My new to me JD 300 just blew the plug right out of the head. Too warm to check the threads right now. Test drove it for just a few minutes before I purchased sounded good. First got it home and ran it around for maybe 5-10 minutes mowed for a couple more. Started making some ticking (not knocking) noises at front of motor. Popped hood saw more vibration than I like and suspected motor mounts. Shut it down and changed the oil as I do with a new/used vehicle. Pulled side panels and checked the motor mounts. Looked aged but not bad. Sat until this afternoon when I fired it up. After a couple minute warm up I opened it up and all sounds good. Mowed for a couple minutes and the ticking reappeared. Motor started running rough. Shut down blade. Was throttling down and POP. Cooling down now. I'll check the head and plug to see if there is any thing glaringly obvious. Anyone experienced similar? I would expect that if the plug was cross threaded I would have noticed a misfire. Didn't notice anything strange till the ticking showed up.
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Blew the spark plug right out of the head.
- Thread starter JoelD 61
- Start date
- Views: 8653
beenthere
Super Star Member
- Joined
- Aug 16, 2001
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- Southern Wisconsin, USA
- Tractor
- JD_4x2_Gator, JD_4300, JD_425, JD_455 AWS, added JD_455, JD_110, JD_X485(sold)
You may find that the engine plug was put in with a helicoil. May have been a temporary fix to sell it.
how to repair stripped spark plug threads using timesert helicoil kit - YouTube
how to repair stripped spark plug threads using timesert helicoil kit - YouTube
Kish318420
Gold Member
May be try a new head and head gasket, it could be as simple as that
Thanks for the reply. Heard of helicoils, never used one. Just watched a video. Doesn't appear so. Looked like some head threads left in the plug threads. Not too bad but not promising either. Cleaned the plug threads and was able to install plug normally and snug it up properly. Started it back up. All good until again the ticking started. Is this possibly a symptom of overheating or possibly a head gasket? The engine is clean and i can see no reason for it to overheat.
Kish318420
Gold Member
Ticking could be valves or valve train related (push rods, valve seats, valve springs, hydraulic lifters, valves themselves, rockers), could be head gasket leaking after heat up, or leak around or through spark plug.
Do compression test on engine, if it holds pressure above lowest spec value then do a leak down test.
Do compression test on engine, if it holds pressure above lowest spec value then do a leak down test.
thepumpguysc
Elite Member
I'd pull the valve cover.. find out what the spec is on the valve adjustment, COLD & HOT..
Which engine is in the unit, Briggs or Koehler. The Briggs had a problem with the rocker arms coming loose and making a ticking sound. The Koehler had a problem with the head bolts loosening and allowing blow by at head gasket which sometimes sounded like a ticking noise.
bruceatlam
Platinum Member
While it certainly won't hurt anything to check the valve train, I doubt that you'll find the problem in the valve train. Ticking can simply be directly related to a loose plug. Loose because there's an issue with the threads or loose because it was simply installed loose. If there is a compression issue of some kind it's a high compression issue not a low compression issue which would tend to lead you away from a head gasket problem. The spec for spark plug torque should be around 12 ft lbs or so ------ good luck. When you figure it out, let us know.