Suzuki DT55 Engine Temperature Sensor

[Toulouse]

Hi,
I am trying to track down an engine performance issue that seems to have something to do with the engine temperature. I have been working from the manual to test the engine temperature sensor. There it says that the resistance across the leads at 25C should be something like 56-84 ohms. I am getting 50,000 ohms (almost an open circuit!). Is this test valid, meaning that the sensor is broken?

 

[cousinabe]

Re: Suzuki DT55 Engine Temperature Sensor

i would go with a yes.

 

[hevysrf]

Re: Suzuki DT55 Engine Temperature Sensor

You don't say what year motor, the old ones used a float switch that would read open with no water in the block. I think the float was 2 wire,later temp sensors had 3. The floats were known to fail, almost impossible to remove to check without breaking, so order new. MartyD

 

[Toulouse]

Re: Suzuki DT55 Engine Temperature Sensor

Hi guys

Spent some more time but I still cannot figure out whether my parts are faulty or what. Just to clarify, I have a DT55 1995 Suzuki.

There are 2 problems. One with the Engine Temperature Sensor - this sits in the head (goes into the water jacket, so works on the water temperature) between cylinders 1 and 2 (counting from the top - the DT55 is a 3 cylinder motor). According to the Clymer Manual I should be getting resistence of 56-84 Ohms at 25C (77F). Test is done when taken off and sitting in water. I get 50,000 Ohms with no change over any temperature range. I got a new sensor and exactly the same readings!!!! Is this senor doing nothing??? Have a paid $170NZ for nothing??

The other problem is with the Overheading Sensor. This sits in the block on top of the engine near the exhaust manifold. This is supposed to be open (on a resistance test) normally but closed (short circuit) when heated to round 100C (212F). I cannot get any reading other than open circuit. So this always indicates that the engine is hot overheating. Again replaced this sensor and tried the test again and the new one does not respond. This means that I get no alarm if the motor overheats!!! Is this sensor also rubbish or at the tests in the Clymer Manual not the right ones.

Talking with my friendly Suzuki Service agent, he seems not to know!!! Not because I am doing the work my self, he is in a distant city and knows he would not be getting my work anyway. He just said that he has never tested these!

Anyone have ideas????

 

[99yam40]

Re: Suzuki DT55 Engine Temperature Sensor

are you sure your meter is functioning properly if all you get is open circuit or real high readings?

 

[Toulouse]

Re: Suzuki DT55 Engine Temperature Sensor

Hi

Yes, my background is in electronics, so I have a couple of meters and use them a lot. I have tested them on a lot of things and they certainly work just fine. Shorting out the probes on the meter give a correct short circuit.

 

[hevysrf]

Re: Suzuki DT55 Engine Temperature Sensor

Is this the Engine temp sensor? Is it 2 wire or 3 ? If 3 wire black to Violet should be about 65 k ohm at 25 C. Black to green/yellow is a float switch, reads open or closed.

My manual only goes to 93, Overheat sensor for 93 is a bimetal, only reads open cold or continuity at 100 C , confirms your info. Are you putting Overheat sensor in boiling water for test? Manual says you need to press it against a red hot car cigar lighter to test. MartyD

 

[Toulouse]

Re: Suzuki DT55 Engine Temperature Sensor

Yes that is the sensor. Mine (and the replacement) are only 2 wire and this is confirmed by the manual. Black and violet/white. This should give the 56-84 Ohms but I get the 50,000Ohms! Just maybe in 95 they decided to "ditch" this sensor but left it there because the hole was in the cylinder head mould!!! Although it is in the manual, so would be nice if someone else has done this test.

The overheating sensor testing according to the manual says to just do this in boiling water.... I will give it a go with heating it a bit more and see if I get a reading.

 

[hevysrf]

Re: Suzuki DT55 Engine Temperature Sensor

My manual(OEM Suzuki) says 56 -84 "K" ohms which is 56,000-84000, so you're close. I'm having mixture problems, can you tell me how many turns out your mixture screws are? Book tells me 1 5/8, but i feel its lean.MartyD

 

[Toulouse]

Re: Suzuki DT55 Engine Temperature Sensor

Misprint is someone's manual and I am not sure which one. Mine definitely says, set the range to R x 10 and that the reading should be 56-84 Ohms. So the highest with whatever misunderstanding would be 560-840 Ohms, nothing like the 50,000 that I am getting. Have you measured yours? I am prepared to accept the misprint, but it leaves me doubting what else is wrong in this manual.

I'll get back to you on the mixture, if I can work out what you need.

 

[hevysrf]

Re: Suzuki DT55 Engine Temperature Sensor

I have the 3 wire, may be a different than later 2 wire models( for 1986) violet to black reads 140,000 at 11 C. The sensor between the spark plugs should only advance timing for engine start, bimetal on side will sound buzzer, limit rpm to 3000 when closed. MartyD

 

[Toulouse]

Re: Suzuki DT55 Engine Temperature Sensor

Ta, for then help. The car cigarette lighter worked just fine to test the overheat sensor and it looks like that is ok. I'll change my manual so I remember in the future.

I now suspect that with your reading of 140,000 Ohms that the manual again is wrong unless someone else comes up with something.

On the other subject, the mixture screw, I cannot see one on my carbs so I am not sure what you are meaning.

 

[Wfyank]

Re: Suzuki DT55 Engine Temperature Sensor

hello all i am having same trouble with my 55 cencer has three wire but one is not hooked up cant tell from manual where it should go it only shows too wires .and shows it run true spark on #1allso is there way to see if there a block in water jacket ?the weep hole just trickels.it well run then seams to cut out after about 30.sec any ideas thanks

 

[Wfyank]

Re: Suzuki DT55 Engine Temperature Sensor

ok starting to look like water pump.checked themostat and working right but no water getting to it or that weep hole and seems the temp sensor is flow switch? starting to make sense. ill check back in once drop bottom.

 

[Wfyank]

Re: Suzuki DT55 Engine Temperature Sensor

Not the water pump was good changed out anyway.cleans carb,stell not running right unplugged slow fast idle and run like champ on muffs but I think the switch has something to do with timing so need more to do more research any ideas?

 

[Wfyank]

Re: Suzuki DT55 Engine Temperature Sensor

Well stell acting screwy no wot after carb cleaning new water pump fuel lines replaced going nuts last time out ran great for ten min.then bog down lights come on wait min then run good took home thinking it's bad controller then get to thinking fuel pump low and behold big hole in diaphragm trying out tonight.

 

[Wfyank]

Re: Suzuki DT55 Engine Temperature Sensor

That was it hole in fuel pump diaphragm need to tweak linkage but boating now