WHY is This Motor ALWAYS having Tstat Debris Issues?????

[lakeseminole]

I've owned a 2008 200hp Opti, 2004 200hp Opti, and now a 2013 250hp Opti. I have used all three in the same ways in the same waters. I have never ever had an alarm or warning on any of the other motors for tstat issues. After 22 months of ownership, I have had 7-8 tstat alarms and have had to clean or replace the tstats 7-8 times. I do fish very grassy lakes with a lot of timber, but I have used all three motors in the same lakes.

Why so many issues with this motor's Tstats??? I have searched BBC and Google and cant find an answer. Engine info below.

Thanks in advance,
Robby

[Bob G.]

When cleaning or replacing the thermostats, what debris are you finding in them?

Are you cleaning the compressor strainer at the same time?

[06 SB]

I know it is only anecdotal but I am with you. I had a 2010 200 ProXS that was a junk collector. It got to the point where I carried extra T-stats and gaskets in the boat along with the required tools. I could actually clean them on the water.

My 2016 250 ProXS and now my 2017 175 ProXS do not seem to collect anything. I now just keep the tools and gaskets in the truck.

[bass.man65]

Lets just say it could have been better designed. Mercury claims it works as designed, just because you run your engine in debris it's not their fault.

[Savage]

It helps a ton to have the motor trimmed up a lot while on the trolling motor in shallow water. I always trim the motor up a bunch before fishing shallow and have only had to clean thermostats 3 times in the last 19 years of owning and operating Optimax motors.

[Bryanmc57]

Not sure what the root of the OP's trouble is, but I've had to pull and clean the stats on my 2006 Opti 200 so many times I can do it in my sleep....

[Rip Bass]

I don’t know why one Opti would be worse than another,but I think having the low water intake right on the nose has something to do with it. I own an Opti also,no complaints here but I am picky about maintenance.

[JOE54]

would think you could order trailer parts from manufacturer or after market and any good auto or frame shop could replace it in hours ,MERC guys gotta eat too , and race cars break also just be patient

[Stroker3.2XS]

Different lower units / water inlet holes on the 200's compared to the 250? Fleet vs Torque master

[Fishysam]

I would bet that the lake conditions have changed not your habits not the motor as an individual. Maybe if it has different water intakes.

[Dan21XRS]

It's the nature of the beast... Next time you have to clean the thermostats reassemble it minus the thermostats, hook the water up the the flush port on the back of the engine and flush it for a couple of minutes, then reassemble it with the thermostats. I think sometimes debris gets trapped in the water passage and if you don't flush the system it just keeps reoccurring... I fish deep clear lakes about 85% of the time that gets floating trash on the surface after spring rains and sometimes I'll clean and flush multiple times a week... Dan

[M4A1]

I've owned a 2008 200hp Opti, 2004 200hp Opti, and now a 2013 250hp Opti. I have used all three in the same ways in the same waters. I have never ever had an alarm or warning on any of the other motors for tstat issues. After 22 months of ownership, I have had 7-8 tstat alarms and have had to clean or replace the tstats 7-8 times. I do fish very grassy lakes with a lot of timber, but I have used all three motors in the same lakes.

Why so many issues with this motor's Tstats??? I have searched BBC and Google and cant find an answer. Engine info below.

Thanks in advance,
Robby

Have you been flushing the motor when you take out the thermostats?

[tomloans]

.

[Z518 Comanche]

It's the nature of the beast... Next time you have to clean the thermostats reassemble it minus the thermostats, hook the water up the the flush port on the back of the engine and flush it for a couple of minutes, then reassemble it with the thermostats. I think sometimes debris gets trapped in the water passage and if you don't flush the system it just keeps reoccurring... I fish deep clear lakes about 85% of the time that gets floating trash on the surface after spring rains and sometimes I'll clean and flush multiple times a week... Dan

^^^^^ this

[99intimidator]

Mine stick all the time but what I found what works for me. I put the motor in gear and run the motor 1500 to 2000 rpms. When the motor gets to around 120 degrees I shut it off . Then I just watch the temp gauge with motor off when it gets to 130 I fire the motor back up and usually they will clean out . Sometimes I’ve had to do 2 or 3 times to get the thermostats open enough to clean out. This works for me but I’m down south where it’s not so cold.

