03 suzuki df70 temp light when trimmed up.

[Pgoss8]

03 df70 on a 17' cobia bay boat with 270 hours. Motor starts and runs great except when at speed and I trim up to get the best rpm's, it sets off the temp light and cuts power after a few minutes. Impeller is new, seems to be getting good flow through the engine. If I DON'T trim the motor up at all it runs perfect. That's what is confusing. It has something to do with the position of the motor. I have checked and the pickup stays well underwater (Motor is actually setting low, need to raise it) I have removed the pickup, it is clean. I'm at a loss. Any ideas?

[Solarman]

How high do you raise it when you trim it up?
Any way to take a video of the foot of motor while running, then raising foot? What rpms do you get when running normally wot, then what are the rpms when trimming it up?

Post back with info when able.

[Pgoss8]

I will get a video next time I take it out. I have a hydrofoil on top of the a/v plate and when on plane, it is completely submerged putting the a/v plate at least 1.5" underwater. At wot with the motor trimmed all the way down, my rpms are around 5200. With it trimmed up they are around 5600. Not sure how to measure how much it is trimmed up when the light comes on, but I know the lower unit is still well underwater. No prop slippage and the a/v plate is still buried underwater.

[Murray]

Here's a long shot. When you trim up could you be putting strain on the wires in the rubber grommet where wire harness exits the engine, causing some weird electrical issue? Once the alarm is triggered (false alarm) the engine will go into safe mode. Is the engine actually running hot?

[Moonlighter]

If that foil is well underwater when you are running at a normal cruise speed, your motor is set far too deep. You will be sacrificing fuel economy and the general attitude of the boat will be negatively affected.

The foil (and thus the AV plate) should be skimming the surface at cruise speed with the engine trimmed normal.

You may have to lift the engine a couple of holes higher. Its not hard to do. See the sticky thread on this forum dealing with props etc it tells you a method to do it.

Liftijg the engine to the optimum height will also help with the general trim, acceleration and handling of the boat, and you will pick up some revs and better fuel economy as well. Lifting it should get you close to 6000rpm at WOT which is where you really want to be.

Engine height Set to the optimum level can really transform a boat’s performance, so it is seriously something you to address and get right.

Also note: if the original reason for fitting the foil was to do with the boat porpoising, or lifting the bow too high when accelerating, then lifting the engine higher will reduce the tendency to porpoise and bow lift, and you may actually be able to get rid of the foil altogether. (This is called addressing the root cause of the problem rather than a symptom)

Your engine alarm issue does sound more like a electrical/wiring issue to me. Wire somewhere to do with the trim may be shorting out as you trim it up.

[Pgoss8]

Good info. I plan to raise the motor up, just haven't yet. Only had the boat 3 months. I installed the foil to reduce bow lift, get up on plane faster, and stay on plane at lower speeds. I was wondering if my issue could be a wiring issue, I guess I need to dig further into it. Probably start by cycling the motor up and down and see what moves and what doesn't. Thanks for the help! I'll address the motor height issue and check some wiring and report back.

[Moonlighter]

Good info. I plan to raise the motor up, just haven't yet. Only had the boat 3 months. I installed the foil to reduce bow lift, get up on plane faster, and stay on plane at lower speeds..

All of which will be improved with the motor lifted to its optimum height!

Here’s a link t the tread on motor height and props:

http://www.suzukioutboardforum.com/s...ight-prop.html

Good luck trouble shooting the other problem. Go at it in a methodical way and you should figure it out. Perhaps start looking at the trim relays and nearby wiring, then the area where the wiring goes thru the gromet into the rigging tube.

[Pgoss8]

What is the best way to check the temperature when this happens? Infrared thermometer? Where do I check it? What are thoughts on installing an actual temp gauge so I can monitor it??

[Murray]

Infrared would be the simplest. I've never taken any external temperature readings on my outboard but I would expect readings around 60C assuming your thermostat would be close to my 09 DF90. I would put the muffs on in the driveway and get the engine up to operating temperature and see what reading you get, play with the trim, see if you can reproduce your symptoms. Have a look at the wires through the grommet while your there. In my case whoever installed the wires through the grommet just stuffed them in paying no attention to route them properly in the cutouts. I had wires just starting to chaff. Take it out on the water and compare readings with your baseline temperatures.

[Pgoss8]

Took it out again today, did it again. Throttled back, light went off after less than 30 seconds and ran perfect with the motor trimmed all the way down. I couldn't see any wires that are moving/ chafed.....

[Murray]

Could it possibly be the High Temperature Sensor acting up, sending a wonky signal? Just seems strange that movement of the engine causes at high temperature alarm.

[Pgoss8]

I know of the temp sensor in the exhaust manifold, is there Another?

[Harper]

Did you have the problem before installing the hydrofoil? If so, try removing the hydrofoil and see if the overheating issue still occurs. With your hydrofoil so deep you could be upsetting the water flow to the point of restricting cooling water input to the engine at speed when trimmed out. Causing turbulance in the water, in other words. Such a condition of course would never show up on muffs.

[Pgoss8]

I've never run the motor without it. But interesting idea..... a quick Google search indicated this is a common problem when trimmed up with a hydrofoil. Might be on to something! I'll remove it and report back!

[Moonlighter]

And get that motor lifted up!

I agree that the foil may be creating so much turbulence at higher speed that water flow to the pump is adversely affected. Root Cause? Motor set too deep so foil is underwater creating turbulence.

If removing the foil solves the problem, then this is telling you to lift the motor a couple of holes and test again.

After that, you can then decide if the foil is still needed - possibly the foil was fitted to solve a boat attitude problem, which would have been treating the symptom vs treating the problem (motor set too deep).

As an aside many of our Suzukis have 2 temp warning alarms - one is for reaching a preset “too hot” temp, the other is a temp gradient alarm where if the temp increases too quicky, even though it might not yet reach the “too hot” level, the alarm will go off. The different alarms will be recorded in the ecu and would show up on the SDS on the laptop.

Lifting a 70 is easy! I am assuming that there are a couple of holes availabe from the current setting so it can be lifted.

Here is a link to a forum resource that tells you how to do it using the “boat trailer” method. See the second post this thread for details:

http://www.suzukioutboardforum.com/f...the-right-prop