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Water light not working

JPS27

Member III
Last weekend went out for the day. Engine always starts like a champ. Alarm sounds, indicator lights come on, and then in about 3-5 seconds they shut off and off I go. When returning to my marina, the neither the alarm nor the 'water' light indicator would turn off. Water was running thru the system and out the back as healthily as always.

But this situation caused some concern given my limited mechanical knowledge, which is enough to be dangerous. So I sailed in as far as I dared given the labor day traffic and reasoned with myself that 'water is flowing, so I should be good to motor in the last 75 yards or so.'

Once back I disconnected the offending 'water' light indicator and switched it to the other alarms connections, and believe I have determined that its not the bulb or the connectors on the bulb side of the wiring. It works on the other light connnectors and the other bulbs don't work on the failed line.
Questions:

The connections don't look corroded. What might be next trouble shooting steps?
And given that it's the water indicator (thermostat?) and water is flowing, would it be a bad idea to not worry about it as far as motoring in and out of the slip? (this is my main concern).

I might add I put a infrared thermo gun on the thermostat, and it was around 110 degrees. I measured it frequently and it was from hi 90s to 112 degrees.

Thanks. Jay
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
What warning lights do you have on the cockpit panel? Basic standard would be a low oil-pressure buzzer, often with an integral warning light. The oil pressure sensor buzzes when the ignition is turned on, and stops when the engine starts (because now there's oil pressure). It also reminds you to turn off the ignition after you shut down the diesel.

But there are many warning lights available for installation, including engine temperature warning, which perhaps you have.

In general it could be said that if healthy water is spouting out the exhaust (engine cooling) and oil is not leaking obviously out of the engine (and dipstick is normal), motoring on a bit is rational. It would be nice if warning lights failed "on."

Others will know more.
 

Bolo

Member III
What is a “water light” and what is it indicating? Water flow? Water temp? Are you sure you’re not mistaking the low oil pressure light for a “water light”?
 

JPS27

Member III
Thanks. Yes, Christian, that is how my panel communicates with me. I have from left to right, "Oil Engine", "Water", and "Charge". They all typically lit up and the buzzer buzzed, and then all shut off simultaneously. I've always assumed the 'water' light indicator is to warn about temperature.

I'm certain the oil light and charge lights are working. All lights are labeled (factory etched on the panel). I attached a yanmar schematic that looks like my harness wiring to the panel.
 

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Tin Kicker

Sustaining Member
Moderator
Pulling the connector off the temp switch and short it to ground should cause the light and alarm to go on, because the temp switch is the path to ground. If you DO get the light and alarm, the problem is probably the switch needing to be replaced.

If you did NOT get an alarm then either see if you get 12 VDC or try shorting to ground from the back of the light for the wire going to the thermostat. If the alarm and light DO actuate (or you can measure 12 VDC) then there's a downstream break in the circuit to the temp switch. If they do NOT then check for 12 VDC on the high side of the light.

By this point you'll be to the power coming off the main switch. Or know that you do NOT have it. Either is pretty conclusive.
 

JPS27

Member III
Thanks, Bob. And I forgot to mention -- important info here! -- that I used my multimeter on each of the light connections and go 12 volts give or take a fraction to the oil and charge wires, and .25 volts to the line for the water indicator. But I have not done the other tests. My electrical skills are at the level of take wire off, put it back where I found it, never mess with AC.
 

goldenstate

Member III
Blogs Author
Cheers fellow Yanmar owner in a sea of Kubotas:

You may have found this thread already:


It sounds like your water temperature switch may be defective (or need to have contacts cleaned) or your engine may be overheating?

I believe your engine is raw-water-cooled. Have you de-scaled the engine at any point in your ownership?

Here is a service manual for your engine. http://j30.us/files/2qm15_servicemanual.pdf

Page 10-23 lists the sender (water temp switch) as part no. 46150-00530

Toadmarinesupply says that part # has be deprecated and the new part # is 46150-00531 which retails for $31.

-Tom
 

Kenneth K

Sustaining Member
Blogs Author
The wiring diagram shows that the "water light" is controlled by a water temperature switch which completes the electrical ground to turn on the light (and buzzer) when water temp is too high.

On both a cold engine, and an engine operating at normal temperatures (usually 160-190 deg F), the switch should be "open" causing the circuit to be un-grounded (open) and therefore, not illuminated.

Most likely (just my guess) is that the switch is stuck closed. This would show as zero Ohms resistance between the engine block and the wire terminal on the switch. No need to check connections/corrosion in this case because the circuit IS being completed when the light illuminates. Just replace the temp switch.

However, since there is also a "test" circuit that makes the light illuminates after startup (ie, a cold engine, when the switch would normally be open), there is a possibility that the problem is in the "test" circuit. This would be harder to troubleshoot and fix (although, just leaving the wire disconnected from the terminal on the switch would mimic the "open" position of the switch and allow you to see if the test circuit is functioing normally).

While I wouldn't want to run my engine very long with no temperature indications, I'd also consider that as long as it's pumping sufficient water out the back, it's probably cooling just fine. I suppose if a situation forced me to motor, I'd keep checking the water flow from the thru-hull, and take a temp-gun shooting every 5 min or so. When you use the temp gun, temps should show at least 160 Deg F. If lower, either your engine hasn't warmed up yet, or your temp gun is unreliable.
 
