1996 DT150S Overheat buzzer and light problem at low speed and idle.

[N2 Fishing]

Thank you booster, I think I’ll just go with factory parts since I am chasing an overheat alarm. I pulled the T-stats and suspended them in a pot of water and discovered that they start opening at about 132F and are completely open by 136F. So I don’t know if that means I should change them or not. They are suppose to start opening between 118-126F so about 6F off. I used both a digital gun with the Thermal couple and candy thermometer simultaneously and there was only about a 1-2F variance between the two. I also pulled both heat sensors. The starboard side philips screw was being very stubborn so I cutout two flats using a dremel so I could get a good grip on that screw with some vise grips. After I got a good grip with the vice grips it came right out pretty easy.

Two of the T-stat bolts were stubborn as well. One more so than the other. I had to work it back and forth about 1/8” -3/16” of a turn back and forth practically the whole way out. The bolt does have some corrosion on it too. Any suggestions on the best way to clean the threads in the head before I put the T-stats back in?

Oh yeah I almost forgot, both sensors have some kind of stuff on them. The service manual states not to use any oil on the sensor or down in the hole the sensors are housed in. The port side sensor has some kind of runny looking oil while the Starboard side has some white goop. I’m not sure what it is, could be white lithium or some kind of thermal compound IDK.

I took pictures but they are on my phone and I’m in bed already on the iPad making my rounds before I crash for the night.

[N2 Fishing]

From start up to the first 7 minutes of warm up the Starboard side will set an alarm at 212F. After 7 minutes from starting at 183F Starboard side will set off the alarm and on the port side 248F will set off am alarm at any time during operation. So at least now I know the T-stats should not be the cause of the alarm.

[N2 Fishing]

Ok I have a little problem now. One sensor has 3 wires The $50.00 sensor and the $70 sensor has two wires. When I test the sensor with three wires at 71F between one set of the three wires I get a reading of 2.22 kΩ which looks normal and when I test another set of wires I get a reading of 79.6 kΩ. last when I test the third option between wires I get OL.

Now on the other sensor I get no reading at all. Additionally when I set my meter for continuity with a beep I get no continuity and no beep. I'm not sure if that means the sensor is dead or what. I have to dig into the manual again to see if it specifies what wires I should be testing on what sensor. and also find out what it says about each sensor. From what I recall it does not specify any differences between the two sensors. So this leads to more confusion on my part.

When I pull the lower unit "soon" I will plug a hose into the line coming form the pump housing up into the block with the T-stats out and turn the water on from my garden hose and see what kind of flow I get at each T-stat exit port.

[N2 Fishing]

Ok no major discoveries as of yet. A guy at browns point informed me that I can unplug the green wires of each sensor one at a time to see if the alarm stops. The port side has a purple wire that needs to stay connected along with the black wire. I told him I was trying to get a Ohms reading of the sensors while out of the boat and he informed me that the heat sensors only make continuity when they have reached the over heat set temperature. Does any one know about this ?

I got some garden hoses hooked up the the T-stat housings so the water exiting the top of the engine will flow outside the engine which will make it easy to see how much flow I am getting per cylinder bank. I am thinking I should get two five gallon buckets and see if both buckets fill up evenly or if one side is so restricted that it does not fill evenly with the other side.

I ran a new plastic water pressure line from the engine to the helm and installed the pressure gauge on the dash. I also installed a different monitor gauge from ebay. It was suppose to be new but I can tell it’s not even close to new. I still have yet to test it. I’ll probably give it a try some time tomorrow.

I also pulled the manual steering crap out of the boat and fed the new Seastar Pro hydro lines from the helm to the engine. I still need to order the water pump but I am waiting to see if I will be needing any other parts for the cooling system before Implace am order. Tomorrow I think I will pull the lower unit off and hook up a garden hose to the water feeder tube that runs from the pump to the bottom of the engine block and see what kind of flow I get with just garden hose water pressure. If everything looks good there then I will put the T-stats back in and reinstall the lower unit and start it up to see what kind op psi I get at the gauge. I got the meter that goes up to 35 psi.

