i cant seem to buy a good quad for my kids. bought a trailblazer for my daughter and ended up rebuilding it from the crank up. now i just bought the 95 scrambler 400 4x4. when its running, it smokes quite a bit. i checked the oil pump and the marks align up fine. i noticed when i shut the bike off i can hear gurguling in the radiator. when its running the exhaust doesnt smell like coolant, but if the bike is compleatly cool and i start it and let it run for 30 secs, then open the radiator there is a lot of pressure under the cap. what am i loking at on this thing. havent pulled the dip stick for the counter balance yet but pretty sure what i am going to see. am i looking at pulling the motor or can i replace the water pump and counter balance seal with the motor in the bike?

 

You can pull the recoil and the case with the water pump while it's still in the frame,but you may have to loosen the top motor mount and the front one for the inlet nozzle on the case to clear the frame crossbar. Seems like everyone I did I had to do this. If you do this yourself I'd recommend a manual since some things are a little tricky. One of them is the slotted nut behind the stator plate is reverse threads,plus the two water pump seals are different and have to go a certain way. Plus the water pump bearing can't cover the hole in the case for lubrication,etc. OPT

 

does this give you acsess to the counter balance seals also?

 

Look at you model "under crank case and cylinder", pictures can show you better than me writing about what all is involved and what seals you may need to replace http://parts.polarisind.com/Browse/Browse.asp
OPT

 

ok. i get how coolant can get in to the counter balance oil. but what i dont see in any of the pictures is where is the seal for the mag side of the counter balance. i see where the bearing is and the retainer. but it doesnt show where the seal is. can the counter balance oil get in to the crank case through the crank seal? also what could be causing the gurgling in the radiator. seems like that would have to be caused by compression getting in to the cooling system which by looking at all the pictures could only be caused by the head gasket.

 

does it go between #6 and the bearing

 

Just get a manual on the 400 engine!! Doesn't matter if it's from a Scrambler 400,Sport 400, or even an Explorer 400. The engine is the same! Most of the time coolant get into the counter balancer cavity through the water pump seals being worn out and a lot of times spews out the counter balancer cover vent tube! Counter balancer oil cant get into the crank case because of the crank seal(plus there is an identical seal on the outside of the counter balancer engine case #3) Look under "Crank Case and Cylinder" Plus you are working on one of the most complicated of Polaris engines,just a lot of parts to deal with,unlike the little 250 air cooled engine. A manual is highly recommended before you start to tear this engine down so you don't end up with a pile of parts. OPT

 

sounds like a head gasket, the instant pressure in the rad is a dead give away.
Is the oil from the counterbalance clean?

 

Try purging the cooling system of any trapped air,this could be part of your problem. Open the 10 mm bleed screw at the rear of the head by the temp sensor and let the coolant run out for about 30-45 seconds while the engine is off. Any trapped air will bubble out with the coolant. Top off radiator and coolant reservoir bottle.Then run it awhile and see how it does. If air isn't purged then this can cause it to overheat quickly,blow head gaskets,warp heads and cylinders. Most people don't ever check for this,especially when they install new top ends or after flushing cooling system,have leaks,etc and could end up with other problems. Have had people ruin new top ends also after I've bored cylinders for them that have forgotten to do this. Counter balancer only holds 75ccs of 30 wt oil and if the dipstick is milky colored,the water pump seals and bearing need to be replaced to stop any damage to the counter balancer bearings and water pump shaft from coolant corrosion. Can get costly if the counter balancer needs to be replaced. Plus excess smoking on the 400 isn't always oil related. A lot of the time just an accumulation of oil in the pipe over the years and running a little rich (needle and seat wear) can cause this. I had this complaint often when customers thought it was too much oil. Again a manual is your best investment on this engine. OPT