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View Full Version : Thermostat....... is it neccessary?



Stix Magill
08-07-2001, 08:14 PM
I bought my Donzi 20' Minx 2 weeks ago and the temp gauge has read only slightly above cold. Today, I asked the previous owner if the guage was fully operable and he said that it was, but he had removed the thermostat so as not to allow clogging and therefore overheating if there was a problem. What's the deal fellas? What should I do, if anything?

Thanks,

Stix Magill

http://stixmagill.homestead.com/files/donzi101.jpg

Philip
08-08-2001, 06:12 PM
I have a pair of 200hp Yamahas, and over the weekend one of them decided to shut down. The mechanic took out both thermostats, and told me to run it, he said better run it very cold than hot. He also told me that it is common to remove thermostats in racing boats.

RickR
08-08-2001, 06:46 PM
A 4 cycle engine needs a thermostat. It will improve your idle, fuel efficiency, reduce engine wear and help remove moisture from the engine oil.
I'd run a 145 or 160 degree. The 145 is available @ NAPA.

Rootsy
08-08-2001, 06:58 PM
Up until a few years back.. oh bout 5 make it merc's standard thermostat was 142 F... now they use a 160 i believe....

blue-z
08-08-2001, 07:15 PM
As long as that gauge shows some temperature reading without the thermo. I would hate to lose an engine due to overheating because my gauge lost a wire, wasn't functioning and consequently I did not know the boat was overheating. We all know stranger things have happened. A bad gauge wire and an overheat unnoticed could prove devastating. They build them with thermos, so I put one back in.

marcdups
08-08-2001, 07:27 PM
Stix, removing a thermostat by a mechanic is a proven fact of his incompetence, they were put there for a reason, ie: to run at specified temps, there has to be another problem if the engine is overheating !! I would install the proper thermostat for your engine and inspect the water pump and if it is good replace the impeller as precautionary maintainance.

Marc
sooner is better than oups :o

RickR
08-08-2001, 07:33 PM
I use a low oil pressure/high water temp audio alarm to suppliment my water temp AND oil temp gauge. They are available @ Weat Marine for $35 and are stock on many Mercs.

BTW ALWAYS let you engine cool to normal operating temp before shutting down! After a high speed run this could take >5minutes. I usually let engine cool at idle and in gear so the drive can cool also.

Moody Blu'
08-08-2001, 08:17 PM
I dont run a thermostat, but then again I am having a problem with rising temperatures, I think my impeller has had it.

One thing you should know before you stick a thermostat in the engine, is that if you run in salt water, at about 160 degrees the water starts to cook the salt into little crystals and after a while it blocks the water flow.
In my opinion anyone who runs a thermostat in salt water is asking for trouble.

another thing is that if you dont run a thermostat and your engine temp does start rise more than usual you have more of a chance of saving your engine.
especially if the thermostat is rated for 195 degrees (like my 351w is) you dont have much of a chance of saving your engine.

If your looking to buy a closed cooling system.
That would be the only time I would run a thermostat in a boat.

temperature control is a very sticky situation which you really need to play right.
stay cool until you get a closed cooling system
"in my opinion"
:cool: :cool: :cool: :cool:

Moody Blu'
08-08-2001, 08:22 PM
oh! one more thing, if you dont want "clogging" in the engine go out and buy a strainer.
I have a sherwood strainer now and it helps a lot I remember before I had one and I had to blow out the junk that was stuck in the engine block.
GO BUY ONE NOW!!!!!

:D :D :D :D