[N2 Fishing]

Made some progress today. I pulled the lower unit and put a garden hose on the tube from the pump to the block and checked water pressure at both t-stat housings and I had plenty of flow through both T-stat housings. Next I installed the T stats so I could check the the water pressure gauge I just installed. I get about roughly 14-15 psi at the gauge with the garden hose on almost full blast.

Next I checked the new meter gauge on the dash and all the lights are working from what I can tell and I left the light green wire unplugged from the port side with just the black and purple wires plugged into the heat sensor and the gauge on the dash indicated an over heat problem code 1-4 with the series of flashes from the Check Engine light. So I plugged light green wire back into the port side wiring and tried turning the key on again. This time I did not get any flashing code for an alarm. The two wire Starboard side sensor was left unplugged the whole time and it did not set off any code.

There was a little cracked cylindrical boot at the rear of the lower unit.

It is #20 in this parts diagram " https://www.boats.net/catalog/suzuki...-200efi-150efi "

I glued it back together using some super glue and some baking soda to make it cure fast. Then put a dab of liquid All laundry detergent on the tube that sticks out the bottom of the leg towards where the skegg type anode mounts. I put some inside the rubber cylindrical boot as well so the two would slide together fairly easy. I'm not sure what that boot does but I'm ordering a new one with the water pump.

I Think I will try to set up the Starboard side temp sensor so that I can unplug it fairly quick while the engine is running to see if it cures the alarm next time it goes off.

I'm getting closer Here is short quick clip that took me forever to make and upload. It's not much. I'm no video expert :/

https://www.youtube.com/watch?v=eDIw...ature=youtu.be

[N2 Fishing]

Well I made an interesting discovery. When at idle I get no water pressure at the gauge. The gauge starts to move at about 1150-1200 RPM.

I also noticed the Port Cylinder Bank was getting upwards of 160F where the temp sensor is housed. I'm not sure if this is normal or not. That sensor is suppose to set off an alarm at 220F as far as I know. The port side does get hotter than the Starboard side.

Both of the Thermostat housings stayed with in about 10F of each other the port side hotter at about 226F and the Starboard side at about 216F.

Not sure what to think at the moment. I ran the engine with out the Starboard side temp sensor plugged in but even if it was plugged in I don't think it would send an alarm unless the sensor is faulty. I shut it down when I saw 160 on the port side.

Does any one know what the water pressure should be while at idle? The Top Port Cylinder seems to be getting the hottest.

[Solarman]

Try running the motor without t'stats and foot. Use the temp gun to see if any hot spots?
What are the other hoses running water from, in your video? Are those hoses off the pressure guage you installed? Plug those closed, before running motor. Where are you connecting your hose to run the motor? You can NOT run the motor from the flush port at the powerhead, this port is for flushing without running motor. This will damage your impeller, because it runs dry. You can only run the motor with muffs on the foot, or if you connect your hose to the water supply pipe that the water pump connects to without the foot installed.
That rubber grommet you glued together (#20) is part of the sub-water pickup tube that helps supply water to your water pump. Look closely at the grommet on the other end of the tube. Make sure it is tight on tube and housing, otherwise exhaust pressure can interfere with water pump (exhaust pressure prevents water getting into that water supply cavity) picking up water to supply motor.

Post back on these questions asap. Thanks.

[N2 Fishing]

I don’t know what you mean by foot.

The water pressure gauge is a factory kit that has a little nozzle that threads into the block on the front side of the port cylinder bank and a little hard plastic line runs from it to the gauge on the dash just lik the speedometer hose. It is factory and permanent now. I had to remove a plug in the boat to thread in the plug with a hole in it for the water line to connect to.

the garden hoses in the video are as follows. One runs from the bottom of of the tube that from where the pump pushes water into the block. The other two hoses in the video that show water flowing are plugged into the thermostat housings with no T stats.

when I ran garden hose water through the system with lower water pressure and no thermostats the exiting water would only flow out of the port side. I had to turn the water pressure up to get the water to flow out of both thermostat housings.

I did not think it was safe to run the engine without thermostats as the engine mixes the fuel to air ratio based on all of the sensor readings. Air psi, cylinder temp and air temp etc.

is running the engine with out the t stats just to show me if I Am getting water flowing all the way through the engine to both thermostats?

