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

[Pilbara]

Hello all,
Just joined, great site for info here and my first post. I’m in a strange situation here as I live about 1500 kilometres away (sorry for all the metric units) from any major city but live in a beautiful part of the world at the moment without COVID.
Anyway I bought this boat a few months ago from a dealer (a long way away) and have had an issue with this engine from day one. Since purchase I have replaced the complete water pump, 2 sets of themostats now running low temp ones, over pressure valve, all anodes, have flushed the engine chemically, etc. However prob still exists as follows.

When I start the unit In the ocean everything seems fine unless you monitor engine temp digitally. Initially engine temp is around daytime temp 38 degrees Celsius (100F) idles at about 620-670 rpm. Over the next five minutes whilst monitoring temp it slowly climbs to 83 degrees C (182F) still only just idling at the boat ramp. If I let it continue it will alarm and go into limp mode. Tell tail is fine and strong all the time.
Here is the strange thing, when at around 182F if I raise the rpm in neutral to about 1000rpm the temp will drop to 134F within 20 seconds, if I then throttle down back to idle the temp will hold at around 134F for as long as the engine is running. However if I then switch the engine off then start it again after 20 seconds the temp will again
increase and eventually over temp again.
I rang a Suzuki dealer up and discussed with them and they thought that I may have a leaking exhaust tube gasket that is giving an gas lock at the top of the engine from either the port or starboard side and told me to replace it.
From what I can gather this involves removing the power head which I have not done. I’m not worried about trying it as I have all the tools just need to get a workshop manual but a large job.
Has anyone experienced a similar issue? And is this a job that can be done by a competent DIYer or best left to professionals? If by professionals I need to travel 1000 miles one way and stay down there whilst they fix it. No warranty left but the dealer I bought it from was willing to do the work if I travel and get him the boat ( they are a Yamaha dealer). But that’s a lot of time and money just to travel.

Any advice and suggestions that could cause the above would be appreciated. Note it does not overheat at speed or above 4 knots forward movement.

Cheers
Pilbara.

[Hoosmatroos]

Have you checked the most obvious parts as the impeller, housing, also the grommet for the water tube, pressure relieve valve (if any) etc? Don't know if this can be done by yourself but a 2000 mile travel is a big trip

[briscoe]

I had a piece of water supply tubing that had plugged.and was causing the front of my engine to overheat. I put water hose on it and pulled each piece of tubing that supplied the water jacket. I used the manual to figure out what hoses to pull. My issue lasted a whole summer before I figured out what was going on. It included one trip to the dealer who told me that I shouldn't idle it that long. It's definately worth a look.
I enlarged the pages from manual and high ted them with different markers so I could easily trace them.
I thought these motors didn't do well at trolling speeds for a long time after that.
It's worth your time to check each one

[Pilbara]

Thanks for the input so far,
Hoostmatroos, yep replaced all mentioned but still no luck.
Briscoe, will try and have a look using the manual and trace all water hoses and see if there are any possible blockages.
Talked to the dealer again today and they absolutely believe it is the pressure valve even though it has been changed and checked multiple times.
because this is only at engine idle I’m thinking of removing the pressure valve and plugging it and seeing if it still goes over temp at idle only just to prove to the dealer that it is not the issue.

[Moonlighter]

Pilbara, I had a wild guess where you are located LOL! The US based guys may not appreciate just how remote your location is!

Can I suggest that you call Jon Eadie at Bayside Suzuki Marine in Cleveland Qld, explain where you are, and what the problem is. And what you have done so far to try to fix it.

Jon is perhaps the most experienced and knowledgeable Suzuki technician in Australia and where others fail, he regularly succeeds.

His mobile number 0407 738 731.

Cheers

[Pilbara]

Hey Moonlighter spot on, great place for fishing boating and lifestyle but need to look after yourself when it comes to maintenance. Absolutely will give Jon a call. I’m looking for new info instead of the dealer just saying “it’s the pressure valve check it again” any suggestions before a power head removal will be invaluable. The last thing I need is to pull the PH and find out something else was missed.
Cheers.

[briscoe]

I have an older motor that used water pressure to show speed. I tied that tubing into a tee that I fit onto the supply tubing, so I hooked up a water pressure gauge. With a new pressure valve it runs a perfect 10 psi when I get above 2K rpms.
If they believe you have issue with that pressure valve lift off the plate and roll up some electric tape to keep it from lifting. Now run the engine and see if it alarms.
Didn't mean to chase rabbit with installing a pressure gauge, but doing so is very easy.

