Technically speaking... you need to know what thermostat is in it.
Generally speaking... 170 is good. For me.

I guess at this point I would put a new thermostat in it & see what you get. This way you know for sure what is in it & what your operating temp should be.

 

thank you.. I was thinking the same changing the thermo, and see what happens.. Question tho, the needle going that high like mentioned does indicate the motor is heating up more then normail right?

Sorry fairly new to boating so im not sure what the normal temp are, but im sure if it passes the middle mark something is not right..

 

Why was the motor pulled? Which out drive is on the boat?

If we assume (never the best idea), that you have a 170 degree thermostat in it, then yes, 190 or 200 would indicate some problem. It could be something as simple as a bad thermostat. I too have limited experience so making assumptions & hoping its a $20 fix is not something you should bank on. Install a new thermostat. If that rectifies the problem then great. Otherwise you have to determine why water is not circulating through the system properly.

 

The drive is a alpha one drive.. Something I should have mentioned on my original post is that when I let off on the throttle after I see it go over the half way mark, the engine cools off rather quickly.. I mean in just a few seconds of dropping the RPM form 3.5 or 4K back down to about 3K or below the thermo goes back to the mid way point, and stays there unless I rev up again..
I have been doing some reading and unfortanetly it sounds like it may be the Manifolds maybe already to rusted, and constricting the water flow to the engine.. So sounds like a pretty big repair.. atleast $1,500.00 I assume.. I pulled the engine out because the starter went bad.. I had it pulled out, and put in new spark plug wires, and spark plug. New distributor cap, new impeller, new starter, changed the seals and oil in the drive, and new hydraulics on the drive as well..

 

First off. It sounds odd to have a Alpha drive behind a 454 after the invention of the Bravo drive.

My 454 (330 hp) uses a 140* stat. My temp stays rock solid 145* Some time ago when pushing 4500 ish rpms for 20-30 minutes, my temp would slowly creep up and hit 200*. I found the side thrusts burnt on the Alpa 1 water pump.

My boat is fresh water cooled and I boat in bottled water.

What type cooling system is on your boat?
When you replaced the pump, did you put in a complete pump or just an impellor?
How much internal corrosion do you thing you have?

Start by pulling that T-Stat and testing it.

 

Well this weekend I went to the Marina to change the thermostat.. To my surprise it did not have one.. I left it as it was, and now im thinking that the problem is going to be with the Manifolds. I took it out this weekend, and again at over 3.5K RPM it starts to hit the 170 mark which is 3/4 mark before hitting top on the meter which is 200..

Now my question is 170 F over heating, or is that normal running temp.. Someone told me that the 170 is normal

 

170F is not considered overheating. I would think that if you don't have a thermostat, it should run cooler. Depending on the cooling set up, not having a thermostat could cause circulation problems. I would put a thermostat in it and try again.

 

I originally suggested a thermostat. Now that we have eliminated that (there is none!) as the problem.


You can move on to..."Otherwise you have to determine why water is not circulating through the system properly."

 

Put a T-Stat in the engine. Otherwise your gona screw around trying to trouble shoot a simple problem and look like Barney Fife

 

You NEED a thermostat. Find out what degree thermostat your motor came with a install that one.

 

Will do.. Thank all you gusy for the quick tips.. Thiws weekend I am going to install the thermo and see if it improves..

 

I have heard that engines will actually run cooler with a thermostat in place since it gives the water more time to cool the engine. Don't know if this is true since I have never tried it. Put in any case put a thermostat in as suggested, then move on to other causes of the motor running hot.

Rick.......

 

I have heard that engines will actually run cooler with a thermostat in place since it gives the water more time to cool the engine. Don't know if this is true since I have never tried it. Put in any case put a thermostat in as suggested, then move on to other causes of the motor running hot.

Rick.......

With a raw water cooling system it should allways run cooler without a thermostat. What you are speaking about above is the old:

"It isn't staying in the radiator long enough to cool story".

That wouldn't hold true with outside water.

I put a thermostat with holes drilled in it to help warm up the jet boat.

 

My 1990 454 runs a 145 thermo and my temps stay at 155 all day. I will do a new impeller next year, Mike.

 

I have the same boat as Scott,1999 210 sundeck 5.0 efi. I live in the Florida Keys and in the summer the water temp in the ocean and gulf is mid to hi 80s. My boat runs at 170 all day and if I put it in the corner it will go up to about 173 and stay there until I back off. Been like that from day one and have had no problems.Merc says that the temps I am running is normal and just fine.I should also tell you my boat is raw water cooled.

 

Mine is also cooled by raw water.. Ric.. quick question where does your meter mark the 17p temp? Mine marks 170 3/4 of the weay before hitting the max of 200