engine temp

[Radarsteve]

I have a 2001 malibu sportster. While skiing boat started running rough water temp gauge had dropped  to 140 degrees What could cause the temp. drop and would that be cause of engine running rough.

[DRB10SEVEN]

4 minutes ago, Radarsteve said:

I have a 2001 malibu sportster. While skiing boat started running rough water temp gauge had dropped  to 140 degrees What could cause the temp. drop and would that be cause of engine running rough.

Engine running at 140 degrees seems fairly normal to me. Boats in general run cooler than cars/truck if that is what you are used to. My Wakesetter runs around 160 degrees usually. Does your boat typically run much hotter than that?

As far an the engine running rough, it could be any number of things obviously. How many hours are on the engine? What conditions made it run rough? Did it get worse or better depending on certain variables such as RPM/ run time etc? Has it been serviced properly or recently? Without a ton more information it will be impossible to give any insight into your issue.

[Radarsteve]

500 hrs on engine as far as it running rough it was running great and all of sudden it changed and saw engine temp at 135-140. checked plugs when I got home all good. could it be asensor

[Radarsteve]

engine tenp always runs at 170-175

[John I.]

Is the engine’s normal operating temperature closer to 160 degrees? (Which would make sense with standard 160 degree thermostat.) 

edit: Noticed you just posted normal temperature of approx 170.

I would start by replacing the thermostat. 

Edited March 12 by John I.

[Radarsteve]

5 minutes ago, John I. said:

Is the engine’s normal operating temperature closer to 160 degrees? (Which would make sense with standard 160 degree thermostat.) 

edit: Noticed you just posted normal temperature of approx 170.

I would start by replacing the thermostat. 

Its always ran  170 since it was new. and it started running rough when temp started dropping. could a sensor cause engine to run rough due to temp drop

[dlb]

Temp drop is probably a stuck thermostat vs a sensor.  Either are easy to replace.

[Rednucleus]

If running cold computer may be waiting for normal operating temperature to run correctly. Start with thermostat change. Can check old one in a hot water bath and thermometer to see where it's opening

[justgary]

1 hour ago, Rednucleus said:

If running cold computer may be waiting for normal operating temperature to run correctly.

This is a presumption that it is an injected engine.  @Radarsteve didn't say if it is injected or carbureted.

[electricjohn]

IIRC, the ECM stops holding back at 120.