[Pilbara]

Thanks Briscoe will tape it shut and give it a try.
Spoke to the mechanic recommended by Moonlighter and interesting chat. He indicated that for a motor with 450 hrs that the exhaust tube gasket would more than likely not be the issue. He pointed again to the water pump and in particular to the housing and the rubber grommet that sits under the base plate in the leg. He also said that some service mechs use ratchet guns to do up the water pump bolts to tight causing the housing to deform. Hence just because it is cheaper I’m going to change the housing, grommets etc. He also mentioned if I knew someone with a V6 that I could borrow the complete left off and put it on mine then test it and see if it overheats at idle. If not the issue will be in the leg. Big ask though to borrow another leg of a motor that is working well. Might have to offer what we here call Pilbara currency ( cartons of Beer)

[Pilbara]

Gday all, thought I would give you an update of what I’ve had to do and the consequences of buying what is thought to be a good condition DF200. Lucky for me a great Suzi dealer help me out on the diagnosis by phone and explaining the issue. Remember I live 1500 km away from any major town and the so called local service people would not even return my calls for help.
Anyway the power head came off to expose the problem. The main engine holder gasket was leaking exhaust into the water jacket and sending the water/ exhaust mix to the top of the powerhead causing it to overheat on idle and run warmer at speed. You can see the leak occurred by looking at the sealing surface on the powerhead side. Also found lots of salt buildup around the jackets which also had to be cleaned. The inlet manifold is also water cooled and it was completely blocked with salt with no flow whatsoever.
Now waiting on parts to arrive. Also going to change the main output shaft oil seAl in the pan holder. Big job but now at least I know how to service my own motor. Attached some before and after pics for those interested. Just note I believe the last owner never washed his engine properly and secondly the so called reputable dealer (not the one I indicated above) did not want a bar of this issue. So buyer beware. This engine only has 400 plus hours on it. And when taken for a test run did not show any issues ( didn’t idle it for long enough I guess). Cheers.

[Moonlighter]

Crikey, that’s some serious salt buildup in there! The PO must never have flushed it out. Jon always says 10-15 minutes to flush it out properly. Put a stopwatch in it, that is a surprisingly long time!

Google “outboard motor vinegar flush” sometime, there is an excellent thread over in THT forum that explains what was done and shows results. A worthwhile exercise. Several members here have done it too and been happy and surprised with the results. I think there are threads here on this forum too.

How did the internal anodes look? Any indication they had ever been changed?

Glad you got to the core of the issues and are underway to get back on the water. Hope my suggested contact was of assistance.

If you ever need anything from over this side of the country, let me know, happy to help out our sandgroper cousins if I can. LOL!

[Pilbara]

Hey Moonlighter, yep spoke to your contact. Very informative and good advice. He’d be surprised though as we discussed this but hey until you break it down and replace the easy bits first you never know. He indicated he’d never seen this on an engine with 400 hrs on it but as you said I reckon the prior owner didn’t look after it internally very well. The dealer has something to answer for as well as he indicated service had been done just prior to me buying it. When I pulled those anode they looked like they hadn’t been replaced for over 150 hrs at least. Also found the front wash port fully blocked at the port water manifold inlet. So an exhaust leak is one thing but all the salt buildup in those areas tell me it wasn’t maintained well. Looks like new externally and the pots are all ok by compression test so very deceiving. I did a 5% phosphoric acid flush of the engine with the leg off and all anodes removed for three hours. I then ran it. Did have good effect. Dropped the running temp from 74 degrees C to 61 so that was good but that didn’t fix the issue. I reckon when I drop all the new gaskets into place and get her back together she’ll be like new. If it isn’t then I’ll be throwing my hands into the air as everything has been cleaned and changed out. So I’m quietly confident. A Suzi dealer here in Perth is helping me out as well. The mechanic immediately told me he has replaced quite a few engine holder gaskets on these V6 motors and he diagnosed the issue over the phone immediately . There sending me the parts. He’s also been excellent. The dealer I bought it from doesn’t want to know me. Don’t care anyway. They would have done a miserable job if I’d let them as there not even a Suzi dealer. I’ll post and let you know how it goes when she’s back together later this week. Thanks for the help and the offer. Cheers.

