Home › Forum › Ask A Member › 2-stroke vs 4-stroke spark plugs;am I dreaming › Re: 2-stroke vs 4-stroke spark plugs;am I dreaming
Out of curiosity, would running an old 18hp (stated to run on a J4J) using a J4C cause an overheat condition?
The reason why I ask, is this is the 2nd 18hp late 60’s OMC I’ve worked on in the last couple of months where it is pumping water like a fire hose, and is showing a progressive overheat condition with a new thermostat and impeller, no water clogs (I pulled the cylinder head and checked all places).
I just read this post and realized I have a batch of J4C’s NOS. If these run hotter, it pretty much would explain this issue. The motors run OK with no thermostat and stay within an acceptable heat range. With the thermostat, the cylinder head thermostat orifice isn’t even reaching 125° at WOT but the cylinders are progressing beyond 170° so I shut the motor down or throttle down to idle, and everything cools down to normal.
This does not happen without the thermostat.