cold hearted 2 q m

[Don Baker]

Can anybody tell me why my 2 Q M 15 runs cold? I replaced the thermostat and it seems like the raw water is bypassing the exhaust manifold like it should, but the engine never gets hot enough to open the thermostat. after a good half hour of running you can put your hand on the side of the cylinder head, and it just feels luke warm. This can't be good for the injectors and the parts that are engineered to work best at operating temperatures.

 

[Terry arnold]

check thermostat?

Check the thermostat which can be done easily by heating it in a pan of water and checking the temperature that it opens.

 

[Jim Logan]

Cold 2QM15

If you have a raw water cooled 2QM 15, the thermostat is designed to run at less than 145 degrees (I think, too lazy to look it up) in order to keep the amount of scale formation down in the engine. If it runs hotter (like the freshwater 2GMF versions do with freshwater cooling), it will form scale in the cooling passages. If it has had the wrong thermostat in it or a lot of hours, it might have a lot of scale and salt formation inside the engine that keeps the cooling water from going through the engine, although it would go out the exhaust just fine - have you had any overheating problems? Those are a sign of cooling passage blockage sometimes. My 2QM 15, which I think is operating correctly, never gets so hot that I can't touch it almost anywhere, and really runs cool this time of year with 50degree intake water.