Thermostat rusting

[Dave Cawley]

I have a 2005 Mercury 30 efi. I bought it new and is on a 21 year old small Boston Whaler. It is moored in Dartmouth, Devon, UK on a public mooring, so no fresh water available.

It get used about every other week, and in August almost every day, about 20 times a year in total. The river is tidal and salty.

The thermostat keeps rusting up, this one has lasted less than 18 months. I got stranded 10 miles away with the continuous alarm. Is there a fix, or to be sure should I change the thermostat every 3 months ?

Thanks

Dave

 

[Dave1027]

Re: Thermostat rusting

How about a 5 gallon can of fresh water and and pump it through the flush connector?

 

[sschefer]

Re: Thermostat rusting

This may sound excessive but I change my therms annually (on the motors that have them) as part of routine maintenance.

 

[Dave Cawley]

Re: Thermostat rusting

They are around $70 which is a lot to pay every year? Five gallons of water? cheap beer maybe.............

Dave

 

[sschefer]

Re: Thermostat rusting

They are around $70 which is a lot to pay every year? Five gallons of water? cheap beer maybe.............

Dave

Yeah I hear ya, I keep a separate bank account just for boating. I can get your therms for 26.25 each but can't drop ship them to the UK.

 

[Dave Cawley]

Re: Thermostat rusting

That's a good price! I'm on the verge of selling it and buying a used boat with a Mercury 60 efi, hopefully it won't have a thermostat the size of a coin!

Thanks

Dave

 

[Dave1027]

Re: Thermostat rusting

I thought of another idea for you. How about you simply remove the t-stat? It would take longer to heat up but may be worth it.

 

[Dave Cawley]

Re: Thermostat rusting

I had thought about that, but would the engine run cold and the plugs foul up?

Regards

Dave

 

[nbnewbie]

Re: Thermostat rusting

just a thought

an exerpt from a web page i found

Here is where the thermostats are. I install 1/8 stainless
steel fender washers in place of the thermostats.
1/8 washers have a hole in them just a little smaller
than 1/8. They will bleed off just enough air and
water to keep the block full without compromising
head temperature. As long as you are using the 1/8
washers it will not mater if you run two hoses off
the heads or go from one head to the other then run
the hose down (the way Mercury does it).

http://www.us1.cc/racingcoolingsystem.html

note the ss won't rust

 

[Dave Cawley]

Re: Thermostat rusting

Now that is a good idea!!

Dave

 

[Dave Cawley]

Re: Thermostat rusting

As suspected the 1/4 price thermostats will not ship from the USA to the UK. But I should have looked at USA eBay!! They are there, about 1/5 of the UK price and the postage isn't too bad either!

Regards

Dave

 

[sschefer]

Re: Thermostat rusting

just a thought

an exerpt from a web page i found

Here is where the thermostats are. I install 1/8 stainless
steel fender washers in place of the thermostats.
1/8 washers have a hole in them just a little smaller
than 1/8. They will bleed off just enough air and
water to keep the block full without compromising
head temperature. As long as you are using the 1/8
washers it will not mater if you run two hoses off
the heads or go from one head to the other then run
the hose down (the way Mercury does it).

http://www.us1.cc/racingcoolingsystem.html

note the ss won't rust

The use of washers in place of the thermostats is a method designed for use with engines that have modified exhaust plates and usually no poppet valves. 1/8 or 3/16 id washers can be used depending on the extent of the modifications. I run the 1/8" in one of my dry stacked motors but I don't run that motor in cold temp water because it does not warm up well and I might risk cold seizing the engine. Too many expensive parts in that motor. I might add that the motor only lives for about 100 hours between rebuilds..

It's always best to stick with the stock cooling system on a stock motor.