Help needed.. 3GM30F Overheated; It's not the seawater pump

[PGIJon]

OK.. With no wind to speak of, the admiral and I went out to recalibrate the autopilot after I added the new rudder sensor. Barely out of our canal, the engine overheating light began to buzz.... I looked at the new temp gauge that I installed off the outlet to the water heater. This showed 140. First thought was that the thermostat failed. However, not being certain, I shut down the engine and went below to see if something failed. Everything was OK. Before we set out, I checked that the sea water pump was working. Not being able to make sense of what I was seeing, I started the engine and made our way back to the first available dock. I shut down the engine.

Let me add that as we were making our way back under the buzzzzzing of the .... buzzer, the admiral noticed that the new temp gauge was shooting up and peaked just south of 200 degrees.

After we docked I looked to see if the raw water filter was clogged, when it hit me as to why the temp gauge took so long to reflect the coolant temperature. First I went to see if there was a leak in the new coolant lines that I just ran to the heater. Nothing... Then I touched the hose. It was cool. I check the hose closer to the engine... while it was warm near the engine, it was cool just a foot or two down the hose. This is when I realized it must be the Fresh water pump!

Has any faced this problem? Does my analysis of the problem seem correct before I rip the engine apart? Has anyone ever repaired or replaced the fresh water pump? Could it be something else?

Hope everyone is having/had a "cooler" weekend.

Thanks
Jon

 

[spraygun]

If the send and return lines to your water heater are not hot.When your engine cools open the cap on the heat exchanger and see if there is coolant.Sounds like you are low.The coolant circulation has nothing to do with your freshwater pump.Because the coolant is circulated by the water pump on the front of your motor.Just like a car.
Check that first and report back.Then we can move on to the next thing to check.

 

[woodster]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

you may have an air lock in the lines scene you did some work on them ...check to see if that is your problem ...burp the lines several times till you are sure you got all the air out

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

Thanks Spraygun and woodster...

Spraygun: My bad, we are referring to the same pump. I called it the freshwater pump because that is how it is referred to in the Service Manual... I should have been more specific since there are multiple fresh water pumps on the boat. That said, I'm going to the boat which is about 8 homes down the canal to bring it home at very low RPM's. I'll check the coolant level first.

Woodster: You're definitely right about my doing replacing the lines. Sorry for such a newbie question but, how do I burp the lines??? The last time I burped anything I put it over my shoulders with a diaper. Though with an engine I suppose a diaper might actually come in handy....

Thanks guys... Jon

 

[woodster]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

just take one of the water heater lines loose loose and hold the end about head high to the engine and keep adding anti freeze until it starts to come out of the open hose when that happens the lines should be full ..stick it back on its fitting tighten it down and check you antifreeze in the heat ex-changer and add more if needed that should do it then fill up the expansion tank to the proper level and you should be good to go

 

[spraygun]

There is a good chance that once everything has cooled completely.And you did not open the heat exchanger cap.Usually once it has cooled.You can just add more coolant.Sounds like you just had air in the line and an air pocket formed near your sensor.Check your reservoir and see if the engine pulled coolant from that when it cooled.That would be a good thing.
Sometimes when that happens,all is now balanced out.Be sure to top off your reservoir.All should be fine.let us know.

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

Both of you hit it on the nose! The coolant was low and there is definitely a leak in the new hose. I can tell that by the level of the coolant. I'm guessing that there is something very sharp that ripped the new hose under the sole. Good thing I bought 50 feet of hose! Maybe I should take up the sole and have a look. Yikes.... Thank you both for pointing out the obvious and for the burping tutorial. I'll definitely do that next time!

I don't think I could have been a good boat owner without this site! You guys are great!

-Jon

 

[kloudie1]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

The coolant is probably low because it is filling the space where the air was, Jon.. If you don't see/smell coolant in the bilge, ya probably good and it will take a couple more hot/cold cycles to finally purge the air pocket..If ya top off the heatex housing, and put the "burp bottle" about half full, ya should see the bottle level drop as it finishes back filling the air pocket.. It is critical that the pressure cap and gasket be in good shape.. Don't pull new hose unless ya find coolant in the bilge.. Sounds like ya have the problem about done.

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

Good point Claude! Last time it made its way forward of the bilge and when I looked there it wasn't present. So, I figured that it was simply in a different chamber.... with what you and Spraygun pointed out, I'll take my endoscope (that's the name of it) and see if I can find it.... if not I'm going to try and burp it as Woodster pointed out, fill it and see if it holds the coolant or if there is a leak... Certainly better to check that before ripping out the sole! Thanks Claude!

