Before I send my Gator to the shop I would like to have a warm fuzzy feeling on what is wrong. It’s been running a little rough so I changed plugs, oil and air filter. No improvement
I did notice that smoke blows out of the dipstick tube while running. Not so much now that I changed oil.

2012 JD xuv550

Thanks in advance!

[video:youtube]https://youtube.com/shorts/56lOTXGDBy4?feature=share[/video]

Think that would be more indicative of shot/broke rings.

Is it air or water cooled? If water and the oil was t milky I don’t think it is a head gasket. The gas coming out the dip stick is blow by, what is getting past the piston rings. It looks excessive to me generally speaking, but not familiar with this buggy specifically.

Yes sir, air cooled. Thanks for your input!

I had a blown head gasket on an Oldsmobile and it had a distinct sound when you gave it gas. Tha-tha-tha-tha-tha almost like baseball cards stuck in the spokes of a bicycle wheel trying to make it sound like a motorcycle. When you pulled the dip stick it had lots of bubbles on it that were kinda milky like redchevy mentioned.

If you want help, shoot me a text.

X2 on the rings Compression blow by into the crankcase

#1 - make sure your air cooling intakes and cowling is not full of grass, hay or other stuff that will impede the air flow.
I've seen quite a few aircooled ATVs and UTVs that are used in tall grass or hay fields get hot enough like this to stick the rings lightly.
#2 - pull the spark plug and pour 2 ounces of Marvel Mystery Oil directly into the cylinder, turn it over slowly a few times to get the oil all around perimeter of piston and let it sit overnight, then turn if over slowly again and let it sit another 12 hours.
#3 - if your oil is low, bring up to fill line with Marvel Mystery Oil.
#4 - Turn it over with starter and spark plug out to remove excess MMO from cylinder.
#5 - Install plug and start it and it will smoke like crazy until it burns out the MMO - with that much oil in the cylinder it may oil foul the plug a few times.
#6 - Run it, it may be fine after this or if it continues to smoke for longer than the time required to burn out the MMO, it probably needs rings.

I have brought quite a few back from the dead like this including my Mule 550 that still runs just fine 4 years later.
Give it a shot, it's cheaper than a top end!

If it were rings, wouldn't you have blue smoke from exhaust and fouled out spark plugs? Hole in piston or a scored cylinder wall?

What exactly is the marvel oil going
To
Do?

These are some innerweb mechanic answers Holy Crap


If your close enough I have a leak down test kit your welcome to use to eliminate the head gasket question,, Just an FYI if it was blow by it would most definitely be smoking as well which you didn’t mention. We need a lot more info to help,

Did the oil have gas in it when you changed the it?
Is it hard to start cold but easier after it’s warm?
Does it have a pre filter and has it been properly oiled?
Is it smoking?
What motors in it, Kawasaki by chance? Those models have some serious health and well known issues.

We need background info to help,,

No gas in oil

Isn’t that normal for a gator, easier to start warmed up?

Briggs and stratton

Some exhaust smoke at various times

No idea about a pre filter?

Thanks

If the rings are stuck from overheating, Marvel Mystery Oil can help unstick them and restore compression.

If the rings are stuck from lack of lubrication or running extremely lean, it won't help.

Im not a Briggs professional but the same principles apply for all engines, it doesn’t sound like a blown head gasket from what your describing to me. If your handy with tools look up how to set the valves and reset those and I’d bet you see a solid improvement. I’m not sure if those style engines actually run a lubed pre filter or a lubed foam filter but with it puffing a little smoke I’d guess at some point the filter has allowed a little dirt by and hurt the rings a bit and in the process of doing that it’s caused the valves to tighten up. It’s a very common problem on all off-road engines over time if the service isn’t kept up with correctly.

It could be something totally different but the valves will cause all the issues your describing aside from the crankcase pressure which if it’s excessive will 100% be caused from worn rings but generally if there that bad it’s burning oil pretty bad at the same time.

Does this have a PCV valve that might be clogged?

UPDATE and special thanks to TexasLefty for his wisdom and help!


Compression test revealed one cylinder at 90 and other 150 psi. Took the valve covers off and on the low compression side one of the push tubes (rod) was off the rocker arm. Reinstalled but ran into correctly setting the lash. Remembered I had a neighbor that moved in that had owned a shop and mechaniced for over 30 years. Reached out to him and he came over. We set the correct lash and did another compression test. Same result. So he performed a leak down test and the cylinder wouldn’t maintain 20 lbs while the other one maintained 60 psi.

I then tried the mystery mare cell oil trick as described above. Increased the compression from 90 to 105. Apparently have bad rings or May piston issue. Gonna take it over to my neighbor next week and let him pull the motor and fix it.

Definitely not head gasket as originally thought.

Thank to everyone for your input!