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

[BadgerND]

Yeah, That oil pump is a mystery. This debacle reminds me of GM engines in the late 70's. We had a mechanic that did nothing but change cams in the 350's. Right about 15,000 miles which is when the warranty ran out the valves wouldn't open anymore because the lobes on the cams had worn down too far.

 

[xcr700]

Polaris oil pump problems

I need to disassemble and inspect an oil pump next. This is ridiculous. At least all of our .007" Wiseco motors are still running. :/

Tom,

I had an email from someone from another web site and he claimed that there is some problem with the oil pump and Polaris knows it. The claim is that the o-ring is not sealing and they are replacing it with a gasket in the oil pump return hose kit.

As I have not looked at mine yet, I cannot vouch for this claim, but it sure seems to fit and its in agreement with your thoughts.

Have you looked at any of the pumps yet? Sure seems like it worth looking at,,,

George

 

[Frostbit]

Tom,

I had an email from someone from another web site and he claimed that there is some problem with the oil pump and Polaris knows it. The claim is that the o-ring is not sealing and they are replacing it with a gasket in the oil pump return hose kit.

As I have not looked at mine yet, I cannot vouch for this claim, but it sure seems to fit and its in agreement with your thoughts.

Have you looked at any of the pumps yet? Sure seems like it worth looking at,,,

George[/QUOTE

This is correct. The oil pump bleed kit does come with a pump gasket. The pump is removed from the engine, the o-ring on the back is discarded, and this gasket takes its place. You also install two hex-head screws to mount the pump in place of the stock two phillips-head screws. I can only speculate they had problems with the o-ring causing an air leak directly into the crankcase, but there is no elaboration in the instructions Polaris provides.

 

[Frostbit]

I forgot to mention, my dealer GAVE me two oil pump kits for my two older 550's. I didn't even ask, he just handed them to me, and told me he was giving them to all his 550 owners.

I sure would like to hear Polaris' take on this kit. One, why does it need the continuous bleed on this 550 motor only? They continue to market a slew of other engines without it? And two, what was the problem with the oil pump to crankcase mounting o-ring?

 

[xcr700]

I forgot to mention, my dealer GAVE me two oil pump kits for my two older 550's. I didn't even ask, he just handed them to me, and told me he was giving them to all his 550 owners.

I sure would like to hear Polaris' take on this kit. One, why does it need the continuous bleed on this 550 motor only? They continue to market a slew of other engines without it? And two, what was the problem with the oil pump to crankcase mounting o-ring?

Good point, why only the 550?

Does the 340 use a different oil pump?

What about the liquid cooled sleds,,,

Very strange,,,

Interesting that my dealer did not offer up the pump kit, didnt even try to talk me into it on my dime,,,

Just a bunch of kids there so who knows what goes on there,,,

Either way mine is parked until I can add the pump upgrade (on my dime no less,,,)

GH

 

[mccbry]

On my 08' Trail, it looks like it has the hex head bolts on the pump, instead of the phillips head bolt on the oil pump, and a gasket between the pump and the block. Did the update the gasket and the bolts on the 08'???

 

[xcr700]

On my 08' Trail, it looks like it has the hex head bolts on the pump, instead of the phillips head bolt on the oil pump, and a gasket between the pump and the block. Did the update the gasket and the bolts on the 08'???

Hummm,,, Just looked at mine and I have the philips screws attaching the pump to the block, but it looks like there is a gasket on mine.

Still no vent hose back to the tank so I'm still planning to add it.

GH

 

[gogglefurnace]

okay boys, i talked to my dealer in idaho falls about the oil pump fiasco. he had no kits in stock. he did say that he put 2 of the oil bleed kits on a 2 rebuilds that they did on earlier edge 550s, and they also got the nik upgrades but nothing was for free. i asked the main service guy about the oil pump running backwards and sucking air when perc is used, and he said the pump is a piston pump not a vane pump and so doesn't know it is running backwards so it cannot be sucking only pumping. he did say that the orifices have check valves like the old banjos and can fail but not often. he also said they have only had these 2 early failures on the 550. of course this is the dealer talking. they also run a rental fleet in island park and as far as fans go they only run the trail rmk with no early failures, but they only run ves oil. so i said " they don't make upgrade kits unless there are problems so WTF" and he didn't have an answer. he did however say that the gasket in place of the o-ring on the pump housing acted like a heat shield. so this is what i'm wondering... on the liquids, at least the edge ones, the oil pump is over on the side off of the water pump = less heat. it receives a lot of air from the front of the hood. on the 550s it is backside of the engine below jugs = lots of heat. i don't think the oil boils as per earlier posts, but maybe the excessive heat causes the pump piston premature wear and or failure hence the air bubbles, and then helps to cause engine failure. maybe the synthetic oil helps to prevent this from happening because it does have higher film strength under high load and high heat situations. maybe this is a combination of events @ high underhood heat from no shielding, high oil pump heat causing failure of pump and the top end just says "thats it i'm done" . i'm sure there's been meltdowns with ves but if they are less frequent than with regular oil, then the ves might be keeping things together longer in spite of poor design on these edge machines. it would be interestin to get the specs on the pumps eg. flow and pressure and be able to test them at the time of an engine rebuild to se if they need replaced. i know my 05 and 08 had the heat shielding and have had nothing but ves in them and are still okay. it would be good to know if the little oil pump piston gets weak and then kills his bigger brothers upstairs.

