Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Briggs Ohv Blowing Compression Into The Crankcase


  • Please log in to reply
20 replies to this topic

#1 916 hydro OFFLINE  

916 hydro
  • Senior Member
  • Member No: 10159
  • 114 Thanks
  • 139 posts
  • Location: dillsboro IN

Posted May 22, 2013 - 06:56 PM

im working in a new riding mower for a family member it has an overhead valve briggs on it itis blowing compression into the crankcase what could cause that



#2 JDBrian OFFLINE  

JDBrian

    Super Moderator

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2507
  • 9,574 Thanks
  • 14,136 posts
  • Location: Hubley, Nova Scotia - Canada

Posted May 22, 2013 - 07:03 PM

Wear of cylinder/rings or lack of ring seal for some reason. One thing I have seen on Kohlers is carbon buildup actually interfering with the piston at the top of it's travel. This causes the piston to be pushed to one side unseating the rings on the opposite side. This caused  blowby and oil leakage from the crankcase vent on a K321. I removed the carbon and that problem went away. I'm not sure if this would be common in a OHV Briggs. 


  • Alc and 916 hydro have said thanks

#3 olcowhand ONLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,588 Thanks
  • 29,831 posts
  • Location: South Central Kentucky

Posted May 22, 2013 - 07:20 PM

Blown head gasket almost guaranteed!  Blown between cylinder & push rod galley.


  • Alc, JDBrian and 916 hydro have said thanks

#4 ol' stonebreaker ONLINE  

ol' stonebreaker
  • Senior Member
  • Member No: 12515
  • 1,304 Thanks
  • 973 posts
  • Location: idaho

Posted May 22, 2013 - 08:46 PM

Blown head gasket almost guaranteed!  Blown between cylinder & push rod galley.

 

   X2.

                               Mike


  • 916 hydro said thank you

#5 EricFromPa ONLINE  

EricFromPa

    Tractorholic

  • Senior Member
  • Contributor
  • Member No: 2135
  • 2,293 Thanks
  • 2,329 posts
  • Location: Bedford County Pa.

Posted May 22, 2013 - 09:51 PM

Blown head gasket almost guaranteed!  Blown between cylinder & push rod galley.

 

 

100% guaranteed to have a blown head gasket. I'm redoing yet ANOTHER OHV briggs with blown head gasket.This 17.5hp on a 2010 Troy Bilt Pony blew because the needle valve in the carb let the block and cylinder fill up with gas.

 

They are well known to blow head gaskets because there is less than 1/4" of material between the cylinder and push-rod galley.I've had to replace the head gasket on Dozens of OHV briggs engines over the last 2 years alone.They're fairly simple to do and only takes me 2 beers and 20-30 minutes.

 

I've found that if you torque the head bolts to 34-36 foot lbs they don't blow as often.Stock torque is 26-28 foot lbs.Valve lash should be set to .003-.006 for both valves for the compression release to function correctly.If not you'll cook the windings out of the starter very quickly.  

 

There are several different designs of OHV briggs engines (3 if I remember correctly) but they all had the same problem.If you give us the numbers off of your engine we can get you a part number for a head gasket.Head gasket will run you $8.00-$18.00 depending where you get it. 

Attached Thumbnails

  • 000_0125.JPG

Edited by EricFromPa, May 22, 2013 - 10:07 PM.

  • Alc, JDBrian and 916 hydro have said thanks

#6 Alc OFFLINE  

Alc

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 1094
  • 5,446 Thanks
  • 6,611 posts
  • Location: Bangor Pa

Posted May 23, 2013 - 05:43 AM

Gets me mad when you hear of a co. poorly design something like the head gasket sealing area , it's not like it's their first motor they designed :mad2:  sorry to rant


Edited by Alc, May 23, 2013 - 05:44 AM.

  • EricFromPa, JDBrian, 916 hydro and 1 other said thanks

#7 superaben OFFLINE  

superaben
  • Senior Member
  • Contributor
  • Member No: 11204
  • 7,664 Thanks
  • 5,677 posts
  • Location: Shenandoah Valley, VA

Posted May 23, 2013 - 06:20 AM

Daniel's the man with the know-how today! 

 

I have to agree with Alc, though.  That's logically a faulty design issue.  But for Briggs defense, why get rid of it?  Job security for head gasket sales!  :shoot2:

 

Ben W.


