T-stat or not T-stat...

Oshkosh1

Ensign
Joined
Jun 8, 2009
Messages
968
SO...
I'm going to start a mess here I'm sure, but here goes.

Seeing, reading, and hearing all of the problems associated with overheating, due in many cases to faulty T-stats. Why is there a need for them in a boat which is running on "warm" water? I understand the function in a vehicle where occasionally a heater or defroster is needed...but a boat?

Can anyone tell me if they've heard or seen an I/O suffer catastrophic failure due to running TOO cool?(Although I doubt that's possible in the summer).

Would it not make more sense to remove it than to risk the meltdown of a multi-thousand dollar engine due to the failure of a $5 part?

In the hot enviroment of an enclosed engine compartment, and high power settings most boats are run at, I would think that there is absolutely no chance of a shock-cooling effect either.

I dont' run T-stats in snowmobiles just because the un-detected failure can QUICKLY lead to piston meltdown and failure. I just let them idle a little longer before taking off, to allow for warm-up.

Just thought I'd throw this out there and see how it flies!
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: T-stat or not T-stat...

Engines run better warm, and you don't boat in 160? water I would bet.
You also need the thermostat to restrict the flow and slow the flow down so the cooling water has time to absorb the heat from the cylinders. The gauge may show cool, but the engine could be overheating (especially the back cylinders) because of insufficient flow.
It's just altogether a bad idea to run without a thermostat.

They make overtemp alarms in case you don't want to check gauges.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,130
Re: T-stat or not T-stat...

SO...
I'm going to start a mess here I'm sure, but here goes.

Seeing, reading, and hearing all of the problems associated with overheating, due in many cases to faulty T-stats. Why is there a need for them in a boat which is running on "warm" water? I understand the function in a vehicle where occasionally a heater or defroster is needed...but a boat?

Can anyone tell me if they've heard or seen an I/O suffer catastrophic failure due to running TOO cool?(Although I doubt that's possible in the summer).

Would it not make more sense to remove it than to risk the meltdown of a multi-thousand dollar engine due to the failure of a $5 part?

In the hot enviroment of an enclosed engine compartment, and high power settings most boats are run at, I would think that there is absolutely no chance of a shock-cooling effect either.

I dont' run T-stats in snowmobiles just because the un-detected failure can QUICKLY lead to piston meltdown and failure. I just let them idle a little longer before taking off, to allow for warm-up.

Just thought I'd throw this out there and see how it flies!

Ayuh,.... Yer perception is off,....

T-Stats are changed like underpants, 'n ignition coils.... 'cause it's Easy....

99% of Overheatin' issues are Impeller related....

As Don says, yer motor runs better, hotter,....
Lake water cooled, it'll rarely break 100?.... that Tooo Cold....
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: T-stat or not T-stat...

Not so much with carbed engines, but the MPIs sense the coolant temperature and adjust the fuel mixture accordingly. If you have no thermostat the ECM will be constantly running the engine too rich... Wasted fuel, poor combustion process, fouled plugs... soot all over the back of the boat... Nah, I'll say with my thermostat thanks.... :D

Chris.......
 

Oshkosh1

Ensign
Joined
Jun 8, 2009
Messages
968
Re: T-stat or not T-stat...

I'm not advocating their demise...just wondering if they're there as basically a holdover from the fact that most of these engines are just auto blocks modified for marine use.

FYI...I just replaced mine, becuase I didn't know how old it was, and as Bond-O stated, " 'cause it's Easy...."

And speaking of alarms...

I do have a working gauge...and do check it regularly, but is there a way to retro-fit an audible alarm for those times when the wife is driving and...well lets just say she's not as vigillant...it may overheat and wouldn't know it until things got REAL bad.

Thanks
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: T-stat or not T-stat...

...I do have a working gauge...and do check it regularly, but is there a way to retro-fit an audible alarm for those times when the wife is driving and...well lets just say she's not as vigillant...it may overheat and wouldn't know it until things got REAL bad.

Yep... Just buy the 2 switches (temp and oil pressure), and the alarm module... Real easy to do.

I'll post up part numbers and a wiring diagram shortly...

Chris......

EDIT: Have a read of this post... It has all the info you need... http://forums.iboats.com/showthread.php?t=544247&p=3734683&viewfull=1#post3734683
 
Last edited:

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: T-stat or not T-stat...


That kit looks similar. The thing is, you will need the tee so you can have the oil pressure switch (for the alarm) and the pressure sender (for your oil pressure gauge) running from the same drilling in the engine block.... Also I have no idea how loud that buzzer is... I recommend the Merc one because I KNOW that one is loud enough over engine noise.... :D

...
Would the watertemp switch just replace the current sending unit in the T-stat housing?...

No... You still need the sender unit for your gauge to work... You put the temp switch in AS WELL as the sender...

Chris...
 

120_i/o

Petty Officer 3rd Class
Joined
Jan 21, 2012
Messages
76
Re: T-stat or not T-stat...

