Overhauling 5hp b&s horiz engine

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  #1  
Old 03-18-04, 06:10 AM
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Overhauling 5hp b&s horiz engine

I've inherited an "old" 4-cycle horizontal shaft 5hp B&S engine. The outside was caked with black oil and grime, and it caught on fire twice when I was using it (attached to an old Ariens rototiller). I figured a complete strip-down was in order.

I have it fully disassembled and found the following issues:

1. There is a sizeable punch mark on the inside of the crackcase, probably when the connecting rod broke some time ago. There are 2 small cracks on the outside. I'm having my brother in law weld it for me.

2. The inside has various gouges and scratches, probably from chunks of metal flying around when the rod snapped.

3. The crankcase gasket is cracked in 2 places.

4. There is a small gouge running almost the full length of the cylinder, again probably from a chunk of metal getting hung up in one of the rings.

5. There is a hard rubber seal on the flywheel end of the crankcase. Should/how is this removed? It looks like there is a metal compression ring holding it in.

What would you recommend as far as getting this back to working order, for around $50? I was thinking crankcase gasket, rings, carb/tank gasket, carb/intake gasket, carb rebuild, head gasket.

Thanks.
 
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  #2  
Old 03-18-04, 12:33 PM
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That engine is in such horible condition, I would highly suggest that you buy a new engine. You will never get a engine that was that damaged to be like new. Right now you are messing with a time bomb. Its caught on fire on you twice, and with all the damage I would take the engine off and chuck it!
 
  #3  
Old 03-18-04, 12:44 PM
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The gasket between the tank and carb was shredded, so gas leaked while I was tilling (tines in front) and ignited. So I'm pretty sure replacing that gasket will prevent that from happening again.

You're right though: it is pretty damaged and will never be the same. I was hoping to get a few more years out of it.

Having said that, what would be the cheapest way to get 3-5 more years out of it? I'm looking for under $50.

Thanks.
 
  #4  
Old 03-18-04, 01:13 PM
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Hello: Teddy

I hate to also be among those whom will offer you bad news. I see no real sure way to salvage the engine. Welding the case not likely nor easy. Pot metal or aluminum not easy to weld.

Most likely the cyclinder wall score mark is the second major problem. All long as it exists, compression will be lost and ring damage will occur. Honing it will not restore it. Only a boring will.

Small engine boring of the cyclinder is not easy and worse yet not available by any small engine shops. Too time and labor consuming for the costs involved.

If any shop even has a cyclinder boring machine for such a small engine. Larger engines have replaceable sleeves but not such a small engine as you have or is common on most small engine equipment.

However, all is not lost. That engine will make a good learn as you go engine rebuilding project. Valves and valve seats will also have to be reground or replaced with new parts.

The valve seats are pressed in. Best to regrind not replace in that engine based on it's condition. Seals on the end shaft are also pressed in. Those seals can be pried out but do not use the case as the leverage point. Case brakeage will result.

Use a board across the case to evenly spread out the applied force. A small pry bar, screw driver or any similar tool can be used. Do not damage the ring which holds the seal in.

Best done from the inside of the case using a socket to fit the seal only. Place case on raised surface, insert socket and tap out.
Reverse process to install using same tools. Socket and small hammer since you do not likely have all the specialized tools.

The above all can be done. May not be for the cost willing to pay, but the rebuild is a great learning method. Have at it.

Post back the results or do so as you make progress. Other members reading this thread will learn from it too.

Use the reply button to keep us updated...

Positive thinking, determination & "Encouragement" helps too..........Good Luck!

Sharp Advice
 
  #5  
Old 03-18-04, 03:07 PM
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I will agree that this prodject would be a great learning experiance! But when you are all done and if you got the engine going again and is actually working, than I would make sure you another tiller in greate condition standing by. What I am saying is pat yourself on the back for getting it running again but don't be so overconfident if it breaks down. I remember one time I did that. I got this weed eater at a junkyard one time. I fixed it up to get it running, but because it was in horible condition it went out on me in the middle of a job! And I was quite unhappy because, I had 3/4 of an acre to weedeat. I am just talking about edging. Thats when I wished I had another weed eater at the time. Now, I do. I own three 2cycle weed eaters. One of them I bought for $450.00 It was a commercial grade trimmer. And the other two were given to me and I fixed them up. I sold the old junker to someone who needed a weedeater.

Go ahead and have fun, I sure do on my prdjects!!!
 
  #6  
Old 03-18-04, 03:30 PM
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I don't know if you will be able to reasonably expect to get the engine running again. It depends on how deeply the cylinder is gouged. I've rebuilt engines in bad shape before where parts had come loose and damaged the inside of the engine. The standard oversized piston is plus 10 thousands. You can use a cylinder hone and with enough time rebore the cylinder to spec plus 0.01. If that is enough to take out the gouges in the cylinder wall you are well on your way to fixing the engine. I've seen up to plus 0.03 sized pistons listed in the B & S parts manuals but I've never tried reboring that big so I don't know what would happen if you tried. I always got a lot of satisfaction out of bringing a "basket case" back to life. Be ready to spend some time & money doing so, however.
 
  #7  
Old 03-19-04, 12:55 AM
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Hello teddymines!

As far as getting a nice, tight, good running engine out of the block you currently have, it's not very likely, for the price of $50.00. However...if you just want to get it going again for occasional use (which most tillers are)...it may last for several years with a minor freshen up. Did it smoke much when running? (other than the fire, lol). If not, the cylinder scratch may not be bad enough to worry about. If the cylinder has a cast iron sleeve, hone it well and re-ring the piston if it is good enough to re-use. If the cylinder is aluminum, it's best not to hone it, unless it is in pretty bad shape. When you replace the rings on an aluminum cylinder engine, use chrome rings. Replace both seals on the crankshaft. Replace the things you mentioned and you'll probably have a useable engine. The valve clearances may need adjusting as well. Let us know what you decide to do and how it goes! I've done a few "patch-up" jobs like this for customers who just want a little more life out of their engine for little $$, and it usually works out ok. (as long as you understand that it won't be perfect when it's done). Who knows, it might just run like a new one !
 
  #8  
Old 03-19-04, 10:57 AM
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Thanks everyone. Seals, rings and gaskets are about as far as I'll go on this engine. It will probably get used about 10 hours a year. Maybe a few years from now I can make the case for a new tiller.

The gouge I described is about the width of a small pencil lead (0.5mm) and about as deep as one of the valleys in the edge of a U.S. dime. I can catch my fingernail in it, but I don't get hung up in it, if that makes sense.

I'll keep you all up to date on the rebuild.
 
  #9  
Old 03-19-04, 01:50 PM
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Have fun!
 
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