Is some water in the bilge expected, or an obvious problem?

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

Great news! No leaks. Dry as a bone!

I replaced the tach... and that's now working.

Still diagnosing the temp gauge. here's what I found:
1) Using a IR gun, I checked temps frequently. the starboard side definitely heated up faster and hotter than the port side. the highest reading I could get was 143, on the lower side of the starboard manifold, near the plugs. (@1300rpm)
2) the gauge is not moving at all.
3) when I flushed it, it took almost 10 minutes at 1300 rpm before the tstat opened, and the only way I could tell was that the output water was discolored for a few seconds, then ran clear. Of course, once the tstat opened, it cooled off, so I don't know if it flushed long enough in the open state.

Previous owner stated that it generally ran at 160 while in use. We were out on an evening cruise, so I didn't get her throttled up much, and when flushing, I maxed at 1300 rpm. I will have to wait until a day run to see if I can get the engine up to 160.

I'm still focused on getting the temp gauge working. I will test and replace the gauge if needed.

Any comments welcomed. Thanks!

 

[alldodge]

Re: Is some water in the bilge expected, or an obvious problem?

Looks like your working through the issues. Since you have a carb and would like the thermostat to open sooner, you could put in a 140 which would help some.

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

Tested the gauge using these instructions:
How to Test a Water Temperature Gauge on a Boat | eHow
http://forums.iboats.com/mercruiser...s/how-do-i-test-temperature-gauge-392402.html

The gauge pegs low when disconnected, and pegs high when grounded. Appears to be working.
I tested the sensor with ohmmeter and it reads ~ 550 at room temp, then drops to 0 when heated in hot water. The sensor appears to be the problem, so I will replace it.

However, when I removed it, this is what I found:


Looks dark and rusty in there! And this may explain the discoloring that I see in the outflow from the risers when the tstat first opens (while flushing). Please tell me this is normal! If not, what should I do?


Thanks!

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

And I know that I've been all over the map with this thread... but I'm not sure if the continuity helps or if I should post a new thread. Please advise. Thanks.

 

[alldodge]

Re: Is some water in the bilge expected, or an obvious problem?

I tested the sensor with ohmmeter and it reads ~ 550 at room temp, then drops to 0 when heated in hot water. The sensor appears to be the problem, so I will replace it.


Looks dark and rusty in there! And this may explain the discoloring that I see in the outflow from the risers when the tstat first opens (while flushing). Please tell me this is normal! If not, what should I do?

The rust is normal for an engine that runs in salt water, you would find rust in fresh as well just not as bad. Salt is the reason the exhaust system needs to be replaced more often.

http://boatinfo.no/lib/mercruiser/manuals/mercruiser13.html#/244

Agree sender should be replaced, according to the manual you temp sender should read 122-147 ohms at 140 degrees, up to 36-41 ohms for 212 degrees. Also note that there is pipe sealant on the threads, use a little anti seize but do not use Teflon tape or pipe dope.

 

[Scott Danforth]

Re: Is some water in the bilge expected, or an obvious problem?

you should replace the impeller about every 2 years.

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

Ok, so this would confirm what I suspected. When the tstat opens up, the outflow looks rusty at first. It's getting rinsed out, but I don't know if it's long enough. Is it possible that once the tstat opens, it cools down, then is closes again? Can I force it open for flushing purposes?

Hopefully, with my new sensor in, i'll be able to better monitor engine temp.

Saltaway sounds more appealing now... maybe worth the cost to extend life of exhaust system?

 

[MarkSee]

Re: Is some water in the bilge expected, or an obvious problem?

Is it possible that once the tstat opens, it cools down, then is closes again? Can I force it open for flushing purposes?
Saltaway sounds more appealing now... maybe worth the cost to extend life of exhaust system?

-Yep, when the water temperature cools enough, the stat will close.
-I've had no issue when running on the muffs after about 10 minutes that the stat opens and will get flushed.
-Not much of a cost dollar wise once you have the little container; buy the large refill jugs. Can only help; just not sure how you can measure exactly how muh.

Mark

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

If I've got the temp gauge working and am monitoring it closely while flushing... does it make sense to turn the water pressure down a little to help bring the temp up, without rev'ing it up to do so?

 

[MarkSee]

Re: Is some water in the bilge expected, or an obvious problem?

Normally you would not need to turn the volume/pressure down but may also depend on the pressure you have feeding the flusher.

