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Info on cylinders

2K views 23 replies 4 participants last post by  Sledhead25 
#1 ·
I have a pair of cylinders from my old Polaris RMK 700 engine that are scared up from me being a dumba** and not realizing until it was too late, of course, that I had a bad coolant leak and let my sled overheat. Luckily I had a backup engine I was able to put in.. I want to rebuild the other engine so I have a backup just in case I have another problem (or create my own problem). My question is, would it be better to by already re-plated cylinders or is there a good place that I can send mine to to have them redone for fairly cheap? Thanks for your input
 
#4 ·
Now I'm wishing I had actually rebuilt that spare engine. Figured, oh I don't need it, the one I already rebuilt is solid, I'll just get rid of the other one ?. Well of course now I have a problem?. Went riding today, sled was running great. Kind of hot rodded it a few times, next thing I know smoke and steam start rolling out of the exhaust and from under the hood, started running like crap, I immediately shut it down and open the hood. Noticed that one of the spark plugs is loose, pull that out steam comes out of there. Started filling the coolant reservoir, steam gets worse. Turned the motor so that piston was up to see what it looked and smelled like (the liquid on the piston), immediately fills up with coolant and is pouring out of the spark plug hole. So needless to say, day ended to soon and I got pulled back to the truck. Now to give a bit of a back story. 2 summers ago I completely rebuilt this engine. New pistons, gaskets seals, the works. On the 3rd ride, like I said previously, bad thing happened and had to rebuild it again. Now my dilemma is I'm not sure whether it blew a head gasket or if the worst happened and it has a cracked head or jug (haven't opened it up yet). So my question is, is there a way I can check everything out without taking it to a machine shop? We don't have one local and I really don't have the extra money for something like that right now. Obviously I'm going to visually check and use a straight edge to check for warpage. Being a mechanic I have access to tools others my not, but don't have machine tools or anything that I can think of to pressure test either of them. With this happening twice now I'm concerned something other than a gasket or an o-ring is the problem. Speaking of gaskets, I've been getting my parts from MFG supply. Ive used their parts quite a few times with no problems. The gaskets they show are a Pro-Formance gasket and give a Winderosa OEM part number. That's what I used the last 2 times. Now I don't remember whether they were winderosa gaskets that I put in or if they were another brand. So my other question is could it possibly be not quite good enough quality gasket/ o ring set that I'm getting from them causing my issue? Thinking about it today on the way home I had a head gasket leak a couple years ago on this engine and I ended up putting parts from Polaris on it and it seem to stop it. But since I went with MFG Supply I've had issues. If I find nothing wrong with the head or jug should I try Polaris gaskets again? Thanks for your input once again
 
#5 ·
If it overheated and blew the head o-ring, it may be due to a broken/worn drive belt on the water/oil pump drive. Another thing to check is the nut on the impeller in the water pump. I went through 3 cylinders and 5 pistons before I figured that one out on my 97 700 RMK.

I would get it on the bench and remove the head. You should be able to use a good straight edge to determine if it's warped. If it is, it will probably be cheaper to find a good used one than have that one machined.
 
#6 · (Edited)
I replaced the belt on the water pump when I did the rebuild, I'm pretty sure, but I will definitely double check that. This time it didn't overheat, it just kinda decided to loose coolant and almost all of the sudden. I installed a temperature gauge last year because it did overheat and there was no warnings. I was watching it very close and looked when it did everything
 
#8 ·
I finally got time to tear into my engine. Took the head off and sure enough, the inner o-ring/ gasket on the PTO side, the side that had coolant coming out the spark plug hole, has a broken section. (Personally I think it's stupid to have a thin little o-ring instead of a gasket. There's lots of pressure there with the compression and combustion, but what do I know I'm not an engineer.) I got everything cleaned up and used a straight edge to check everything. The only issue I found is the top of the combustion chamber (pictures attached) for the PTO side has a tinny bit of a gap, 0.005" to be exact. I'm curious if I can put a really thin layer of silicone around that surface with the o-ring. I've done it on cars/trucks water pumps and things like that before and not had problems. If not it's probably looking like I might have to find a new one.
 

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#9 ·
Silicone won't hold, the compression and temperature will render it useless very quickly.

So are you saying the flat part of the head is not sealing? (left pic)

If so, get a sheet of glass (thicker is better, doesn't break) about 12"x12". Attach some emery cloth or very fine wet/dry sandpaper (600 grit or tighter) and flatten the flat part using a figure 8 pattern. Go easy, aluminum sands really easy.

Glass is very flat so your result should be as flat as the glass. You should be able to easily gauge your results as you go so you don't disrupt the squish band in the head...
 
