Restore This Stihl BR420 Blower to Its Former Glory

This Stihl BR420c backpack blower has seen better days. It needs a spa day, as well as a new spark plug boot, spark plug, blower tube, fuel filter, and a thorough carburetor clean and rebuild to restore it to its former glory. This process of checks and adjustments applies to most any backpack blower, including those made by Husqvarna, Echo, Red Max, Shindaiwa, Craftsman, Troy-Bilt, and others.
Watch this video next: • Stihl BR550 4-Mix Valv...
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Champion RCJ6Y spark plug: amzn.to/3QAq97U
Zama ZF-4 fuel filter: amzn.to/3G2Z6NI
Walbro K10-HD carburetor rebuild kit: amzn.to/3QyyKYM
Stens air filter # 102-414 : amzn.to/47fjjfg
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The tools I like and use most often:
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Tachometer: amzn.to/3sHibiH
Vessel Megadora JIS screwdriver set: amzn.to/363RFqO
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OTC Leak-down Test Kit: amzn.to/3CyUhJn
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Any links to products are likely affiliate links, and I may earn a small commission from qualifying purchases (Thank You!), with no additional costs to you.
00:00 I'm not Norm
00:52 Remove damaged blower tube
01:50 Nice sunny day at the spa
04:30 Replace spark plug boot
08:03 Spark check and plug replacement
09:23 Inspect and clean spark arrester screen
11:10 Replace fuel filter
13:41 Remove carburetor to clean and rebuild
19:56 Check metering lever height
21:12 Pressure test carburetor
22:24 Replace carburetor
23:41 Replace air filter
25:54 Replace blower tube elbow
27:31 The Money Shot
29:42 Idle speed adjustment
Wear your safety glasses, or you'll shoot your eye out. Try on some gloves. Take off that spark plug boot. Clean your room. Open the windows, those fumes are nasty. Just 'cause I do it, don't think it's the end all, be all solution. There's plenty more ideas out there, I can't take responsibility if you slice off a few fingers after watching my videos. And don't just pour that toxic stuff down the sewer or in the ditch, dispose of waste responsibly. Just be safe, OK?
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Titles, opening graphics, and music by AbleVFX.
Disclaimer: The content of this video is purely for my entertainment, and is available to you for informational and educational purposes only. It's not substitute advice from small engine mechanics with professional training and certifications, nor does it create any kind of relationship between the The Lawnmower Lady and you. Your situation may be different, and the The Lawnmower Lady makes no warranties, express or implied, as to the fit, accuracy, or applicability of the information shown in this video, and implies no guarantee of results. The Lawnmower Lady and any sponsors of this video are not liable for any damages of personal injury, property damage or loss of any kind that may result from the use or reliance on this video and/or any parts and procedures represented in this video. You are using the information presented in this video solely at your own risk.
#lawnmower #smallenginerepair #DIY

[@TheLawnmowerLady]

If this video helped you, please consider hitting the THANK$ button below the video 🙌 If your Stihl blower is a newer 4-Mix machine, you'll want to adjust your valves. Watch that video here: kzbin.info/www/bejne/m5nQi6yAatStrqs

[@johnA012]

Thaaank You! My BR420 is breathin’ like new!

[@TheLawnmowerLady]

Happy to help. Cheers!

[@williamcarl4200]

I always preferred these over the clam shells. And never a 4 mix. Love the show. Thank you.

[@TheLawnmowerLady]

I sort of get the 4-mix idea, but in any case, just more moving parts in my book. Thanks for watching.

[@BrucesShop]

Great Video Norm. You know I have only seen 3 Backpack blowers in all the years I have been fixing things way up here in Canada. Interesting.

[@TheLawnmowerLady]

Thank you Mr Bruce! I've got 6 kicking around the shop, only one I need to fix for someone else. The other five are "some day" projects. I appreciate you watching!

[@KensSmallEngineRepair]

Translations from Customer quote to Small Engine Shop Reality: "I'm in no hurry" means "you'll get it in 6 months to a year!" "When you get a chance" means "Never, as I never have a chance to do anything I need to do!" and My favorite "Can I wait for it" means "Price just Tripled, and No, you can't wait for it!"

