Hey Guys

I got a 2003 polaris sportsman 500.

I brought it recently then found out it was overheating. Mechanical thermostat wasnt working. I removed it. Doesnt seem to over heat.

I went to drain oil and it was a bit milky.

Coolant didn't have oil in it.

Did a compression check on engine ( cold ) and it was 80psi , i pulled the throttle and it went up to 140 psi.... i dont get how that is possible for a start ? In the past when i tested something it usually goes up 10psi more with throttle sort of thing.

Any ideas?

should i pull the head off , any other tests i can do before i pull it off?

thanks heaps

 

Coolant pressure test. Must hold 10psi with no leak down.This can usually tell if the head gasket is ok or not. Milky oil is either from a leaking head gasket or water ingestion through the air box,etc.

 

Might take several oil changes to get rid of that milky oil. Just get the cheapest oil you can find and fill, drain, and repeat several times or until it doesn't look milky anymore and you might get lucky.

 

Can i pressure test the radiator through the over flow hole that fills up the coolant bootleg? or does it need to be through the radiator cap? I now see that steam is coming out from the water pump housing where it seals onto the motor, it also looks like it doesnt have a proper gasket ( like the gasket sealent in a tube ? )
cheers

 

Pressure test at the radiator only. You can rent these kits at most auto supply houses or buy at cheap places like Harbor Freight or Northern Tools. Check for any leaking at the water pump housing and also at the weep hole underneath. If it's leaking from the weep hole a water pump seal has failed. Replace the water pump gasket if it's just leaking around this area and make sure you bleed the cooling system properly. Any time you have a coolant loss and over heating you take a chance of blowing a head gasket also.

 

Im in new zealand and those radiator testers arnt avalible for rent and cost $200usd to buy. I took rubber seal off the spring inside radiator cap and put 10psi from my compressor into the cooling system. coolant was coming out from around water pump. Have ordered a new gasket set from USA. i also notice pull start handle is not where it should be and water will be getting down the hole. also 2 breather tubes weren't connected to carb so also could get moisture through there. I left the compression tester on the engine for 2 weeks and its gone from 140 to 90psi over that period, so i would have thought that was a good sign. what Oil should i run in this quad , is 10W-40 ok , it doesnt get very hot or cold over here....

 

Hopefully the coolant leak around the water pump was just around the gasket and not in the drip hole underneath indicating a faulty w/p seal also. Moisture as you say could have gotten in through the carb vent or air box over an extended period of time and may not be a head gasket problem. Yes hook up the carb vent line and you can silicone the recoil handle to the housing nipple to help keep water out of the flywheel/stator area. Easy to break the silicone loose if you ever need the recoil. Since Polaris doesn't have a wet clutch you can use a wide range of engines oil,not just oil designed for atv use only. 0w40,5w40,10w40(if in warmer climates or used as a work horse) and even 5w50 or 10w50. Just needs to be a good synthetic oil whatever weight you use. The oil filter is a common, almost universal size used on a lot of atvs and motorcycles. The oem Polaris filter would have even fit my old Honda 750 Nighthawk I used to own. Here's the alternatives to the oem Polaris oil filter if dealers are to far to get to or you have another brand preference.
POLARIS 3084963 - Alternative oil filters

 

Got some of that expensive penrite 10w-40 synthetic oil. Put it in, but its already pretty black after idling for 30 mins. Did a cooling system pressure test with a old radiator cap with the inner rubber pulled off and gauge through the overflow tube, after 10 mins had 7psi... Water pump or anything else doesn't seem to leak now, but each time i run it for 15mins the coolant all disappears... I took the header tank off and cleaned it. the plastic elbow seemed to be blocked so i drilled it out bigger inside, was it meant to have only a pin hole? the coolant goes down but the oil level doesnt seem to get higher from measuring the dipstick...

 

Sounds like you still have some trapped air in the cooling system. Leave the radiator cap off,jack the front end up,tires off the ground and get it warm enough to allow the fan to cycle on and off several times.As the coolant level goes down you can top off it off.After about the third fan cycle you should be able to top off the coolant,replace the cap and fill the overflow bottle to the max mark. Then take it for a drive and see how it does. Some machines do take quite a while to purge air pockets.Manual even calls for squeezing radiator hoses as it's running to help in removing air. If in doubt about the plastic coolant neck(some can warp at the cap area) you can replace it for about 20 bucks or less. Item #3.

 

I did what you said and jacked the front up, let it go on for like a hour so fan came on and off a few times, squeezed all the pipes etc. Took a little video of bubbles in the radiator if you could please have a look and tell me what you think.....

https://www.youtube.com/watch?v=kwcS...ature=youtu.be