dt85 heat sensor

a friend of mine says his engine runs fine at half throttle,but if he opens it up the alarm starts going off.has new w-pump,head gasket,and no t-stat.just leaves the sensor,maybe?any help would b appreciated

Re: dt85 heat sensor

Hi,<br />I had similar problem with my Suzuki DT65 (1991) I had before. It was actually a defect water level switch in my case.<br /><br />There are two types of overheat sensors on the 2-strokes Suzuki:<br /><br />- Water level switch (it looks like a clothespeg or similar).<br />- Heat sensing switch (it is round).<br /><br />To run without thermostat is not that good. The engine does not get proper and even temperature then. If You plan to mount it back make sure the vent hole is pointed in right direction (toward the end of cylinder head, toward the spark plugs).<br /><br />It is possible to test the overheat sensor with an ohm meter.<br /><br />Water level switch: float in lower position continuity should exist, with float in upper poosition no continuity should exist.<br />Heat sensing switch: at room temperature no continuity should exist. Using a 12 volt cigar lighter for a vehicle (or a heat gun) heat the end of the sensor and as sensor warms continuity should exist.<br /><br />Good luck!

Re: dt85 heat sensor

thanks bo,been outa town will ck again and let u know

Re: dt85 heat sensor

ok,changed the sensor and added thermostat.still have the same problem.where is the water level switch located?

Re: dt85 heat sensor

Hi,<br /><br />It is<br /><br />- Water level switch (it looks like a clothespeg or similar). On older Suzuki I belive.<br /><br />OR<br /><br />- Heat sensing switch (it is round). On newer Suzuki if I'm not misstaken.<br /><br />Assuming it is an overheat alarm??:<br /><br />When You run the engine, how hot does it get? Run without cowl so You can place Your hand on cylinderhead and You should be able to keep Your hand on it. So not as hot so You need to remove your hand (to not get burned). I belive there are heat stickers you can glue on the cyl head to see temp also (I do not know where to buy).<br /><br />Make sure the water tube that goes from waterpump up to powerhead has the grommets correctly seated in both ends of the tube. I had a Suzuki DT65 before and when changing waterpump (impeller) I also changed to new rubber grommets on that water tube.<br /><br />Also, the alarm: is it really overheat alarm going on? Ask your friend again and check the Owners manual what alarm is going on.<br /><br />If it is overheat alarm going on it can also be obstruction in water cooling channels. It is possible to flush the channels in reverse direction but you should remove the lower unit then.<br /><br />Is this outboard used in saltwater?<br />If Yes, it could be salt built up inside the outboard cooling channels restricting water flow, asuming it is an overheat (alarm) situation we have here.<br /><br />How long can be outboard be running and at what RPM before the ??? alarm goes on?

Re: dt85 heat sensor

hi,bo personally i have never run this engine except on ear muffs.my friend just bought the boat.owner said he had w-pump and head gasket installed.i installed the t-stat and heat sensor.the water coming out of the p-hole is hot,but not hot enough that u can't hold your hand under it.my friend says,when u leave the dock and try to plane it out,it almost planes and the alarm starts.he says u can run all day at 1/2 or3/4 throttle and alarm never goes off.any chance of a tps on this engine.i think he needs to take it to a shop.have never worked on suzuki.mostly mercsif u have another idea,i will try and let u know.thanks roy

Re: dt85 heat sensor

Check the engine rpm at WOT before the alarms go off. The engine should be able to make ~5800 rpm at WOT. If it doesn't he could be overpropped which would contribute to an overheat at WOT. Get an infrared point and shoot thermometer at Radio Shack ~$50 and verify whether or not the engine is actually overheating. Aim the thermometer at the flat area on top of the engine cylinders just behind the flywheel but in front of the cylinder head. Temp should be less than 163 F. Cylinder heads will runn hotter than that, around 190-200 F. If the engine isn't overheating the problem is in your sensors. Depending on the year, that engine also has an oil flow sensor that will slow the engine if the oil flow slows due to a clogged filter (underneath the oil tank) or other restriction.

Re: dt85 heat sensor

thanks guys for all your help.he is taking to dealer.will let everyone know what dealer says.thanks again,roy

Re: dt85 heat sensor

Hi,<br />Probably wise to take it to a professional marine mechanic. If he is good he should solve the problem at not to much cost, assuming the repair/adjustment does not involve much teardown and expensive parts. Time spent to find the fault can not be avoided of course but if he has the right diagnostic tools it should be rather quick to find, hopefully.<br /><br />Please post back when You know the cause and solution so others may learn and take advantage of this case.<br /><br />/Bo