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Ideal Water Temp

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bill_cunningham

Contributing Member
"What is the ideal operating w

"What is the ideal operating water temperature for a 5.7 Alpha1 sucking lake water? Just curious.. My engine used to get pretty hot when run at low speeds in a canal/lock system.. Would have to pop it out of gear, and run it up a bit to cool things down.. At the end of last season, when I changed the oil, I went to castrol syntec 5-50 and this year at all speeds the temp goes up to about 140 an stays there..
The When I pop the engine compartment open, and feel the exhaust chambers, their hot, but about the same temp as the Gauge says.. Now, I don't know if I'm just getting better cooling with this oil, or the thermostat is stuck open, or the gauge is not right, or every thing is just f.i.n.e.(*)!!! The boat comes out of the water next weekend Managed to put a whole 8 hours on it this year -- Just no time anymore -

*f.i.n.e.
F=freaked out..
I=Insecure
N=Neurotic
E=Emotional"
 
170 seems about right although

170 seems about right although my Firebird with the same engine likes 200 -210. I have never figured this out.
 
"Bill:

"engine used to

"Bill:

"engine used to get pretty hot when run at low speeds in a canal/lock system"

My first impulse would be to replace the OD impeller and change the T'stat since that cured my idling run hot problem last year.

"went to castrol syntec 5-50 and this year at all speeds the temp goes up to about 140 and stays there"

All synthetic oils have been touting for years that your "engine runs cooler" vs. mineral oils. You seem to have proven that statement. But, you could have had some debris lodged in the water inlet that finally passed through.

I use synthetic oils in my truck and SUV with low micron synthetic material filters that seem to keep the oil clean for 5,000 miles. I will try the oil in my 4.3L the next service but will use 20W50 oil. I have been using Shell Rotella 15W40 due to its high pressure rating with good results.

"the exhaust chambers, their hot,"

You should be able to lay your hand on the risers and not get burned or feel you need to pull your hand off due to the heat. Risers may need to be cleaned or replaced; fresh water use gives longer life to risers which can be soaked in a muriatic acid bath for 90 min. or cleaned in a radiator shop's ultrasonic tanks.

Exhaust manifolds are also cleaned in the same manner mainly to remove rust and mineral deposits from the cooling jackets. Again, fresh water use provides longer life for them but eventually manifold and risers need replaced. When used in a salt water environment you are lucky to get 3 or more years our of them. A salt neutralization system helps extend the useful life of them.

If you pull the risers take a look at the exhaust "flappers" since your risers have been hot, the rubber seal around the edge may have melted which can allow backwash of lake water to enter the engine and cause hydrolock; "very bad".

Temperature sending units have a copper end the contains a thermister that reacts to temp. changes. The changes in resitance allow the gauge to display different temps. The pellets will develop a dark coating of oxidation on them from exposure to raw water. This coating can act like insulation. I have remove mine and cleaned them with a synthetic scuff pad to provide a clean surface to conduct heat."
 
"Thank for the replys....
Gu

"Thank for the replys....
Guy.. I had replaced the impeller at the start of last year before I was having the heat problems at slow speed, and yes, I can now hold my hand on the risers without getting burned.. That was the part I assumed was about the same temp as the gauge 135-140 F. Is this to low? Roaming around the posts, someone else on here said the T-stat should be a 140 so if thats the case, everything must be ok, and I'm seeing the results of the better cooling synthetic.. I'll probably move up to 5-30 this year, because I usually by it at Costco, and they don't seem to have the 5-50 ..5-30 makes more sense anyway.. With only 8 hours on the engine this year, I'm gonna keep that oil, and put it in the car next change..Why waste it..."
 
"I run my boat in salt water.

"I run my boat in salt water. What is a good working temp at cruising?? I cruise at 3,500 rpm."
 
""...move up to 5-30 this

""...move up to 5-30 this year...Costco, and they don't seem to have the 5-50 ..5-30 makes more sense anyway."

Due to the high pressure requirement of your engine, consider using at least a 10W30 oil and preferably a 10W40 or 15W40. I stopped using Castrol Syntec when I read that they reformulated it. I've been using Mobil 1 or Pennzoil in my vehicles with synthetic media oil filters (Mobil 1 @ $10 ea) since they have a lower micron filter rating. Keeps oil clean.

"With only 8 hours on the engine this year, I'm gonna keep that oil, and put it in the car"

If you do that drain it COLD so it doesn't bring alot of suspended particles with it that could affect your engine. Put it into a milk jug and let it sit for 72 hrs. in direct sunlight and any micro crud in it will drop to the bottom. Don't use the last cup in the jug."
 
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