Engine Operating Temp Question

SurlyTodd

Recruit
Joined
Apr 12, 2012
Messages
1
I have recently purchased from a private seller a 2009 SeaRay 195 Sport with 53 hours on the 5.0 Mercruiser Engine. I brought the boat in for service to change the oil in the lower unit and motor. During this process while the boat was running in dealers pool the operating temp was about 175. They suggested a new water pump and impeller. Okay, so they re-ran it in the pool still 170 to 175. Said the proper temp is 160, for sea water cooled engines. Recommend changing the thermostat. After swap, boat still around 170. Dealer now suggests that its the manifolds and dry joint elbows. $3500. I ran the boat at full throttle and steady cruise last weekend temp would fluctuate between 170 175, at full open would momentarily get to 180 and immediately come back down. I guess my question or advice i am looking for is: Is this temp something to be concerned about? Can i Keep operating the boat at 170-175 without engine damage? Is the dealer actually giving me good advice? Any suggestions would be great!
 

picklenjim

Chief Petty Officer
Joined
Mar 11, 2009
Messages
528
Re: Engine Operating Temp Question

At this point easiest and cheapest thing to try next would be get a different gauge you could temporarily connect up to the engine and see what it says. Another thing it could be the sending unit.

Know anybody that's got one of these?
http://www.harborfreight.com/infrared-thermometer-93984.html

Another thing you could try is take the thermostat out and see what it does.

Manifolds I would suspect BS. The boats only an '09 with 53 hours?
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
Messages
52,565
Re: Engine Operating Temp Question

I would verify the gauge works by using an IR thermometer. I suspect your gauge is off.
 

Bondo

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Apr 17, 2002
Messages
71,449
Re: Engine Operating Temp Question

Ayuh,.... Welcome Aboard,.... Is all 53 hours/ 3 years in Saltwater,..??

If not, I'd do some more diggin' to see what's wrong...
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
19,180
Re: Engine Operating Temp Question

I have recently purchased from a private seller a 2009 SeaRay 195 Sport with 53 hours on the 5.0 Mercruiser Engine. I brought the boat in for service to change the oil in the lower unit and motor. During this process while the boat was running in dealers pool the operating temp was about 175. They suggested a new water pump and impeller. Okay, so they re-ran it in the pool still 170 to 175. Said the proper temp is 160, for sea water cooled engines. Recommend changing the thermostat. After swap, boat still around 170. Dealer now suggests that its the manifolds and dry joint elbows. $3500. I ran the boat at full throttle and steady cruise last weekend temp would fluctuate between 170 175, at full open would momentarily get to 180 and immediately come back down. I guess my question or advice i am looking for is: Is this temp something to be concerned about? Can i Keep operating the boat at 170-175 without engine damage? Is the dealer actually giving me good advice? Any suggestions would be great!

It ain't broke . . . so don't pay a bunch of money to fix it.

If I were me, I'd see what I could do to verify the temperature accuracy of the gauge. Your engine will tend to run at a higher temperature than the thermostat spec'd temperature

My boat engine has a 143 degree thermostat and the temperature runs at 155 all day long . . . so a 160 degree thermostat in your engine will probably have the it running at 172 all day long.
 

mpdive

Chief Petty Officer
Joined
Apr 23, 2011
Messages
567
Re: Engine Operating Temp Question

I put about as much faith in the accuracy of temp gaues as I do the trim senders.
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: Engine Operating Temp Question

imho,
find out what value t stat is supposed to be in place. my guess is a 160*F t stat from looking at s/m 31. a t stat starts to open at it's stated value. the goes to full open at + 20*F. so range is 160-180. your rig operating at 170-180 is within the normal operating range of the t stat.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine Operating Temp Question

Which thermostat housing do you have? The lower housing in the picture below has a 170? thermostat (#24).
The chances of needing manifolds and risers is very near zero.

housings.jpg
 
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