 

[Tom400CFI]

Thanks for the post ^ and interesting "stories" from yet another dealer.

he said the pump is a piston pump not a vane pump and so doesn't know it is running backwards so it cannot be sucking only pumping.

That's not true. He's right that it's a piston pump, but dead wrong that it won't pump backward. I argued the same things to my techs when they first told me that the pump, pumps backward when the engine runs backward, for the same reason; that it's a piston pump! But they proved me wrong. you can start the engine, flip it into revers and you can WATCH the oil being sucked backward through the lines from the carbs toward the pump.

on the liquids, at least the edge ones, the oil pump is over on the side off of the water pump = less heat. it receives a lot of air from the front of the hood. on the 550s it is backside of the engine below jugs = lots of heat.

I don't know. It may be a FACTOR, but all other Fuji/Polaris Fan engins locate the oil pump in the same place; on the case, under the carbs. The 340, the 440, the 488...all same location. I don't get it.

maybe the excessive heat causes the pump piston premature wear and or failure hence the air bubbles, and then helps to cause engine failure. maybe the synthetic oil helps to prevent this from happening because it does have higher film strength under high load and high heat situations.

Maybe on the premature wear thing. We tried Polaris VES GOLD oil for 1/2 of one season, last year, and it made no difference in our failure rate...just the weight of our "wallet".

maybe this is a combination of events @ high underhood heat from no shielding, high oil pump heat causing failure of pump and the top end just says "thats it i'm done" . i'm sure there's been meltdowns with ves but if they are less frequent than with regular oil, then the ves might be keeping things together longer in spite of poor design on these edge machines. it would be interestin to get the specs on the pumps eg. flow and pressure and be able to test them at the time of an engine rebuild to se if they need replaced. i know my 05 and 08 had the heat shielding and have had nothing but ves in them and are still okay. it would be good to know if the little oil pump piston gets weak and then kills his bigger brothers upstairs.

I agree. It would be good to know WTF is up with this roach of a motor. POLARIS, why don't you tell us?? And do so w/o the ridiculous "boiling/Flashpoint/only VES/this kit/that kit" etc. urban legend-stories.

 

[gogglefurnace]

makes you wonder if the check valves are messed up. they should only let oil go in one direction. but then what happens in reverse? does the pump cavitate? is this the air issue or is the air issue because of bad check valves? or maybe air leaks around the fittings? as far as the oil pump location, i was just thinking that on the edge fan with less efficient underhood cooling and higher engine temps that the oil pump might be more likely to go to crap then the liquids or the old fans that were cooled properly. tell me this tom, on the pre edge 550's did the oil go into the carb throat or into the intake passage like on the 488s?,.maybe some little stupid change did all this, exacerbated by underhood heat. i'm googling the crap out of 2 cycle oil pumps to find out testing specs or anything. i think maybe something had to change that a guy could put his finger on' other than a gun, and put his sleds out of their misery.

Tom, do you happen to have a make and model # of these oil pumps? its raining and i'm retired, so i have time to research these pumps. maybe i'll find something out. maybe the gen2 550 also for comparison. thanks

 

[ttyR2]

You could probably plug all but one of the hose nipples on the oil pump and use a MityVac to find out if there's an air leak on the pump.