  • JDBrian and 916 hydro have said thanks

#8 Guest_gravely-power_*

Guest_gravely-power_*
  • Guests
  • Member No: 0
  • 0 Thanks

Posted May 23, 2013 - 06:40 AM

I just did a Briggs OHV. There was so much carbon build up that it broke loose and got between the intake valve and the piston and bent the push rod. That is pi@@ poor engineering.


  • EricFromPa, JDBrian and 916 hydro have said thanks

#9 JDBrian OFFLINE  

JDBrian

    Super Moderator

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2507
  • 9,574 Thanks
  • 14,136 posts
  • Location: Hubley, Nova Scotia - Canada

Posted May 23, 2013 - 10:30 AM

As an aside, wouldn't a lot of carbon in the head raise the compression ratio and cause more stress on the HG as well as causing problems with pre ignition. I also wonder how much overheating has to do with all the failures. A mower needs to have the cooling fan and air flow path cleaned on a regular basis. If the cooling design is marginal then that would be a contributing factor to overheating and whatever comes from that.



#10 olcowhand OFFLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,588 Thanks
  • 29,831 posts
  • Location: South Central Kentucky

Posted May 23, 2013 - 11:06 AM

As an aside, wouldn't a lot of carbon in the head raise the compression ratio and cause more stress on the HG as well as causing problems with pre ignition. I also wonder how much overheating has to do with all the failures. A mower needs to have the cooling fan and air flow path cleaned on a regular basis. If the cooling design is marginal then that would be a contributing factor to overheating and whatever comes from that.

 

Yes, tons of carbon would raise the compression, and I'm sure overheating would stress the gasket as well.


  • JDBrian said thank you

#11 EricFromPa ONLINE  

EricFromPa

    Tractorholic

  • Senior Member
  • Contributor
  • Member No: 2135
  • 2,293 Thanks
  • 2,329 posts
  • Location: Bedford County Pa.

Posted May 23, 2013 - 02:06 PM

I just did a Briggs OHV. There was so much carbon build up that it broke loose and got between the intake valve and the piston and bent the push rod. That is pi@@ poor engineering.

 

I've had that happen on 2 of them.1 I was able to straighten out but the other got kinked and had to be replaced.

 

 

They are a very good running powerful engine and easy of fuel when they work the way they should.

 

 

On another note,I've taken a 15.5hp OHV engine and gutted it and put the Piston,rod and crank in a Non OHV 12hp cast iron bore block a few years ago.The guy I sold it to is still running it in his Snapper Rer.That High compression piston transformed an old worn out 12hp into a mowing beast.


  • JDBrian said thank you

#12 JDBrian ONLINE  

JDBrian

    Super Moderator

  • Super Moderator
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 2507
  • 9,574 Thanks
  • 14,136 posts
  • Location: Hubley, Nova Scotia - Canada

Posted May 24, 2013 - 05:30 AM

This is interesting stuff. Thanks everyone for contributing.



#13 Alc OFFLINE  

Alc

    Tractorholic

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 1094
  • 5,446 Thanks
  • 6,611 posts
  • Location: Bangor Pa

Posted May 24, 2013 - 05:41 AM

Got to thinking , if there was a certian model motor that carboned up more then others would using synthetic motor oil keep it from getting carboned up? I've been using synthetic in my 2 cycles .  If so might be cheap insurance .



#14 916 hydro OFFLINE  

916 hydro
  • Senior Member
  • Member No: 10159
  • 114 Thanks
  • 139 posts
  • Location: dillsboro IN

Posted May 24, 2013 - 05:00 PM

thanks for all the help guys i pullled the valve cover and saw the chunk of head gasket poking into the lifter galley


Edited by 916 hydro, May 24, 2013 - 05:00 PM.


#15 ol' stonebreaker OFFLINE  

ol' stonebreaker
  • Senior Member
  • Member No: 12515
  • 1,304 Thanks
  • 973 posts
  • Location: idaho

Posted May 24, 2013 - 05:58 PM

  It's a cheap and easy fix for us DIYers, but what about the poor folks that don't know which end of a screwdriver to grab? I'm sure B&S and a lot of shops have made a ton of $$$ off a poor design.

                                                  Mike






Top