My son and i just brought an 89 Pilot back to life after rescuing it from a side yard. This sight has helped alot trough the process. Thank you so much for all your help it has been greatly appreciated. The Pilot turned out great. Changed all the fluids and adjusted the front breaks (which makes a huge diff in stopping power). Put new pads on the back and it has been running great.

We took it to the sand dunes for its first real ride this weekend ( it was great never over 85 degrees outside ) and after several hours of seat time it performed better than expected. My son and i we so excited how well it was running ( thanks to the help and expertise here) and were having a great time. So the fuel light finally came on, (Check that off as working) so we made our way back for a fill up. We then went back out about an hour later over to a big bowl where i could watch my son ride and the first 4 laps were still performing great. Then i heard a sound difference and my son did to as within 30 seconds he stopped and turned off the Engine. I hiked over and he said the sound changed and it started loosing power so he stopped. When i got there i saw coolant coming from the overflow tank and it was all the way up to the top above the full line. When it cooled down i opened the radiator and it was very low on coolant. So two questions. 1. Why didnt the radiator pull the excess coolant form the overflow tank back into the radiator? 2. What damaged could this have cause my very well running Engine as now it will not start? Also to note the Fan was working fine and had been from the start. It now will not start. Turns over fine but will not start at all. Not sure what to do next or where to start.. I am no Engine expert by any means.

What to you guys think happened and where should i start on the fixing?


I also found that the gasket for the fuel cap needs to be replaced as with a full tank it leaks a bit.

Attached is a pic..... Didn't put the plastics on yet as the first ride was the sand

You need to learn how the cooling system works. Assuming you have a full system, as the fluid heats it expands and as it expands it creates pressure. If the pressure is enough to overcome the spring of the radiator cap, the larger spring of the cap, fluid is moved to reservoir. The fluid does not return to the system until the system cools and creates a vacuum strong enough to over com the radiator cap, the small spring in the center of the cap, and draws the fluid back into the system.

I second CO theory that you have a head gasket leak. Instead of leaking coolant into the combustion chamber, it appears you have a leak of compressed air and fuel into the cooling system, increasing the pressure in the cooling system, burping fluid into the tank. Check the coolant for black flakes like pepper. This will confirm a blown head gasket.

Hope this helps.

Remove the plastic from the fan shroud and the fan look through the radiator fins make sure they are not plugged up. If there is dirt and bugs blow out with compressed air then blow the fins out with water.

Blow through the fins 90 degrees to the radiator is you hit it at an angle it could fold over the cooling fins.

As rmesser said check the coolant for black specks. If the head gasket it blown take too many detailed pics and post, including the old gasket. NOT pulling the coolant back into the radiator as it cooled could be a bad radiator cap.


As you noticed walking over to the Pilot SAND takes about 3x more power so given a hot day it might have simply overheated.

See if you can extend the hose from the coolant overflow bottle vent to somewhere inside the drivers area until the cooling system over heating is resolved so when the coolant bottle gets too full you will see the coolant that normally over flows on the ground and you can not see.

Hope you resolve your issue soon so you can get back to enjoying! side note, the chrome cage looks good but keep an eye on the lower weld area of the front down tubes, I saw one on mine was cracked, inspected the other side, it was also cracked, you want those in good condition if you ever roll and find that you need them!

Any progress?

Have not been able to work on it too much as it has been so hot here 104 plus every day so my shop has been over 120 not even good to work in at night. I very much appreciate all your help i really need it. Okay so that makes sense why fluid did not get pulled back into the radiator if it only pulls it back when its cools. There does not seem to be any specks in the coolant or the res tank. The radiator is super clean as we just had the entire buggy apart and it was completely cleaned up inside and out. The Engine was rebuilt not long before i bought it and installed it. It still will not start and the pull start does not seem to have the resistance it had before. Prior to this it was very hard to pull, very hard actually could not imagine having to start it that way. Now it seems to be much easier to pull.

It is starting to cool off now and my son and I are starting to get over the huge let down of this and want to get back out and get her running again. It was just really discouraging as it was running so well and we just finished rebuilding her. So it was a major bummer and it just felt like it was avoidable.

So where should i look first what could it have done to the motor (( Internal Combustion Engine ? )) to make it no longer run or start? I worry even though it was shut off quickly that it did some major damage.

Also the upper cage is not chrome. We sand blasted it to get off all the rust and my son wanted to paint it silver. I for sure checked all the welds during that process.

Thank you again for all your help it is appreciated more than you know as i am new to 2Stroke motors.