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Discussion Starter · #1 ·
Hey guys

I've been in denial about the noise my engine has been making on my 2012 Ranger 800XP. I know most people say these engines are noisy but I'm convinced I have cam lobe wear. What's the best way to confirm this? Rotate engine and feel rocker/pushrod play?

Does the engine have to be removed to replace just the cam?

Thanks
 

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2015 Polaris ranger 570 XP
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Rocker/pushrod play tells you nothing about cam wear. It only tells you about valve clearance. If you have hydraulic lifters play may mean that the lifter has failed (causing noise) or that enough valve train wear has taken place to allow the hydraulic lifter to have reached it's maximum range and valve adjustment is necessary. Valve train wear is not limited to the camshaft. Lifters wear on the face that meets the cam and valve seats wear allowing the valve to fall deeper into the seat increasing clearance on an OHV engine. In addition, hydraulic lifters can collapse due to lack of lubrication or lack of maintenance allowing the tiny passages within them to become clogged or the tiny clearances between the hydraulic components to become stuck due to varnish buildup or other trash/particles. When the hydraulic lifter internal components are stuck the lifter cannot take up clearance as it is supposed to and your valve train will be noisy due to excess clearance.

Camshaft wear is tricky to determine. Measuring across the base circle to the top of the lobe with a micrometer and comparing to specs will tell you if the lobe and the base circle in that area are worn. However, the specs must be stated for the base circle diameter as well as the lift, the two added together and your measurement subtracted from that value to determine the amount of wear.

Placing a dial indicator on the lobe and rotating the cam through a complete cycle and comparing it to specifications will tell you whether lift has been compromised by wear.

Determining wear on the lobe flanks by measurement is much more complex. You would need specification information not generally provided in service manuals and more specialized equipment. Fair estimates can be made using a dial indicator and degree wheel and the process is tedious and not necessarily absolutely accurate.

In each process mentioned above the measurement must be taken for each lobe on the camshaft. As little as .001" of wear can change valve timing by 3 degrees, depending upon the can grind.

Camshaft wear can also be determined by visual inspection in most cases. Pitting, scuffing and spalling, scoring, brinnelling can be seen visually. Rollers or lifters can also provide clues.
How camshafts fail, failure mode pitting / spalling

Before I blamed a camshaft I would be certain valve seats are not severely worn and that lifters are in good condition.
 

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Discussion Starter · #3 · (Edited)
Thanks for the thorough response, very helpful indeed. I'll start by taking off the head and inspecting the lifters.

If a lifter is stuck, is it reasonable to just replace the lifters temporarily without replacing other components? I can't have the Ranger down for very long during the winter.

In your first paragraph you mention valve seat wear. Can collapsed lifters lead to valve seat wear, or were you explaining them being mutually exclusive of eachother?

Thanks
 

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I haven't worked on your particular engine however engines are engines, for the most part, with some differences and peculiarities. Before you pull the head to check the lifters try to ascertain whether you have hydraulic or solid lifters. I think I read on this Forum somewhere that the 800s have hydraulic lifters, but that may vary my year so don't take my word for it. Check with your Service Manual or someone more familiar than I am with the 800.

If you do have hydraulic lifters the next thing to ascertain is whether you have adjustable rocker arms. If so you may be able to adjust them (using factory specs as described in a Service Manual) and solve the problem. If not, then replacing lifters and inspecting the cam while the lifters are out might be a good next step. If you want to test the camshaft for lobe wear you could do it before tearing things apart by putting a dial indicator on the pushrod side of the rocker arm and measuring the cam lobe lift, but don't bother if you don't have the specifications. Cam nose wear (at the highest point of lift) is more common because valve spring pressure and ramp angles leading to the nose are highest at that point. That does not mean that lobe wear does not take place on other areas of the lobe. Lift at less than specified is an indication of a worn cam but a cam may be worn on other parts of the lobe and still be withing specs at full lift.

I didn't mention it previously, but a camshaft that has incorrect end play or was manufactured with lobes slightly out of place can cause lifters to wear on the bottom. Lifters ride slightly off center on non roller cams which causes the lifter to rotate in it's bore and keeps wear at the bottom of the lifter even.

Worn out lifters are not the only cause of lifter collapse. Hydraulic lifters are generally fed oil via ports in the lifter bores. If an engine has been poorly maintained these ports can clog preventing oil from getting to the lifter so no hydraulic take up of clearance can take place. The small channel and oil port in the side of a hydraulic lifter can also become clogged.

If I am not mistaken, 800s also have some oil pump peculiarities. Jungleman and some others here are better versed than I about such things, however, if the pump isn't primed properly or isn't producing proper pressure collapsed lifters may result.