EDIT: when I ran the motor to check temps after posting the water flow and gauge check video the lower unit was put back on and was submerged in a large yellow trash can full of water with the garden hose supplying fresh cold water to the can. I wanted to eliminate any added pressure the garden hose may add to the pump pressure if at all possible when using the water ears/dogs or what ever those things are called. Hope this clears up any confusion as to how I was testing if there was any.[/QUOTE]

[Solarman]

Foot is the lower unit, with the prop and water pump assy. When I asked where you connected the hose, I didn't recognize that was it at the bottom going in.
Yes, running the motor without thermostats and without those two lines hanging loose (for guage, off thermosts) can help you identify if motor is heating up, or running too cool. Then running the same way with the thermostats might indicate if your thermostats are working properly.

If your motor is still running too hot with thermostats out, use the temp gun to see where the cylinders are heading up.

What temp are your thermostats rated at?
Does your sensor measure flow of water, some 3-wire sensors had a flow switch incl.

Post back when able to let us know.

[N2 Fishing]

EDIT: Ok I see run the motor just from garden hose pressure to see what kind of temps I get and to know if it's a pump or bushings from the block down to the pump causing not enough water pressure. I'll do that check soon .

The sensors are surface mounted to the exterior of the engine block on the outside of the painted surface and there are no water flow sensors unfortunately. Suzuki got rid of those on the newer engine like mine. Thermostats are rated to begin opening at 118F - 126F and they both seem to do this and are fully open by about 134F.

I pulled the garden hoses from the thermostat housings and plugged the black rubber hoses from the lower section of the motor back into the thermostat housings when I ran the motor. I was not using any garden hoses when I put the lower unit back on and tested out the motor for temperature readings. One thing I did not do is unplug the hoses from the thermostat housings to see what kind of flow I get with the thermostats installed.

I will test the flow with thermostats installed and the two bypass garden hoses hooked up first then pull thermostats and test for water flow and temps again. If I notice a decrease in water flow with the thermostats out I will stop the testing as over heating will be soon to follow.

[N2 Fishing]

I found the other 15 psi water gauge. I also did some more testing with t stats in and water tubes unplugged from T stat housings to see how water is flowing while running with T stats in. I will post some videos later. The Port side seems to get higher temperature readings near the sensor and also starts flowing water sooner than the starboard side. Next test will be pull the lower unit and test running with garden hose at different water pressures. Or maybe it should be to test w/o T stats to see if flow is different with stats out.

[N2 Fishing]

Made another pretty big discovery by accident. I was moving the hose clamp on the bottom of the hose for the thermostat hose and bumped into a head bolt by accident to discover it was loose. I though oh could it really be that easy? So I grabbed my torque wrench and 12mm socket to start tightening the bolt. Guess again....

Broken head bolt all the way at the bottom #6 cylinder. All the other bolts seem to be tight and very difficult to loosen. I did not try to hard to loosen the other bolts. I don't need more broken head bolts that I already have but from what I have read the Suzuki's like to break off head bolts.

With all this ^ information I am wondering what is the best way to remove the head bolts. Run the engine until it is hot then try to loosen them little by little? I am thinking I could probably get the bottom snapped off bolt out using a mig or tig welder to build up some material on the broken stud down in the block which by looking at it, my geuss is it's probably broken off flush at the top of the cylinder.

[N2 Fishing]

Water flow with Thermostats installed.

https://www.youtube.com/watch?v=Stg538ybYDc

Water flow with out Thermostats installed.

https://www.youtube.com/watch?v=Yac6jg-_qcg

Discovery of Broken Head bolt.

https://www.youtube.com/watch?v=JtRQvXiP03E

[N2 Fishing]

Compression readings look with in range all are with in 10% of each other. Thinking I should do a leak down test on Cyl #6.

Cyl 1: 105 PSI
Cyl 2: 102 PSI
Cyl 3: 101 PSI
Cyl 4: 100 PSI
Cyl 5: 104 PSI
Cyl 6: 100 PSI

[N2 Fishing]

I got the HF leak down tester and all cylinders checked out cold and warmed up. This has me stumped. Number 1 cylinder and number 6 cylinder spark plugs did look cleaner than the rest of the engine. I got a reading of 170+ today at the port side sensor