Magnum 20 Rebuild
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Magnum 20 Rebuild
Ok..well im finally going to do it. Let me start by saying I'm pretty nervous about the whole process but if I take one step at a time...and your guys help .....it might run again. I have done a couple car engines years ago so I'm not a complete stranger to this type of stuff. I plan to mostly post pictures with little dialogue. Feel free to comment or ask questions.... as I will also b asking some from time to time. I'm already into it but I see this taking a couple months to finish.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
I forgot to mention that this was a good running engine w about 1700 hours. It did burn a little oil ,was hard starter when hot, fuel pump was shot, and starter would not throw out too well below 40°.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
-
- Posts: 114
- Joined: Sun Mar 10, 2013 10:51 pm
- First and Last Name: john carolan
- Location: decorah, IA
Re: Magnum 20 Rebuild
Looking forward to following this thread
-
- Posts: 295
- Joined: Wed Apr 11, 2012 12:39 pm
- First and Last Name: Ben Michaud
- Location: Richmond, Ontario
Re: Magnum 20 Rebuild
I am confident you'll do just fine!!dag1450 wrote:Ok..well im finally going to do it. Let me start by saying I'm pretty nervous about the whole process but if I take one step at a time...and your guys help .....it might run again. I have done a couple car engines years ago so I'm not a complete stranger to this type of stuff. ...
Not being in a rush is a good policy...
Cheers,
PTWannaHave
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Thanks guys. The engine was greasey and dirty but not too bad. I was thinking the cooling fins on the cylinders would b somewhat full as the screen under the steering column has never been on....but they were clear. Took off the flywheel and checked the magnets...only one loose. Ok first question right here. Best method for reattachment.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- BigMike
- Posts: 1359
- Joined: Mon Sep 06, 2010 8:45 pm
- First and Last Name: Mike Andrews
- Location: Niles,Michigan
Re: Magnum 20 Rebuild
Dave, you are going to do juuuuust fine
Slow and steady wins the race. As has already been said, clean, clean, clean......then clean it some more.
Brace yourself for parts prices......I did not find aftermarket stuff and used all Kohler but I made a commitment to build it the best I could and have a great running engine that makes loads of power.
Slow and steady wins the race. As has already been said, clean, clean, clean......then clean it some more.
Brace yourself for parts prices......I did not find aftermarket stuff and used all Kohler but I made a commitment to build it the best I could and have a great running engine that makes loads of power.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Yea Mike I have been looking for aftermarket to no avail. I'm good w the real stuff. I found a pretty complete kit...pistons seals and gaskets. Like said before I also need a fuel pump, starter, governor gear and im sure other stuff. Talking to a local machine shop....ouch!
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- BigMike
- Posts: 1359
- Joined: Mon Sep 06, 2010 8:45 pm
- First and Last Name: Mike Andrews
- Location: Niles,Michigan
Re: Magnum 20 Rebuild
Well, if I don't have complete faith in a machine shop I am not leaving parts with them.....period.
You are not all that far from Engine Mike are you? UPS the stuff to him or Kevin at Pipestone Small Engine near me.
You are not all that far from Engine Mike are you? UPS the stuff to him or Kevin at Pipestone Small Engine near me.
-
- Moderator
- Posts: 1175
- Joined: Tue Sep 07, 2010 6:22 pm
- First and Last Name: Joe Motuzick
- Location: Torrington Ct
Re: Magnum 20 Rebuild
mike and I where just texting about him doing a batch of kohler cranks real soon.... get some mesuments and yours will get added to the stack!
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Thanks Joe. Yes the machine work has been one thing I have been stuglin with. I called around to several and out of the six I called one guy said..." Yea bring it in..and I might b able to do it". So then I called the shop that I used 30 yrs ago( I thought they were out of business) when I asked if he does lawnmower engines he said no but gave me a name of a shop close by. I went up to the shop and it is full of crankshafts, heads, flywheels, and really all kinds of stuff. It seems to b a very busy shop. He seemed willing and gave me the time of day. I thought about shipping it somewhere... And that would b fine I guess when u get good recommendations w history ..thanks BigMike. Its hard making a new contacts... But at some point there has to b a first time.....sometime. I will talk prices when I get further along.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- Dave C
- Web Developer
- Posts: 1014
- Joined: Mon Sep 06, 2010 7:12 am
- First and Last Name: David Chester
- Location: Wallingford, CT
Re: Magnum 20 Rebuild
I plan on sending at least 2 magnum cranks to mike also.... they like to group their work up there... if your gonna set the machine up for 1 crank you can do 10 just as easy.
