MerCruiser 4.3 MPI ECT Temperature Too Low Problem /Guardian Tone Comming On

[50sniper]

I have a 2012 Stingray 195LX with a MerCruiser 4.3 MPI ECT / Alpha 1 combo. Only 40 hours on the engine, still under factory warranty, bought it used when it was 1.5 years old and have not been able to run it for more than about 30 minutes at a time, for a total of about 2 hours between shop visits. Getting real good at taking it on and off the trailer! When I fist start the engine the temp gauge goes up to 170 degrees, normal operating temp. . After just a few minutes of run time the temp gauge drops back to the left, lowest temp indication which is 100 degrees, it never comes back to the normal 170 degree mark, stays pegged on the lowest 100 degree mark. After about 20 minutes of run time at around 3000 rpm the "Guardian" tone goes off every 60 seconds for two 1/2 second beeps. I know this is a SEVERE Guardian condition per my owners manual. I am sure it has to do with the low engine temp issue. All other gauges look and operate in the normal range. Don't think the gauge or the temp sender is the problem. From my car experience it looks to be something with the thermostat operation. I have had it to two Mercury service centers, the first told me the low operating temp is fine and there is no problem--if you don't mind the Guardian tone going off every 60 seconds. My guess is they could not read the stored error codes. The service writer after the 4th time I returned the boat for service told me he was tired of seeing the boat come back for service!!! Will sell the boat before I take it back to them. The second Mercury service center told me the engine was too new and they could not work on it. It is now at the third Mercury service center and after a week at their shop they are trying to find the tool from another service center to read the codes. Guess that will turn out real good also! You know the old saying, If you can't do it yourself you are screwed! Can anyone help me? I can not be the only person to ever see this service issue.

Thanks in advance: 50sniper

 

[alldodge]

Re: MerCruiser 4.3 MPI ECT Temperature Too Low Problem /Guardian Tone Comming On

I have a 2012 Stingray 195LX with a MerCruiser 4.3 MPI ECT / Alpha 1 combo. Only 40 hours on the engine, still under factory warranty, bought it used when it was 1.5 years old and have not been able to run it for more than about 30 minutes at a time, for a total of about 2 hours between shop visits. Getting real good at taking it on and off the trailer! When I fist start the engine the temp gauge goes up to 170 degrees, normal operating temp. . After just a few minutes of run time the temp gauge drops back to the left, lowest temp indication which is 100 degrees, it never comes back to the normal 170 degree mark, stays pegged on the lowest 100 degree mark. After about 20 minutes of run time at around 3000 rpm the "Guardian" tone goes off every 60 seconds for two 1/2 second beeps. I know this is a SEVERE Guardian condition per my owners manual. I am sure it has to do with the low engine temp issue. All other gauges look and operate in the normal range. Don't think the gauge or the temp sender is the problem. From my car experience it looks to be something with the thermostat operation. I have had it to two Mercury service centers, the first told me the low operating temp is fine and there is no problem--if you don't mind the Guardian tone going off every 60 seconds. My guess is they could not read the stored error codes. The service writer after the 4th time I returned the boat for service told me he was tired of seeing the boat come back for service!!! Will sell the boat before I take it back to them. The second Mercury service center told me the engine was too new and they could not work on it. It is now at the third Mercury service center and after a week at their shop they are trying to find the tool from another service center to read the codes. Guess that will turn out real good also! You know the old saying, If you can't do it yourself you are screwed! Can anyone help me? I can not be the only person to ever see this service issue.

Thanks in advance: 50sniper

:welcome: to iboats

That's pretty bad when even the deal is no good. Have you called Merc customer service and discussed 1 (888) 427-5373 ?

Has anyone tried to replace the thermostat or discussed why it is not warming up? It takes very little time for a tech to do a ride along to find the problem and use a scan tool. Looks like none of the dealers in your area have customer service in mind. Sure wish we could know what the actual thread code was.