I remember reading somewhere about only turning the hose on about half-way but at my house or any of the ramps where I've flushed at, when I start the engine and the valve all the way up there is no water existing from around the muffs; all seems to be sucked in.
The one time I did turn the volume down some, I could defineatly see a difference in the amount of water coming out the idle relief ports so I turned the valve all the way open.

Mark

 

[bruceb58]

Re: Is some water in the bilge expected, or an obvious problem?

Don't turn the water pressure down. Excess pressure will just leak by the muffs.

If you actually turn down the water lower than the pump is trying to pump, you risk getting air into the impeller. You may not burn it out since you still do have water there but you are taking more risk.

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

Thanks! I'll make sure there is ample water.

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

The one with the Yel and Blk wires is your temp sender to your gauge. The one with the single screw stud is the temp switch which when hot closes and sounds the alarm horn.

I believe this is backwards... the tan single post goes to the gauge.

 

[thumpar]

Re: Is some water in the bilge expected, or an obvious problem?

I believe this is backwards... the tan single post goes to the gauge.

AllDodge is correct. Single wire for warning alarm.

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

I'm confused.

The wire that connects to the gauge is tan. and its a single wire. It appears to be the same wire that is connected to the single post sensor. And, when I ground out the tan wire at the engine block, the gauge moves to 240.

I'm the newbie here... but I'm pretty sure that the tan wire connects to the gauge.

 

[alldodge]

Re: Is some water in the bilge expected, or an obvious problem?

I'm confused.

The wire that connects to the gauge is tan. and its a single wire. It appears to be the same wire that is connected to the single post sensor. And, when I ground out the tan wire at the engine block, the gauge moves to 240.

I'm the newbie here... but I'm pretty sure that the tan wire connects to the gauge.

Guess I need to retract my previous. The Tan wire goes to your temp gauge. A Tan with a Blue stripe goes to the warning horn, but your engine shows no connection to a temp horn connection.

Need some help from you. Previous statement indicated the Yellow and a Black wire went to another sender. There is no solid yellow wire which goes to any sender (old guy guessing why I came up with previous), the black is also a puzzler to the sender. I have you as a 1990 4.3L engine, have seen no serial number that I remember (old guy again). So if this is a 1990 what color are the wires?

 

[ShoalSurvivor]

Re: Is some water in the bilge expected, or an obvious problem?

2004 4.3 4bbl Quicksilver repower. S/N: 807736R11

This shows the water temp sensor location (sensor is removed, part#806490T), and about 2 inches below it, you'll see the second sensor with yellow/black wires. This appears to be a Coolant Temperature Sensor (part#805218T)



This is the wire harness for that sensor, and the wires appear to be solid yellow/black. The wires run into a chase and to the ICM.



Where is the alarm? Is it in the ICM?
What is this red button with a 50 stamped on the end?

 

[thumpar]

Re: Is some water in the bilge expected, or an obvious problem?

My alarm is under the dash. The red button is the 50 amp circuit breaker reset.

 

[Fun Times]

Re: Is some water in the bilge expected, or an obvious problem?

This shows the water temp sensor location (sensor is removed, part#806490T), and about 2 inches below it, you'll see the second sensor with yellow/black wires. This appears to be a Coolant Temperature Sensor (part#805218T)


This is the wire harness for that sensor, and the wires appear to be solid yellow/black. The wires run into a chase and to the ICM.
Where is the alarm? Is it in the ICM?
What is this red button with a 50 stamped on the end?

Yes the yellow and black wires are for the overheat alarm and it is tied into the ICM.

The tan/blue wire mentioned previously for the alarm water temp switch has been removed on some later engine models and they went with this design into the ICM. And as you found, the tan wire with the new sender you just bought is for the gauge. Though it's unsure if it's working correctly or not at this point.

I would recommend buying a new thermostat and related hardware so you remove the guessing if it's working correctly or not. The thermostats due fail somewhat often. I can tell just by the thermostat housing your temp should be 160 degrees. When things are running correctly, it's not unusual to see a 170 -173 degree reading on some gauge models.

The red 50 amp circuit breaker protects the ignition side of the electrical system.

 

[alldodge]

Re: Is some water in the bilge expected, or an obvious problem?

Yes the yellow and black wires are for the overheat alarm and it is tied into the ICM.

Fun Times, I'm looking at service manual number 7 for the 1990 4.3 and I don't see the wiring. What am I missing?