Question about normal engine temp

[gregtay]

I had my new boat out on the lake for the first time in a few months and i noticed that the temp was hovering around 178* which had me a little worried. I believe it is usually a bit lower (160ish?), but can't remember for sure. Boat was winterized (water drained, etc.) but i keep it in the garage at my house, so it didnt' go through an harsh freezing, etc. Just wonddering is 178 is normal (and it was a cold night with cold lake water!) or if i should start looking around for a problem (waterpump/impeller?, thermostat?, etc.

Info:
2007 Mercruiser 5.7/350MAG with a Bravo III, raw water cooled. about 7 months old and 60ish hours on the motor. Boat is a 2007 Crownline 240ls.

Thanks.

 

[bigbrownbuku]

Re: Question about normal engine temp

180 is a little high for a raw water cooled engine but nothing that will start a fire. its possible you picked up something on your intakes that cleared but did damage? recheck the winterize work first, all the plugs back in, hose clamps tight, no leaks etc.

 

[QC]

Re: Question about normal engine temp

Yeah 178 is a little hot for a raw system. They run 160 degree stats, so it should run down there. I dont' trust gauges, so I always want to verify with a second source before I start freaking out. Maybe a thermostat, I doubt pump as it wouldn't like 178 either You can check your pump easily on the trailer, if it's pumping water out of the exhaust on muffs then you're pumping.

 

[cbavier]

Re: Question about normal engine temp

My raw water Cooled 4.3 Mercruiser 185 HP runs about 160-165 dg . New Impeller was installed last year.

 

[Lou C]

Re: Question about normal engine temp

Do you have a 160 thermostat? My OMC does and pretty much runs at 160 all the time, unless the stat is starting to get a little sticky, then it runs a little cooler. 178, if accurate, may be a little high, but electric gauges are not always accurate either.

 

[dcg9381]

Re: Question about normal engine temp

MPI motors are 160 degree stats also?

 

[Don S]

Re: Question about normal engine temp

If you normally run in the 160? range, and it suddenly goes up, then something is wrong.
First thing to check would be the raw water pump impeller. You may have picked up a plastic bag, kelp or whatever, over the water pickup that may have damaged the impeller without you even knowing it.
But without checking, your are walking a fine line of having an overheat and not knowing it.

 

[cbavier]

Re: Question about normal engine temp

Do you have a 160 thermostat? My OMC does and pretty much runs at 160 all the time, unless the stat is starting to get a little sticky, then it runs a little cooler. 178, if accurate, may be a little high, but electric gauges are not always accurate either.

Yes 160 is correct and the correct one for the 4.3 185 HP according to my Engine manual. I think the impeller is as critical as the thermostat however. The Impeller should be changed every three or four years depending on how much you use your boat (Hour meter) and if it's used in Fresh water or salt water. We put about 85 hours on our Boat last summer in Michigan ( 5 months). I'm not Mechanical Savvy so my Boat a 1986 has been maintained by the same Marina all it's life. They have a folder on every boat they sell as well as service. When I take it in to be winterized, Spring prepped or for whatever. They always pull my folder and do a review. They are honest and very thorough. If I was shopping for a new Boat I would go straight to them. Thats 21 years of service for a satisfied customer and further. They are a Mom & Pop Marina and have kept the same customers because they KNOW ME BY NAME. I've had the same two mechanics about 18 years and they know me and they know my Boat.

 

[Haut Medoc]

Re: Question about normal engine temp

178* is warm.....
Verify with temp gun, if guage is correct,
check/replace the impeller & proceed from there.....​

 

[dcg9381]

Re: Question about normal engine temp

The Impeller should be changed every three or four years depending on how much you use your boat (Hour meter) and if it's used in Fresh water or salt water.

I know this is up to "debate" - but I'd do an impeller every 2 years maxium. It isn't the hours that kill the impeller, it's the dry starts and drying out of the rubber... Do it more often if you're running in dirty water.

I've seen impellers fail (on dry stored boats in MI) simply after sitting in the barn all winter...

 

[gregtay]

Re: Question about normal engine temp

Thanks all for your help. I will first verify that it is indeed runing above normal, and if so i will replace the impeller (it only 6 months old..b ut if i am going to pull everything apart i will just throw a new one in.)