 

[gogglefurnace]

You could probably plug all but one of the hose nipples on the oil pump and use a MityVac to find out if there's an air leak on the pump.

thats an idea. i found out they are mikuni pumps in a wide range of apps and the concensus is they can fail but it is rare. still looking for specs and or service bulletins. i have found some DPM specs but only for motorcycles. i also think mighty vac could check the orifice/checkvalve. it would be nice to isolate the oil system out of the equation for these burn downs. on snowmobileworld.com there is a thread as big as this devoted to the 550 burn down, and i get the feeling from the guys that seem to know their stuff it comes down to heat and poor quality control on the 550s top ends. it seems the gen2 chassis had enough air flow to keep these flaws in check for the most part, but the edge chassis exacerbated them. theory is bigger displacement/horsepower = more heat and the cooling system was not adjusted up to take care of it. kind of like 440 cooling on a 550 motor. i think tom is getting it right on the rebuilds as to quality control, which narrow the threshold on the burn downs, and then if the heat problem is taken care of there might be some longevity. of course this doesn't explain some of his short run burndowns which seem like they would be oil related. i know there are a lot of pi$$ed off 550 owners out there. POLARIS on this deal are a bunch of idiots. oh yeah, call your state attny general and inquire about the implied warranty law. in Maine it is four years regardless of the manufacturers warranty. maybe a guy can get some satisfaction.

 

[LRD]

I would verify the carb tuning components on the old compared to the new. Pilot jet, fuel screw/airscrew, air bleeds, slide cutaway and I think the needle is just starting at that 1/4 throttle. Being that lean at 1/4 throttle is what is killing them.

Good Luck

OK finally found the tuning component chart for the mikuni round slides in my old Aaen carb book

air screw and pilot - full effect at 0 throttle opening tapering to 0 effect by 1/4
throttle valve - 0 effect at 1/8, max at 1/4, tapering to 0 by 1/2 throttle
needle - 0 at 1/4, going up to max by 3/8 to 1/2, tapering down to 0 by 3/4

For years I have put white tape on my handle bar under throttle flipper and put a white line
on the throttle and black lines on white tape for 0, 1/4, 1/2, 3/4 and full throttle. This with the EGT's is incredibly effective for tuning with the tuning component chart for your particular style of carb. TMX and TM are a bit different from the old rounds.

 

[gogglefurnace]

LRD, i can't believe you are here. I have read all your posts on doo-talk, because i am a fan guy. You are a bada$$ when it comes to tuning and weight reduction. Did you read all of this thread? Tom did a good job of trying to figure out all of the probs with these sleds. I agree there is a hot spot at around half throttle under cruise, but i think there is more too it with these poo's. Have you ever run temps with your 550 doo under similar conditions as TOM did ealier in this post, and if so what were they? I think that the FUJI engine should be good for more, but it is not in the 550s. Quality control is always in the shadows, but what about engineering failure? All the micro tuning in the world will not make up for lack of cooling when it comes to longevity. Fan sleds should be able to play, work, and not go down. At least not from the factory. Maybe when a guy starts to tweak, the considerations of failure become more of a concern, but for hells sake a sled should be somewhat good from the factory. Tell us about some 550 doo meltdowns, are they simular? Or are there any at all? Does doo use the Mikuni oil pump? What carbs are on the doo? How are they setup? What about hood vents as per underhood heat management? What about heat shielding? This is perplexing, and i know you have done some serious work with these fans. What if FUJI just screwed it up on the 550 and BRP got it right? Maybe FUJI got it okay and POO screwed up on the EDGE cooling? Any help would be appreciated!!!

 

[Golsovia]

It seems to me that the 550 simply makes too much heat. Some failures seem to result from heat in the top end, perhaps some are related to heat down below and consequently oil/oil pump issues. The nicasil cylinder may better move heat from the top end, but what is accomplished if it just creates trouble down below. Using a gasket to isolate the pump from the heat seems like wrong-headed engineering. Solve the problem instead.

A leaking O-ring should not be an issue. That design has worked perfectly well on all the 340, 440, and 488 fans Polaris ever built.

Why did they go and make so many changes at once to their well-proven design? It seems to me that they could have simply upgraded the case design and improved a few things like their shrouds without also changing displacement, adding reeds, etc. (Wouldn't simply adding reeds to their proven engine sizes in an "improved" case been good enough?)


And what, if anything, has anyone done to modify or play around with the reeds? t would seem to me that softer or even slightly ventilated reeds might affect lower and mid-range operation in a possibly advantageous way in terms of reliability. Anyone here try anything that way.

FWIW, my trouble with the 550, personally, have been few. I have a 2001 SS with around 8500 miles and I've only been into it three times for rebuild. The last time the case was very hot to the touch. I run a low flash-point oil: Sea&Snow in it. I believe that are or have been makers of the similar product that Polaris sells as "Blue" semi-syn. (I kind of hate to say "only"; my 97 RMK Trail has over 24,000 miles and I have opened it once to change pistons and rings - at 13,000 miles. I decided only to do the rings as the pistons were in perfect shape yet, so it's had rings, gaskets, and seals...only.)

