Brand new 2005 Volvo 496 8.1 420 hp.....Running temp seems to be around 175-180 but when I open it up for a few minutes she seems to go to 190....especially when I come back down to idle....the motor is fresh cooled too. I asked the guys at my marina who installed the motor and they say all is good.....is it ??

Hi Johnny,

I say that 190 is a bit high. You should have a 170 thermistat in there. My closed cooling 540 runs at 170 - 175 no matter what I do to it. You know I am usually on the throttle. I dont remember, did you get a new exhaust system with that new motor? Did the motor always run at that temp? Maybe it is time for a new sea pump impeller?

Vinny

What's up Vinny....original exhaust....added silent choice at time of install..the motor originally ran a little cooler (170-180) then I noticed it running a little higher and It did go into guardian mode twice. The marina said impellar was bad and cleaned out old one and installed new. Now she doesn't go into guardian but still seems hotter then when I first ran it. The guys at the marine keep telling me it's because the water is warmer now then in the very beginning of the season......My season is over so I guess I will have to run it next season and see what happens....one more year of warrenty........I have got another question for you Vinny...I will PM you in a few...

The thermostat on closed cooling is rated at 140F I believe. My engines are sensitive to the ambient water temp and I'm experiencing some of same symptoms you are--high temps at WOT (more dramatic on STB engine)--but they both do it. Also have a 10/15 degree differential between engines.

I'm gpomg tp put in new thermostats, flush the coolant and put newe coolant in, fkush sea strainers and change the senders and see what the results are. The impellors are new and they get riun at least every week and water volumes out exhaust seem sufficent and equal across all four outlets.

We're also going to put new GLM exhaust manifolds, risers and riser blocks on both engines. It may be that these 5 year old manilods have scale and ehatever built up.

Film at 11--

I posted some bad info above--I actually read the amnual for another project and the Tstat for closed coolin on my MarinePower 454EFI's with closed cooling i s speced 170 degree's.

Now ive got to rethink some odd reedings on my water temp gauges.

Sorry for the bad data.

No problem Poorsche.....thanks for your correction.....and good luck with the engine....

My 496HO runs about 170 consistantly. I think 190 sounds high. Your dealer should be able to run some diagnostics and find out what's going on. Water pressure, port, strb, exhaust temps, etc.

My previous boat had the same motor, Volvo 8.1GXI 420. I installed closed cooling on it. The kit replaced the 140 stat with a 170 unit. After installation, the motor warmed right up to 170 and was stable there running idle to WOT. After running it would maybe inch up to 175 at idle for a moment then settle to 170.

Sounds like you motor always ran hot. Either sensor is off somewhere or possible blockage. A scan tool will put that mystery to bed.

Here's something you guys might be interested in----probably one of the best investments I have made is purchasing this neat, little hand held tool pictured below. I have used it many times on my engines to find out exactly what the temps are on various spot/points on my oil lines, water lines, lines going to and from oil cooler, headers, thermostats, block temps, heads, intakes---everything! I don't know how the picture will come out on here, but it is called a "MiniTemp" made by Raytek. This one cost me about $115 or so and has been/is a great time/headache saver. When you need to know what the temp is, just point and shoot and it will give you a digital readout. There is a small red laser that allows you to pin-point exactly where the temp reading is being taken from.

I have used this tool while a friend would drive the boat so that I could get as close to real world, accurate temp readings as possible, however the only way to do this was to run the boat without the engine hatch on.

When you need to know the temps of everything on your engines as they are all working together, then this little tool is a great help, and removes just about all the guess work.

My 540 only gets to about 175 but only on hard or WOT runs and that includes in 100* temps wiht water temps close to 90*.

In cooler weather and water, same thing. I won't expect water temp to make a huge difference unless you're not running a t-stat.