Mercruiser 3.0L - Engine Temperature

[dtdodd1422]

Ok, I have a Mercruiser 3.0L engine just had work done on it. New thermostat and new temperature gauge. With thermostat installed engine warms to 180 on muffs. If you take thermostat out it will cool and operate at like 120 on the muffs. I though normal temp hould be around 160.

Was told the thermostat housing needed to be replaced to fix this. Something does not sound right.

Any ideas please?

 

[Don S]

Re: Mercruiser 3.0L - Engine Temperature

Does this 3.0L have a year? When was the impeller in the drive last replaced?

 

[dtdodd1422]

Re: Mercruiser 3.0L - Engine Temperature

Has lots of water pumping through and coming out the back as it should. I don't know the exact year as the prvious owner bought the boat new in 2004 and had engine replaced in 2008.

 

[dtdodd1422]

Re: Mercruiser 3.0L - Engine Temperature

Sorry forget to answer one of the questions. Have no clue when the last time the impeller was changed. boat sat from July 2010 till know and I think before that it sat the prevoius year. only had 24 hours on the quote new engine and drive. working on finding our exactly what year it is I have serial numbers on both but have not found a site to tell me the exact year.

 

[Don S]

Re: Mercruiser 3.0L - Engine Temperature

Start by replacing the impeller. That is the first thing that is checked in any overheat problem on a marine engine.

You will find info here http://forums.iboats.com/showthread.php?t=329915

 

[dtdodd1422]

Re: Mercruiser 3.0L - Engine Temperature

Don, I know you said to start with replacing the impeeler. Just something is wierd. Put boat in the lake today. When thermostat was in the temperature rose to close to 200 degrees. However, the engine was not too hot to touch. I immediately killed engine and removed thermostat. Engine seemed to operate at like 100 degrees from then on. Seems wierd that when the thermostat is removed there is no getting hot issue. I would have thought that if the impeller was not pumping properly then it would still get hot? Found out the engine is a remanufactured 1998 3.0L . Could it be the temperature gauge or sender? Is there a way to test those or would you still replace the impeller? The engine on has 25 hrs. on the rebuild. Trying to determine where to start. Thanks in advance.

 

[dtdodd1422]

Re: Mercruiser 3.0L - Engine Temperature

Ok replaced the impeller and it was bad. Had two fins broken. However took boat out today and it still heats up with thermostat in. As soon as you take thrmostat out once again temperature drops to under 100 degrees. I am thinking bad thermostat. Any other suggestions? thermostat body also or exhaust elbow?

Please help.

Thanks in advance.