Hello im new to this site. I just got back from my local Arctic Cat dealer were my ATV is right now. I had a very bad knock in the engine and took it in. When they took the engine apart they for the piston had atleast a 1/8" gap between the cylender and the piston. They told me it is from cold starting the machine and not letting it warm up. The knock started last week and I only rode it for about 30min like that just to get it home. The machine has less than 600 miles on it. Every time I start the machine I let it warm up atleast 5 min. before moving it. I have owned several other machines and never had a problem like this before. The only thing I could think of is that the oil pump is not functioning fully. My dealer said there is no way to check the oil pump flow. What do you think caused it? I dont ride the road I mainly use the machine to plow the driveway and to pull brush and limb wood from my land. Could the work strain I put on the machine wear the piston down like it that? It damage could not happen in 30min of riding could it?

 

Welcome to the connection!

I don't think that could have caused the problem, espicially if you warm it up! What year is your machine? Was it under warantee? [img]i/expressions/face-icon-small-cool.gif[/img]

 

Was the top of the piston melted, maybe a crater or a hole in it? An over rich condition will wash the cylinder wash clean of oil. Also not shutting off the fuel valve will do the same thing and on start up the rings and cylinder walls wear badly. However, if this all happened in 30 minutes, from first knock to shop and it was still running, it sounds more like the carb leaned out and fried the piston. With such a short time it doesn't sound like a cold start up problem with wear. I'd tell the dealer, I want a second opinion if they try to cop out on the warranty.

Oh yeah, welcome to the forum.

 

It is a 2004 and yes it is under warantee until 9/15/2005. My dealer said he would see what he could do. This is not the first purchase I have made from my dealer. In the past 5 years this is what I have bought from them,

Used 1999 ZR 600 EFI
Used 1999 ZR 500 EFI
New spring order 2003 F7 Limited Editon
New 2003 ZL 600 EFI ESR
New 2 Place Karavan Trailer

So it is not like I have not bought any thing from them. They always bent over back wards to fix my sled even out of warantee. Now they are acting like the might not be able to get my ATV fixed under warantee. This is BS.

 

No the piston top was fine and it still ran fine but with a loud knock. It did lose a little high end. I never did turn off the gas when I parked it..

 

Ditto on the welcome, KBP-

Are you sure about the 1/8" gap? I can't believe it would even run like that. Seems like you might be seeing a gap at the head of the piston above the rings, but the rings are still tight to the cylinder wall.... did the knock come on suddenly or gradually get worse over time? I know you say it started last week, but did it come on all at once or get worse as you rode it? Generally a "very bad knock" that comes on suddenly but doesn't then get worse is a sign that something let go (like maybe a piston ring(s)/wrist pin/bearing gave up the ghost). Excessive wear issues generally start small and get worse as the wear increases.

Sounds as if maybe your dealer is trying to say that you put a load on a cold engine that wasn't yet fully lubricated and damaged the rings somehow, but you indicated that you let it warm up first. Oil level o.k.? Depending on what happened, 30 seconds of running it could have done more damage, let alone thiry minutes. How did it run otherwise, besides the knock?

 

It wasn't caused by not letting the engine warm up, lack of oil has to be the problem. Make sure a new oil pump is included. If they do fix it make sure the carb gets check out before you take it back. When I worked in the business we alway rebuilt the carbs during an overhaul repair job because we had two engines go out without the carb work do the same thing again and after us paying for the second repair and the carb overhaul they engines were fine. Very cheap insurance. And alway turn the fuel valve off for overnight or long engine off periods.

 

The day it started to knock it was about 0 degrees out side. I started it up to do some work on the snowmobile trail. After about 3min of warm up I pulled the ATV just out side the garage door, about 10 feet. As the ATV sat and warmed up I loaded up the sledge hammer, shovel handles for signs, drill, signs, etc. I then went in the house got my helmet and put on my carharts and waterproof boots. Took me about 5-10 min to get everything together. I then road down the snowmobile trail at 1/2 speed for about 2 miles. As I slowed down coming over a small crest in the trail it just died. There was not a sputter or anything just out right quit. There was nothing more than a slight lifter tap in the engine up to this point. The fist thing I thought that water got in the carb and froze. So I hit the stater button and it fired right up like it nothing happened. At that point I could hear the loud knock. So i turned around and headed home. I noticed a slight decrease on top end speed heading home. I parked it and plowed my drive way for 20min one last time the day i took it to the dealer and it seem to get hotter than normal.
So when I went to the dealer today to look to see what was wrong with the ATV they said I did not let it warm up to get the oil up to temp. They then put the piston in the cylender and it sloped around like I never seen before. I did not look at the rings but it did not smoke lik the honda I bought before I rebuilt that. I have rebuilt a 1987 Suzuki LT 250R, a 1989 Suzuki LT 250R, A 2001 Yamaha Wolverine 350(that a friend ran with out oil), and my curent 2002 Honda 400ex. All of the mentioned I bought in box's already blowen up and rebuilt all on my own. Every time I sold one and made money I saved it until had enough to buy this Arctic Cat brand new. I was told by a local back woods shop not to buy a Arctic Cat because he used to work at a Cat Dealer and now im thinking he maybe right.

 

Sounds like a lubrication problem to me. Like the oil pump was going bad or low oil level.

 

The oil level was fine. I check the oil during every ride. Just a habit after what my friend did to the Wolverine I ended up buying.