outboard temp

[jmsjordan]

just installed a temp sensor on a 2000 200hp Mercury EFI. Its running at 210 operating temp, tell tale temp is dead on 143 deg. The temp sensor is on the block. does this temp sound to high? cant find any info on what it should be. anyone else have a comparision?
Thanks
James

[Jdkxtreme]

just installed a temp sensor on a 2000 200hp Mercury EFI. Its running at 210 operating temp, tell tale temp is dead on 143 deg. The temp sensor is on the block. does this temp sound to high? cant find any info on what it should be. anyone else have a comparision?
Thanks
James

Water boils at around 212....

[tkwalker]

just installed a temp sensor on a 2000 200hp Mercury EFI. Its running at 210 operating temp, tell tale temp is dead on 143 deg. The temp sensor is on the block. does this temp sound to high? cant find any info on what it should be. anyone else have a comparision?
Thanks
James

I really don't like fooling with these new big block motors ... But in comparrison I realize that this is theromstat controlled powerhead ... Not like a closed loop system that you have in your vehicle.. A closed loop system is controlled pressure and temp ... That is why it is not uncommon that some auto cooling systems operate at 240 deg's ... (closed loop sys. using a radiator)They are not open to the atmosphere this is why open systems boil at 212 deg's ... (Remember you don't have to winterize an outboard cooling system)

Outboards are open systems ... It has a water pump that takes cooling water from the lake. The only temp control it has is in the combustion area of the powerhead via the thermostat where it develops it most heat ...

With that said ... 140 deg's is the threshold of pain ... To me this is excessive at the tell Tail.... I have never felt Tell Tail discharge that hot ... I am not sure what the power head temp should be depending on the control element, the thermostat... The tell tail discharge is just a small precentage and is not in the actual water flow cooling system it is in parallel ...

Can you hold your hand in the discharge flow ?? It may be warm even in lake water or hose ... But not so hot you can't keep your hand there or or be even uncomfortable ...

If you have good water flow out of the Prop and tell tail... You should be able to comfortably hold your hand in both places ... But stay away from the prop ... If you want to check this water temp remove the prop and feel the water coming out of your lower unit or Leave that to a professional !! ...

I will do a little research and see what range of temps these motors should run ... <'TK>< :)

[jmsjordan]

thank you much for the info!!! The therm's are 140 deg. the overheat warning has never gone off, i have just noticed steam from the tell tale and now making me wonder and brought forth the temp switch so I can monitor it. If the thermostat is 143 deg, I assumed the tell tale would be close to that. And NO i certainly cannot hold my hand under it for more than about a second, or on the heads. It has always "sputtered" a little at idle and streams pretty well at higher RPM's. Water pressure is around 5 at idle and moves up to 12 until valve opens around 1500 rpm and drops down 7 and goes up to 15 at WOT. Seems to be getting pressure. just need to know if this temp is "normal" or start looking at a blockage or poppit valve. Therms replaced last year.
Thanks again TK!!

James

[tkwalker]

thank you much for the info!!! The therm's are 140 deg. the overheat warning has never gone off, i have just noticed steam from the tell tale and now making me wonder and brought forth the temp switch so I can monitor it. If the thermostat is 143 deg, I assumed the tell tale would be close to that. And NO i certainly cannot hold my hand under it for more than about a second, or on the heads. It has always "sputtered" a little at idle and streams pretty well at higher RPM's. Water pressure is around 5 at idle and moves up to 12 until valve opens around 1500 rpm and drops down 7 and goes up to 15 at WOT. Seems to be getting pressure. just need to know if this temp is "normal" or start looking at a blockage or poppit valve. Therms replaced last year.
Thanks again TK!!

James

James, how long has it been since the water Imp has been replaced ... Also has the boat set idle (Not used for any length of time since Spring ) <'TK><

[tkwalker]

James I re-read your last post ... Steam is bad ... One of these three things is your problem .... Improper water flow!! <'TK><

1. Water pump Imp. needs to be replaced.

2. Replace the thermostat.

3. Blockage in the water passages ... (Mercury's for some reason are real bad for hosting Dirt Dobbers, I don't know if it is the size of entry areas or volume of passages. But I'll have to clean out 4 or 5 merc's a year for this reason. I have never had to clean out OMC/Bombardier's Don't know why ??)

James, there is a lot of unknown's here It is hard to trouble shoot Outboard problems of the internet or phone .... Hope this helps <'TK><

[jmsjordan]

Thanks for the help so much!! I will change out the water imp and test therms. What is best way to clean out any blockage? Thanks again for you time.
James

and there are a lot of dirt dobbers around the house

[SAMBOLIE]

I have a Merc Optimax that attracts dirt daubers. I launched last year and as usual checked the pee tube before leaving the dock. No water was present. The pee hole was full of mud. I found a piece of weed eater line near the ramp. It was the .105 size. I was able to insert this through the mud and clean open the hole. Apparently there was an unborn dauber up in the tube because when I started up the water blew it and more dirt out.
The weed eater line is perfect for cleaning the tube because it will not damage the rubber hose as wire might.
I now keep a piece of the line in the hole when the boat is not in use.
You have to double the line and insert both tag ends to fit properly.

[Halli]

Keep us posted as I have just bought an 89 BMC with a 200 Black max and replaced imp but now see no pee but it cools at mid/open throttle yet seem to get hot when slow running Ie not on plane.


I am so used to my old 50 merc (16' bass tracker) that Never had a problem.

[jmsjordan]

Had a Johnson 25hp for years...so easy to fix. This is a big difference.

Bought a temperature gun. block is 145 at bottom to 165 at top. The gauge isnt reading correctly, but I'm sure there shouldn't be such a difference in temps.

Put the ears on and water from prop was luke warm, water from lower unit was the same. Water from tell tale..145 deg and is after the thermostats, I think it may be normal for these mercs to have the high temp coming out. Water from top of motor has plenty of flow (disconnected to check) and likewise from poppit. will continue to watch it.
Thanks for the help
James

[jmsjordan]

Keep us posted as I have just bought an 89 BMC with a 200 Black max and replaced imp but now see no pee but it cools at mid/open throttle yet seem to get hot when slow running Ie not on plane.


I am so used to my old 50 merc (16' bass tracker) that Never had a problem.

Stuck thermostat can cause this, on the Mercury's a Poppet Valve opens up at higher RPM's and would cool engine down. But at idle, therm's are doing the cooling and if stuck closed...then a overheat condition will come about.

[tkwalker]

Since we were on the subject for Motor over heating This is a motor I am working on for a fellow member wordty ... Overheat and seized motor ... Cool off and restart ... <'TK><

This is a 37 year old 15 HP OMC (Johnson/Evinrude) , whether a 15 HP or 250 HP ... Basic principle ... Here are pic's of this 15 HP ... Found the Thermostat to be the culprit ... Also removed head to check for seize damage ... None found ... ...