Yanmar YM2500

[boonesmith]

Underwaterdog,

You are correct. I used a nipple with 1/8 BSPT on one end and 1/8 NPT on the other. I used an NPT "tee" on the end of the nipple to preserve the sending unit and dash light function.

The thread was 1/8 BSPT for the YM1500D, however, I am not sure if Yanmar uses this thread on all models.

[Underwaterdog]

Boonesmith,
so if the light sending unit was originaly BSPT, did the light sending unit screw into the NPT T or did you replace it with a NPT sending unit? The 1500 must be different, because 1/8" NPT pipe is about .405" OD, which is about 10mm. Could it be that tmar04's sending unit was actually tapped
3/8" BSPT, but was close enough to 16mm that it worked after he chased it? 16mm is .6304". 3/8" pipe od is .675.
If the threads are close it might just work.
Just need to know because that is on my list of things to do, and I hate to loose the light, you know, for my wife.

[boonesmith]

Sorry, I had forgotten about the sending unit "incident" until you asked the question.

I went from the nipple to a 1/8 NPT tee. I made up the assembly without remembering that the sending unit should have been 1/8 BSPT. The sending unit was new and I never checked the threads.

I decided to leave things as they were since I had probably damaged the threads on the sending unit, the tee, or both and the connections did not leak. I should have used a 1/8 BSPT tee with a 1/8 NPT adapter to the copper line running to the guage.

I will send some photos tomorrow. I used a quick and easy(lazy) way of mounting the gauges. I mounted the set to the steering column tube using a "U" bolt and an adapter/spacer.

[California]

Just to clarify here: The water temp sender and the oil pressure sender have different threads.

16 mm X 1.5 is when we're talking about the water sender. You can't 'T' it because the sensors won't both be in hot water.

1/8 BSPT (British Standard Pipe Thread) is similar enough to 1/8 NPT ([American] National Pipe Thread) that they can be jammed together - sometimes. On Yanmar that's the thread for the oil pressure sender. A T works fine, pressure is equal in all parts of the pressurized system, you can have both a gauge and a warning light.

I think.

[Underwaterdog]

Just to clarify here: The water temp sender and the oil pressure sender have different threads.

16 mm X 1.5 is when we're talking about the water sender. You can't 'T' it because the sensors won't both be in hot water.

I understand this, we started out talking about the engine coolant temp sensor. Did you mean you used the tee on the OPS? Is this because of the possibility of air in the tee, or because the sensor is not inside the block, reading the actually temperature of the water because it is not reading the temperature of the water in the block? If it is air, you could loosen the fitting and bleed the air out of it. I read somewhere that water transfers heat something like 24 times as effectively as air. However, I also know that there could be a substantial temperature difference at the T even if there is no air in the line. I wonder if you could insulate the tee with an industrial grade fiberglass tape and mastic and significantly reduce the temperature drop. I'm talking about the kind that is used on steam lines, not the hardware store variety for insulating potable water lines that will disintegrate at high temperature. I have a gallon out in the shop and can get the info off of the bucket if necessary.

[California]

For me, neither tee.

After I bought the tractor I did the research on adapters and bought a temp gauge, with its own sender and the correct adapter.

Then I learned the importance of flushing chaff out of the radiator when mowing. I've never seen my temp light on since. I concluded a temp gauge was not needed.

I didn't see any way to expose the new sensor for the gauge, and the old sensor for the light, to hot water at the same time. Reading here in the Yanmar forum convinced me it was impossible.

Also reading here I've seen several owners add an oil pressure gauge and still have the oil light, by using a tee and BSPT/NPT adapters.

That's all I meant to describe. Sorry if I wasn't clear.

[Keith6]

what is thetempature supposed to be. On the gauge for how hot the tractor gets

[Gunny]

Another way to install a temp gauge is to mount the sensor in the radiator hose. There are several sellers on EBay that sell couplers for that purpose. You just install the coupler inline on the radiator hose, then screw the temp sensor into the coupler. Very easy to install and you don't have to worry about thread sizes and clearance issues. Hope this helps