5 Common Problems with John Deere 997 (Solutions Included)

The John Deere 997 is a zero-turn mower with a hydrostatic transmission. It comes with a 31 HP Yanmar 1330cc 3-cylinder diesel engine. It is easily a grass cutting beast!

However, the most common problems with the John Deere 997 are no power issues, PTO problems, cutting issues, overheating of the engine, faulty transmission and fuel delivery issues.

In this article, I have included all these issues along with their solutions. I have also included the solutions of these problems. And finally, you will find some genuine reviews from real people who own the ZT mower. So stay tuned!

Problems and Solutions at a Glance:

Problems with John Deere 997Solutions
No PowerReplace broken glow plugs; troubleshoot.
PTO ProblemsFix switches.
Cutting IssuesGet longer bolts and use the rear discharge for cutting longer and stem-like grass.
Overheating Of the EngineTroubleshoot the vapor lock.
Fuel Delivery IssuesClean seal, troubleshoot.

5 Most Common Problems with John Deere 997 and Their Possible Solutions:

Many reasons exist why a John Deere 997 manifests problems. Here are some of the reasons and how to solve them.

1. No Power

The diesel engine particularly fails to start often. When you engage the deck, it will seem to have no power. As a result, the mower can get stuck in even about 5 inches of grass.

Gas engines seem to have more power than diesel engines on this mower. It will take away any horsepower. If the air filter is dirty, it might smoke when working under load.

The diesel John Deere is admirable, but not everything green or diesel is the best thing. The 997 is an old mower, and many smaller gassers from other brands perform better than it.

Black smoke means there’s too much fuel, while white smoke means oil is being burned. A bad glow plug makes the engine have less power and dumps raw fuel into the exhaust.

The Fix:

Get a photo tachometer and check that the motor’s RPMs are correct. Check to see if the drive belt is too loose.

Replace any broken glow plug and unclog the fuel filter if needed. Switch to the gas engine as soon as you can.

2. PTO Problems

This is a common issue with the entire 900 series. The PTO or the PTO clutch won’t work. All the relays, PTO switch, fuses and the solenoid may be fine. But you still may find problems.  

The problem is usually with the wiring or with the transmission or deck. There is an “air gap” around the actual PTO that needs to be set with a feeler gauge.

 It won’t work if the air gap is too big. If the machine shuts down when you try to turn the PTO, it could be the seat switch.

The Fix:

First, use a multimeter to check if your solenoid is getting power. This will let you know if it’s the wiring or the transmission that’s faulty. You may need to replace the relay.

You might need to fix the switch for the park brake or adjust the PTO clutch. Fix seat switch if needed.

To adjust the PTO clutch, you need a 9/16″ wrench. You’ll be needing it to turn all three lock nuts on the clutch a half turn at a time. Then try the clutch again. Keep doing this until the clutch will stay in place.

3. Cutting Issues

Normal grass is easy for the mower to cut, but it has trouble with large patches of “goosegrass” and “dallisgrass.” Especially while applying side discharge.

The use of twin blades or meg-mo blades has been up for discussion. Running doubles on this mower is not recommended.

So, twin blades (highlifts or T configuration arrangement bolted down as firmly as possible is not an option.

The ordinary J.D spindle bolts are just long enough. However, to attempt doubles in the JD, you will need longer bolts.

Moreover, crabgrass, goosegrass, and other grassy weeds have substantially higher moisture contents. Therefore, when it is clipped by the JD 997, the trimmings have a tendency to clump together after being discharged.

The Fix:

Get longer bolts and use the rear discharge to cut longer, stem-like grass.

4. Overheating of the Engine

The John Deere 997 will stop when overheating. This mainly occurs due to diesel vapor lock. If it gets too hot, an alarm will go off and the blades will stop moving.

This is explained by the DLCS, which is part of the 997’s safety. If the oil is low or the radiator gets too hot, the PTO stops working and a loud beeper goes off.

The problem can also be a very small screen at the end of the tank’s suction hose. It can get clogged up. Also, the line going into the tank is very small and possibly made of cheap plastic.

The Fix:

If the mower goes to vapor lock, the gas cap vent will probably be blocked. But first, the plastic sides of the tank will start to pull in first. Just use an ice pick to open the cap’s hole.

Put a stainless steel flyscreen over the radiator’s surface, pull it out, and clean it twice a day. Check the oil, clean the radiator, and let it cool down.

Use your air hose or a backpack blower to clean out the radiator. Then wash out the coils. Dirt gets stuck in there.

If there is vapor lock, just take off the top and tap it hard against something while holding it upside down.

Take off the small screen at the end of the tank’s suction hose. Put a filter on it.

5. Fuel Delivery Issues

The tractor runs weaker over time. The engine would only run for a few seconds before it dies. Changing the fuel filter will not make things better.

There is an inlet screen inside the fuel line that can get clogged. This stops fuel from getting to the engine.

The Fix:

The fuel goes through a water separator that has a valve to turn it on and off. Make sure to use a drain to get rid of any water in the bottom of the can.

If the fuel isn’t well filtered, it wears out fuel systems quickly and costs a lot. So, use a good filter and change the fuel at least once a year.

If you pull out the fuel tank’s supply tube and see that the inlet screen is dirty or clogged, you should take the tank off and clean it. You might have algae or other debris on the screen, which will cause it to clog up again and give you more downtime.

What Majority of the Users Feel?

There aren’t too many problems with the 997. It’s a big, heavy beast that looks like a tank. Around 1500 hours is an economic amount of hours on a second-hand JD 997.

The hydro drive motors are problematic. And you shouldn’t be getting a 60-inch deck. It will be too heavy and strong for a 60-inch cut.The 72-inch deck model weighs around 1700 pounds.

They do fine on dry slopes. But on steep slopes, they can get squirmy. A ZTR is not a good choice if you need to do a lot of side hills and ditches. I would think about getting a 4WD front deck mower or a 4WD tractor.

Frequently Asked Questions

How often should you service the Engine Oil Filter on John Deere 997?

Every 200 machine hours.

What is the part number of the Hydraulic Oil Filter on John Deere 997?


How many machine hours will a John Deere lawn tractor last?

4,500-5,000 hours

Final Thoughts

According to my research, it is safe to say that you can buy a 997 ZTR. It is worth it and don’t necessarily have too many issues. Most owners would recommend it despite some inconveniences.

So I would suggest you to go for it.

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