 

[Golsovia]

Tell us about some 550 doo meltdowns, are they simular? Or are there any at all? Does doo use the Mikuni oil pump? What carbs are on the doo? How are they setup? What about hood vents as per underhood heat management? What about heat shielding? This is perplexing, and i know you have done some serious work with these fans. What if FUJI just screwed it up on the 550 and BRP got it right? Maybe FUJI got it okay and POO screwed up on the EDGE cooling? Any help would be appreciated!!!

Doo uses a mikuni pump mounted remotely from the case. It would appear that the drive for it may be less reliable, but it wouldn't be subject to heat- except for heat from the muffler.

And I don't think cooling should be rocket science. Many people in this part of the world have, for years, added scabbards and other stuff which often covers hood vents. On the older machines it never was an issue. Even in these 550s, as long as the shrouding from the head exhausting vent is taken off, it doesn't seem to cause problems. I suppose it might actually help prevent back-pressure on the head fins though it does dump the heated air directly into the engine compartment. But these engines will go down regardless of ambient air temps. And it seems so arbitrary. MY second burn down was a cold air temp failure and high speed; my latest burn was a warm -barely freezing- burn-off at fairly low speeds - and possibly negative air speed. Both involved pulling moderate (200-500 pound) sled loads.

 

[Frostbit]

If the piston failure can be attributed to the oil pump, I wonder if Tom would be willing to take one or two of his rental sleds and set them up for pre-mix. I know it would be a pain to monitor, but it might be a step in making a firm diagnosis.

I am not certain if the big end bearing on the clutch side would get ample lubrication with pre-mix. It has a separate oil line feed from the oil pump.

Boy, sure would be good if Polaris would offer some insight. Somehow, I get the feeling they are grasping and headscratching as well.

 

[xcr700]

I was up late last night and I saw a post on some other site where the poster said he was told that the cause was an issue with fuel starvation (fuel boiling in the lines to the carbs) hence the fuel pump relocation. (Hummm,,, sounds like a fire safety recall issue to me,,,)

At this point I don’t know what to think, Polaris has more different updates on this than we have threads going on the subject,,, And yet there doesn’t seem to be one clear and guaranteed fix.

This is damn frustrating and Polaris really needs to step up and deal with it.

Sure hope someone from Polaris is monitoring the internet and seeing what were saying, because as a long time customer of theirs, I’m not going to buy or even suggest their product to another person if they don’t address this and soon.

GH

 

[tuney443]

I'm sure glad you guys are brainstorming this since apparently Polaris won't.My 05 2 place 550 touring melted down last Sat. up in Indian Lake,NY by Old Forge.2oo miles on the rebuild from last Winter when the sled had 1200 miles on her when she broke down the first time.I was actually told at first I was causing the problem by riding too slow{I don't go more than 45} and too warm a day{app.28-30*}. I laced into my dealer on that one--asked him to show me in my manual where it says you have to go fast.Polaris anted up $1500 in parts last year,I had to pay $200 in labor--seemed reasonable, but the parts were original-same crap--I didn't know nor did they suggest the nicasil upgrade at that time.Now they won't do anything so far.The owner of the dealership says he's going to some Polaris convention Mon.{tomorrow} and will talk to some big mucky muck{s} to plead my case.Some guys I know will drive 200 miles in 1 day--this is just so wrong. Sorry for ranting.Sledless in Dutchess County,NY

 

[gogglefurnace]

That fuel boiling in the lines theory is crap. For one any percolation if there was any would get to the bowl and dissappear out the vent. The sled won't run lean because the main is submerged in the bowl. if there was enough air in the bowl then basically the sled won't run at speed= no chance to get hot enough to cook. As for the relocation i can't figure it out. Why move it closer to the motor? Maybe its an iceing theory which is also dumb. Iceing probs usually are evident in the carbs/metering the fuel into the engine. I think the half throttle medium cruise hot spot is aggravating the lack of cooling and the poor piston to cylinder clearance, not to mention general quality control. All of the polaris fixes seem to center around heat. IE: making the motor produce less at certain throttle openings, hence the needle jet/jet needle change, oil pump gasket to help reduce convective heat between pump and case, just in case, and shielding and venting to produce more underhood cooling. Its like a three legged horse, I don't care how much grain and hay and loving care you give him, he's still a three legged horse and he's gonna cost you a lot and still leave you stranded. Polaris is gonna EAT POO on this one.