With out the engine getting hot from the thermostat, the engine cannot burn off moisture in the crankcase. This will result in having acidic engine oil!!!!!!
 

Oshkosh1

Ensign
Joined
Jun 8, 2009
Messages
968
Re: T-stat or not T-stat...

No... You still need the sender unit for your gauge to work... You put the temp switch in AS WELL as the sender...

Chris...

So if I understand correctly, I'll need to drill another hole into the current T-stat housing?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: T-stat or not T-stat...

If this is for the 165, there MIGHT be a hole in the water pump, but otherwise, yeah bang another port in the thermostat housing....
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: T-stat or not T-stat...

Make sure it is under the thermo to get the actual block temp.
Also plumbing is kinda dependant on having the restriction there. You could easily end up with hot pockets in the engine. (not the kind you eat)
 

Old Boat Luvr

Seaman Apprentice
Joined
May 15, 2012
Messages
34
Re: T-stat or not T-stat...

Three reasons for thermostat use:
1. Carburated and FI engines have a choke setting that runs the engine rich until the engine is hot
2. boils off water and other volatiles in crankcase that condense and collect.
3. relaxes steel in cylinder walls reducing bore wear.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: T-stat or not T-stat...

So if I understand correctly, I'll need to drill another hole into the current T-stat housing?

From the drawings I've looked at there appears to be a plug in the main thermostat housing, next to the temp sender. If that's the case use that hole....
 

rednecktech00

Petty Officer 3rd Class
Joined
Aug 28, 2005
Messages
75
Re: T-stat or not T-stat...

I had a new engine put in by a central Illinios moron marina. One of the first screw ups I noticed was the thermostat housing was only finger tight. They had not installed the thermostat.

I discovered this when the bilge filled with water out on the lake. I shortly had a ruined new starter and have recently discovered water in my bellows.

Any way. I also had the head gasket blow out with very few hours. I have wondered if the absence of a thermostat caused the head gasket to blow since it wasn't getting warm enough. Some of the comments on this thread are re-enforcing my thinking.

Can anyone tell me if they've heard or seen an I/O suffer catastrophic failure due to running TOO cool?(Although I doubt that's possible in the summer).

I would say yes.

Before replacing the thermostat and after replacing the carb, the idle was terrible. Starting was tough. After replacing the head with the thermostat in, it finally runs the way I expected the first time I ran the new engine.

I noticed the temp guage never got much over 120. I knew this was too low. Now, I see the comments above:

If you have no thermostat the ECM will be constantly running the engine too rich... Wasted fuel, poor combustion process, fouled plugs... soot all over the back of the boat...

I had noticed the soot on the back of the boat. I had not figured out that link until now.

With out the engine getting hot from the thermostat, the engine cannot burn off moisture in the crankcase. This will result in having acidic engine oil!!!!!!​

Make sure it is under the thermo to get the actual block temp.
Also plumbing is kinda dependant on having the restriction there. You could easily end up with hot pockets in the engine. (not the kind you eat)​

and

Three reasons for thermostat use:
1. Carburated and FI engines have a choke setting that runs the engine rich until the engine is hot
2. boils off water and other volatiles in crankcase that condense and collect.
3. relaxes steel in cylinder walls reducing bore wear.​

I wanna be smart like you guys when I grow up
 

sethjon

Senior Chief Petty Officer
Joined
Jun 8, 2010
Messages
692
Re: T-stat or not T-stat...

SO...
I'm going to start a mess here I'm sure, but here goes.

Seeing, reading, and hearing all of the problems associated with overheating, due in many cases to faulty T-stats. Why is there a need for them in a boat which is running on "warm" water? I understand the function in a vehicle where occasionally a heater or defroster is needed...but a boat?

Can anyone tell me if they've heard or seen an I/O suffer catastrophic failure due to running TOO cool?(Although I doubt that's possible in the summer).

Would it not make more sense to remove it than to risk the meltdown of a multi-thousand dollar engine due to the failure of a $5 part?

In the hot enviroment of an enclosed engine compartment, and high power settings most boats are run at, I would think that there is absolutely no chance of a shock-cooling effect either.

I dont' run T-stats in snowmobiles just because the un-detected failure can QUICKLY lead to piston meltdown and failure. I just let them idle a little longer before taking off, to allow for warm-up.

Just thought I'd throw this out there and see how it flies!

NEVER "not T-stat".
 

Volphin

Lieutenant
Joined
Jun 5, 2011
Messages
1,405
Re: T-stat or not T-stat...

Um, most modern thermostats fail open not closed. Just sayin...

V
 

joewithaboat

Lieutenant Junior Grade
Joined
Jul 3, 2011
Messages
1,172
Re: T-stat or not T-stat...

Um, most modern thermostats fail open not closed. Just sayin...

V

Ive had a 2002 and a 2005 vehicle that stuck closed recently. Never heard of a stat built to fail open, its a good idea though.
 
Top