Conquest Engine Cooling

[Ozzy]

Has anyone ever had their cooling temperature constently vary while running. Mine will reach the normal run temp of 180 & then climb to just below 210 (220 is hot on the gauge). When it hits that it drops back down to 180. It continues this cycle as long as I run it. I did have a small head gasket leak last winter which is when it started doing this. I have checked my temp in the radiator & it stays right at 180 (checked at the cap). I have had the radiator out & cleaned & flushed it. I have run it without the radiator cap & it still does it. I also put a new thermostat in it but it does the same thing. It sure acts like the thermostat is opening at 210, allowing the motor to cool down & then closing at 180 allowing it to heat back up. I thought maybe it's the sending unit for the gauge but even if it was out if range the temperature wouldn't vary like that when warmed up. Any one run into this problem.

[Mike]

Did you replace the head gasket? A bad head gasket would cause what you are describing. Since you replaced the thermostat you can probably rule that out. A faulty sending unit on the gauge is possible but not likely. Is the coolant level full? Could there be any air bubbles in the system? Do you get any smoke out the exhaust?

[Ozzy]

I didn't replace the head gasket. It wasn't a major leak. Compression was good but was loosing a little coolant. I was getting a little moisture in the oil filler tube & some black moisture droplets out the exhaust. The oil wasn't milky white so most of the coolant was going out the exhaust. I end up running some head gasket leak stop (made for aluminum blocks) thru the system in April. The only difference after that is I am not having to add any coolant to the system. As of yesterday I haven't needed to add any & it stay right in the range on the fill tank. I also wondered about an air pocket but I have drained the system at least twice. I have not put a pressure gauge on the cooling system to see if it holds pressure ok but since it isn't loosing coolant now I don't see why it wouldn't hold pressure fine. I did talk to a local mower shop tech & he said he has had that Kawasaki motor do that after changing the cam gear from the plastic gear to a metal gear. He told me running an electric fan instead of the belt one has help. He did also tell me the those motors like their heat. So I guess the short is I don't really know why it does it.

[Mike]

I guess by adding an electric fan, it would help to better regulate the coolant temperature, preventing it from changing as much, but really, you shouldn't have to do that. Has it acted like this since you bought it or is it something new that has developed? And did you do any engine work to yours? You mentioned the metal cam gear on the engine that the mower technician had worked on, so I didn't know if that was something you had done to your motor as well?

I guess ultimately the thermostat is doing its job and protecting your motor but that is strange. Maybe someone else on here has experienced a similar issue and can chime in.