[@TheLawnmowerLady]

Hahahahaha!

[@kencurtis228]

Thank You for Sharing

[@TheLawnmowerLady]

My pleasure. Cheers!

[@rtt1026]

these old blowers are great.just rebuilt one

[@TheLawnmowerLady]

I agree! Fewer moving parts than the 4-mixes. Thanks for watching!

[@jcondon1]

Cannot wait to watch! Just finish working on a BR380 and two older BR400's. They were a mess. One almost beat me.

[@TheLawnmowerLady]

I have a soft spot in my heart for these older machines. Cheers!

[@jcondon1]

Great video!

[@TheLawnmowerLady]

Glad you enjoyed it Mr James, I do appreciate you watching.

[@Rein_Ciarfella]

Stella! It’s been two months, girl! ❤️

[@TheLawnmowerLady]

I know! Sometimes life gets in the way of living. Thanks for watching!

[@jimbrewer2893]

Good one! Hope everything is good on your side of the interstate.

[@TheLawnmowerLady]

All good Mr Jim. Thanks for watching. Cheers!

[@Rein_Ciarfella]

Whenever I use my pressure/vacuum tester I always bend the hose over on itself and hold it tight with my fingers to confirm there are no leaks in the gauge or connections I’m using. That’s a good point to make sure the needle and seat have some liquid on them so they have a chance to seal correctly.

[@TheLawnmowerLady]

good idea

[@jonathanwheatley1424]

Cool vid!!! I’m just trying to rebuild my br380, I’m a total noob so this video is a great start to figure out the problems I have 👍👌

[@TheLawnmowerLady]

Good luck! I appreciate you watching.

[@chatrkat]

Wow another good old Stihl blower. 😁 I was using my trusty BR420 yesterday. Once you go backpack, you never want a handheld again!

[@TheLawnmowerLady]

They are great little blowers for sure!

[@chrisbrown7362]

This was a fun one. I like when things are physically dirty and they get all cleaned up, apart from the repair. And I appreciate you using the metric system. When I was a kid Jimmy Carter said we had to switch but instead of just GOING to the metric system, teachers kept having us convert back and forth, which was confusing and unnecessay. We weren't comparing US measurements to anything, our fingers or feet, why compare metric to US?!

[@TheLawnmowerLady]

I appreciate you watching. I try and include metric and SAE measurements, to make my videos as accessible as possible. Cheers!

[@rickthelian2215]

That was a huge job, she’ll be right for many years…😊 I couldn’t imagine the bill😊

[@TheLawnmowerLady]

I did have a lot of hours in this, and close to $100 in parts. I wound up taking some other equipment in trade. All in all, a fair deal. Cheers!

[@rickthelian2215]

@@TheLawnmowerLady great to hear 😁🇦🇺

[@Rein_Ciarfella]

It’s much easier to fit the spark plug boot over the wire first, then mount the connector, lubricate and pull the boot forward over the connector.

[@TheLawnmowerLady]

Yep! Hindsight is 20/20, LOL.

[@Turningwrenches85]

Nice work stella it cleaned up nice

[@TheLawnmowerLady]

Thank you John! Cheers!

[@danielrobert7181]

Very thorough and informative video. Merci Stella !

[@TheLawnmowerLady]

Glad it was helpful!

[@wayneberry8703]

Great job, absolutely love how you go right through the unit and renew and clean all of the necessary running gear.

[@TheLawnmowerLady]

Thank you! I'm no professional, just a gal in her shop, but I try to do things right the first time. I appreciate you watching!

[@Bean-sz7sr]

I have this same blower and I've only had a few issues with it. 👍🏼

[@TheLawnmowerLady]

It's a reliable machine, and fewer moving parts than the newer 4-mixes.

[@rewlawnservice]

Nice job I wish you was near me I been in business lawn service for 24 years I do my own maintenance but it’s nice to have someone professional

[@TheLawnmowerLady]

Thanks 👍 I'm glad you enjoyed the video. Cheers!

[@INSIDEHOUSEGARAGE]

excellent work!

[@TheLawnmowerLady]

Thank you! After all that cleaning, I wonder how you avoid the EPA with all the cleaning you do, LOL. Cheers!

