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'96 DT150S BASS Over heat Alarm issue

N

N2 Fishing

New member
So I have this annoying over heat alarm that have been going off at idle and lower sub 2200 rpm range while in gear. New water pump installed, Thermostats checked out ok over the stove in a pot of water and both are fully open by 135F.

I installed a Suzuki 35 psi water pressure gauge and get practically no water pressure at idle and the gauge does not start to move until about 1150-1200 rpm. I get 15psi or more at about 3000 rpm.

I pulled the thermostats out and lower unit off to test for flow from the thermostat housings in the video below. I get good water flow when I turn the water pressure up from the garden hose spigot. If I don't turn the water pressure up to almost full blast I only get water flowing through one thermostat housing. I think this is because the water exiting the thermostat housing is about equal to the amount of water going into the lower pick up tube.

I also recently installed a different monitor gauge because the original was left outside for a few years and weather took it's toll so some of the lights were no longer working.

I have had this issue since about 2006 when I purchased the boat this engine is on.

I checked the Port side heat sensor and I get Ohms readings but on the starboard side I get no Ohms readings at any temperature. Is this normal?

https://www.youtube.com/watch?v=eDIwiGwJKvI
 
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 wow could it really be that easy as I though to my self? 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 than 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 guess is it's probably broken off flush at the top of the cylinder.

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
 
Last edited:
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
 
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 :eek:
 
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