Rebuilding a Redmax 7001

Discussion in 'Mechanic and Repair' started by crepitus, Nov 10, 2008.

  1. crepitus

    crepitus LawnSite Member
    from N
    Posts: 3

    I was offered a Redmax blower that has a seized engine cheap. Was wondering if its worth being rebuilt? If it just needs piston, rings and a cylinder then it will be around $120 to do. Could there be other damage to the blower? You guys think its worth? Any chance I might be able to get it unseized and have it work without replacing anything?
     
  2. salvagedrover

    salvagedrover LawnSite Member
    Posts: 59

    good news bud, you have asked the right person, the right question. I have bought/ aquired over 30 of these, and rebuilt about 20. you will need to get the cylinder off first. remove the air filter assy. with a phillips, slide out the square nuts from the top of the housing, and thread them back onto the bolts which should keep those all together in their holes in the a/f assy. next, remove the s. plug and spray a liberal amount of wd-40 or pb blaster or something similar down the plug hole. next, remove the engine cover, and replace the phillips screws back in their holes in the housing. remove the carb assy from the black insulator block attached to the cylinder, but don't remove that block. its fine, just leave it. next, remove the plate at the top of the cylinder; loosen the screws with a wrench first to make sure they don't strip. then, with a 4mm allen, remove the lower bolt to the muffler, and then the two 5mm allen bolts from the top. they all may need some persuasion, so a small punch, or nail set will work to jar them loose. don't forget the wd or blaster. then remove the 4 4mm bolts securing the cylinder. spray them first w/ the wd or blaster, and then slide a 6" 3/8 extension into the holes. hit that with a ballpeen hammer about 2-3 good whacks ea. the bolts should come out w/ ease. now, seeing as the piston and rings are already garbage, stick a metal rod into the s. plug hole, and whack the top of the piston. keep the device off of the cylinder walls for obvious reasons. spray some more ky into the cylinder to lube everything a bit before you start whacking away. a good idea would be to wear a glove and hold the cylinder up, while hitting the device down on the piston. it will come apart easier, and cleaner this way with minimal damage. like peeling off a bandaid vs. ripping it off. now that the cylinder is off, inspect it for deep gouges, and lines. there really shouldn't be any, but if there are, try and get rid of them w/ emery cloth. try to blend in the repair by feathering past the damage a bit. if it's too extensive, just chuck it and get a new one. do not remove more mate ial than is necessary. if need be, bring this to an ope shop to quickly be honed. now, you will need a new piston, two rings, a wrist pin, wrist pin bearing, two piston pin circlips, no keepers, as the orig. ones should be ok. also a new carb to insulator block gasket as well as a muffler gasket, and obviously a new base gasket. now, there is a muffler recall. the old muffler will have the lower mount stamped on the inside of the muffler closest to the block, while the new design will be welded on from below. if this is an old muffler, bring it back to a redmax auth. dealer. t e replacement is COMPLETELY free. if they say otherwise, let me know, and i'll give you a number to call the n.e. div. dist. for redmax and you can report the shop. you pay nothing, not even shipping. you WILL get a new muffler, two new mounting bolts, (no lower bolt, so don't strip it,) and a gasket. this is also a good time to replace the pullcord, s. plug, a/filter, fuel filter, fuel lines, and air filter pre cleaner. essentially your motor will be pretty much new, save for the lower end. which reminds me, pull the recoil w/ an 8mm socket. grab the round thing and look into the motor as you pull it back and forth looking for OVERLY excessive play. now, look down at the crank. pull the rod straight up, so the flat areas of the counter weights are facing you. put your thumb and forefinger on each flat spot of each counterweight, and try to move the weights in different directions w/ your hands and fingers. needless to say, there should obviously be no opposing movement. lastly, spin the bottom end slowly, to look for and binding, flat spotting of bearings, or stiction in them. if there is any, they might need to be replaced. if so, I will walk you through that too if need be. anyways assuming all is well in your motor's world, install the new bearing- btw., dip all internal parts in 2-cycle mix prior to assy., or spray with mix in a spray bottle. put enough into the lower end, to reach 1/2 way up the bearings. so, as I was saying, the arrow on the piston points to the muffler, denoting the flow of fuel. with the arrow pointing to your right, install the new circlip to the rear. now, install the bearing and CAREFULLY the spacers. slide the piston over this sandwich, and run the new piston pin, which should slide right in, through to the circlip on the other side. now, install the front clip. a pick is useful for removing them at the two indentations, and needlenose to push the pin all the way in, as well as installation of the clips. now, install the base gasket, providing you removed all previous gasket material from both the block as well as the cylinder. hold the rings as compressed as possible, with your left thumb and index, while CAREFULLY sliding the cylinder down with the right. once the rings go into the taper and both disappear into the cylinder, tighten the four bolts, install the muffler, top two bolts first, then tighten the lower bolt. install the plate on the top of the cylinder, and the recoil if you didn't already. install the carb, throttle cable first. then, re-attach the air cleaner assy. and fill up the tank. full choke till it starts to start, then, 1/4 to 1/3 throttle and take off the choke. goose the throttle to full maybe 3-4 times, then let it idle at 1/4 for 30 secs. or so. now, gradually bring it down to idle. you may or may not need to change the idle screw. idle is 21-2200 rpm if memory serves correct. the top end should be 7100-7200rpm. otherwise, the carb needs attention. now, leave it idling for say 5-10 minutes. next, recheck the idle rpms. gradually over the course of a minute, bring it to full throttle, leave it for 15-20 seconds, then another gradual minute bringing it back down. you basically want to use it for 30 -60 mins at 3/4 throttle, going through the rpm fange to seat the rings into the cylinder at different rpms. any porsche mechanic will tell you this. now my friend, you should be good. I recommend stihl hp or hp ultra oil. its better than even echo, redmax, and stihl. I saw a comparative study w/ 8 oil brands and types of the same no load motor run for 500 hours. the stihl oil kicked the crap out of everyone else, hands down. my email is salvahedrover@yahoo, and I'm an ope tech that specializes in echo and redmax, specifically 7001 and 8000 backpacks. and further questions, please don't hesitate to shoot me an email. hope this helped, -dave
     
