DF200 2012 slowly overheats and alarms at Idle or in forward idle

[Pilbara]

Have not been able to kick it over today but will do tomorrow. Some prelim figures though. Air temp at the following measurements was 33 degrees C.
Port bank with sensor disconnected was 4.69V. Connected it was 1.878V. Temp with IR was 33.1
StarB Bank was 4.69V. Connected it was 1.892V at 33.3 degrees. NMEA temp reading was 35 degrees.
Cyl Sensor was 4.69V Connected it was 1.886V at 33.3 degrees.
tommorrow I’ll put it on the muffs and see how low the voltages go when it heats up.

Is there any temp vs voltage gradient known that I can use as a guide?

[Pilbara]

Hi all, just as an update, I changed all three temp sensors on the unit and measured their voltages. On the hose at home I could not get the fault to occur so with some hope I put her on the water. Yet again after a run I slowly pulled to idle over the course of 5 minutes just to make sure the engine cooled down slowly, not just straight to idle too quickly. Engine temp showed 58 degrees. All good. After idling for 5 minutes temp started in to increase to 68 degrees, I gave her 200 more rpm in neutral and the temp dropped back to 58 within 20 seconds. All good for the next 5 minutes temp sitting at 58 then all of a sudden overtemp alarm went off again. Shut her down. Started her up again and all good.
Apart from the overtemp error, how can the engine go from 58 degrees to 68 degrees and climbing by just idling in neutral. Then with giving a slight amount of rpm it drops straight back down for a while?

Ive ordered the Suzuki SDS laptop software Kit . Hopefully I’ll be able to see in real time what the ecu is seeing.

My gut tells me this thing is not holding its water pressure and a small amount of rpm is required to keep the water jacket full or flowing. Since I’ve completely rebuilt the water pump and everything else within the water circuit could the orings in the water tube not be sealing or could my displays be indicating an rpm higher than it actually indicates? When I look at an alarm error it logs it on my Garmin GMI10 as “overtemp” 58 degrees, rpm can logged can range from 650 down to 420. However I don’t know if it logs this info after it enters limp mode. I guess the ordered Suzi software will tell me. Thanks for the inputs so far and I apologise for the large posts. Real frustrating though.

[47matthew87]

Hello Pilbara, have you any updates?

I've a similar problem on my DF200 2007, In reality my engine goes into alarm as soon as it reaches 104 c ° at the exhaust, in only one of the cylinder banks. However, in the same way the temperature rises very quickly at low rpm and as soon as you get some gas, above 1000 rpm it immediately goes back down.

check: https://www.suzukioutboardforum.com/...t-only-at-idle

[Pilbara]

Hi 47matthew87, what temp is it running at normal engine rpm? Although I still get an overtemp at idle the powerhead at anything over 1000rpm sits at 64 degrees C. At idle us goes into overtemp even at 68 after about 10 minutes. I’ve changed all the sensors and still does it. I’ve now ordered the SDS software so I can view each sensor in real time. I’m thinking that the port bank runs warmer at idle than starboard and what I see is an average. If this is the case I have one if 2 options. Remove all anodes and flush with citric acid 10% for about 10 hours to see I if I can clear whatever is built up in there and try again. If still no luck pull the powerhead again and take off the cylinders heads and clean them up.. As soon as the SDS arrives and I can download the history and see in real time I have a much better idea of what’s going on.

[47matthew87]

My engine runs regularly at 65-70 C °, only that a few times at low rpm the temperature spikes upwards, only by giving a little gas the temperature goes down steeply. I'm also waiting for the diagnosis made by an official Suzuki mechanic to see if he can get more precise information. If I have any news I update you, I will try to check the oil pan cover as suggested by another user who had a similar problem.

[Pilbara]

Hi mate, yep I undid those and cleaned them also found the inlet manifold water cooler blocked. Not with salt but calcium which is harder to move. Think we have the same issue bought mine without being told it had this issue from a dealer in Perth. Engine has 490 hrs on it so whoever had it last really didn’t look after it. I’ll keep you posted as well as I learn more. Cheers.

[Pilbara]

Just a further update. Was finally able get someone to read the ECU using Suzuki sds. Engine shows a number of overheat events all on the starboard head and all tripping at 104 degrees C. The software was placed in real time monitor mode for about 5 minutes. Monitored points were all three temp sensors, RPM, IAC and timing. The two ex manifold temps and cylinder temp came up to temp evenly. Port stabilised at about 60 degrees as did cylinder sensor but the starboard ex manifold sensor kept going up. At about 90 degrees I gave the engine a quick increase in rpm to about 1200 then back to idle and immediately over about a minute the temp on the starboard head dropped Back to about 58, then slowly climbed and went all the way to 104 degrees C over the next 5 minutes. I’m now certain there must be a decent scale blockage in the port head or very near it on the block. Probably going to require a power head removal and this time heads removed to have a look and clean. I’m also wondering if it can still be the exhaust riser tube gasket leaking exhaust into the starboard side of the engine from within the oil pan assembly. I’ll hope to post the final outcome in a couple of weeks.

[redlowrey]

It would be cool if you could remove the sensor and get a video camera down the hole for a look. There might be a large salt build up right where the sensor is, the temp seems to come down too quick for a restriction.

[Remington]

It seems like you have identified the problem. The water pressure is insufficient at the factory setting idle speed of 600-650. Here is a YouTube video of a guy with the exact same problem. He increased the idle speed to 700 rpm and that solved his problem. https://youtu.be/sXqkZ4P9MO8