Trying to save cubs... one at a time.......
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
What size magnums Dave? Is it wishful thinking that I won't need crank work? I sure hope not but will have to check somehow. I could have my nephew bring over his mics. I saw undersized rods..for an arm and a leg...bearings were just as much. Please tell me some cranks don't need work.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
-
- Moderator
- Posts: 1175
- Joined: Tue Sep 07, 2010 6:22 pm
- First and Last Name: Joe Motuzick
- Location: Torrington Ct
Re: Magnum 20 Rebuild
Sadly most do....
Get that mic set and measure mesure again just to be sure. Then mesure again!
Get that mic set and measure mesure again just to be sure. Then mesure again!
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
I'm about as far as I can go on this until I firm up some details w shop....I hope this week.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Pistons skirts looked good and the bore has no lip i can feel....but the pistons had some small chipping on the top edge...only thing I can think this is from the carbon. Have u guys seen this? Valve clearance to tappits....way to tight. I guess as the seat wears the valve sinks. I did some reading and this seems to cause my hard hot restarts.
Oh...and intake valve seal...Hahaha. They were toast!
Oh...and intake valve seal...Hahaha. They were toast!
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
ok guys....If u have not figured out im on somewhat of a budget. Tom Scott contacted me once he saw my thread and talked to me about doing some of the machine work myself. Needless to say i am a little apprehensive about the whole idea....he seems to think no problem. He put me in touch w this video laying out the boring measuring and honing process for the do it yourself er. Im just not sure i have the right tools....https://www.youtube.com/watch?v=bT1nRq-cM7M
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- Tom Scott
- Chief Moderator
- Posts: 1776
- Joined: Mon Sep 06, 2010 9:11 pm
- First and Last Name: Tom Scott
- Location: Bentley Springs, Maryland
Re: Magnum 20 Rebuild
Dave - I'm really disappointed that you shared that; this was going to be our new business venture, and now everybody knows the secrets to proper machining!
I can't believe you turned on me like that...
I can't believe you turned on me like that...
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors: 1541, 2135
<><
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors: 1541, 2135
<><
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Tom...I told u I was not comfortable with this. I feel we r moving way too fast! It's not u..its me!
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- bbaker
- Posts: 777
- Joined: Mon Sep 06, 2010 8:47 pm
- First and Last Name: Bryan Baker
- Location: Evansville IN
Re: Magnum 20 Rebuild
I thought you were serious before I watched the video.... lolTom Scott wrote:Dave - I'm really disappointed that you shared that; this was going to be our new business venture, and now everybody knows the secrets to proper machining!
I can't believe you turned on me like that...
Only thing I'm concerned about is he didn't address making the rings bigger?
Cub Cadet, John Deere, New Holland, bobcat, Chevrolet, and Harley Davidson just a few brands I'm proud to own.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Bryan..... With the "piston shim material" ......no ring work needed!
This guy is my new go to for how to's
This guy is my new go to for how to's
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Ok....back to the real show. I hope to pick up the machine work today or tomorrow. I will post as soon as I get.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
I found a nice rebuild kit at Pat's small engine warehouse I think was the name. Came with pistons rings seals gaskets. To my door for like $390. No aftermarket parts r available for the mag 20. Not that I could find. I also picked up a governor gear, exhaust valve guides, and a few other goodies from eBay.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
I still need to order a new and improved breather and tube....plus that green grass thing inside. I guess I will b buying a micrometer after all to check the crank stuff.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Picked up the cylinders and heads the other day. It looks good but I really have no idea if they did a good job or not. I can only look at it.....it feels nice and looks clean. Bored, cut seats, installed new exhaust guides, cut heads, decarboned everything too.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Ok so I'm back at this project...... I failed to update u guys about the prices for the machine work labor only. Cylinders and head work only. Bore, cut heads, cut valves seats, install new guides, hot tank.....all for $400. Ouch! It sounds high i know. The guy has a busy shop so I guess he can set his prices.
