[jstatham]

Hello everyone my father in law has a 2012 550 XUV that starting fouling plugs about 3 month after he got it in 2012. He is the original owner and the machine has 272 hours on it. He has done the regulars oil changes, maint and changing plugs constantly. I starting doing some googling and found that some of these engines came from the factory with bad head gaskets and John Deere was fixing them for free up to 300 hours. I called several dealerships and they act like they have never heard of the issue. I am sure its too late now. Anyway, The only thing I have done to the machine is a compression test and it all seemed fine. I was going to do a leak down test but my tester was bad. I am looking for some guidance on what I can do to 100% identify the problem before I just replace the head gaskets. I am thinking I should start with a valve adjustment. Is there somewhere I can get the service manual? Any help would be greatly appreciated. My plan is to fix it the next time he is out of town. He is 80 year old retired engineer and I want to surprise him.

 

[200mph]

I’d focus on carb/fuel calibration and ignition integrity.

 

[dane]

I had bad head gaskets on mine. The main symptom was rough running as though it's rich and it fouled the spark plugs. It also became very sensitive to a dirty air filter. I had my machine back to the dealer several times with well less than 100 hours before they agreed to replace the head gaskets.

A leak down test is possibly the most reliable way to diagnose. You can also try removing the dipstick while the engine is idling. Some smoke and gas coming out is normal but if it's really blowing that's a sign of trouble. You can also see if the engine is overheating. I think mine ran hotter with the blown gaskets but I didn't have numbers from before to compare so it mostly fell into the "just isn't running right" category.

Certainly check for signs that the engine is running rich. It's a long shot as a gummed or clogged carburetor usually results in it running lean, but anything can happen. Something like a failed float valve could allow it to run richer but you'd also likely see the oil level rising and the oil might smell like gasoline.

You can get the service manual from any Deere dealer or you can order it online. There are also companies that sell downloads.

 

[Autodog61]

I had bad head gaskets on mine. The main symptom was rough running as though it's rich and it fouled the spark plugs. It also became very sensitive to a dirty air filter. I had my machine back to the dealer several times with well less than 100 hours before they agreed to replace the head gaskets.

A leak down test is possibly the most reliable way to diagnose. You can also try removing the dipstick while the engine is idling. Some smoke and gas coming out is normal but if it's really blowing that's a sign of trouble. You can also see if the engine is overheating. I think mine ran hotter with the blown gaskets but I didn't have numbers from before to compare so it mostly fell into the "just isn't running right" category.

Certainly check for signs that the engine is running rich. It's a long shot as a gummed or clogged carburetor usually results in it running lean, but anything can happen. Something like a failed float valve could allow it to run richer but you'd also likely see the oil level rising and the oil might smell like gasoline.

You can get the service manual from any Deere dealer or you can order it online. There are also companies that sell downloads.

Is there somewhere I can get the service manual?

I got the technical manual for my 590 on Ebay. Ran around $60 and came on a CD. Of technical manuals I have experience with, the JD Tech manual is a trailing 5 on a scale of 1-10. Regarding the feeling you got from the dealer, yea, thats about right,. Mine here in the northwest is dumbfounded when I bring up common issues known. But, after walking around it with them in a 20 minute conversation they somehow seem to recall again. Dealers are generally not wanting to do anything per warranty because John Deere doesnt stand behind their products making it difficult for dealers to get reimbursed for repair work. Again, found this out by dancing around with the dealer service lead for 20 minutes in conversation and this was the end statement from them. Very Frustrating.