XR2 problems continue

**ctered** · 09-06-2007, 01:52 PM

I have finally got water pressure after relocating where I tap off. I then replaced both thermostats and lo and behold I now have a steady pee stream. The problem now is after it warms up and I turn it off and then start it again the overheat warning buzzer comes on and stays on. Only once has the buzzer gone off when the motor has been running. The motor is not hot and the oil tank is full. The buzzer stays on constantly. If I leave the motor for a half hour or so and start it there is no buzzer. Let it warm up and shut off then start and alarm is back. Any ideas.

Mark

**MidnightCarving** · 09-06-2007, 01:56 PM

check all the senders by disconnecting them individually, if its not one of them, then its the oil warning module, warning modules fail alot on these motors and cause odd behaviors like that.

**ctered** · 09-06-2007, 01:59 PM

Thanks. I will go try that.

**transomstand** · 09-06-2007, 02:02 PM

You mentioned 15 psi at idle on the other thread, that's a bit high, and could indicate a restriction.
Before you go ripping the whole thing up, do 2 things, independantly verify engine temp, you can stick a jar under the telltale with a candy thermometer in it, water temp should be about 150°. Then you need to confirm you have the correct temp sensor in the head (Merc makes 2). They can be identified by wire length, but I don't recall off the top of my head which is which.
It's normal for engine temp to rise after shutdown, so you may be running on the edge of overheating constantly.

Pete

**macutty** · 09-06-2007, 02:04 PM

over heat is a constant alarm where low oil is a beep-beep-beep-beep.

If its a constant alarm then look at the acutal temp sensor (in the head on the 1,3,5 bank of cyclinders).

Mine was doing this and after checking the sensor the lead on it was badly corroded and needed to be replaced (and this is a fresh water only motor).

Also check the actual alarm buzzer itself and make sure all electrical connections are tight and corrosion free.

**macutty** · 09-06-2007, 02:08 PM

The shorter sensor (merc part# 97465) is for ME-6042946/MA-6038681 and above, the longer 19.5" sensor (merc part# 78799 is for motors below these serial #'s.

Originally Posted by transomstand

You mentioned 15 psi at idle on the other thread, that's a bit high, and could indicate a restriction.
Before you go ripping the whole thing up, do 2 things, independantly verify engine temp, you can stick a jar under the telltale with a candy thermometer in it, water temp should be about 150°. Then you need to confirm you have the correct temp sensor in the head (Merc makes 2). They can be identified by wire length, but I don't recall off the top of my head which is which.
It's normal for engine temp to rise after shutdown, so you may be running on the edge of overheating constantly.

Pete

**Hydrophobic guy** · 09-06-2007, 02:12 PM

Definately get a temp guage.
And if you turn a lot of rpm get rid of the oil injection.
If you do those things you can round file all that alarm crap.
I have a red light and a buzzer still hooked to the overheat sender
with a seperate temp and pressure guage. Better to be safe than buy a PH.

**transomstand** · 09-06-2007, 02:54 PM

Originally Posted by macutty

The shorter sensor (merc part# 97465) is for ME-6042946/MA-6038681 and above, the longer 19.5" sensor (merc part# 78799 is for motors below these serial #'s.

The later sensor is much higher temp as I recall, something like 210°?

Pete

**ctered** · 09-06-2007, 07:49 PM

Water temp coming from pee stream is around 118F and the hottest temp read was on middle cylinder head at 138.5 F measured with a temp gun. The engine by all means is not hot. Water pressure is 15 psi at idle(1000rpm). When throttled up to around 1100rpm the pressure goes from 15 down to 7 and back and forth as if the poppet is opening and closing. Go higher in rpm and the pressure goes back up to a constant 15 psi. I pulled the green wire for the temp ground and alarm stayed on. I pulled the wire for the oil and the alarm stayed. I shut the motor off and had to remove a tie strap to unplug the temp sensor white wire and restarted the motor. No alarm. Plug the wire back in again no alarm. I am beginning to think the module is bad.

**macutty** · 09-06-2007, 08:00 PM

is it just me or does that idle sound WAY to high? You should be idling aroun 750-800 in neutral and ~650 in gear I though?

**macutty** · 09-06-2007, 08:01 PM

Also 15lbs pressure is too low at WOT....you should have something like 25-30lbs

**transomstand** · 09-06-2007, 08:23 PM

I'm not too good at diagnosing those modules, oil, idle, advance, because the only place I ever see them in my shop is in the trash can

I just never cared for them, and I've seen plenty of good engines turned into junk because of them

**T-REX** · 09-07-2007, 08:16 AM

amen My Brutha!!!:d

**rossi** · 09-08-2007, 04:20 PM

I had the same problem and it was the temp sensor. I went through the process that Midnight Carving had described. My temp gauge was reading normal so I figured it was a sensor.

**stiletto200** · 09-09-2007, 06:43 AM

sorry for butting in but..
i noticed that hydrophobic had connected a red light to the warning alarm. how did you do this? is there not an issue with resistance differences in the wires/reading for the alarm?
also my temp guage has never read real hot but i am only running about 10pds of water pressure at WOT and 0pds at idle, but when the t-stats open the pisser is really gushing......please explain?(i t-ed in the pressure guage at the fitting at top of the block like everyone suggested too)

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