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JPS27

Member III
Ken,
where is the best place to take the temp in this case? I have put my gun to the thermostat right near the exhaust elbow. Is that right?

And thanks everyone for the assistance. I'll be taking these suggestions to the marina first chance I get.
 

JPS27

Member III
The panel doesn't have a temp gauge. Just a space for a tach (I put one in) three warning lights, buzzer, starter button.

edit: added a pic of the panel I found on the internet.
 

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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Note that virtually all of the engine providers have a menu of instrument panel options, with more gauges added as the price rises. The factory panel for our Universal diesel was supposedly their best (?) panel, the "Admiral" panel.
(Like other OEM's, Ericson may not have paid much more to buy the better panel, since they were buying them by the gross.)

I have seen Yanmar panels with very few parts, and others with all of the gauges; I paid extra for a panel displaying more information when buying a new Betamarine.
 

JPS27

Member III
old posts of mine will attest to the kludge of an experience it was for me when my A4 died not long after taking ownership of my 27. The 1980 vintage 2qm15 was what I could find to put in at a price I could afford. I haven't see a fancier panel from that era, although they may exist. Incidentally, Loren, if ever faced with another engine replacement, I'm thinking Beta (based on the myth of "the drop in") or electric. But hopefully that won't happen for a good while.
 

Kenneth K

Sustaining Member
Blogs Author
Ken,
where is the best place to take the temp in this case? I have put my gun to the thermostat right near the exhaust elbow. Is that right?

Hmmmm..... On a freshwater (antifreeze) cooled engine, the thermostat would be located on/near the engine block to control whether the antifreeze flows through the block or not.

On a raw-water cooled engine the setup may be different, but not something I'm familiar with.

Do you know which you have?

As for where to take the temperature readings, I'd probably want to shoot it at the block or cylinder head (where there are moving parts that would be damaged by excessive heat). The exhaust elbow is designed and meant to handle extreme heat.
 

JPS27

Member III
My 2qm15 is raw water cooled and the thermostat is on the exhaust manifold and the sender is on the backside of the cylinder head. A clear pic is on p. 7-1 of the manual. Also, going back to your earlier post, I'm confident that the temp reading from my gun on cylinder head was 165. While at the thermostat housing it was considerably lower 110 + or - several degrees.
 

Kenneth K

Sustaining Member
Blogs Author
Yeah, that makes sense now. And taking dual readings at both the sender/block and exhaust/thermostat confirms that the cooling system is doing what it's supposed to do. That would give me some confidence in running the engine while the warning light is out.

If you need to replace the temperature switch anyway, you could just replace it with a temp sender and add a water temp gauge. That provides much more useful information.
 

Christian Williams

E381 - Los Angeles
Moderator
Blogs Author
>>add a water temp gauge.

I look at that gauge every 10 minutes while the engine is running, and I'm not the only one. It's a habit, especially when running anywhere near Wide Open Throttle. The relative readings over time let you know the rate at which the cooling system is gumming up from scale, hoses and the passage of time.. The formerly expected 180F becomes 185, then occasionally higher, then eventually pushes 200F. More a message than a warning.

It is a comfort to monitor the running temperature. A warning light is OK, but not a comfort.
 

JPS27

Member III
Great advice, all. Many thanks. I will definitely put the gauge on my list of things to do. Definitely the type of 'enhancement' I put higher up on the priority list.
 

1911tex

Sustaining Member
>>add a water temp gauge.

I look at that gauge every 10 minutes while the engine is running, and I'm not the only one. It's a habit, especially when running anywhere near Wide Open Throttle. The relative readings over time let you know the rate at which the cooling system is gumming up from scale, hoses and the passage of time.. The formerly expected 180F becomes 185, then occasionally higher, then eventually pushes 200F. More a message than a warning.

It is a comfort to monitor the running temperature. A warning light is OK, but not a comfort.
Interesting....I do the same monitoring sequence and my temps run very similar to yours...mostly 185-190 degrees...I now have a 180 deg. thermostat which makes no difference, just opens at 180 rather than 160 deg. The temps run the same whether idling, full bore or anywhere in between.
 

JPS27

Member III
Reviving this thread to update and ask some follow up questions. My "water" (temp) alarm issue seems to have been a simple wiring issue. The ancient connection was a female connector to the sender on the engine that no longer functioned. Incidentally, my mechanic walked me through this and offered advice but told me what to do. Teaching me how to fish. I bought a new sender that I could screw a ring terminal too, and that is done. Engine and alarm working as expected.

Mechanic had me check temps over time from cold start for 20 minutes or so under load. He was puzzled that the engine took so long to warm up and wasn't warming up sufficiently. He suspected a faulty thermostat. Turns out my old engine doesn't have a thermostat! Today, I opened the housing with the new thermostat in hand and was rather perplexed to find nothing.

I cleaned up the mating areas as best I could and also I had to gently smooth out the deposits along the inner rim with a file to round out the opening so the thermostat would slide in. It was gunked up along the edges deforming the opening just enough.

After starting this small job (but my first time doing it) I'm wondering...
  1. is there a reason the previous owner would have not had a thermostat? And if so what does that mean for me?
  2. Do the pics reflect a good enough cleaning of mating surfaces? or put differently, how spotless does it have to be? I'm afraid to go at it too hard and end up scoring the area. I worked at it with a new razor blade.
  3. And should I use sealant with the paper gasket? if so, on each mating surface with gasket in between? What kind?
Thanks. jay
 

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