2015 DF15 overheating issue

[Murray]

All I can think of is you still got some of that sludge in the water passages in the block. How the heck you would get it out, perhaps a small snake like plumbers use? The sludge you pulled from the thermostat was fairly stiff you said, I doubt that the water pump has enough pressure to remove the sludge IF thats your issue. Suzuki have a diagnostic tool that can be hooked up to a computer and the engine which will read any codes thrown, you would have to check with a dealer if they can read a 15 HP engine. I know they can pull codes off the larger engines not sure about yours. Oil pressure, or lack of would also cause the engine to go into safe mode but with yours you let it idle for a while(cools down?) and it clears itself and you can carry on. If low oil pressure was your issue one would think the warning light and safe mode would come on a lot sooner and stay on. You may have to take it to a dealer to have the codes read, to verify it is an overheating issue, if they can read codes off your engine. What does your service/owners manual say about overrev? Overrev, at least with mine you back off the throttle immediately and all is good. I’m out of ideas, hopefully someone else will chine in with possible solutions.

[Murray]

See diagram on your post #36. Did you remove hose #1 and #4 to check for sludge? What does your manual say about your fuel cooler re disassembly and checking for more of that sludge? You have to make sure you have checked all the easy stuff(external components) . The SDS (Suzuki Diagnostic Software) if possible with your engine, will confirm Overheating issue. If you can confirm you have an overheat condition and you have checked ALL the easy stuff then I suspect your next step will be much more involved.

[TommyDee51]

I've been following the overheating problem and just wanted to know if there is a way to flush the cooling system beside the port and the ear muff procedure. That gentleman may have the same problem I have with my Suzuki Df 200. I flushed with saltaway and right after that the engine overheats every time with no water coming out of the pee hole. I think the saltaway loosened deposits and caused them to solidify somewhere else. Is it possible to take thermostat off and blast water through the water lines from that area? Did he use saltaway

[Murray]

Not sure how you would blast water though the thermostat and maintain any pressure though the engine unless you used a firehose? I’m a fresh water boater so I’ve never used Saltawy, I thought Saltaway dissolved the deposits as opposed to breaking it off in chunks. Have you given any consideration to trying another round of Saltaway treatment? See post #17 for another option.

[TommyDee51]

What I did was remove the thermostat and replace just the housing, then blasted water up into the water tube. No good. After I put everything back together the motor, (200 DFA) ran for about five minutes and once again overheated and shut down. No water coming from pee hole at all. It is still under warranty but, I don't think it is covered. New impeller, new thermostat, new anodes. no water coming out pee hole at all.

[Murray]

Start a new thread explaining what you did (basically a copy and paste) Give all details on how you are supplying water to the engine, year and hours of the engine. Perhaps you’ll get more input. Is the engine sitting in salt water 24/7/365?

[Dan_333]

im having exacly the same overheating problem with my df15 and ive done the same steps to try and fix it witn no luck.

did you end up finding out what was wrong?? any help would be very much appreciated

[Bretto]

I had overheating issues (DF50). The problem started with a faulty pressure release valve. So a lot of the cooling water was being dumped straight out the leg before it even got to the block. It’s a decent job to the pressure valve on a DF50...remove the powerhead, remove the oil pan, there it is under the oil pan. The previous owner drove it for years at low revs so he didn't trigger the overheat alarm. And that caused more problems, in particular the water channels blocked up. I managed to dig out a fair bit…..accessing through any point I could find like thermostat, anods, grommet screws….& used tiny screw drivers and thin wire to scrape around. But it was still overheating of course. I mean, those channels go so many places I had no hope of reaching. So I went next level and put Rydlyme through it. Twice. Finally it looks like I've cleared the water passages and fixed the overheating.

RYDLYME - Here's how you do it....
Take off the foot.
Then figure out how to hook up a bilge pump to the water inlet pipe that goes up into the block. Put the blige pump in a large bucket under the motor. (nb I bought two cheap pumps from eBay…I wrecked both of them in a couple of hours using Rydlyme)
Remove the thermostat. Put the housing back in place.
Re-direct the tell tale stream into the bucket. Or just block off the pipe.
Pump the solution through for a couple of hours.
A lot of junk came out. Problem number two solved. Now I've gotta deal with a carbon build up issue.

BTW....don't think you're being kind to your motor my minimising the revs. They don't like trolling. They dont like mid-level revs. They do like WOT or somewhere close to it.

[doubl0h7]

Little late to the party on this thread but this is probably what’s going on.

The DF 9.9/15/20A has a design flaw if you are going to run it in salt.

From all the feedback I’ve got from cruisers 3 years is how long they last before the lime buildup makes them overheat and go into limp mode.

Flushing them isn’t a realistic option as you have to conserve drinking water when you are out for weeks and month. Also there are lots of reports that the flushing doesn’t really help that much anyway.

Just for future reference, you can leave the power head, flywheel, etc on when you pull the cylinder head despite what the Suzuki manual says. Heck you could leave the motor on the dingy but that would be sketchy over water and expensive parts would undoubtably go kersplunk. Make sure you mark the timing and have a 8mm (or 5/16th) 12 point socket.

I ended up spending $1600 at the dealer trying to get it fixed long distance ($1200 was trauma to the prop and a corrosion cracked shaft) I would have thrown the motor in the dumpster and been way ahead as it came out of the dealers acid treatment still over heating.

The Suzuki dealer had undoubtably massively softened and removed a lot of the goop with the flush. We were able to wake speed the dink all around and only overheated after a full speed short run.

I think all the hard stuff was calcium. 95% of it was in the block behind the thermostat passage.

I was tempted to copper coat and reuse the head gasket but I sprang for the $70 new one. Ouch.


Zero reports of this happening with the Tohatsu so it’s a superior choice.