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I've been reading a lot about Polaris have engine trouble in the 550's. Mostly i've read this was between 2002-2006. I haven't seen this in 2007-present forum posts. Was this issue resolved? Should I be worried about these "newer" 550's?
 

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I have read that some problems persist in the IQ chassis with the 550, I don't know if they ever got a "fix" for it, or if they ever acknowledged there as an issue in the first place.. just like there's no problem with the big block 800 crankcase/crankshaft, either.

550 fan Jetting and burn-down issues.... - SnoWest Forum

This is a thread regarding the 550 on Snowest, you have to be a member to read it, but it's very insightful...
 

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I know this is an old thread but I wanted to add this info/observations just in case somebody with this problem runs across it now. Like they say "hindsight is 20/20" and there still seems to be a fair number of these used sleds around.

I recently purchased a 2007 Polaris Trail Touring which has the Edge chassis and the 550 fan cooled engine. I haven't had much of a chance to use it due to not much snow but I've made a few passes around the yard and everything seems OK. It has 3400 miles and seems to be in above average shape. As with many others, I became aware of the issues with these sleds after purchase. If you're reading this, you have probably already ran across all kinds of horror stories, hate for Polaris, explanations of the problems and fixes. I just wanted to throw in my two cents worth so as to share what I've learned. This is mostly for Edge sled owners but if you stay awake to the end there's a bit about the newer IQ models. I certainly am no expert but there is a lot of info out there on this problem and I'm just trying to make sense of it myself so as not to crash and burn.

First off, it's kind of a chicken and the egg story, but everyone seems to agree that the root cause of the problem is the inability of the Edge style sleds to get rid of the heat that builds up in the engine compartment. This compounds a variety of issues with the 550 fan engine in the Edge such as poor design of the fan system (intake too close to the muffler), too close tolerances of the pistons in the cylinders and lean jetting of the carburetors. But I did a little research on the modifications that were made to the Edge chassis during it's production and I think it explains some of what caused the engines in some of these sleds to fail. The Edge chassis was introduced in limited numbers on special race machines in 1999 and 2000. It went into widespread production in 2001 and lasted until 2010. When you look at the vents in the early Edge cabs they are very similar to the Gen II chassis that preceded it which were relatively trouble free with their 500 cc fan cooled engines . There is also a heat shield by the intake for the cooling fan. In 2004, for reasons known only to the engineers at Polaris, the heat shield was no longer used, the rear vents on the console were considerably downsized and the intake vents on the front and sides of the belly pan were removed. Under the hood cooling had to have suffered and I believe this is when the problems with the overheating began. It was also around this time that the fuel/oil mixture was leaned out to improve performance and economy. Leaner settings on the carburetors would have produced more heat in the engine which was now less able to dissipate it. Driving styles seemed to play a role as well. Engine failures often occurred at midrange speeds (25-40 mph). It seemed these speeds caused a "perfect storm" of lean fuel conditions and heat build up under the hood. Owners who "drove it like they stole it" were less likely to experience any problems. A number of "fixes" were introduced to the engine over the next few years to alleviate the meltdowns that were occurring such as improved cylinders, better jetting for the carbs and putting a shield back on the air intake. But the airflow to the engine compartment was still lacking. In 2008 a cold air fan induction kit was added to the fan system, the vents in the belly pan were reintroduced and the rear vents were enlarged again which would seem to indicate that someone had figured out that removing them hadn't been a good idea. These improvements continued until the model ended in 2010. Owners of previous years sleds who were experiencing overheating were told to install the cold air kit (which is still available today for $287 Canadian).

Poor ventilation in the Edge models is often discussed but the concentration seems to be on the front vents in the hood or shielding the fan from the exhaust heat. Extra foil protective insulation was also added, I presume to protect the plastics on the hood, but this probably contributed to the raise in temperatures. There never seems to be any mention of improving the venting in the console and belly pan on the 2004-07 sleds which seemed to suffer the bulk of the problems. You can put as much air in the front as you want but if it can't get out it the back, the flow through system is not gonna work.

The IQ Shift and Touring models introduced in 2009 were available with the 550 fan which is essentially the same motor. They have the cold air fan induction kit and I presume more adequate venting for the engine compartment which would alleviate the overheating as it did in the later Edge models. Although, there is a fair bit of hate out there for the IQ models which may be deserved or may be just guilt by association with the Edge.

My sense of it is the 550 fan cooled engines, which were built for Polaris by Fugi Heavy Industries in Japan, were pretty reliable. Unfortunately Polaris used them in some questionable applications that placed them in a position to fail and they did. Which cost a lot of people a lot of money and Polaris and their dealers weren't maybe as quick to remedy the situation as they might have been. This has lead to a poor reputation for the Polaris 550 fan engine which maybe isn't completely deserved. It's the engineers who should have to answer some questions about the mistakes they made and then took so long to correct. Leaving the buyers of these used machines to figure it out for themselves. I've modified my sled with a homemade cold air induction kit and enlarging the console vents. Will see how this works. May ad extra vents to the belly pan if I feel that things are still too hot. As a 2007 model it has the better cylinder linings and with 3400 miles with no problems, I'm assuming that the fuel mixture/carb jetting issues have been sorted out by previous owners. Service guy at my Polaris dealer said one of the main things to watch is the color of your spark plugs. Tan or gray - good, white - too hot! Hope this has been helpful.
 

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Hello,

I was given this 2004 - 550 edge touring snowmobile back in 2017. It had a catastrophic engine failure and it only had 700miles on it. I sent it to a Polaris technician in early 2018 who said he knew exactly what this machine needed. He charged me a bunch of money and fixed it. It starts the first or second pull each time. I have put maybe 40 miles on it since 2018. This year the Speedometer stopped, the cable was pinched and the electric starter never worked. I ordered a new starter, a new speedo cable and started some maintenance. I found something disturbing when I pulled the carbs off. There was a line from the oil pump to the crank that was not connected. I was able to find the bolts and washers but I am worried I am in for another huge repair bill. The machine has run perfectly for the last 3 seasons and 40 miles. I have not even put one tank of fuel in this thing. Do you think I amin trouble?
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Oh oh, You could be in trouble. I personally would drain the thing of old gas, fill with new and put some 50 -1 in the tank with it and then do a compression test on the engine and if good then ride it for a 100miles and see if it all holds together. (with stops to check those oil lines cause if they are "blowing off" when riding then you might have a clogged check valve. Gotta test this thing good. Make sure it's going to work IMO.
 

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The line that popped off was a threaded fitting that went from oil pump to the crank. And I did mix it 50:1 when I filled the tank. I will go ahead and dump the gas and start over.

I read about someone priming the oil lines but they didn’t explain it. I assume this won’t need to be done because of the 50:1 in the tank?

Oh oh, You could be in trouble. I personally would drain the thing of old gas, fill with new and put some 50 -1 in the tank with it and then do a compression test on the engine and if good then ride it for a 100miles and see if it all holds together. (with stops to check those oil lines cause if they are "blowing off" when riding then you might have a clogged check valve. Gotta test this thing good. Make sure it's going to work IMO.
 

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Right, you are safe then. I'd still dump that gas and put new in it with 50-1 at least.
You won't have damaged anything at this point IMO. I'd still check the compression though. But that engine may not be "re" broken in yet though since you haven't ridden it enough. I'd ride like I said. Get it running good somewhat and checking it closely as you stop on the trail and look it over good. (loose bolts falling out etc..)
 
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