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Discussion Starter · #1 ·
I have a 2006 Ranger 700 XP with 1000 hrs. My problems started from an oil pressure issue- it blew the seal on the filter, which created a knock. Took it into my local dealer, and they fixed the oil pressure relief valve, but didn't notice the knock. They also replaced the TPS and TBAP, as well as some other things that needed attention.

Took machine home, and the knock was back, as soon as I pulled it off the trailer. Took machine back to the dealer, and they diagnosed it with a rod knock. Purchased a rebuild kit from Hot Rods (Crankshaft, pistons/rings (Namura), and all gaskets/seals. Removed engine and tore down. Cylinders didn't appear to be damaged, heads were not warped. No metal in crankcase. Confirmed rod knock- driver side rod had obvious play (horizontal and vertical). Removed gaskets completely, and cleaned everything up (carb cleaner and elbow grease. Cleaned valve side of head, but didn't remove or re-seat valves.

Re-Assembled engine following service manual, with the exception of replacing valve seals. Filled oil filter to 3/4 with oil, primed oil pump, and put the rest of the oil (2 qts) into engine. Filled coolant and bled system.

Engine started great. Let idle while I checked for leaks, then took it for a short drive (2 blocks, @ 10 mph). There was a cloud of smoke behind me. Slowly returned to garage. Checked coolant level and oil level, which both seemed fine. Let machine idle and noticed oil droplets on floor under exhaust.

Pulled the spark plugs and could see a small amount of what appears to be oil on piston heads, and plug on passenger side was wet. Thought it might have been oil from assembly, so put plugs back in and started/idled for 5-10 minutes. Pulled plugs again, and there seemed to be more oil on piston heads than before.

Pulled plugs and did a compression check. 140 on both cylinders. Checked oil level again, but since the oil was so clear/new, I couldn't tell of the level dropped. Oil does not appear to have coolant in it. Coolant level is stable, and looks good- I did have to add to the reservoir a couple times, but stable since.

I'm no mechanic, but this is what I'm thinking:
1.) I have a blown gasket that is allowing oil into both cylinders, but no coolant, which seems unlikely.
2.) I have two bad valve seals.
3.) There are piston ring/seating issues. I still have the old pistons, and am considering putting them back in, with new rings.

Before I pull the valve cover and head, replace valve seals, gaskets, pistons and rings, and reassemble, I thought I would get some opinions to help diagnose.

Anyone else run into this, or have any suggestions? Thank you in advance for your help!
 

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you gapped and offset rings to spec? Oil ring installed properly? You have oil in both cylinders, what are the odds you got both sets incorrect?...interesting symptom. Have you run it long enough to actually seat the rings? Aside from the smoke/oiled plug does it seem to be running fine? Looking forward to JM's take.
 

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Welcome to the forum lc. Sorry for your woes. :very_drunk:
 

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Discussion Starter · #4 ·
Thanks for Natethedog- Other than the oil and smoke, it is running great- didn't burry the throttle, but power seems to be fine, start and idle are perfect.

I started and let it run 3-4 times. Not sure if that is enough (or if it ran long enough) to have seated the rings. While working on it, one of the plug wires pulled out of the boot, so won't run it again until I get the parts.

I thought about using Q-Tips to remove as much oil as I can before starting, then see if the oil appears again.
 

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Discussion Starter · #5 ·
you gapped and offset rings to spec? Oil ring installed properly? You have oil in both cylinders, what are the odds you got both sets incorrect?...interesting symptom. Have you run it long enough to actually seat the rings? Aside from the smoke/oiled plug does it seem to be running fine? Looking forward to JM's take.
I offset rings close to 180 degrees- oil ring was installed correctly, and not lined up with gap on first. Since they are aftermarket, I was considering new Polaris rings on the old pistons.

The uniformity of the issue has me thinking it must be oil in cylinder from assembly... If the rings were the issue (gap or seating), would I still have good compression?
 

