6.2L cooling issue
 

So I finally got around to replacing the oil pressure sensor today and when I cranked her up, everything seemed fine for the first several minutes. My temp started rising like it should and then after about 10 mins. I noticed that the temp gauge suddenly dropped to 100. After 5 seconds or so, it then jumped to about 160 for about 5 secs, then back down to 100 again. So I shut her down. I then felt the risers...here is the odd part...the starboard was warm( I could keep my hand on it for about 4-5 secs) but the port wasn't warm at all!

Ay ideas?

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I forgot to mention...I do not have a closed cooling system. I am running off a garden hose. I do not connect thru the outdrive but I have a T on my raw water pickup line next to the water pump.


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Re: 6.2L cooling issue
 

Hey cst ,
from what I understand a broken flapper can cause this type of grief. Might be worth a shot to check them both.

Just a thought :)

Larry

Are you talking about my exhaust flappers? I did just have them replaced late last year when I had my risers replaced, but I will check them to make sure. But doesn't that keep water from flowing back into the engine from the outdrive?


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Re: 6.2L cooling issue
 

Yes , ain't them then I doubt.
One other thing is there are 3-4 different riser to manifold gaskets according to mercruiser.

Larry

Re: 6.2L cooling issue
 

I have replaced my temp sensor on the thermostat housing. Come to find out that I have a second temp sensor that is located directly across from the first one. According to Merc, I should only have one and it is the regular sender that has one wire that slides onto the threaded end. So does anyone know what this is and why?

Re: 6.2L cooling issue
 

Here is second pic of mystery item...

Re: 6.2L cooling issue
 

I also have two on my 4.3 Chris.
The one your talking about on mine is a sensor for the engine alarm system. :)

Would that be the over temp alarm? I guess then that would not be the cause of my temp gauge going crazy. i guess I will start chasing ground wires and see if that is the issue. I also can't find that item in the parts diagram. I even called our local Merc dealer and they didn't know either. Maybe I'll look under electrical instead of cooling...


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Re: 6.2L cooling issue
 

Yes Chris.
Here is a pic:

http://www.mercruiserparts.com/Show_...Point+Drain%29

#6 is the sensor. If you look up your serial # it will give you the exact one but I think they are all the same for the 6.2L

Hey Colorado. I couldn't open that page on my ipad, but I found it. Marine engine is listing it as a "temp sensor". I guess I need to trace the wires and see if both sensors I have go to the gauge. Thanks for the help!


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Re: 6.2L cooling issue
 

See if you can find the wiring diagram in the Merc manuals section. I'll look too.

I just got a message from someone that the single wire temp sensor is wired in the same circuit with the outdrive oil sensor and the oil pressure sensor. And all 3 are for the alarm circuit. The other sensor that has 2 wires is for the temp gauge. That makes sense, but I haven't confirmed it yet.


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Re: 6.2L cooling issue
 

After looking at you attachment again , it looks as though silicone was used on the sensor. That is a no no. That could be your grounding issue right there. Clean it good and reinstall , and see if that solves the prob.
Sorry I didn't catch it before.

Are you talking about the red "thread dope" on the threads? That is supposed to be used instead of thread tape is what I was told. When I bought the other single wire temp sensor from the dealer, that thread dope was already pre applied. The sensor in the pic has not been replaced but has the same stuff on the threads.


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Re: 6.2L cooling issue
 

OK , my bad. Just happened to notice :)

No worries Colorado...it's all good! I really appreciate all of your help.


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