 

[spraygun]

I really doubt you ripped the new hose.It would take alot to do that.You would smell coolant or see it.The way you described the hose cool a foot from the motor. That alone throws up a red flag.Look for leaks.But after that just a really good warm up of the engine to running temp.And a good cool down.The reservoir is your friend.All will be fine.

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

This morning, I filled up the coolant tank and filled the reservoir then started the engine. After a few minutes I took some temperatures with the IR meter. Once I was getting around 130+ degrees around the thermostat, I check the hose around the water heater... Not warming. Also the new temp gauge did register. I increased the throttle to around 1200 RPM for a minute or 2. I then began to feel hot coolant in the both hoses, in and out of the water heater. However the temp sensor never left 120 degrees. I let it idle about 5 more minutes and shut it down. I am now waiting for the engine to cool and then check the coolant levels. BTW, A cursory glance under the bilge did not revel any hints of coolant. I'll update in a couple of hours when the engine cools and I can buy some more coolant. I really appreciate everyone's help! -Jon

 

[spraygun]

This morning, I filled up the coolant tank and filled the reservoir then started the engine. After a few minutes I took some temperatures with the IR meter. Once I was getting around 130+ degrees around the thermostat, I check the hose around the water heater... Not warming. Also the new temp gauge did register. I increased the throttle to around 1200 RPM for a minute or 2. I then began to feel hot coolant in the both hoses, in and out of the water heater. However the temp sensor never left 120 degrees. I let it idle about 5 more minutes and shut it down. I am now waiting for the engine to cool and then check the coolant levels. BTW, A cursory glance under the bilge did not revel any hints of coolant. I'll update in a couple of hours when the engine cools and I can buy some more coolant. I really appreciate everyone's help! -Jon

Not trying to tell you what to do.But if it were me.The engine needs to come up to operating temperature.Yours did not.It needs to build up pressure and fully cool down.Then check reservoir after cool down. You can put it in gear at the dock and run it.But it sounds like you fixed it.

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

Spraygun, thank you and PLEASE tell me what to do! I am very appreciative of everyone's comments and instructions! However, if the temperature gauge isn't responding due to the possible possible air gap, how long should it run for? How long should I wait for the warning buzzer? Is there a particular location to get an IR temperature that reflects the actual coolant temp?

Thank You -Jon

 

[spraygun]

Spraygun, thank you and PLEASE tell me what to do! I am very appreciative of everyone's comments and instructions! However, if the temperature gauge isn't responding due to the possible possible air gap, how long should it run for? How long should I wait for the warning buzzer? Is there a particular location to get an IR temperature that reflects the actual coolant temp?

Thank You -Jon

I can't tell you how long to run.I am not familiar with your setup.I would assume 20 minutes in gear should be plenty long.My 3gm 20 runs at 160.In that time it has already produced hot water in the water heater.If you have a guage it should not mislead you.It sounds like at this point, the air is gone.The main thing is let the engine completely cool down then check your reservoir.Preferably overnight.And if you feel like,you can check the heat exchanger.I would not worry to much.It appears you have fixed your problem.

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

Went to take a look this morning and found evidence of coolant in the bilge. Then taking a look through the hole just forward of the bilge found a higher concentration of coolant. Looks like one of the hoses snagged something and tore through it. Both under the engine and under the water heater was clear. Arggggh! Although this is definitely better news than the fresh water pump going out! -Jon

 

[kloudie1]

Sorry to hear, Jon. Hope your luck on the hoses improves

 

[PGIJon]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

"Along with the sunshine there's gotta be a little rain sometime!" Thanks Claude!

 

[PGIJon]

Update: New lines very carefully pulled and connected. I filled the coolant in the lines by putting a funnel in the hose and slowly filling and allowing it to burp. Then connected the lines to the engine and topped off the coolant. I ran the engine for about 10 minutes at idle and then about 5 minutes around 1200 RPM and then finally about 5 minutes or so at idle to allow the engine to cool. Eight hours later I opened and noticed the coolant level was again down. Taking a deep breath I refilled the coolant and let it sit overnight. Without all your help, I would have though I had another leak! The next morning I ran the engine as earlier. To my surprise and relief, the coolant level held steady!!!!!:dance:

On to the next project. :stirthepot: Pulling new bilge pump wires.

Thanks all for your help!
Jon

 

[kloudie1]

Re: Help needed.. 3GM30F Overheated; It's not the seawater p

Ahhhh.. good job Jon