[EuropeanAM]

I've owned a 2008 200hp Opti, 2004 200hp Opti, and now a 2013 250hp Opti. I have used all three in the same ways in the same waters. I have never ever had an alarm or warning on any of the other motors for tstat issues. After 22 months of ownership, I have had 7-8 tstat alarms and have had to clean or replace the tstats 7-8 times. I do fish very grassy lakes with a lot of timber, but I have used all three motors in the same lakes.

Why so many issues with this motor's Tstats??? I have searched BBC and Google and cant find an answer. Engine info below.

Thanks in advance,
Robby

Your 250 ProXS has a totally different gearcase- which is perhaps a portion of the problem.

The book answer is the most obvious: Your engine's cooling system was designed to be cooled with simply clean water. Avoid debris laden water to prevent debris in the system.

Ok... yeah right. So look at Savage's comment. I have a couple dozen anglers that couldn't keep the same thermostat in a motor for 3 weeks. Even back in the 200/225 Standard Optimax days. But now- they're running 250 ProXS Optimax models and MIGHT see one thermostat event a year.

The reason? They listened and recognized the areas where they were picking up the lions-share of their problems:

-TRIM THE BIG ENGINE UP when on the trolling motor and in shallows.

-FLOAT the boat off the trailer (rather than "powering" it off)

-Drop trailer deeper in water when trailering to shorten attempts at "power loading".

The same will apply to the 4-stroke models. While they have their own gearcase versions- most of them have the same or similar water inlets, and the same basic water pump.

[lakeseminole]

Thanks for all the input. The different gearcase is what I was thinking but didn't know for sure.

[Louie]

I had a 2016, now a 2017, 250 pro xs with tm lower on it. I had replaced thermostats in both motors sub 100 hours due to starboard side t stat faults. I too have had everything from small pebbles lodge in them, to small hunks of wood. 100% of the time, I would notice the temp not reach operating temp on the digital gauge. If you don't have one that provides a read out, its well worth the investment. I have become quite good at taking these things out lol. Pretty annoying. I also believe on the new motors, if you let them idle too long, I believe it must run a self test and will throw that code. I didn't know at first your not supposed to let them idle more than a few minutes. I would launch, start it, park the truck, walk back down, push off and idle out past buoys... and it would chime at the exact same time every time, even with new t-stats on both engines, very low hours.

I did a new impeller kit last night and took some wood out of a t-stat, I did not know about the flush port. Is there a procedure for that? Is it the plastic pipe plug opposite of the pee hole on the back of the cowling?

[EuropeanAM]

I did a new impeller kit last night and took some wood out of a t-stat, I did not know about the flush port. Is there a procedure for that? Is it the plastic pipe plug opposite of the pee hole on the back of the cowling?

Please remember that we should have only one engine per post, to avoid confusion and/or Post Hi-Jacking. See the Announcements at the top of the Forum for more information.

The coastal flush port is located where you suspect- it should be used with the engine OFF, and trim set to LEVEL TRIM (down and level) ONLY. It's purpose is to assist in the removal of brackish water and salt (it does not do much for removing wood or pebbles).

Don't forget the Air Compressor Strainer... and that it's quite common that a brand new thermostat may become subject to more of the same debris if you still have debris trapped in the coolant passages.

[fishraptor]

Mine stick all the time but what I found what works for me. I put the motor in gear and run the motor 1500 to 2000 rpms. When the motor gets to around 120 degrees I shut it off . Then I just watch the temp gauge with motor off when it gets to 130 I fire the motor back up and usually they will clean out . Sometimes I’ve had to do 2 or 3 times to get the thermostats open enough to clean out. This works for me but I’m down south where it’s not so cold.

Thats very interesting. What's the philosophy behind why that sometimes works ? Did you hear this from another or is this your own find ?