor teflon nylatron

tad117,his blowers do not have any strips,low boost blower.

Although its really hard to see in the photos, it looks like a timing issue to me. Did it suddenly get very noisy or just never sound right causing the removal.
I did see one look like that on a very large blower at work that was a bearing failure. It was Very loud !

Just to update my situation with BDS.
After hard discutions whit BDS they made the rotor repair under waranty. I have made my personal inspection i have remouve the front cover and what i have see is a set of used gear that he is having some issue like you can see in the pic. Note that i have buy it new in april 2015 and BDS told me they have made the waranty repair with my parts So i see 2 option i have buy it new with that bad gear or they swap my original good gear for that crap during the waranty repair!.

Dont know what BS business it is but i Just want to let you all know what kind of bad qualité product i have buy...

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Wow, I`d be livid.
That`s inexcusable.
Thanx for the heads up about BDS

are you saying this is how you recieved it AFTER the repair?

Yes this is how i have received after the rotors repair.
They are no reason that the gear was like that the only issue i having with that blower is anormal rotors wear after 50h since buying new in april 2015.
This blower have never broke or having issue in the gear casse at all so no reason for that bad gear.

Screw BDS... goto Dyer's... http://www.dyersblowers.com/

Excellent customer service and will help you get it right!

I Just notice that he have a litle gap between the te teeth of the gear with no oil in them, with oil in the casse the gap is gone, is that normal?

I am nervus to used them now with all my storie and bad experiance with BDS.