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I'll defer to JM's expertise...all engine rebuilds/refresh that I have done (cars & motorcycles)...to seat the rings you want to "load" the engine with smooth acceleration up and down several times on the lower end of the torque power band. I would expect UTV engines to not be much (if any) different. Oil in the cylinders can mask compression issues, oil acts a bit like a hydraulic system and can create what I'll term "false compression". That's why when doing a compression test, often you'll see people put some oil in the cylinder. If it "seals up" and temporarily increases compression then generally you can suspect a ring problem. If it doesn't "seal up" then you look more towards open valves or a head gasket issue. It's a bit of a hack compression leak down test in a way, which is what I'm in the middle of on another thread.
 

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Lots of possibilities.
#1-Just because a cylinder "looks good" doesn't mean it will spec out good. The only way to assure the cylinder is good is to measure it. Cylinders can become oval, too large, larger at one end than the other and still "look good". Excess clearance can allow pistons to rock in the cylinder which allows oil to get by and wears rings quickly. If the cylinder is not round and within clearance spec for the piston installed it won't matter whether you re-install the old pistons with new rings or use new pistons, your problem will not be resolved. Good, accurate measurements are the basis for any positive result during an overhaul, even when all brand new parts are used. Even with new parts factory tolerances can allow clearances that are too large.
#2- New rings need the glaze in the cylinder broken before installation. When you don't break the glaze the new rings will not seat.
#3- As others previously stated, ring gaps too large due to worn cylinder that "looks good".
#4- Rings installed on pistons upside down
#5- Forged pistons require different clearance in cylinders than cast pistons. Generally forged pistons will expand more than cast pistons after the engine warms. Given that there are a couple of considerations. First, if your pistons are forged and clearances are loose you they will allow oil to pass the rings until the engine reaches operating temperature. Loose clearances in cylinders also can cause piston slap which wears both pistons and rings more quickly. You didn't mention whether your aftermarket pistons are forged or cast. Generally, OEM uses cast in some form because they are less expensive and expansion can be controlled using various engineering methods. Many aftermarket pistons are of the "performance" type and are forged. Engines with forged pistons installed should be allowed to warm thoroughly before being run hard. In addition "performance" pistons may have increased deck height which increases compression ratio and could be giving "normal" cranking compression readings even with other issues. A cylinder leak down test is a more definitive method of measuring cylinder leakage. As foggybottom states, excess oil in a cylinder can mask ring issues and boost compression giving false compression readings.
#6- Valve guide seals can harden, break, become brittle and allow oil to enter the cylinder without affecting compression. The same is true of worn valve guides which will quickly wear new valve guide seals. Often when you see a vehicle that idles for long periods and when accelerated blows out blue smoke the problem is valve guide seals. When valve guide seals are bad oil smoke will be visible after deceleration such as using engine compression for braking or deceleration.
#7- Some pistons can be installed 180 degrees out. (I don't know whether that is the case with this particular engine) In such cases the piston pin is offset slightly in the piston to reduce noise during cold engine starts. Installing them 180 degrees out can cause poor ring seating.
#8- Proper break in is essential, no doubt, however, I've never seen a properly rebuilt engine allow as much oil past the rings as you describe. I doubt break in is your issue.
#9- a cylinder leak down test will allow you to diagnose and differentiate head gasket issues from blow by issues. I agree, oil leakage into the cylinders without coolant leakage is unlikely, but remotely possible
#10- Unless specified otherwise by the manufacturer, compression ring gaps are generally spaced at intervals of 1/2 the circumference of the piston (180 degree intervals) and 3 piece oil ring gaps are 120 degrees apart.

Sorry for your troubles and sorry to deliver so many possibilities. However, without knowledge you will have even greater difficulty tracking down your problem.
 
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Discussion Starter · #8 ·
Pyromedic- thanks for the informative response. I am going to the dealer tomorrow for parts. Leak down test sounds like a good place to start. Thanks again for the response- will post what I find...
 

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Pyromedic- thanks for the informative response. I am going to the dealer tomorrow for parts. Leak down test sounds like a good place to start. Thanks again for the response- will post what I find...
Glad to be of help.
 

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I have a 2006 Ranger 700 XP with 1000 hrs. My problems started from an oil pressure issue- it blew the seal on the filter, which created a knock. Took it into my local dealer, and they fixed the oil pressure relief valve, but didn't notice the knock. They also replaced the TPS and TBAP, as well as some other things that needed attention.