[Pilbara]

So my saga continues. I rebuilt the power head unit. By rebuilt I mean, cleaned all the water galleries available without tearing the heads off. Cleaned the oils cooler water jacket, crank case cooler, inlet manifold water cooler. Anything I could get too and sighted down into the water head galleries which weren’t to bad. Put it all back together, new gaskets, sealent etc as per the Suzuki workshop manual. After a day of letting sealants solidifying started her on two water lines, muffs at the bottom and another feed in at the top flush point as we have low water pressure in this neck of the woods. Idle temp settled between 58 and 61 degrees. Almost 13 degrees Celsius lower than I was getting before!!! Let it run for about half an hour no issues. Anyway threw the boat into the water switched the engine on and let it sit idling for a while, temp sat at the same again 58 to 61 degrees. Went for a run and throughout the next hour the engine ran though various rpms all the way to WOT, all through these the temp alternated between 58 and 64 degrees the 64 being at WOT 6000 rpm at 41 knots for 10 minutes. Brought her back down to just above idle over the next 5 minutes and then click her into neutral temp was 59 degrees displayed in the nmea 2000 on both my sounder and Garmin gmi10’s. After 5 minutes at idle with the temps still showing 59 degrees the engine went into overtemp limp mode. Shut her down for 10 seconds restarted her and all was fine again with the temp showing 61 degrees for the next 20 minutes te
hen at 60 degrees at idle it did it again. Now I was total confused. How can I be getting a differential temp at only 60 degrees? Next day I got a infrared temp gun and went out again with the engine cover off. When the nmea system indicated an engine temp off 58 degrees the port bank read 46.3 degrees ( pointed just below the temp sensor at the water manifold) and 44.5 degrees on the starboard bank. Now I’m even more confused as to how I’m getting a 15 degree temperature difference reading between the nmea read out and the ir sensor readout. I’m seriously starting to think I have either got a temp sensor issue or my ecu is playing up or some calibration of sensors on my nmea network is out. I had my batteries checked to make sure they were all good and they were. Anyway I’m getting three new temp sensors sent up. After that I may have to send my Ecu down to Suzuki to see if they can download data from it to see what the hell is going on. In short the motor is now running a lot cooler at all rpms but my original problem of overtemp at idle still remains. I’m really staring to think these OT errors are false errors.

[tsturm]

So my saga continues. I rebuilt the power head unit. By rebuilt I mean, cleaned all the water galleries available without tearing the heads off. Cleaned the oils cooler water jacket, crank case cooler, inlet manifold water cooler. Anything I could get too and sighted down into the water head galleries which weren’t to bad. Put it all back together, new gaskets, sealent etc as per the Suzuki workshop manual. After a day of letting sealants solidifying started her on two water lines, muffs at the bottom and another feed in at the top flush point as we have low water pressure in this neck of the woods. Idle temp settled between 58 and 61 degrees. Almost 13 degrees Celsius lower than I was getting before!!! Let it run for about half an hour no issues. Anyway threw the boat into the water switched the engine on and let it sit idling for a while, temp sat at the same again 58 to 61 degrees. Went for a run and throughout the next hour the engine ran though various rpms all the way to WOT, all through these the temp alternated between 58 and 64 degrees the 64 being at WOT 6000 rpm at 41 knots for 10 minutes. Brought her back down to just above idle over the next 5 minutes and then click her into neutral temp was 59 degrees displayed in the nmea 2000 on both my sounder and Garmin gmi10’s. After 5 minutes at idle with the temps still showing 59 degrees the engine went into overtemp limp mode. Shut her down for 10 seconds restarted her and all was fine again with the temp showing 61 degrees for the next 20 minutes te
hen at 60 degrees at idle it did it again. Now I was total confused. How can I be getting a differential temp at only 60 degrees? Next day I got a infrared temp gun and went out again with the engine cover off. When the nmea system indicated an engine temp off 58 degrees the port bank read 46.3 degrees ( pointed just below the temp sensor at the water manifold) and 44.5 degrees on the starboard bank. Now I’m even more confused as to how I’m getting a 15 degree temperature difference reading between the nmea read out and the ir sensor readout. I’m seriously starting to think I have either got a temp sensor issue or my ecu is playing up or some calibration of sensors on my nmea network is out. I had my batteries checked to make sure they were all good and they were. Anyway I’m getting three new temp sensors sent up. After that I may have to send my Ecu down to Suzuki to see if they can download data from it to see what the hell is going on. In short the motor is now running a lot cooler at all rpms but my original problem of overtemp at idle still remains. I’m really staring to think these OT errors are false errors.

Bad temp sensor?

[redlowrey]

The good thing is you can do some voltage drop testing of the exhaust temp and cyl temp sensors while it is idling and monitor the voltage change as the engine gets hot, this problem is hard to do when the problem is only there at wide open throttle. using the temp gun and watching the voltage drop as temp increases, you will soon see if a glitch happens and the signal voltage drops below 200mv.

Depending on the water temp you should see between 2 and 3 volts on the meter when cold, and gradually drop to under one volt at operating temp, and the light will come on just under 200mv.

If it was a wiring problem between the sensors and the computer it would have to be shorting not high resistance.

[Pilbara]

Great suggestion redlowrey, going to try this ASAP.