johnson/suzuki DF70 false overheat warnings?

[Krille]

Have a new johnson 70 4-stroke (repainted suzuki engine). It warns occasionally for over heatning (red light "hot" and signal for 10 seconds) on low rpms but cooling water is coming and the water is cold. When I turn of the motor and restart it immediatelly it works fine and no warning. Then it can run ok for a perioid of time before the error returns. My local marina have replaced the whole motor and the rpm/system check gauge to brand new ones but the error still returns. Can it be a electrical installation problem? The batteri is a 5 years old but has 13,5-15 volt when motor is running depending on rpm and the number of electric things in use such as sonar and autopilot. What triggers the warning system? Anyone else had a similar problem?

 

[jim dozier]

Re: johnson/suzuki DF70 false overheat warnings?

This could be a number of things. I have an older Suzuki 2 stroke with a similar problem, don't know if the same cause. Mine was ultimately traced at least in part to an overly sensitive overheat sensor in the cylinder head so it does happen. Search the form for Suzuki last 10 days and see my post "87 85hp Suzuki overheats WOT update (a cautionary tale)".<br /><br />Have you or the dealer been able to verify when the alarm goes off whether the enginge is acutally overheating. Don't know about the temp range for the 4-stroke but they make heat sensitive crayons you can mark the block and see if it is actually overheating or not. I didn't fix my problem until I got a temp gauge and compared that to the factory settings on the temp sensor and saw the discrepancy.

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

The marina connected the first motor to the computerized diagnostic program and found the one of the sensors wansn´t calibrated correctly. But after recalibrating it only got less sensitive. the problem didn´t dissapear. Then they replace both the motor and the gauge to a new one but it still gives "false" warnings. My conclusion is therefore that the motor is ok, and the gauge is ok but something triggers the alarm to go off anyway. Strange and irritating...

 

[jim dozier]

Re: johnson/suzuki DF70 false overheat warnings?

Do I understand you correctly that they gave you a new outboard motor and the new motor still has the same problem?

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

That is correct, two different motors and two different gauges but the same boat, battery and the same electrical installation (cabels to throttle and gauge and so on) for both motors.<br />Therefore either all their new motors have the same problem or something is wrong in the electrical installation. But what..?

 

[jim dozier]

Re: johnson/suzuki DF70 false overheat warnings?

Odd. That would point to a short or loose connection in your boat wiring somewhere. Maybe some saltwater has gotten somewhere it doesn't belong and is acting as a current drain or grounding some wire somewhere. Good luck with this. Hopefully better minds than me will help on this forum.<br /><br />Is this a single engine or one of a set of twin outboards? Is there anything in the motor setup that might obstruct proper cooling intake?

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

Single engine, the boat has been used only in freshwater for 5 years.

 

[jim dozier]

Re: johnson/suzuki DF70 false overheat warnings?

Strange. I'm out of ideas.

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

Me 2 .... <br /><br />Thanks anyway

 

[jegervais]

Re: johnson/suzuki DF70 false overheat warnings?

WHat do the diagnostics show them in the warning history screen. There are 2 types of overheat "codes" - an immediate overheat, such as if you were running and suddenly picked up a plastic bag or got a bunch of weeds around the gearcase restricting water flow. the other a "gradient overheat" - over a certain period of time the temp rose steadily until the overheat occured. Do you know which is happening?<br /><br />How is the engine being operated when this happens? first thing in the morning or? What is the rpm you are running when it happens? What's the sea or lake-water temp?<br /><br />-John

 

[JB]

Re: johnson/suzuki DF70 false overheat warnings?

Hmmm.<br /><br />Your engine is either identical or close to my '01 Suzuki DF70.<br /><br />This uncommon feature may be contributing to your problem and may be unknown to your Johnson wrenches:<br /><br />There is a supplemental water intake under the AV plate. There are two times it can cause an overheat light.<br /><br />1. On the muffs if it is not blocked by duct tape it can suck enough air to allow the engine to trigger the light after a few minutes, even with no load on the engine.<br /><br />2. If your prop is ventilating it can also suck air with the same result.<br /><br />Some of what you describe suggests that this is not the problem, but. . . still. . . maybe.<br /><br />Good luck.

 

[jegervais]

Re: johnson/suzuki DF70 false overheat warnings?

JB-<br /><br />I'm pretty certain the supplemental water pick up feature is not used on the current Johnson versions. I'll double check when I go to work in the morning...<br /><br />-John

 

[petryshyn]

Re: johnson/suzuki DF70 false overheat warnings?

Krille<br />Try shutting off or disconnecting all onboard electronics. Try engine again. Some electronics can emit radio noise which can corrupt the ECM. Antenna grounds, or electronic system grounds are important and should be made at or close to the battery. Keep cell phone away from the craft when testing as well..... <br />Reconnect or turn on each accessory, one at a time, until culpret returns the symtom

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

PROBLEM IS SOLVED!<br />It turned out to be a small silicon plug that blocked one of the exhaust outlets. It´s a facotory misstake and has apparently only been found on two other motors (except the two I tested) here in sweden so it´s not exactly a common error. Thanks everyone that has answered my question!

 

[jim dozier]

Re: johnson/suzuki DF70 false overheat warnings?

That's pretty weird that you got 2 of the mistakes. Are you sure its not something your dealer forgot to undo out of the crate?

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

Yes, apparently the motors have the serienumbers after oneanother so I think that the same jackass has made the same misstake on all his/hers motors at the factory.

 

[jim dozier]

Re: johnson/suzuki DF70 false overheat warnings?

Probably made on a Monday or the Japanese equivalent of a Monday (saki hangover). Glad you got it fixed.

 

[Krille]

Re: johnson/suzuki DF70 false overheat warnings?

He he you are probably right Thanks for all the help jimd!

 

[fridays]

Re: johnson/suzuki DF70 false overheat warnings?

Did you see the problem or is it just what your dealer told you? I've seen the problem a dozen times with Suzuki and it's the exhaust temp sensor with the tip corroded away. Replace the sensor and the problem goes away. The alarm beep sequence will tell you what sensor is going off. Your dealer needs to get his act together or perhaps the Johnson doesn't have all the bells and whistles like Suzuki. Sorry I didn't see your post earlier.

 

[uvdynamics]

Re: johnson/suzuki DF70 false overheat warnings?

I have a 1999 df 70 with very low hours, about 250. Last season it ran fine but the telltale stream was looking a little weak so I had my mechanic, a Suzuki dealer intall a new pump this year. My first time out it was pumping great and started right up. I went out for a cruise and ran it up to 4200 with no problems. The rest of the day I ran it at about 1500. After being out for a few hours I was idling and the overtemp alarm came on. The water was coming out fine and it was cool. I checked the block and it was cool too. I checked the oil and found it way overfilled and the oil looked milky. I do not think I have any head gasket problems beacuse the motor had plenty of power and ran great. Shut it down and brought it in for service. Anybody have any experience with this or any ideas?