The main rule when removing lifters is don't swap their places if you plan to use them again. Keep the same lifter on the same cam lobe. In fact it's good practice to keep all moving parts in their original places and orientation if they won't be replaced. Parts wear and conform to each other at a micron level. Moving parts around accelerates wear since the parts now have to wear into each other again.

Replacing lifters with new on a used cam is OK. Just be certain to lube them with some molydisulfide break in lube on the contact surfaces when reassembling.

If you're going to pull the head it would be a good time to inspect and freshen up valve seats.

Running with collapsed lifters for many hours may lead to valve seat wear, however, valve seats wear with normal use. Valve seats are metal to metal contact surfaces with no lubricant. The exhaust side is subjected to extreme heat and the intake side is subjected to being washed by fuel in engines that are carbureted or port injected. Camshaft profiles have a tiny area at the beginning of the lobe and at the end of the lobe called "ramps". They are the opening and closing ramps, receptively, although they do contribute minutely to duration. The existence of these ramps is why most camshaft manufacturers measure duration at .050" lift, to exclude the ramps since that area provides such little lift that airflow is inconsequential. A worn cam can lead to more rapid valve seat wear because the valves slam shut rather than closing at a controlled rate which the ramps provide. In engines originally designed to run on leaded fuel, lead provided a lubricant for the valve seats. Today leaded fuel is virtually unavailable so valve seats on older engines (the pre unleaded era) will wear more quickly. Designers got around the problem of unleaded fuel by using hardened valve seats. If your heads are rebuildable and do not have hard seats, hard seats may be available as replacements.

You seem to be certain that the noise you hear is valve train related. I submit that engine noise can come from many places and be difficult to pinpoint. I've heard exhaust manifold leaks that sound exactly like a collapsed lifter on automotive engines. Piston slap makes it's own particular noise. There can be rod knocks as well, and some engines are just inherently noisy. Worn clutches can contribute to noise that sounds like engine noise in nature. Personally, before I went tearing into things I'd do my very best to isolate the sound and be certain where it comes from. It would be a shame to put the effort and expense into replacing parts only to find that the exact same noise was there when you fired it up again.
 

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Just fyi guys, back in 2011, there were numerous cases of Ranger 800 camshafts that escaped the heat treating process and In just a few engine hours the exhaust lobes were.............. non existent. Not say'n that is your problem but I thought you should know..
 

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Discussion Starter · #7 · (Edited)
Well after digging into it tonight to test, it seems like it's a crank or rod bearing. When I try and move the flywheel/clutch assembly very lightly, I can feel maybe 1/16" of rotational freeplay, I'm guess there should be nothing that I can feel correct?

What shop manual do you guys recommend to assist with my rebuild?
 

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The Polaris Paper shop manual was too rich for my blood so I got a digital shop manual download for about $10 for my 570. I now print off the pages I need as I need them and keep them in plastic page protectors in a three ring binder. I can also take my laptop to the shop and have the whole maunal indigital form with an easy to search feature. You might do a web search for one or maybe someone here can tell you were to download one.

I'm not certain you can tell if a rod bearing is bad using the method you describe. I think it would have to be really bad to feel that kind of motion. if there is movement from wear it could also be the wrist pin, either at the small end of the rod or in the piston itself. I think if you want to try to detect lost motion (wear) in the reciprocating assembly by feel the best chance of any kind of guestimate would be with the piston at mid stroke, not at either BDC or TDC. Even then on a multi cylinder engine the outcome would be questionable.

A better method which would be more accurate (but not infallible) would be to attach a degree wheel to the crankshaft and install a piston stop in the spark plug hole keeping the piston about mid stroke. The Turning the crankshaft until the piston gently touched the piston stop, checking the degree wheel and note the reading. Then replace the piston stop with a dial indicator preloaded and set to zero. Then carefully rotate the crankshaft slowly in the opposite direction until the dial indicator just began to move, stop and check the degree wheel again and note the reading. A tenths indicator would be best but an indicator with .001" resolution can work as long as careful attention is paid that the needle only moves minutely before you stop rotating the crank. There should be much less than a degree of difference in the readings.

One way to check rod knock on a multi cylinder engine is to start it and let it idle, then remove the spark plug wires one at a time. If only one rod bearing is bad the noise will diminish on the cylinder with the wire off.

Something you haven't mentioned is the number of hours on the engine and whether it has been properly and regularly maintained. Also, is the noise you hear something new, getting worse or something that's been there for a long time? Are you actually experiencing problems like overheating or a loss of power or does the noise just concern you?

