Yesterday's Tractor Co.
Shop Now View Cart
   Allis Chalmers Case Farmall IH Ford 9N,2N,8N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   Traditional YT Forum ViewClassic View   RegisterRegister 
 ProfileProfile    Log inLog in 

compression!!!


 
Post new topic    
View previous topic :: View next topic  
Author Message
bdunegan
Regular


Joined: 09 Jun 2008
Posts: 238


Report to Moderator

PostPosted: Thu May 30, 2013 1:25 pm    Post subject: compression!!! Reply to specific post Reply with quote

I have a 21hp B&S ohv single cylinder with problems. It starts and runs great, but you have to hand spin the flywheel past compression first. I have tried a new heavier battery, set the valves according to specs, and checked flywheel key to make sure it wasnt sheared and throwing timing off. I even thought starter may be dragging, and put another good starter on it. nothing helps. you can turn the key to start it, and it will spin to compression, but wont spin past without hand turning it. just hoping it is not internal problems. anyone have any suggestions!
 
Back to top
View user's profile
69val6
New User


Joined: 21 Jan 2011
Posts: 11


Report to Moderator

PostPosted: Thu May 30, 2013 1:40 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

Try adjusting the valves again. If the exhaust valve isn"t adjusted properly, the compression relief doesn"t work properly. If it"s within spec"s, the compression relief has likely broken on the camshaft. You"ll have to split the cases and check it. Some of the Briggs engines have plastic camshafts and don"t last too long

Hope this helps.

Joel
 
Back to top
View user's profile
bdunegan
Regular


Joined: 09 Jun 2008
Posts: 238


Report to Moderator

PostPosted: Thu May 30, 2013 3:51 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

just went out and re-set valves just in case they may have been off, and no luck. I can hand spin it backwards about a turn or so and then hit the key, and it will spin past compression and start right up, but if it is close to compression at first, it will not turn past. this is on a 2011 craftsman mower that looks it is brand new. it cant have more than 20 or so hours on it. Surely the acr on the cam is not bad already. is it possible for them to stick?
 
Back to top
View user's profile
504-1
Long Time User


Joined: 05 Dec 2009
Posts: 572


Report to Moderator

PostPosted: Thu May 30, 2013 4:10 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

Try shorting the starter, bypassing the switch, I am guessing a bad solenoid.(Too much resistance)
 
Back to top
View user's profile
bdunegan
Regular


Joined: 09 Jun 2008
Posts: 238


Report to Moderator

PostPosted: Thu May 30, 2013 4:37 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

I tried that one too. i went directly to starter using heavy cables from another runing mower. still no luck but thanks for the input. this one has me flubbered!
 
Back to top
View user's profile
joe csuti
Tractor Expert


Joined: 30 Mar 2009
Posts: 1884


Report to Moderator

PostPosted: Thu May 30, 2013 5:21 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

First if you're not doing it is valves must be set with piston 1/4" into downward travel after TDC of compression stroke otherwise valve tappets won't be clear of cam lobes & acr cam & you can get false settings.

If you are setting valves as above & still have problem,remove plug & crank eng 3-5 sec,reinstall plug,crank eng,if eng now cranks over then most probable cause of problem is float valve in carb leaking flooding eng & hydrolocking piston on compression stroke,if carb not the problem other possible cause of problem,acr or cam bad.
 
Back to top
View user's profile
bdunegan
Regular


Joined: 09 Jun 2008
Posts: 238


Report to Moderator

PostPosted: Thu May 30, 2013 6:47 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

I set valves 1/4 down on compression stroke, and also took plug out and cranked. put in plug and same thing again. I know fuel solenoid is working and shutting off fuel. dont notice any signs of flooding. Not to sound like a dummy, but walk me through normal procedure for tdc just to make sure my mind hasnt slipped. i am going to check valves again tomorrow just to make sure something didnt slip. only other thing i can think of would be the acr. thanks for your response, i appreciate it.
 
Back to top
View user's profile
joe csuti
Tractor Expert


Joined: 30 Mar 2009
Posts: 1884


Report to Moderator

PostPosted: Fri May 31, 2013 2:22 am    Post subject: Re: compression!!! Reply to specific post Reply with quote

If you're rotating eng to top tdc of compression stroke(both valves closed)then dropping piston 1/4" & setting clearances,then you're doing same correctly,I'm also assumeing whatever manual/spec sheet you're looking at calls for .003"-.005" on intake & .005"-.007" on exh,then you're setting valves correctly,a lot of guys like to set both for .004" on both to make for a longer time between adjustments,you might try that.

If carb not leaking other possible cause's of problem,if cam gear plastic,gear may be worn or bearings for cam worn & cam jumped it's time,acr cam worn or one of the pushrods may be bent.
 
Back to top
View user's profile
ACSam
Regular


Joined: 03 Oct 2002
Posts: 210


Report to Moderator

PostPosted: Fri May 31, 2013 3:52 am    Post subject: Re: compression!!! Reply to specific post Reply with quote

I have a friend that works for a company that does warranty and repairs for Sears. He says this is a fairly common thing on the large single cylinder B/S like yours. He said some of them don"t get 10 hours before this happens. It is the acr on the cam.
 
Back to top
View user's profile
bdunegan
Regular


Joined: 09 Jun 2008
Posts: 238


Report to Moderator

PostPosted: Fri May 31, 2013 1:56 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

just re-set valves for third time, set both at.04 1/4 inch down after tdc. checked both push rods and neither one bent, put it back together, and a lot better now. every once in a while it will still hang and not crank past compression, but most of the time it will start right up. if it hangs, i just roll it backwards a turn or two then hit it and it will start. I am guessing valves still not set just perfect but i can live with that. at least i can get it started now pretty easy. thanks for all the responses, it really helped a lot!
 
Back to top
View user's profile
bdunegan
Regular


Joined: 09 Jun 2008
Posts: 238


Report to Moderator

PostPosted: Fri May 31, 2013 1:59 pm    Post subject: Re: compression!!! Reply to specific post Reply with quote

OOPS! meant .004. Thanks again
 
Back to top
View user's profile
Display posts from previous:   
Post new topic    Yesterday's Tractors Forum Index -> Garden Tractors All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  

TRACTOR PARTS TRACTOR MANUALS
Fast Shipping!  Most of our stocked parts ship within 24 hours (M-Th). Expedited shipping available, just call! Most prices for parts and manuals are below our competitors. Compare our super low shipping rates! We have the parts you need to repair your tractor. We are a company you can trust and have generous return policies. Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ About Us ]

YT Home  |  Forums

Modern View Forum powered by phpBB © 2001, 2005 phpBB Group

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters