Mercruser 3.0 2010 model overheating

[1laurentk]

Hi there
I have a crownline 18 with inboard mercuser 3.0 about 50hours that is overheating. The engine was running fine until one night we anchored close to the beach and with the low tide it sort of got stuck in sand, a few minutes after taking off it started overheating. I took it home flushed the engine and it seemed to run fine on low idle checked the oil it was fine so took it back to sea and overheated again. Does anyone know why is this happening? thanks

 

[achris]

Re: Mercruser 3.0 2010 model overheating

Hello and :welcome: to iboats.

Could be a few reasons, but I would start with removing and checking the drive raw water pump impeller. If that checks out, then check the thermostat for sand build up, then I would remove and flush the manifold and exhaust elbow.

Chris......

 

[thumpar]

Re: Mercruser 3.0 2010 model overheating

I am with Chris. Impeller is probably damaged and could be clogging other parts of the cooling system.

 

[dingdongs]

Re: Mercruser 3.0 2010 model overheating

needs investigating b4 you take to the sea again or a new engine at vast expense will be imminent.
best not to beach your vessel as this is what happens when the drives not raised fully. Its worth getting your feet wet, to save hull and drive from damage too.

 

[1laurentk]

Re: Mercruser 3.0 2010 model overheating

Thanks for the responses i will start by checking the drive raw water pump impeller but can anyone tell me where it is located or where i can find instructions on how to changed?

 

[achris]

Re: Mercruser 3.0 2010 model overheating

Have a look at this post. Plenty of information there. even one called 'How to change the impeller on an Alpha drive'. Also look at my video collection, I've done a couple that cover the gen II water pump (which is what you have)...

http://forums.iboats.com/mercruiser...cellaneous-mercruiser-information-329915.html

 

[thumpar]

Re: Mercruser 3.0 2010 model overheating

If you find that the pump has missing pieces make sure you backflush the system to get the missing pieces out.

 

[stonyloam]

Re: Mercruser 3.0 2010 model overheating

Could be a few reasons, but I would start with removing and checking the drive raw water pump impeller. If that checks out, then check the thermostat for sand build up, then I would remove and flush the manifold and exhaust elbow..

I'm with Chris, except don't bother to inspect the impeller (except to see if all of the fins are there), toss it in the trash and put in a new one. Inspect the inside of the pump housing for scoring.

 

[1laurentk]

Re: Mercruser 3.0 2010 model overheating

Finally got around and changed the water pump impeller last night changed the gear oil too at the same time, the old impeller was all in one piece and didnt look bad but there was a bit of sand there the rest looked fine took the boat out today it over heated again. I guess i will change the thermostat next?

 

[thumpar]

Re: Mercruser 3.0 2010 model overheating

Take the thermostat out and put it in a pot of water. Turn the stove on and see if it opens up. If you have a a cooking thermometer put in so you know the temp.

 

[fat fanny]

Re: Mercruser 3.0 2010 model overheating

i advise you to use ALL the advice given to you! back flush the cooling system along with replacing the T-stat. If that does'nt do it you might need to replace the circulating pump on the engine.