Do carbed motors need a thermastat?

[G8trbait]

Does a 2003 90hp ELPTO need a thermastat? Without the stat it will just make the engine run cooler wouldn't it?! Does anyone know the negative consequences without one?

Thanks

 

[coastalrichard]

Re: Do carbed motors need a thermastat?

The thermostat helps the motor to maintain the optimum operating temp. Removing them allows water to flow unrestricted through the motor and prevent the motor from attaining adequate temps. Running too cold, just as running too hot, can cause severe damages to your innards. Are you having temp issues?

 

[Chris1956]

Re: Do carbed motors need a thermastat?

Motors are specially designed to run at a given temperature. For example, pistons are expressly machined to expand to very close to round, at operating temperature. Whereas you can run a motor without a thermostat, it will not generally be as efficient.

I am not sure I agree that internal damage will be done, if the motor is run w/o a thermostat. Many Mercs did not have thermostats for many years, and worked just fine, running dead cold at idle and warmer at cruise speed.

 

[merc850]

Re: Do carbed motors need a thermastat?

Here's a page from an article about the first 100 h.p. that explains heat transfer in an inline Merc.

 

[Faztbullet]

Re: Do carbed motors need a thermastat?

The old inline did not have a t-stat and cooled by long water flow and restriction,that one reason you will only see about 15 psi at WOT on a water pressure guage on these. The new motors with t-stats can be damaged for a cold sieze,overheat as water move to quickly and poor performance due to combustion temps...if it got one run it.

 

[G8trbait]

Re: Do carbed motors need a thermastat?

I took my boat an (1860 alumacraft tunnel hull) out this Saturday ran out to where we fish about 8 miles or so and fished all day. On the way back in I had to stop three times because the over heat alarm would go off. I felt the water and it was warm but not hot. It only lasted about 10 mins like I sucked something up. After the 3rd time of stopping I ran another 6 miles with no problems. (although my water pressure gauge apparently got clogged) I pulled the stat out when I got home and it looked like it needed to be replaced, but not horrible. My mechanic/neighbor who has an 05 merc 150 ELPTO mentioned he took his tstat out so I let him take mine out. We cranked it up on the muffs and it ran fine. It was less pressure than normal at idle, but was definitely colder water. I figured my main problem would be less gas mileage on the water since the block will be running cooler. But then again I may not get stranded for a stuck tstat.....??!! Thanks for the many replys.

 

[carholme]

Re: Do carbed motors need a thermastat?

Why don't you just hot water test the thermostat to see if it opens at the right temperature. The test is in the manual.

Gerry

 

[Chris1956]

Re: Do carbed motors need a thermastat?

Merc850, That article had a definite "marketing" feel about it. I doubt it was published in any independent technical Journal. The picture is not a 70s or 80s inline six, as the inline sixes I am familar with have an exhaust cover on the port side, covering the exhaust port and a transfer cover on the starboard side. That picture shows the cylinders on the port side, but has no exhaust port. There is no water cooling on the starboard side.

 

[1nebel0]

Re: Do carbed motors need a thermastat?

Faztbullet nailed it.. I bought a 200h.p and it ran fine on the hose on a stand...got it home and one cylinder had only 50lbs. Popped the head off and saw the damage..Took the front of the motor off and pushed out the piston..."Cold Siezed" The guy had taken out both t stats so the piston expands fast than the cylinder and takes it out..trashed motor been sitting in the garage now for 3 years...School of hard knocks....these motors run great on the hose but unless a compression test is done you are taking a big chance.....

 

[Chris1956]

Re: Do carbed motors need a thermastat?

How do you know the piston seized due to no thermostats? Maybe the PO had a bad waterpump and took out the 'stats because it kept overheating? Maybe the carbs are dirty? Maybe the timing is too advanced?

You had better find out the issue, or it will happen again.