140 degree thermostat?

[dburns]

My raw water a4 has run at 180+ degrees for the past five years. Vinegar flushes and pressure flushes with the water hose haven't changed anything. I finally pulled the thermostat and it had 140 stamped on the bottom, so I assume it's a 140 degree thermostat. It was cleaned in vinegar and placed in water on the stove. It opened at 160 degrees. Is it defective? If so, should I replace it or just leave it out and use a bypass valve?

I've been lurking on the site for the five years since I purchased JaVa.

The engine is an early '70s model that replaced the original 1963 model in my Morgan Tiger Cub, best I can tell. Can't imagine what caused the replacement. The engine was covered in rainwater for several years when JaVa was a derelict in a boatyard in the '90s and early 2000s after hurricane Fran. The previous owner r&r'ed it and it runs like a top, starts easily and has only stranded me when a coil failed on a 200 mile trip two years ago. (At the worst possible time, half-way through the extremely narrow Alligator/Pungo River Canal at night, with tugs/barges coming every hour. That's a story unto itself...)

After reading all the posts I can find about thermostats, I hope to get an opinion or two.

[Dave Neptune]

dburns, first welcome to the Afourian forum!
If you have been running in salt water at 180 you probably have a good coating of calsefied salts in the engine. I suggest that you flush well preferably with acid before doing anything. The T'stat should open at the stated temp or it is faulty. The t'stats can be a problem around salt water when RWC'd as anytime the BLOCK gets to 160 the calsefied salts can deposit and it starts again. You need to stay below that temp. Running with the t'stat is a choice regarding the engines temp vs longivity according to most. I have run for 26 years without one and have had no issues with my 42 year old RWC'd beastie. I ran until last year with the standard bypass configuration and would show around 125 when cruising and 150 after shutting down. I have since modified the plumbing and now cruise at 135 and still hit 145~150 after shutting down an improvement in my humble opin.
Where and in what temp waters do you play?

Dave NEptune

[Mo]

I second that.

I think along the same lines as Dave....no T-stat and do an muriatic acid flush of the engine asap. It will stay cool for you after that.

[JOHN COOKSON]

If so, should I replace it or just leave it out and use a bypass valve?

Do you have a bypass valve now? I can't tell from the post.

In a RWC engine, with a properly functioning thermostat, you need adequate output from the water pump, clean engine passages to let the water flow and the heat to transfer and you should be good to go.

1. Acid flush.
2. Valve on the bypass if you don't have one already.
3. Check the water flow through the engine. This is best done by pulling the hose off at the hot section water injection point and aiming it into the cockpit. Should be like a garden hose at ~ 1500 RPM.

TRUE GRIT

[dburns]

I sail out of Topsail Beach NC. The water temperature can easily get into the 80s and air temperature 90s to 100 in the hotter months.

I just got the parts and pieces for a bypass valve and installed it. Looks like an acid flush in the making for this weekend. Two questions about the flush procedure:

Is the thermostat removed or left in?
What position is best for the bypass valve?

Many thanks for the advice!

[Mo]

I would leave the T-stat out and leave the by-pass 1/2 open....keep an eye on your temp guage...it might even stay as low as 130...

also...I use NGK XR4 plugs...a bit hotter than your everyday A4 plugs. They keep the combustion chamber clean and just finished my second year on them without a hitch. So, no t-stat and the plugs will keep the carbon at a minimum...it works. Plugs number 1 to 4 ..right to left.

[ndutton]

Bypass position for the flush procedure is closed and as Mo said, thermostat removed.

[roadnsky]

Is the thermostat removed or left in?
What position is best for the bypass valve?

Many thanks for the advice!

Flush procedure...

http://www.moyermarine.com/forums/sh...pressure+flush

[Sony2000]

''also...I use NGK XR4 plugs...a bit hotter than your everyday A4 plugs. They keep the combustion chamber clean and just finished my second year on them without a hitch.''

Not only are they hotter, their reach, reaches the center of the combustion chamber. I dislike the regular plugs for that reason.
Or is it, they are hotter because their longer reach makes them hotter?

Anyways, I'm sold on them.

[Mo]

Sony...I think you are the first convert to the NGK XR4's...glad you like 'em too. Mine are in a photo in post #6....two years on those as you see them.

[edwardc]

...Or is it, they are hotter because their longer reach makes them hotter?...

I believe that its the longer electrode and insulator that makes them hotter. It provides more thermal resistance to the flow of heat from the tip of the electrode to the body of the plug and the block, causing the tip reach a higher temperature at equlibrium.

[JOHN COOKSON]

dburns

The standard advice is to remove the thermostat before acid flushing. I,like you, knew that my thermostat was working correctly. So rather than remove it here's what I did:
In a 5 gallon bucket mix the acid and water. Remember to add acid to water slowly with stirring. Eye protection is a good idea.
Run a tube from the water pump to another 5 gallon bucket. Supply enough water to this bucket to keep the water pump pumping. Start the engine and run it long enough and fast enough to get the thermostat fully open. Idle back and clamp or restrict the bypass hose. Put the intake tube into the acid and aspirate it into the engine. While the acid is sitting in the engine you can rig up your catch system. Start the engine and aspirate 5 gallons of water into it. Stop the engine and remove the catch bucket. Finally start the engine and flush it with fresh water.
===============================
The water temp in my area is 60*-70*. I run at ~ 150* - about 80* higher than the outside water temp (RWC). I have the original 3 spring thermostat which does restrict the flow a bit. If you can get your engine temp down to 160* in 80* water, with a thermostat, you will have done good.
==============================
The amount of bypass restriction necessary is different for each engine. One size does not fit all. Here was my experience:
The Moyer kit came with a fixed restrictor and a valve. With the restrictor in place and the valve wide open the temp was under 120*. With the restrictor removed and the valve wide open I run at 150*. If I close the valve 1/4-1/3 turn the temp goes down to ~ 125*. Apparently the wide open valve supplies the amount of restriction my engine needs.

Have fun.

TRUE GRIT

[dburns]

All of this helps a great deal--many thanks to everyone. Now for the really tough decision: leave the thermostat in or take it out for the duration.

[hanleyclifford]

I agree with the others; lose that thermostat (but keep it on board)....but I gotta know; what were you doing in the Alligator/Pungo Canal at night?

[Mo]

T-stat out

T-stat out and welcome to the world of trouble free cooling. Install by-valve (MMI has them)... I do a muriatic acid flush every 2 or 3 years just to ensure passages remain clean...run the hotter plugs. Wait for it. The day may come when you have to push hard in chop and it's nice to look down at that temp gauge and see you are nowhere near the verge of overheating. You may indeed watch your gauge and maintain a happy little grin as the spray hits you in the face Peace of mind.