Took machine home, and the knock was back, as soon as I pulled it off the trailer. Took machine back to the dealer, and they diagnosed it with a rod knock. Purchased a rebuild kit from Hot Rods (Crankshaft, pistons/rings (Namura), and all gaskets/seals. Removed engine and tore down. Cylinders didn't appear to be damaged, heads were not warped. No metal in crankcase. Confirmed rod knock- driver side rod had obvious play (horizontal and vertical). Removed gaskets completely, and cleaned everything up (carb cleaner and elbow grease. Cleaned valve side of head, but didn't remove or re-seat valves.

Re-Assembled engine following service manual, with the exception of replacing valve seals. Filled oil filter to 3/4 with oil, primed oil pump, and put the rest of the oil (2 qts) into engine. Filled coolant and bled system.

Engine started great. Let idle while I checked for leaks, then took it for a short drive (2 blocks, @ 10 mph). There was a cloud of smoke behind me. Slowly returned to garage. Checked coolant level and oil level, which both seemed fine. Let machine idle and noticed oil droplets on floor under exhaust.

Pulled the spark plugs and could see a small amount of what appears to be oil on piston heads, and plug on passenger side was wet. Thought it might have been oil from assembly, so put plugs back in and started/idled for 5-10 minutes. Pulled plugs again, and there seemed to be more oil on piston heads than before.

Pulled plugs and did a compression check. 140 on both cylinders. Checked oil level again, but since the oil was so clear/new, I couldn't tell of the level dropped. Oil does not appear to have coolant in it. Coolant level is stable, and looks good- I did have to add to the reservoir a couple times, but stable since.

I'm no mechanic, but this is what I'm thinking:
1.) I have a blown gasket that is allowing oil into both cylinders, but no coolant, which seems unlikely.
2.) I have two bad valve seals.
3.) There are piston ring/seating issues. I still have the old pistons, and am considering putting them back in, with new rings.

Before I pull the valve cover and head, replace valve seals, gaskets, pistons and rings, and reassemble, I thought I would get some opinions to help diagnose.

Anyone else run into this, or have any suggestions? Thank you in advance for your help!
Here is a bit of info indirectly from a Polaris tech about the cylinder coating and ring seating...
Via a service tech for polaris , the cylinder is Nikasil coated which requires a diamond hone, and most shops don't have one....It also means that the cylinder walls are MUCH harder than the rings....
He told me he has done 3 top end re-builds on the rzr's, and in all 3, the cross hatch marks were still visible in the cylinders....The rings were the only thing that had to be replaced...
He also noted to me that he wondered whether the problems of oil comsumption that most related to dust ingestion were not actually due to the rings being too soft for the
Nikasil cylinder, and the rings wearing down before they ever seated....

He also noted that ring grooves that are required for a good seal were at a minimum in the cylinders....One he referred to was a machine with 800 miles on it, and the rings still had not seated in the cylinders....

 

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...they fixed the oil pressure relief valve...
Kris, seems like there has been a rash of bad ones where the dealers have done less than a stellar job fixing them. Could this be a possibility?? (beyond my pay grade!)
 

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Kris, seems like there has been a rash of bad ones where the dealers have done less than a stellar job fixing them. Could this be a possibility?? (beyond my pay grade!)
That is always a possibility and if I started having oil pressure related problems, I would be installing a oil pressure gauge muey pronto. They are a bit spendy but so is overhauling the engine. In this case, I am guessing that the OP has cylinder problems but guessing is all that I can do from here. I would think that it wouldnt take much of a break in period to have nearly 200 psi cylinder pressure on a NEW 700/800 if the rings were seating properly in the cylinder .
 
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When I rebuilt my 900xp top end (I know different motor) it only took a minute or two to get 200psi of compression. I'd suggest a leak down test.
 
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Discussion Starter · #14 ·
Thanks for the reply and note Jungleman!

I went to the dealer today and bought (gaskets and spark plug wire)/ordered parts (2 sets of piston rings). They thought the valve seals were the most likely cause, followed by the piston rings.

Today, I plan to replace the valve seals, remove as much oil as I can, then run again to see if oil comes back. If oil is back, I will do a leak down test. Will update later.
 
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