[@Rein_Ciarfella]

I got an app called Engine RPM that makes it much easier sometimes to check and adjust running speeds. It works on my iPhone using sound waves. I can prop it up near the engine I’m working on and have hands free to hold the machine and adjust settings. I can also measure engine speeds on videos! I confirmed your idle was at 3047. How cool is that?! The easiest way to learn how to use it (after reading the directions!) is to stand in front of your fridge or freezer to zero in on the speed of an appliance. Once I got comfortable with it, it was easy enough to transition over to small engines. Will do any number of cylinder engines, 2T or 4T.

[@TheLawnmowerLady]

I've seen those apps, easy for DIYers to use.

[@martinburgess4814]

Ģreat job Stella.Good to see you again.

[@TheLawnmowerLady]

Thank you! 😃 Cheers Martin!

[@almclean4835]

Great job Stella. The old unit tidied up nicely

[@TheLawnmowerLady]

I think so too! Although it did take several hours more than I expected. Cheers!

[@Shawnee.Hills.Small.Engine]

It's running great, and looks great too. I recently got a can of Tri-Flow, and it's good stuff! Much better for cables than WD 40.

[@TheLawnmowerLady]

I agree on the Tri-Flow. It's pricey, but it works. I appreciate you watching. Cheers!

[@ackack1]

That's a keeper alright. Specs say 742 CFM which is way up there for a unit that old ... probably in the 2000-2010 date range when Stihl used the square housing (couldn't find a mfg date). I have a BR600 from 2011 with the newer oval shape.

[@TheLawnmowerLady]

Good little machine, despite the low PSI. Nothing a ring job can't easily fix in a few years.

[@Big_Johns]

Nice job STELLA, yes he should be mighty happy with the outcome. 🙂 It cleaned up really well. 👍

[@TheLawnmowerLady]

I think so too! I really appreciate you watching. Cheers Mr John!

[@Big_Johns]

Anytime nice lady, it’s always fun. 🙂👍🏼

[@toddosterhout9866]

Great work!! You really did a good job. Thanks for all the info! I’ve definitely learned alot from you!!

[@TheLawnmowerLady]

Awesome! Thank you!

[@doglegjake6788]

Thanks for sharing a great video

[@TheLawnmowerLady]

Thanks for watching. Cheers!

[@1jantheman1]

Always enjoy the educational vids you produce Stella. You have taught me plenty. Thank you! Glad to see your still putting it out there. Best to you, always. :)

[@TheLawnmowerLady]

My pleasure! I appreciate you watching. Cheers!

[@andersforrad]

Epic video and great job. The only reason this survived is the quality of those epic blowers. The Stihl 350/400/420/450 from early days are by far the best machines made without a doubt. Cheers and nice weekend

[@TheLawnmowerLady]

I agree Anders, so much better quality from years ago. Cheers!

[@Rein_Ciarfella]

Stella, you’ll be happy to hear I finally broke down and got a complete set of drill drivers and a set of screwdrivers - all JIS! I’ve got in an Echo leaf blower to service and well over half the fasteners are JIS, so I figured it was about time! What a difference these make! I may just retire all but the largest Phillips screwdrivers I have as well as all the driver bits.

[@TheLawnmowerLady]

I have zero regrets for my purchase of JIS screwdrivers.

[@robertmailhos8159]

That is just like the one that I have except mine is a br 400 which I will have 26 years bought it back in 1997 December to be exact

[@TheLawnmowerLady]

Great little machines. Long life if taken care of, as you have demonstrated. Thanks for watching. Cheers!

[@robertmailhos8159]

@@TheLawnmowerLady that is the truth about that young lady 💐🌹

[@shoptalkwithbrett6572]

Very nice video Stella. I ought a used BR400 from OfferUp several years ago for $30 and all it needed was a new rope and a few little things. I replaced the filter cover and the lower blower tube plus a plug which was around 40 bucks and she rocks & rolls like a new one. It’s on my channel. I use it year round.

[@TheLawnmowerLady]

Sounds like you got a bargain! I appreciate you watching.

[@nashguy207]

I still have an old BR400. I let me dad use it. They were good blowers back in the day. The only thing is that you have to be careful start it it floods pretty easy always has but still runs great! Good video Stella great to see you posting again!

