How to Troubleshoot Power Loss in John Deere X500 with Kawasaki FH731V Engine?
Asked Oct 19, 20170 views1 answer
I am experiencing issues with my John Deere X500 lawn tractor, which has a Kawasaki FH731V liquid-cooled engine. It starts well and runs strong, but after about half an hour of mowing, it begins to miss and loses power, as if one cylinder is not functioning properly. I took it to the shop and checked the compression; one side showed zero compression. I then checked the valve gaps on both sides, made minor adjustments, and the engine ran well for a while. However, the same issue recurred, and this time it seemed to be the other cylinder losing power. Recently, I also heard a clanking noise, so I haven't used it since. Could this be a camshaft problem causing the valves to go out of adjustment? Any suggestions would be greatly appreciated. Thank you!
Troubleshooting Power Loss in John Deere X500 with Kawasaki FH731V Engine
Experiencing power loss and misfiring in your John Deere X500 lawn tractor can be frustrating. The Kawasaki FH731V engine, known for its reliability, can still have issues, especially if it starts to exhibit symptoms like missing or losing power after running for a while. This guide will help you troubleshoot the problem effectively.
Symptoms and Initial Diagnosis
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Starting and Running Conditions:
- The engine starts well and runs strong initially, which indicates that the battery, starter, and fuel system are functioning properly.
- After about 30 minutes of operation, the engine begins to misfire and lose power, suggesting that heat or wear-related issues may be at play.
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Compression Check:
- You mentioned that one cylinder showed zero compression. This is a critical finding. A low compression reading often indicates a problem with valves, piston rings, or a head gasket.
- A second compression check after adjustments showed a similar issue in the other cylinder, suggesting a systemic problem.
Possible Causes
1. Valve Adjustment Issues
- Valve Gaps: You’ve already checked and adjusted the valve gaps. The appropriate valve clearance for your engine is approximately for both intake and exhaust valves. Double-check these settings, as incorrect gaps can lead to power loss.
Expert Answers
RD
Relly De Jesus
Answered Oct 19, 2017
It sounds like you're dealing with a frustrating issue. Given that you've already checked the valve adjustments multiple times without success, it might be worth considering the possibility of fuel flooding, which can lead to misfires. Since you mentioned that the spark plugs are new and dry when removed, that suggests they are not burning all the fuel supplied to the engine.
You should also take a closer look at the valve clearance. For your `X500` model with the Kawasaki `FH731V` engine, the valve clearance should be set between 0.075 and 0.125 mm (or 0.003 to 0.005 inches) when cold. Make sure that the spark plug gap is set to 0.75 mm (0.030 inches) and that the spark plug torque is at 15 N•m (11 lb-ft).
If everything checks out with the valves and plugs, consider the possibility of overheating. Excessive heat can sometimes cause the camshaft to bend, which would lead to misalignment and further issues. However, if you're suspecting the cam bearings, that could be a more likely culprit. Worn camshaft bearings can lead to the engine going out of adjustment, which might explain the intermittent performance you're experiencing.
Taking these steps should help you narrow down the problem. If you find any signs of wear or damage, addressing those issues promptly will be key to getting your tractor running smoothly again.
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