Scotts 21" Push Mower smokes

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  #1  
Old 07-27-04, 06:25 PM
mormiston
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Scotts 21" Push Mower smokes

Hi Folks, I wrote into this forum a few weeks ago about a Scotts mower that would not start, I now have it starting thanks to folks here advice, however the mower now smokes soemthing terrible.

I pulled the mower down to the crank case to find out why it would not start, the piston, rings and barrel looked OK, there were no signs of scoring.

The mower has a white smelly (oil) smoke which is thick and start about 30 seconds after the mower has started, sometimes it will smoke for 5 - 6 minutes and then stop, most recently it smoked pretty much the whole time I mowed the lawn.

It smokes even if the air cleaner is not in and carb has been thoroughly cleaned. Mowing the lawn twice was enough to burn all the oil in the sump such that the dip stick showed almost empty.

I want to think piston rings are causing this but didn't see any evidence of such. The sump is not overly full and I am using SAE30 oil as specified by the manufacturer. I also changed the spark plug.

Inspecting the new plug after mowing the lawn, it is covered in carbon that cannot be scratched off, it is not oily.

Any ideas on what might causing this. I think the neighbours are sick of me smoking up there back yards.

Thanks
Matt
 
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  #2  
Old 07-27-04, 11:59 PM
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Hello Matt!

Sounds like you probably have a bad oil ring. Possibly a worn cylinder. Is it an OHV engine? If so, a blown head gasket can cause this too. A bad breather valve could also be the problem.
 
  #3  
Old 07-28-04, 09:15 AM
mormiston
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HI Cheese, the engine is made by John Deere for Scotts the model I have is 6213. It has a B&S 6.5 Intek Edge motor model No - 121602, an OHV engine.

If it is the cylinder, than there is not much I can do, without it going to the shop. I'll have to check the head gasket, it's been off one or two times in the past and not caused a problem. Am I looking for a nick or tear in it all the way through?

Just out of interest how does a blown headgasket cause smoking, is it because it allows air into the chamber?

I think I have seen the breather valve you are talking about. How would I test to see if it is OK. I took it off in the pull down and it looked fine, but I didn't really know what to look for.

Thanks again.
Matt
 
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Old 07-30-04, 05:41 AM
mormiston
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I removed the breather tube that goes between the breather outlet and the air intake. The mower smoked straight away and didn't give up. I ran it for about 3 -4 minutes.
I am assuming then that my problem is not oil getting into the carb. I have not checked the carb and bowl for oil yet though.
 
  #5  
Old 07-30-04, 11:48 AM
Azis
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The overhead valve assy is lubricated by engine oil most likely pumped through the pushrods. This oil then returns to the sump via gravity through passages in the head and block. The head gasket and plate keep the returning oil out of the combustion chamber or should. Check the correct instalation of gasket and plate and if any leaks are present they should be obvious by looking at the sealing surfaces for signs of burned or carbon trails....??? Tears, rips, or ??? on the sealing surface would be reason to replace.
 
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Old 07-31-04, 01:34 AM
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Agreed. If it has been off before, and a new gasket was not installed, then that's probably the problem.
 
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Old 08-29-04, 06:32 PM
mormiston
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Hi Guys

Had a chance to look at the mower again today and check out the ideas that have been posted.

I took the head off and there was clean looking oil near the intake valve and also a small amount in the bottom of the barrel. The head gasket and the plate for the OHV look fine there are no pits or rips in the gasket and no signs of oil leaking from the OHV chamber into the combustion chamber.

I can only conclude now that it must be rings or worse still a scored barrell.

Before I put this mower out to pasture does anyone have any last thoughts or other ideas I should try?

Thanks again for your help
 
  #8  
Old 08-29-04, 11:35 PM
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Does the cylinder have any scratches deep enough that you can feel them? If so, then it's toast. If not, a new head gasket might be worth a try, or install a set of rings (not expensive) if you want to fix it.
 
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Old 08-30-04, 01:30 PM
mormiston
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Thanks. To my untrained eye the cylinder looks good. If I run my finger around, it feels smooth, there are no signs of scoring.

Should I buy the standard size rings or the next size up, ie slightly over sized.

I'm assuming you would looking for a gouge you could feel in the barrel.
 
  #10  
Old 08-30-04, 02:50 PM
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Ideally, you want to accurately measure the bore to be certain it is not worn excessively. The point at which you need to re-bore is - 2.6915" or if .0015" out of round. The reject sizes for the rings are as follows - Top ring, .020" or greater; center ring, .030" or greater; Bottom (oil) ring, .035" or greater. Be aware that if you decide to re-bore you will have the machine shop charge to do such, adding to the cost of repairs - typically $45-60.
By the way, what weight oil are you using?
 
  #11  
Old 09-02-04, 09:09 AM
mormiston
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Thanks.

I'll have to pull it down again and check the cylinder, I'll get the rings and gasket for it and then its RIP if it still doesn't work.

On another note I sent a letter to the presidents of John Deere and Scotts about the relatively poor quality of my mower and the unusual amount of trouble I have had with. Scotts never came back. John Deere sent a form letter about they take every concern seriously and then another requesting I call them. I got to speak with their helpdesk who were non plussed about the issue and offered that I could take it to their service centre an hours drive away from my place and pay to have it looked at.
I shouldn't be surprised but customer service from these companies leaves a lot to be desired. They have lost this customer, I'll go out of my way not to use their products now.
 
  #12  
Old 09-02-04, 08:54 PM
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Sounds like the issue is with briggs, not deere, right? Deere doesn't make the engines. The scotts products were cheap products aimed at homeowners and sold at home depot. They were as good or better than most other low-end consumer brands. The engines were the same engines that were bolted onto millions of other pieces of equipment sold by many manufacturers. I don't think Scotts lawn mower co. exists anymore, but could be wrong.
 
  #13  
Old 09-03-04, 05:40 AM
mormiston
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You might be right about Scotts. At the end of the day though, I purchased the mower at Home Depot warrantied by JD, so whether it is a BS engine or not they should be willing to support it. I already had to send it in for warranty repair a summer after I got it. I know that in the overall scheme of things they are cheap, but not when you look at what is on offer from craftsman and others.

Anyway I have broken the engine down again and will measure the bore over the weekend. There is no obvious signs of damage or extensive wear to the cylinder or the rings.

There does seem to be evidence of oil on the head gasket, even though there are no carbon marks or tears.

The oil I am using is SAE 30 as prescribed in the owners manual.
 
  #14  
Old 09-22-04, 01:17 PM
mormiston
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I got the engine gasket kit and new standard sized rings.
Rebuilt the mower and no more smoke. Although the gasket was not torn I could see evidence of oil seeping from the OHV chamber in the cylinder.
I don't think the new rings really did anything but it can't hurt.
Mowed the lawn only light smoke in really think grass otherwise no smoke at all.
Thanks for the tips and ideas. This one is solved.
 
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