94 Polaris sportsman 400 my first 4x4 four wheeler but not my first wheeler. I am new here and saw a lot of good answers and knowledge here so I figured it was best place for me to ask my questions.

Background of wheeler. I got the bike on trade and it didn't run. So I did the basics like clean carb and gas tank and well starter was squalling pretty good but it got it started so I replaced the starter all new. Well noticed crack in reservoir and fixed it with resin and plastic weld held up good. Noticed a few other little things such as throttle cable replaced due to breakage on oil pump side. Adjusted everything in specs by the manual and still could not get the thing to stay idle due to the ETC and was adjusted by the book to its specs. Alrighty fixed that by unhooking it for now. Will not idle ion revers or go in reverse by speed wise with the rev limiter hooked up so I unhooked it and it works good until I replace it. That's the way im going to run it for now.

Alrighty my questions I have.
1. Motor over heated and popped line off of the top of the head and now When you pull cap off of radiator it shoots antifreeze 5 feet in air. What do I need tostart checking?
2. I know lights on dash are blown so im going to swap those to LEDS if I can or can I?
3. I have not checked the fan and how do you check it?

4. I know most likely since the bang with the line popping off that the head gasket needs replaced. How hard is it?

5. With me doing it by myself. Do I need to go ahead and replace the seal in between the water pump and inner case ? or do you think I can just get away with replacing the head gasket?

6. I am pretty mechanically inclined so I know I can do the work myself just realy never messed with a 2 stroke engine before so is this going to be an Easier task or pretty hard to accomplish?

 

Open the 10mm bleed screw on the head with the engine off first. Close it once all the air is expelled and just coolant flows out. This may be all you have to do and may not be a warped head or blown head gasket. With the key on,ground the two prongs on the sensor at the rear of the radiator with needle nose pliers and the fan should come on. If it doesn't the fan motor is probably bad. You can try 12 volts direct to the fan also. If the fan does come on the radiator sensor has shorted. You can match these up at a lot of auto stores. The small glass indicator bulbs plug into a socket strip. You'd have to rig up led type indicator bulbs,but I've seen stranger things than this people have done.Polaris 4030042 BULB
Before you go too far get this manual as this is one complicated engine with many parts and the two water pump seals have to be positioned right if you have to go into the engine.http://visit.tradebit.com/visit.php/...75/264162958/9

 

thank you OPT for answering so fast. I really appreciate it. But i did try the bleed screw trick but its building enough pressure up to shoot thruough a hole in reservoir cap taklingstream style. But i did try it. tghe fan have ot yet tried bc i can not get the front end off the bike without anotherperson jelp due to the way the previous owner bolted it on there is pain in at a@@ to really try and do by yourself.
The manual i thank you for the link but i do have the manual and read through it a bunch but it really dont elaborate on my problem that im am having which is the pressure build up.

 

If the over flow bottle is shooting out coolant before the engine really has a chance to get hot it still may be trapped air.You can lift the front end of the atv and try bleeding again. Plus easy to do a radiator pressure test to check for leaks,plus the 13psi cap is easily over looked when having cooling problems. You can get one of these at any auto store. On the pressure test should hold at least 10 psi with no leak down.

 

Sorry took me so long to get back to you about this. I will be getting a radiator leak test kit soon but for now i replaced the radiator cap with an original specifications one and checked all lines and caps with new rubber seals inside of em. The Polaris front end is off the ground about 18" and left sitting like this for awhile before opening the bolt. I opened it up and air came out so i bled it twice until no air and then tried to start and it was shooting antifreeze out of the cap on the reservoir tank. So i really don't know where to go from there im so read to ride this thing because it is a fun little fast machine. But i really appreciate it OPT for the information.

So where can i go from here in your opinion what would you do to resolve this and find the problem?

 

Could possibly have a seeping head gasket,a radiator problem itself,but the pressure test should narrow down where the problem is.Normally these are easy machines to get air out of the cooling system.

 

Hey there OPT I finally ended up just pulling the head off and found a very warped and gasket that was peeling its cover off and found signs of water in the cylinder. BTW the reason I pulled the head was due to the antifreeze that was on the spark plug this last go round. So I ordered a new OEM one and going to install it as soon as it gets here between Monday and Wed. but as I am doing this what else do you think I need to do or look at exactly? I'm going to do the lifted front end trick to bleed air of the system but any other checks or anything else I need to really look at with this before I try and start it again. but if this doesn't solve it where do you think I need to go from there? I really do appreciate al the help I am just really excited about getting this machine back out and riding again.

 

If you have a good,flat,solid surface(we had a huge slab of granite at the shop) run the head in a figure 8 while rotating it on some 600 grit sand paper. Check that the head is smooth and clean all around. Also see if you can slip a .001 feeler gauge around the head while on the flat surface. Hopefully the head and cylinder are ok,just a blown head gasket. No special bleeding procedure needed since you found the problem other than making sure all the air bubbles are removed when you open the 10 mm bleed screw on the head. Close it when nothing but straight coolant is flowing good. Top off the radiator and coolant bottle and you should be good to go. Check that fan is operating ok,if not it can over heat again quickly! Recheck coolant level after a few minutes riding.Blown head gaskets happen a lot when fans or sensors go south and people keep riding them,also when people rebuild them and forget to do the bleeding procedure or don't torque the head nuts properly.

 

alrighty OPT time for an update on everything. I have had the head on the flat surface and could not get anything under it so I am assuming that it is good to go. Sorry took so long I've been working on another project that I picked up and haven't had a chance to install gasket yet. So let me make sure I will be doing the bleed process right.
Step 1 fill up atv and reservoir with fluid
step 2 lift front end up so that radiator is highest point on atv.
Step 3 open bleed screw and wait until no bubbles are coming out and then finally
Step 4 just filler back up one last time and then try and run it from there
Ill check the fan I finally picked up light bulbs and if the fan doesn't work I will get back to you asap with that answer as I do not want to have to do this again for a while as I am interested in seeing how it really holds up with me.
What was the ft lb torque specs for the head? I do have a manual I just like to verify everything before I put back together and I appreciate all the help I really do man this is helping me a lot.

 

Not necessary to lift the 400 but wouldn't hurt. Bleed procedure as you mentioned. Head bolts torque between 17-19 ft pounds in a criss cross pattern.Cylinder bolts 28 ft pounds. If you don't have a crows foot adapter or something similar, criss cross on these and guess like many have done... Fan is easy to check.Just have the key on and use needle nose pliers to touch each side of the radiator sensor spade connectors. This completes the ground path for the fan to kick on.