I found it, I found it, I found it!!!!! Well I think I found it :-)

[ob3135]

I THINK I FOUND IT! What a hunt it was! :-)

Ok, so you probably know by now I have been having all kind of problems. I finally got the re-build of my Sportsman 500 done and running good only to almost immediately blow a head gasket, and it was knocking a bit from the get go but me and the polaris guys hear at dealer said "Heck they all knock and rattle a little bit, it's fine"

Well, then of course the head gasket blew.

So I tore it down as yall know. Found water/A-freeze in oil, and found the head gasket was blown. Also found the head was out of tolerance by .003 and supposed to be max .002.

First we all thought must have been a crappy head gasket cause I used an aftermarket gasket kit and it wasnt one of those thre piece metal crush gaskets. It was top "Gasket material" center "Metal" bottom "gasket material" ... So we all figured, OEM gasket and your good.

Then I decided even though I checked the head with a strait edge and feeler guage the first time and it was good, to go ahead anyway and mill the head, the shop found it was out by 001 thousands , so it was warped.

Well, I thought thats odd. It never got hot enough to spew out the resivor but it did seem hot as far as the heat I felt off the engine on my skin...

So I got more curious and figured what the hell, lets test the thermostat! Even though it was new at rebuild.

So I started a pot of water. and attached is the picture of the two thermostats side by side. The new one bought today and the one I put in it at time of re-build. The picture was taken instantly after taking them out of the pot and the water temp in the pot was 180. they are supposed to start opening at 180 degrees. Notice the old one is not open. The new one is. The old one finally opened at 205. So the machine was running 25 degrees to hot thru all the test rides and the test run idle's in the shop for 10 minutes to 20 minutes at a time letting it run to break in and inspect.

So my theory now in the end is that it was just barely hot enough to cause the knock, cause the very slight warp'age, and with the gasket not being the bes tone in the world, in the end enough to blow the gasket.

Yippppeeee I found it , I found it!!!!!

Well wait, did I find it? What say all you bad to the bone posters?

[RENOBADBOY]

I , for one , think your on the right track. Good find on the thermo!!!

[IGotSoldJunk]

doesnt the bike have at least a idiot light that comes on when it runs hot?
seems like you should be getting some warning if its running that much hotter than normal.
all in all good job figuring out your issue
makes me want to put an actual temp guage on my rig somewhere

[Born2rescue]

this is what i did.. helps let me know before trouble starts..

[tekrsq]

Yep, yep. I added a temp gauge as well.

[map.isme]

I like the temp gauge, makes me wish i had one. I don't know why we have this smiley, but okay... Wondering, what the other buttons do.

[ob3135]

Originally Posted by tekrsq

Yep, yep. I added a temp gauge as well.

So where did you put the sensor for the guage? Drill hole in thermo housing?

[IGotSoldJunk]

i would like to know where to place the sensor for the gauge ..i'm gonna do this mod immediately

[tekrsq]

The thermostat housing needs to be drilled and tapped for the sensor. Quadovator makes a kit that comes with a pre-drilled housing, gauge, and all wiring needed to install for around $70. That's what I bought because I didn't feel like tapping the housing (just being lazy).

Polaris ATV Temp Gauge Kit Coolant Switch Illuminated System Quad

As for the other buttons, the top one is the "turf mode" switch (stock on my quad), and the lower switch is one that I added to have back up/ work lights. When the switch is in the left position, they work when I'm in reverse, right position is constant on (work lights), and center is off all together.

I'd like to know what else Born2rescue has on his beast as well, lol.

[BugsOnMyTooth]

Tekrsq Thanks for the link to Quadovator. Its a new candy store for me.