[@TheLawnmowerLady]

Thanks Bob, I really appreciate you watching. Cheers!

[@joegustin7158]

Great Job Runs Nice

[@TheLawnmowerLady]

I appreciate you watching!

[@petefroud5308]

Nice job Miss Stella.

[@TheLawnmowerLady]

Thank you Mr Pete. Cheers!

[@tinkeringtaylor3053]

Great video Stella,you did a excellent job cleaning it, it runs and sound really good 👌👍(you will be able to pop round and help your neighbour clear the leaves off his roof 🤣🤣)

[@TheLawnmowerLady]

Cheers Nev!

[@SheikShak]

Thank u….well done …

[@TheLawnmowerLady]

Many thanks!

[@heathwilson2572]

Lawnmower Lady NGK spark plug is recommended for STIHL backpack blower

[@TheLawnmowerLady]

Yep. That champion works too.

[@VintageEngineRepairs]

What a mess! Looks great now though!!

[@TheLawnmowerLady]

It was a mess, LOL, all better now.

[@KensSmallEngineRepair]

Spark Check R, Ya Baby!!!!

[@TheLawnmowerLady]

Cheers Kenny! One of the better tool splurges I have made. I wish they were more widely available. Great tool for one person diagnosis.

[@mikethomforde7326]

Thanks for sending the link to this blower, my BR400 sat years and bought it and got it to run only with choke on and then it won’t start unless next day cold, is it a carburetor adjustment?

[@TheLawnmowerLady]

Thanks Mike. I'd suggest the carb needs a clean/rebuild. A clogged fuel filter will contribute to those issues as well.

[@heathwilson2572]

Champion spark plug will work

[@TheLawnmowerLady]

I think any new spark plug would work better than the old one honestly.

[@monroehoskins3937]

Great job as always!!! What's the name of the decreases you're using?

[@TheLawnmowerLady]

It's HF degreaser. Apparently they have changed the formula to make it more corrosive, and the new label even lists to avoid using it on aluminum. I appreciate you watching!

[@DH-mf2lv]

what years was the STIHL BR420 manufactured? Thanks for the video.

[@TheLawnmowerLady]

I think it was in the early 2000s. If I recall, this one was 2006? Thanks for watching.

[@jaimepadilla9548]

Great work as always. Quick question. I have a weedeater that starts fine but once I lift it to use it it turns off. Any idea what it could be?

[@TheLawnmowerLady]

Thanks! Often a bad crank seal can cause something like that to happen.

[@jaimepadilla9548]

@@TheLawnmowerLady ok thank you!

[@gmw1964z]

What degreaser did you use?

[@TheLawnmowerLady]

My favorite is old (bad) gasoline. After that, we have a product sold at the dollar store called LA Awesome Cleaner. I mix it 5:1 with water. Works well. Thanks for watching.

[@garyclifton2180]

Like a rolls Royce Stella

[@TheLawnmowerLady]

Cheers Mr Gary! Thanks for watching.

[@mikethomforde7326]

Why does my BR 400 only runs well with the choke on all the time? It shuts off when I turn it open?

[@TheLawnmowerLady]

It's starving for fuel.

[@geraldinelunde5177]

how do you get the pad on the backpack off..... did everything except that.... thanks...

[@TheLawnmowerLady]

Ummm, not sure what you are referring to?

[@geraldinelunde5177]

The padding on the back of the blower. Protects (softens the pressure) the back. Looks like it is held on by rivets, do you just break the rivets off and but new ones?

[@geraldinelunde5177]

Foam padding is shot.

[@TheLawnmowerLady]

@@geraldinelunde5177 Ahhh. I don't own the blower, so I can't get a good look to see how it's attached. Sorry.

[@geraldinelunde5177]

no problem, finally got it figured out myself.... pop off the old rivets and old padding and pop on the new one.... comes with rivets.... lived your restoration, really like my unit. outdoes anything anyone else has around here.... the best of the new year to you..... blessings...@@TheLawnmowerLady

[@imageaware]

I've followed you on the recommendation of @VintageEngineRepairs

[@TheLawnmowerLady]

Cheers mate! Thanks for watching.