6 Common Problems with John Deere Z665 (Solutions Included)

If you’re looking for zero-turn mowers, John Deere has been the key player in that business. Especially for so many gardening enthusiasts in the USA. John Deere Z665 High Capacity Mower Deck is not an exception.

It does have a Briggs and Stratton engine. So the Z665 does have some engine problems like oil leaks and engine noises due to a bad valve or a blown rod. It also has particular idler issues, hydraulic pumps giving out causing the mower to not turn, and some additional issues.

These common problems with the John Deere Z665 are discussed in this article. I will also suggest possible repairs to these issues. So stay tuned till the end to find out.

Problems and Solutions at a Glance:

Problems with John Deere Z665Solutions
Oil LeaksPut a filter in the inside of cap, take it to the dealer.
Rough IdleReposition the throttle cable.
Engine NoisesTake it to the dealer.
Engine Not StartingPistons and flywheel replacements or troubleshooting.
Blown Hydraulic PumpsChange hydraulic fluid, pumps and adjust rods.
Drive Belt CorrosionRemove the drive and try changing the oil. Make sure all drive bolts are present.

6 Most Common Problems with John Deere Z665 and Their Solutions:

You may experience John Deere Z665 problems due to many reasons. Here are some of the issues and how to solve them.

1. Oil Leaks

After being parked for a few days, an oily area can be noticed under the Z655. However, the engine oil gauge can display full.

This can be the result of a transmission leak. A hydraulic leak could also be present. The leak can also come from bottom main seal or the o- ring on the oil adapter.

The Fix:

If the leak is due to a hydraulic leakage, drill a hole on the inside of cap. Then put a filter in the inside of cap.

In case of the transmission leakage, taking it to a dealer is your best bet.

Usually these leaks show up early so you will have some warranty coverage.

2. Rough Idle

The engine is difficult to start and has a choppy idle. In addition, the single-lever throttle/choke system is terrible. This is because the choke throttle cable is not correctly positioned.

The throttle cable or the choke cable may be misaligned during delivery. Due to this, it is difficult to start when the engine is cold.

The Fix:

Reposition the throttle cable. If it happens during delivery, your dealer should re-tune it for free.

3. Engine Noises

The oil leak in the engine is usually what starts the engine noises. While mowing grass, sometimes loud noises start. Generally in the form of tapping. A loud metallic clank can follow this and then the engine backfires.

Engine knocking can be due to a broken rod or a dropped valve. The metallic clank usually means it’s a broken rod.

The Fix:

You can take it to the dealer. This problem usually shows up within a year so the warranty covers it.

4. Engine Not Starting

With the progression of the engine noises, the motor sometimes shuts off. Before completely giving up, it may make loud bangs. In addition to this, it may sound like the mower is being slowed down by too much grass.

This problem is quite a mysterious one because the fuel pump and the solenoid mostly remain in good shape. However, you may notice that there is no compression on either cylinder.

The result of this is no fuel going into the cylinder. The most common sign of this is a dry spark plug (when you open it up).

The Fix:

Pop a stick into the cylinder and locate the top of the piston with it. Then rotate the engine carefully by hand and see if the pistons move. The rocker covers should be taken off and the valves checked to see if they open and close as the piston moves. Removing the flywheel cover ensure the square key hasn’t been sheared.

This check will give you an idea of any replacements or troubleshooting. You may also try cleaning the PTO sump.

5. Mower Weak On One Side

The most common issue with this mower is the mower being weak on the side. Therefore, the other side must not be engaged when you need to go straight. Additionally, you will find that there’s low hydraulic fluid on that side.

The hydraulic fluid is low because a hydraulic pump seal has been blown, particularly on the problematic side. Moreover, it may also be due to a disengaged lever.

The Fix:

Ensure the rod you pull to disengage the hydraulic motors didn’t come out slightly on the weak side. The single hydraulic tank that supplies both hydraulic motors should have its fluid level checked first (pumps). Then inspect the filter on the soft side.

Replace the fluid on the weaker side. The pump is the next item to examine. There is a pump on each side. The valve system would be reliable enough for no problems in the future.

The disengagement lever would be the issue most likely. Examine the spelunker pump as well. If you discover a free-wheeling rod coming out, press it in, and the mower will run perfectly.

6. Drive Belt Corrosion

The belt keeps rolling till it breaks. Because the pulleys’ axes are at an angle to one another, belts move. Motion levers frequently break out. In particular the ones on the right. The tensioning pulley is usually the first to be blamed.

The Fix:

Check that the pulley is on the belt and moving. If the problem persists, you must remove the drive and try changing the oil.

To fix the issue due to stuck air, move the release lever in the back of the mower to the “released” or “push mower” position.

Then, move the right control all the way forward and hold for 5 seconds before going all the way back and hold for 5 seconds.

Finally, verify that all of the drives’ bolts are present and securely fastened.

What Majority of the Users Feel?

Because of its 54″ high capacity, the John Deere Z655 is popular with most users. It has enough power to do the job and will cut practically any length of grass the first time. Although you must use caution, it performs admirably on slopes.

Because the engine is directly behind the operator’s seat, it is noisier than a tactor. This frequently experiences incorrect adjustment of the belts and cables. Re-adjustment might only be effective till the conclusion of the mowing season.

The issue occasionally results in a difficult mower start when the engine is cold. Because you can travel much faster with less turning, it takes less gas than a diesel Kubota. The transmission’s design, though, can be perplexing.

And the problems highlighted in this post are still present. However, the owners also think this is a very strong zero-turn mower that can provide several hours of logging. 

Frequently Asked Questions

How Much Engine Power Does a John Deere Z665 Have?

24 HP.

What is the current price range of the John Deere Z665?

$3,950 and $4,000 USD.

What type of fluid goes in a John Deere hydrostatic transmission?

Low Viscosity HY-GARD™ (J20D) transmission oil.

Which John Deere zero turn mower is rated the best?

John Deere Z515E is overall rated the best.

Final Thoughts

As far as zero-turn mowers are concerned, John Deere Z665 has delivered consistent performance.

The complaints will often come through, and the mower lacks extra features that bring customers to the yard. However, in terms of reliability, the JD Z665 delivers. So you can go ahead and give this one a try!

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