Last edited by dag1450 on Sat Mar 26, 2016 9:26 pm, edited 1 time in total.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Yesterday I split the block. Stinking oil pressure sensor adapter broke off... I had to drill it out. I guess I should try to chase the threads but its pipe threads...idk. Washed everything today in the old parts washer ( Rubbermaid) with k1.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
So...I see this "10" on the back of the old bearing. It surly looks like an oversized bearing? Can anyone verify how they mark the bearings for size.....thanks
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- Tom Scott
- Chief Moderator
- Posts: 1776
- Joined: Mon Sep 06, 2010 9:11 pm
- First and Last Name: Tom Scott
- Location: Bentley Springs, Maryland
Re: Magnum 20 Rebuild
dag - Since pipe threads are tapered you can always just tap a little deeper if the threads were injured by drilling. Just don't go too deep or the fitting will bottom before the threads get tight. Also, must use a pipe thread tap, no other tap will work.
On the bearings, you will have to mic the crank and bearings reinstalled in the block (without the crank) to judge clearance wear, since I know you are hoping to not machine the crank. These should be mic'ed in many spots if you are trying to skip machining these, as they can wear unevenly; they can be egg shaped when worn, have taper from front to rear, etc. And scoring, uneven bearing surface wear, embedded contaminants in the bearing surface, etc.
Also the thrust wear matters too. I haven't rebuilt a Magnum, but one bearing will have a thrust surface to control axial movement of the crank. The bearing in your pic has a thrust bearing surface on each side. With the crank installed in the block with those bearings you can measure how much thrust clearance you have.
I'm sure it is all in the Kohler manual...
On the bearings, you will have to mic the crank and bearings reinstalled in the block (without the crank) to judge clearance wear, since I know you are hoping to not machine the crank. These should be mic'ed in many spots if you are trying to skip machining these, as they can wear unevenly; they can be egg shaped when worn, have taper from front to rear, etc. And scoring, uneven bearing surface wear, embedded contaminants in the bearing surface, etc.
Also the thrust wear matters too. I haven't rebuilt a Magnum, but one bearing will have a thrust surface to control axial movement of the crank. The bearing in your pic has a thrust bearing surface on each side. With the crank installed in the block with those bearings you can measure how much thrust clearance you have.
I'm sure it is all in the Kohler manual...
1872, 46", 50C decks, Haban dozer blade, 450 snow blower
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors: 1541, 2135
<><
2182-1, Kwik-Way Loader, 3-pt & rear pto, 442 tiller
2182-2, 54" deck, 551 snow blower
Past tractors: 1541, 2135
<><
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Thanks Tom. I guess I should look at the book!
Man....that oil reducer fitting is a weird one. Cheapest i could find was $12 for a steel one. Cub wants like $30. 1/16" male x 1/8" female...npt. It seems to b used today for mustang fuel rail something or other.
Washed most parts again today...this time w purple power and hot water. Really blasted oil passages.
Sorry no pics.
Man....that oil reducer fitting is a weird one. Cheapest i could find was $12 for a steel one. Cub wants like $30. 1/16" male x 1/8" female...npt. It seems to b used today for mustang fuel rail something or other.
Washed most parts again today...this time w purple power and hot water. Really blasted oil passages.
Sorry no pics.
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.
- dag1450
- Posts: 2377
- Joined: Fri Apr 01, 2011 3:16 pm
- First and Last Name: Dave Gibson
- Location: Chalfont, Pa
Re: Magnum 20 Rebuild
Used jb weld. I hope I got it on the right way....I was going to mark the top but in moving it around and washing it did not get done. I was able to use the old glue on the back to tell "North and South"
127, 1650, 1572, 1872, 2072 . A mower, blower and blade for each.