  3. redmax fan

    redmax fan LawnSite Bronze Member
    Posts: 1,116

    thanx for all the info sr . and im thinking about rebuilding a few redmax whips , are they more beat up than a backback because of alot more stress on them . and thusly maybe not worth rebuilding after a certain amount of use ?
     
  4. crepitus

    crepitus LawnSite Member
    from N
    Posts: 3

    very nice salvagedrover. thanks for that awesome write up. I will let you know how things go when I dig into it. May be a week or so.
     
  5. viper00085

    viper00085 LawnSite Member
    from NC/VA
    Posts: 237

    as mentioned above, just be VERY careful to check the condition of your bottom main crank ball bearings. Hate to see you spend good dollars and time on cylinder/piston work then find out your bottom end is bad and growling.

    That was the problem with the 7001's. The 1st design had major lower end brg failures ( to small a brg for the rpms/power and loads). WE had to update hundreds of these units with new short blocks under wty. The new shortblocks and units came thru with much larger diameter crank bearings that held up better.

    when you have the cylinder/pistons removed, kind of hold the rod centered and spin the motor over, carefully listen for brg growls/noise or resistance. if you feel it may be an issue, look into the cost of a complete shortblock. it might be worth it( cost wise) vs a new unit.
     
  6. salvagedrover

    salvagedrover LawnSite Member
    Posts: 59

    I wouldn't hesitate rebuilding a trimmer motor. on an echo. redmax makes a pretty good trimmer, but I just enjoy repairing echos a whole lot. lots of interchangeable parts. run forever, and lightweight too. just keep an eye on the carbon in the exhaust port. I have bought so many string trimmers w/ the only problem being a clogged ex. port, and with a slightly modified stihl carb screwdriver, (kids, don't try this at home,) I can usually get them running again in 5-8 minutes.
     
  7. encorelawn

    encorelawn LawnSite Member
    from 11788
    Posts: 3

    Before you invest a dime make sure the lower bearings are good. If they are shot leave the blower at the curb
     
  8. redmax fan

    redmax fan LawnSite Bronze Member
    Posts: 1,116

    thanx for the tip .

    ive considered echo's before by looking over how theyre built and liking them , but the handles just dont fit my grip type . where as the redmax's i can keep a real good grip on , which for me is needed because my mode is to go fast and do alot of fine detail work on our completely residential route .
     
  9. battler

    battler LawnSite Member
    Posts: 2

    Hi guys, I found this site on the net,as I have a Redmax BC340DL brushcutter ( a bit old I admit), but if you could help, much appreciate. It's done a few miles like me, and I'm getting a few probs: 1. Starts ok, prime & tickle.
    2. Lately I've had to run at half choke and warm up about 3 mins
    before operating, juggling choke & throttle to get good revs.
    3. It's almost died, although will start, but seems to have a 'flat
    spot' when giving it the juice.
    I've fiddled with the mixture screw, turned it right in, then screwed out 1 and a half turns or thereabouts, no dice, as far as the juice is concerned when gunning it.

    Ok, did some minor exploration, checked throttle lag, blew out seat and screw, replaced plug, cleaned air filter, no visible build up of carbon in exhaust, but spark arrestor gone, it just seems like it's not getting enough juice on load. Should I assume the next thing is the carby diaphram worn and perforated, and needs a carby kit? Thanks for any help. Sorry if I've posted in the wrong place here.
     
  10. redmax fan

    redmax fan LawnSite Bronze Member
    Posts: 1,116

    with our redmax whips like %95 of the time a carb kit or new carb fixes the that problem . maybe can get a new carb cheap on line by searching redmax parts . you probably do but just in case you dont make sure drive shaft is greased because lack of grease can bog it down .
     

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