# BS Intek 20hp Vtwin Issues



## pyromedic (Jul 24, 2011)

Afternoon all,

Need some help with an issue that a fellow Firefighter is having with his JD L120 mower, it has 153 hours on the engine is about 4yrs old and no issues other than a safety switch going out. The mower normally purrs like a kitten and mows with no problems. Last week will mowing he states that the unit sounded like he had hit something, loud and metalic sounding, being out in a wideopen area of his yard he could not find any debris. He states that immediately he killled the blades. He states that the unit started running very rough at idle and occasionally smoking, he then turned blades on and finished mowing but the unit was definitley running bad. After discussion we decided to pull flywheel to see if key had sheared , it had not. When we pulled the plugs both were very oiled up not wet but jet black on both. We cleaned them and fired it back up running about 1 minutes. Strange things was that the left cylinder got too hot to touch, while the right side was luke warm. Should this be occurring and what would have caused the noise, then the abnormal heating up of the one cylinder more than the other. This has got us wondering and prior to taking it in to the shop for the full monty dress down he would like to get some ideas. Thanks in advance for the help.

Stay safe.


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## RKDOC (Jun 20, 2006)

Pull both spark plugs out and do a compression test. If you have the equipment a Leakdown Teat would be better. If one cylinder has no compression turn the engine by hand with a long screwdriver in the spark plug hole and see if the piston is moving up and down. If it is not moving up and down, you probably have a broken rod. Check both sides. Then on the cylinder that is not getting hot, pull the valve cover off and see if the rocker arm or push rod has come off the valve train. It sounds like the cylinder that is not getting hot is not working properly. Best of luck.

Posting the model and type number from the engine would also be very helpful.


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## 30yearTech (Sep 14, 2006)

I agree with RKDOC in that the cylinder that is not getting hot is the one with the issue. You could have a dead ignition module on that cylinder loosing spark and power for that cylinder. I actually think that it's more likely that the push rod has come off of the exhaust valve on that cylinder. This would account for the loud noise, and the rough running. Pulling the valve cover on the cold cylinder will likely reveal the problem, but checking the spark on both cylinders would also be a good idea.

Best of luck... :thumbsup:


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## pyromedic (Jul 24, 2011)

Thanks for the info, model type number 406777 typ01281, we did check both for spark and they were both firing. I will see about getting compression checked and do the check to see if piston is moving in cylinder. If it is a broken piston rod it will be going to the shop for sure to repair, however if it is the exhaust valve issue is this something that can be accomplsihed in the average home garage or will we need special tools ? I am not that well versed on tearing into the 4 stroke stuff but trying to keep the cost down to get it back operational. I appreciate all of the suggestions. 

Stay safe,


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## justin3 (Apr 10, 2007)

Pyro, Volunteer or Paid Firefighter? I am a Volunteer in CT, anyhow you are on the right track. If you haven't already pull the valve cover on the dead cylinder. If my memory serves me right these engine are known for the valve guides loosening up and moving outward jamming up the valve and bending the push rods. Just check for valve movement. The cylinder head assembly is only around $90 if this is your issue.


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## pyromedic (Jul 24, 2011)

I am a volunteer Ff/paramedic in our now combination dept., just outside of Dallas. I have been doing this for 28yrs. How long have you been vol up there in CT ? Do yall run EMS ? We average about 500 calls a year and most of them being EMS as we transport as a BLS system with all volunteers after teh m-f day shift clears the station, even though several of us have certified as paramedic they still want a guarantee of a medic every call to change to ALS even though TX has BLS with ALS as a unit cert. I have gotten to attend the NFA in Emmitsburg a few years and it was really good to interact with everyone from across the US.
We will get to tearing it back down to determine what is going on, I am thinking valve issues but I cant figure it out on an engine with 150 hours, 550 maybe but not 150. Engines sure aint what they used to be with in some areas.
Stay safe up there.


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## 30yearTech (Sep 14, 2006)

pyromedic said:


> We will get to tearing it back down to determine what is going on, I am thinking valve issues but I cant figure it out on an engine with 150 hours, 550 maybe but not 150. Engines sure aint what they used to be with in some areas.
> Stay safe up there.


Briggs recommends valve adjustments every 100 hrs. They are a mechanical setup and require maintenance periodically. If they get too loose, it's possible for the push rods to simply fall off the rocker arm and render a valve inoperative. I have seen rods fall off and slide through the oil drain and into the crankcase of these engines.


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## usmcgrunt (Sep 16, 2007)

Here are the service manuals for your engine.With the great advice of the other members and this reference,you should have no trouble finding the problem and doing the repairs.Hope this helps.

Servicing The Valves-

http://www.briggsandstratton.com/engines/support/frequently-asked-questions/Servicing the valves/

Engine Service Manual-

http://www.mymowerparts.com/pdf/Bri...73521 Twin Cylinder OHV BRIGGS & STRATTON.pdf


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## pyromedic (Jul 24, 2011)

Thanks for the update on the valve adjustment and on the manuals. This site and its members have been extremely helpful and hopefully we can resolve it with parts and some garage time. If not it will go to the shop for repair.

Stay safe.


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## justin3 (Apr 10, 2007)

Just to answer your question I have been a volunteer for 2 years now since I was 16. I am an Interior firefighter/EMT however our fire department doesn't run medical calls, we have a private Ambulance company in town which I also volunteer at but they are separate from fire. We run about 3000-3500 fire calls per year and have 4 stations in town. 

As you probably already guessed, they don't make engines like they used to, I've worked on cars with less than 10,000 miles on them, blown motors, rod knock, burning oil. Gotta love GM


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## pyromedic (Jul 24, 2011)

Thanks for the info and congrats on getting in early and staying with it. Us seasoned ones are needing to pass on info to the Dot com generation. LOL
We will tear into it this weekend and the assistance of the forum has been invaluable. 3500-4000 man , yall are way busier than us but I it is hard to convince people that there are depts all over the US like yalls that run full vol or combi that are making your number of runs; they think that if you go over 1000 calls it is all career and no more vols.

Yall obviously have active explorer program to get you in at 16, which helps groom you for the service and you will educate yourself in an effort to stay on the leading edge; i have been at this stuff for 28 yrs but I still make every effort to expand my knowledge of everything involved with response.

Stay safe and everyone goes home.


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