I'll repeat something I said previously, noise can come from other things than the engine or it's internal components. I suggest that before you decide the engine is the problem you remove the primary clutch and run the engine without it. If the noise disappears the problem is likely elsewhere.

Before tearing into the engine you might want to have the oil analyzed (about $20 last I checked). Oil analysis can tell you about the wear taking place in the engine and even what kind of materials are wearing. If the engine is running OK you can do oil analysis at two or three oil changes and compare them to see if metal wear is increasing. See the 5th paragraph in the following:
https://www.chevronlubricants.com/e...rial-machinery/interpreting-oil-analysis.html
 

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Discussion Starter · #9 · (Edited)
I don't know the history of oil changes on the engine before I owned it. I have about 402hrs on it. I've owned it for maybe 250 of those hours. I'm pretty sure the noise did not exist when I first got the machine. I noticed it end year winter 2020 and it is all I can hear now. It seems like it has gotten worse or I am just focussed on it now. I'll get a video tomorrow.

When I rotate it gently in the freeplay, I can make it clunk.

I don't have any symptoms other than noise. No overheating, no oil loss, no perceptible loss of power. My next step is to take off the primary clutch, just waiting for the tool to arrive. I'm doubtful, the bulk of the noise is coming from the engine area and not around the clutch. If it's still inconclusive, I'll have to wait until winter is over, I use it for my driveway snow clearing. I'll take the top end off and feel the rods afterwards.
 

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Discussion Starter · #10 ·
Come to think of it, in early 2020 I had the intake boot come off partially and I didn't notice for quite some time. It's possible that the engine had ingested enough dust to wreck this over time.
 

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Come to think of it, in early 2020 I had the intake boot come off partially and I didn't notice for quite some time. It's possible that the engine had ingested enough dust to wreck this over time.
I believe that if ingested dust was the issue the issue would be low compression rather than noise. BPS is quite experienced. If he thinks you have lower rod bearing issues he's probably right. The old school test I mentioned in a previous post (removing plug wires one at a time) may help in this diagnosis, but no guarantees.

In the end, if the noise has gotten worse and it coming from the engine for certain a tear down and overhaul is probably the solution.
 

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It would seem like it is time to do a leak down or at least a compression test to determine if the engine is still viable. Would probably save a ton of time guessing.
 

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Yeah, I was just guessing on the rod bearing thought. It came from the feel of the crankshaft having the play he described but without personal inspection it's just a guess. Has it had regular oil changes and has it been run without oil or very low on oil?
 

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Discussion Starter · #16 · (Edited)
It was on the low end of the oil range at one point when I did my first oil change before I really knew a single thing about it. No denying that it needs a rebuild at this point. I'm planning to do a full top and bottom rebuild including cylinder and cam while in there. Definitely going to take better care of it after this.

Can you guys let me know if this kit listed for a 2010 Ranger 800 XP would fit mine? Some kits say Ranger 800 and RZR800 but those heads look different to me. Does the 800XP have a different engine than the non XP 800's? On my engine, the head bolts are all inside the rocker cover, but other 800's I see two bolts are outside the rocker cover.


thanks for all the expert direction
 

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Polaris changed a lot of stuff after the initial 2010 800 in the Ranger. For one, the cams are different. You're 2012 has a cam phase sensor where the 2010 does not. In that regard alone the kit you posted won't work. I'd try to find a kit specific to your 2012. Give Rev6 a call if that's the brand you're leaning towards. They seem to have a good product but I've only used them once (very recently).
 

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Discussion Starter · #18 ·
I took a look at my ownership paper, it's actually a 2011. Same engine as the 2012 I presume? It does have a cam position sensor.

Still in denial, but gonna have to face rebuilding it once winter is over. Sucks, cause I wanted to sell it this year. Here's a video

 

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Sounds like worn camshaft lobe. Pull rockers and pusrods out and take a magnet and see if you can pull lifters up and out of their guide holes. You wont be able to pull lifter out of motor unless you pull the head off but if the lifter only comes up a short distance the bottom of the lifter is mushroomed and the cam is missing a lobe.

Sent from my SM-G991U using Tapatalk
 

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Discussion Starter · #20 ·
Sounds like worn camshaft lobe. Pull rockers and pusrods out and take a magnet and see if you can pull lifters up and out of their guide holes. You wont be able to pull lifter out of motor unless you pull the head off but if the lifter only comes up a short distance the bottom of the lifter is mushroomed and the cam is missing a lobe.

Sent from my SM-G991U using Tapatalk
So a normal lifter shouldn't be able to move at all with the head still on with pushrods out?
 
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