Many of the new sensors have had issues with grounds. Many of the fixes require the sensor to be removed, clean all Teflon tape and pipe dope off, then reinstall clean to make a good circuit. Others have required an additional ground wire to the side of the sensor.

 

[achris]

Re: MerCruiser 4.3 MPI ECT Temperature Too Low Problem /Guardian Tone Comming On

For a dealership not to have a scan tool is unbelievable (as they are not expensive)... I'm no longer a dealer, but I have a 4.3 MPI and I decided to buy my own, and not just the scan tool, I bought the full PC package. It may just be a case of that particular dealership doesn't have anybody there who can use one :facepalm:... Nothing would surprise me.

If you're unhappy with the service you're receiving (and I'm getting that) it may be worth your while buying the scan tool and doing the job yourself (as you have already intermated). Have a look at the Diacom range of tools and software from www.Rinda.com

As for your particular problem, the PC software would be what I would be connecting up.... BTW, low temperature does NOT set the Guardian... The ECU will just respond by making the fuel mixture richer... If you're getting a Guardian, then you have another problem as well... And for that you need, a scan tool/PC software....

One more question... Are your gauges slave from the ECU (ie digital gauges) or analogue supplementary gauges (old style gauges)... Reason I'm asking is because if they are digital slaves from the ECU, you may have a faulty sensor, but it they are independent analogue gauges, the likelihood of a gauge fault/sender AND a digital sensor failing in exactly the same way is, well, lots of zeros in that number....

Chris......

 

[50sniper]

Re: MerCruiser 4.3 MPI ECT Temperature Too Low Problem /Guardian Tone Comming On

I have contacted the Mercury mfg and they said the temp of the running engine should always be in the 165-170 degree range, just like a car engine temp. I had the service guy ride along and he said it was no problem the engine was running cold, the mixture would be adjusted for the temp issue, not the way an engine should run! He did not ride long enough to see the Guardian tone start sounding. My gauges are analogue. Looks like I have more than one problem? I can't get even a simple problem like engine temp corrected, so the Guardian alert problem will be way out of the service shop possibility. I will look into the scan tool and PC SW pkg.

For a dealership not to have a scan tool is unbelievable (as they are not expensive)... I'm no longer a dealer, but I have a 4.3 MPI and I decided to buy my own, and not just the scan tool, I bought the full PC package. It may just be a case of that particular dealership doesn't have anybody there who can use one :facepalm:... Nothing would surprise me.

If you're unhappy with the service you're receiving (and I'm getting that) it may be worth your while buying the scan tool and doing the job yourself (as you have already intermated). Have a look at the Diacom range of tools and software from Rinda Technologies Inc. Marine and Industrial Engine Diagnostic Tools

As for your particular problem, the PC software would be what I would be connecting up.... BTW, low temperature does NOT set the Guardian... The ECU will just respond by making the fuel mixture richer... If you're getting a Guardian, then you have another problem as well... And for that you need, a scan tool/PC software....

One more question... Are your gauges slave from the ECU (ie digital gauges) or analogue supplementary gauges (old style gauges)... Reason I'm asking is because if they are digital slaves from the ECU, you may have a faulty sensor, but it they are independent analogue gauges, the likelihood of a gauge fault/sender AND a digital sensor failing in exactly the same way is, well, lots of zeros in that number....

Chris......

 

[Fun Times]

Re: MerCruiser 4.3 MPI ECT Temperature Too Low Problem /Guardian Tone Comming On

I have a 2012 Stingray 195LX with a MerCruiser 4.3 MPI ECT / Alpha 1 combo.
The service writer after the 4th time I returned the boat for service told me he was tired of seeing the boat come back for service!!!

Wow not very nice to say! What area do you live in?

Calling Mercuiser like suggested or finding a helpful Merc Dealer, using your engine serial number hopefully they might be able to give an idea if there is something known about your temp issues as I believe they had two service bulletins pertaining to temperature issues.

