New Merc Thermostats

Does anyone know if the new V8 Pro XS 250's are as bad about getting small debris hung in the thermostats as the 2 stroke Pro XS? I've pulled very small debris from my 14 model 250 several times. I've even got trash in mine after running on clean lakes like Greers Ferry. Must have run over a floating leaf or something. Hoping Mercury resolved this issue.

This topic has 18 replies, 10 voices, and was last updated 6 years, 5 months ago by mike dominick.

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November 1, 2018 at 8:25 am #464913

Redngoo
Participant

I had this same problem with my 200 pro xs when i first got it. A member on this board give me a part number to a plug core kit. I have a verado style(standard) gear case. I have not had a thermostat issue in nearly 2 ys know. The lower unit has to be dropped to install. Meaning the gen 2 gear case and standard gear case are similar i bet the kit will work. I was told it voided no warrantys. As long as the low water picks are where they are there will always be issue. I tell you wood, gravel, leaves, straw and etc. The size of pencil erasers can pass straight through to the impeller and on to the stats. It surprises me there arent more burned impellers as well.

November 1, 2018 at 7:41 pm #464914

00sabre
Participant

Redngoo and Mainliner, I have become an “expert” at cleaning my thermostats. Thank goodness for the Merc Monitor or I would never know they even need cleaning.
I think that the 4-stroke thermostat is a completely different animal than what we have in the 2-stroke but I also would like someone to chime in who owns the new model.

November 1, 2018 at 8:18 pm #464915

Redngoo
Participant

JEHinLa wrote:

Redngoo and Mainliner, I have become an “expert” at cleaning my thermostats. Thank goodness for the Merc Monitor or I would never know they even need cleaning.
I think that the 4-stroke thermostat is a completely different animal than what we have in the 2-stroke but I also would like someone to chime in who owns the new model.

I knew after cleaning mine 3 times in one month something was gna have to be done! And yes a monitor has been the best money i ever spent!!

November 1, 2018 at 9:18 pm #464922

mike dominick
Participant

Up in the northwest this is a constant battle with the ProXS, I switched to Yamaha this year, the SHO I had several years ago never had a problem with it. I
hope Merc has figured a better system for the 4 stroke. It wasn’t a big deal, I always carried spare gaskets and they are easy to change or clean out, but it
was frustrating.

November 1, 2018 at 9:20 pm #464923

JEH in La
Participant

Swimrunbike wrote:

JEHinLa wrote:

Redngoo and Mainliner, I have become an “expert” at cleaning my thermostats. Thank goodness for the Merc Monitor or I would never know they even need cleaning.
I think that the 4-stroke thermostat is a completely different animal than what we have in the 2-stroke but I also would like someone to chime in who owns the new model.

Is MercMonitor an altogether separate thing from having SmartCraft gauges (2012 boat) ?

I’m not familiar with the smart craft gauges. Can you scroll around and see “coolant temperature” on them somewhere? If so then you are good to go.
But yes, the Merc Monitor is altogether different from the gauges you have. It gives you much more information from your engine.

November 1, 2018 at 9:28 pm #464924

basscathash1
Participant

Last couple trips out while running down the lake, the temp is 96 deg. While idling it will get up to 156 deg, sometimes 170 before I see the thermostats have opened and the temp goes back down. This is on a 2018 150HP Pro XS.

November 2, 2018 at 1:40 am #464925

Wheelman
Participant

I know this thread is about water temps, but I’m curious what oil temps are on the new 4-stroke as I believe the merc monitor shows this if I’m not mistaken.

November 2, 2018 at 1:48 am #464917

oldtimer57
Participant

Hard to fix. Problem is fresh water intake => trash in water. This problem has been around forever. Suspect it will continue as long as we depend on direct circulation of seawater for cooling…

November 2, 2018 at 2:11 am #464918

Swimrunbike
Participant

JEHinLa wrote:

Redngoo and Mainliner, I have become an “expert” at cleaning my thermostats. Thank goodness for the Merc Monitor or I would never know they even need cleaning.
I think that the 4-stroke thermostat is a completely different animal than what we have in the 2-stroke but I also would like someone to chime in who owns the new model.

Is MercMonitor an altogether separate thing from having SmartCraft gauges (2012 boat) ?

November 2, 2018 at 2:28 am #464919

basscathash1
Participant

JEHinLa, what tipped you off with the Merc Monitor? Were you running cooler than usual?

November 2, 2018 at 2:44 am #464920

oldtimer57
Participant

When they get stuck, you often get an alarm tone sounding. Mercmonitor will tell you it is a temp issue. Usually happens when either you can’t get to 125 degrees F while idling, or sometimes you do but since there are ‘stats on both heads, you only see the temp on one and think it is OK. The mercmonitor will give you a text explanation concerning the fault condition raised, “temp” is a give-away.

November 2, 2018 at 3:15 am #464921

JEH in La
Participant

basscathash1 wrote:

JEHinLa, what tipped you off with the Merc Monitor? Were you running cooler than usual?

Here is my routine when I launch my boat. I start the motor with the merc monitor on “Temperature”. I idle until I see that the thermostats are operating properly. I will see the temperature climb past 125 deg f and reach somewhere around 139 deg f.and then the temp will drop to 125 deg f and stay there. That is a proper operating thermostat.
When I have trash in it, it will not reach 125 deg f. It will always go above 100 before I will ease off but I won’t run it hard and usually the temp will reach above 125 later because the trash will move and sometimes get flushed out if it is just grass or something like that. If I see this I always clean both thermostats before I go out again. I always find some small piece of wood or leafy stem in them somewhere.

November 2, 2018 at 12:26 pm #464916

Mainliner61
Participant

Yeah I hope the new 4 stroke has a better set up on thermostats.

November 2, 2018 at 4:01 pm #464926

CrappieCat1
Participant

I had a 6 beep alarm earlier this year on my 2015 Pro XS 200 , while idling, with debris in a thermostat. My dash is full, so don’t think I have room to add a MercMonitor. I was wondering about going with the Mobile Vesselview, to monitor engine data. It shows that I will be able to see live engine temp. Has anyone had any experience with this product/app ? Thanks..

November 2, 2018 at 5:06 pm #464927

Redngoo
Participant

CrappieCat1 wrote:

I had a 6 beep alarm earlier this year on my 2015 Pro XS 200 , while idling, with debris in a thermostat. My dash is full, so don’t think I have room to add a MercMonitor. I was wondering about going with the Mobile Vesselview, to monitor engine data. It shows that I will be able to see live engine temp. Has anyone had any experience with this product/app ? Thanks..

Can’t remember exactly when they changed dash styles in the p2. But if you have a speedo you can simply put a monitor in its place. The speedo are mostly useless anyway
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