#10 ·
Yes, the flat side, pic on left, is the side that doesn't seal to the cylinder. The exhaust side of it is where the gap is. I wondered if there was a way to get it flat again, but was worried that if I tried, it may not seal in other places. I will definitely try that and let you know the results. It seems like that little of a gap wouldn't add up to all that much when torqued down.
 
#14 ·
I would make sure both sides are flat.Your call if you want both of them to be exactly the same, but I doubt that the engine will run any differently with only .005" removed from just the one side. Check the compression when you are done, it should be close to the same.
 
#15 ·
After about 2 hours, mostly due to fear of going to far and messing up, and 5 pieces of sandpaper I finally got both sides flat again. Thank you so much for the advice on that. Was a little nervous about doing the first one, but worked out perfectly. Luckily my coworker, who has a background in machining and engine rebuild, looked at the other side and noticed a gap that I hadn't. Hoping to get it put back together tomorrow. And test ride it Sunday. Is there anything else I can do or need to do to possibly prevent another failure like this? I was wondering if there's anything that would help it seal better. We use gasket cinch to help on certain gaskets, but usually on actual gaskets not o-rings. Also, do I need to run it any different? I mean hopefully it's completely fixed but I don't want to do something and cause another issue. Thanks again for the advice.
 
#16 ·
I would put a bit of grease on the 0 rings when installing, just enough to make them glossy. Polaris parts will fit better and last longer than after-market ones.

I had a 700 engine that I had to rebuild 4 times because of overheating. It ended up being the nut on the water pump impeller. The nut was loose on a brand new engine. When idling, the water would flow pretty much normally. When under force, the nut would jamb the impeller and no flow, resulting in overheating. Was pretty costly for me to figure that out! It's worth a look, I've heard of other Polaris big blocks where that happened to, as well...

Good luck!!
 
#17 ·
Got it back together and running again. Seems like it runs a lot better, has a much better exhaust tone than it did before and idles a lot better. I honestly think that it's been like that since I rebuilt the engine and never knew. I was pretty sure I checked everything, but obviously overlooked some important areas. I checked the belt on the water pump, the water pump impeller, and the nut. Everything checked out good. I figured, better be safe than sorry. Hoping to go on a short test ride to make sure everything is good to go. Thanks again for the advice, don't know what I would have done without it other than spend a lot of money either replacing or paying to repair. It cost about $9 for a 5 pack of sandpaper and 2 hours of my time to surface it. Was roughly the same price to go with Polaris parts and didn't have to wait on them or pay shipping.
 
#19 ·
It runs excellent. Rode it two days in a row, pretty hard both days. No more problems.:thumbsup::thumbsup: Smoked like a freight train for a couple miles trying to burn all the coolant out of the exhaust the first day. After that, it was great. One more question though, about what temperature should I be running? I cant seem to find any info in my service manual. I installed a mechanical automotive style gauge that starts at 130. Where I had no warning of overheating originally that caused this whole problem, I didn't want to take another chance. I was watching it really closely both days. A lot of hard pack riding the first day and hard pack trail part of the second day. Had the ice scratchers down all day both days. There was a couple times that I noticed the temperature getting up around 190. Being on packed snow with no soft areas, it was difficult to keep it cool. There were times it'd start climbing and I'd just have to shut it off and let it cool down for awhile. Just curious where it should be and whats too hot
 
#21 ·
Polaris sleds like to run cool. When I had my RMK 700, I added a temp gauge and the sled ran 140-150. I did the same to an Edge 800 with the same results, 140-150. My IQ sleds run 120-130 when on the trails, maybe 140 when riding slow while boondocking. If I get up above 150, I pack snow on the rear tunnel to aid in cooling. Hard pack is the worst, you also risk melting the hyfax to the track clips because of lack of snow. Scratchers help a little with that. When you are riding in the hard stuff, and stop, check the amount of snow in the rear tunnel. If there is very little snow in there, stop more frequently and kick some snow into the rear to keep the hyfax lubricated. I would pack snow on your running boards if I was seeing over 150. That way the coolant going through the boards gets a bit of extra cooling before it hits the rear heat exchanger.
 
#22 ·
Is there anything else I can do to keep it cool? Second set of ice scratchers on the skis maybe? I put a cover on the heat exchanger to keep it from getting damaged (previous experience). Thinking about modifying it so I can pack snow around the exchanger especially during the warm, spring rides
 

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#24 ·
The cover is on top of the tunnel. Don't know if the picture loaded. I had one that was damaged. Don't know how, it was damaged when I got my old sled and leaked.
 
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