While it could be the thermostat your thermostat housing should be of a different design vs past years. If so it should utilize a poppet valve that could be getting defective/stuck causing unusual temps. You may want to open it up and have a look at it. Also they had an issue with the circulation water pump sometime around late 2012 I believe it was that was causing very weird temperatures.

http://www.mercruiserparts.com/Show...desc=Thermostat+and+Housing,+Standard+Cooling

The engine temp needs to be in the correct range because if it's not, he's right the PCM will adjust but in the wrong way that he is thinking. It would add fuel thinking it's running cool when it really isn't. It's even more important with your engine due to the emissions control technology (catalyst system) you have on your engine. Don't really want to impede their functions.

Keep us updated on your findings please.

 

[Rowdyts]

I'm having the same exact issue with my 2012 Bryant with a 4.3 220 hp. I've too had it in to a shop 4x, and no one can figure it out. They replaced the thermostat twice and an impeller, and a sensor. The alarm keeps going off and the guardian had gone off over ten times. Have u solved your issue yet? Some think it may be the cat. converters.

 

[G1FishnSki]

Hey Sniper and Rowdy. I have the same issue in my 2012 Merc 4.3 MPI. I was leaning toward the thermostat also, till I read your post and some others. My dealer says it is the water pump impeller. Not the one in the lower unit, but on the front of the engine. The shaft is spinning side the hub of the impeller. You can prove it by removing the belt, pulling the plug out of the top and holding the impeller in place while you spin the pulley. If the pulley spins and the impeller doesn't, bad water pump. I am picking mine up tomorrow and will be in the water Sunday, hopefully. I will let you know if it fixed it. By the way, my dealer says there is a tech bulletin on it because Merc knows they have defective impellers out there. Another impeller issue to watch out for, my lower unit one did the same thing two weeks earlier. Inside hub had a perfectly straight split right through the hub, allowing the shaft to spin inside the hub. Tech said he had never seen one like it. That one shut me down completely requiring a tow boat.

 

[G1FishnSki]

Got mine back Friday. The metal impeller inside the water pump on the front of the engine was broke in half. Hope y'all figure yours out.

 

[Rowdyts]

Hey Sniper and Rowdy. I have the same issue in my 2012 Merc 4.3 MPI. I was leaning toward the thermostat also, till I read your post and some others. My dealer says it is the water pump impeller. Not the one in the lower unit, but on the front of the engine. The shaft is spinning side the hub of the impeller. You can prove it by removing the belt, pulling the plug out of the top and holding the impeller in place while you spin the pulley. If the pulley spins and the impeller doesn't, bad water pump. I am picking mine up tomorrow and will be in the water Sunday, hopefully. I will let you know if it fixed it. By the way, my dealer says there is a tech bulletin on it because Merc knows they have defective impellers out there. Another impeller issue to watch out for, my lower unit one did the same thing two weeks earlier. Inside hub had a perfectly straight split right through the hub, allowing the shaft to spin inside the hub. Tech said he had never seen one like it. That one shut me down completely requiring a tow boat.

Glad I asked...brought the bulletin to my dealer and they looked into it. This was exactly it!!! Said it was the Impeller on the front of the engine. Funny, our mechanic said the same thing, "Never seen one like this in 30 years." Looked at the part and it was shattered. After they fixed it, brought it out a few times now and it runs great. The thermostat is finally staying around 140 and no alarms. Thanks for the help!!!

 

[jabone327]

have the same problem with my 2012 bayliner 4.3l. pulled the water pump and sure enough its bad. will post a result if it fixes the problem of low temp.

 

[GA_Boater]

have the same problem with my 2012 bayliner 4.3l. pulled the water pump and sure enough its bad. will post a result if it fixes the problem of low temp.

jabone327 - When you post the result, make a new thread please, Look at the Help Tip on top of the page.

Closed.