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  1. #1
    Super Member California's Avatar
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    5,652
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    Sonoma County
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    Yanmar YM240, YM186D, and another YM186D

    Default Low oil pressure? No, bad sender!

    I sometimes see questions here about what should temperature and oil pressure gauges show, and what causes the oil light to flicker. Maybe this longwinded narrative will answer some of these questions.

    I have owned my YM240 several years now with no issues at all, after an initial month 'renovating' it. (Mostly finding and putting Yanmar parts back on it where the previous owner had butchered something, and an extensive servicing). Then after a recent oil change, and after the engine was warm, the oil light would flicker at 1300 rpm and brighten to solid red at lower speeds. I first suspected the oil or filter. But this didn't seem likely while the oil had only 5 hours use.

    I shut it down and got my infrared remote temperature sensor. Temperatures were normal. I found 140 degrees on the bottom of the oil pan, 165 at the lower block, and 195 near the injectors, at the upper radiator hose fitting, and at the radiator upper tank. The radiator lower tank was below 100. Ok, this is what I normally measure so it wasn't overheated.

    So I installed a HF oil pressure test gauge (like this except fewer adapters, under $10 on sale). I found its hose fit in place of Yanmar's oil pressure sender without any adapter.

    For the technically curious: Yanmar used 1/8" BSTP, British Standard Tapered Pipe, while this gauge is labelled 1/8" NPT [US] National Pipe Thread. The diameter and threads per inch match up but I've read that the depth of the threads is quite different between the two standards. At any rate it threaded easily by hand for a few turns then sealed properly with wrench tightening. In my opinion these standards seem interchangeable.

    Since the pressure looked good I went back to work and got it warm again. Yanmar specifies 35-50 psi 'at working RPM'. I assume that means 1800 to 2400. I found 40-42 at PTO rpm after warmup. And 35 psi at 1500 rpm, down to 22 at 1100 rpm, where the idiot light had been red.

    Conclusion: No problem with the engine's oil pressure, but the oil pressure sender was failing. From what I've read, and after consulting a Japanese-specialist auto mechanic, that sensor should keep the light off down to under 5 psi.

    I went to Autozone and looked at oil pressure sensors used on Datsun and Toyota in the 70's, since I have noticed that Yanmar often used the same third party 'soft parts' as 70's Japanese autos. Those senders had the right thread but none had the screw terminal I needed, they were all blade or pin cable connectors. So I opened boxes until I found a match. I see it is listed for 80's Corolla and 70-90's Subaru but it really is a 'universal' connector with a blade added on top of a screw terminal. I could have used any of the blade-connector sensors and hacked the Yanmar's wiring, but this one has the screw terminal like the one I removed. It was only $5.99. Problem solved.

    And a tip of the hat to rScotty, if you're reading this, whose wisdom found elsewhere was a guiding light through this maze.

    Last edited by California; 10-27-2009 at 03:04 AM.

  2. #2
    Veteran Member MJPetersen's Avatar
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    Feb 2007
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    1,255
    Location
    Warsaw, Poland
    Tractor
    YM 1510-D

    Default Re: Low oil pressure? No, bad sender!

    This was on the 1510 that you have as a "second" tractor? How is that tractor working out for you?

    Mike
    "In all your ways acknowledge Him and He will direct your paths." Solomon
    YM1510D, YM 1202 tiller, The following home made tools: Quick Hitch, KK copy dirt scoop, imitation Gannon rollover box blade, Forks on 3pt, a Rear Blade with gauge wheels and a 1.5 yd dump trailer.

  3. #3
    Super Member California's Avatar
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    Sonoma County
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    Yanmar YM240, YM186D, and another YM186D

    Default Re: Low oil pressure? No, bad sender!

    Quote Originally Posted by MJPetersen View Post
    This was on the 1510 that you have as a "second" tractor? How is that tractor working out for you?

    Mike
    Oops. I should have been clearer. No, this oil pressure sender, $5.99, is the second repair I have made in the six years since I initially cleaned up my YM240 and put it in service. The previous repair also this year, was the 75 cent rollpin that keeps the shift lever from revolving. I'm really pleased that the YM240 has been so troublefree for so long.

    I went back and edited the post above to explain I'm talking about the YM240. I think YM186D and most Yanmars use that same oil pressure sender, however. I've seen other threads here where the unanimous recommendation for a flickering oil light was "Change the sender!"

    I'm still tinkering with the YM186D. (US version of YM1510D). I am finding that this one is more abused than the YM240 was, despite the YM240's weathered appearance. I have the 186D in service while I think about how much I want to put into it. It runs fine but it looks well used. Well, worse than well used.
    Last edited by California; 10-27-2009 at 03:57 AM.

  4. #4
    Platinum Member Neat 1500's Avatar
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    Aug 2009
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    596
    Location
    Melbourne,Australia
    Tractor
    Yanmar YM1500 Red & YM14 MkII

    Default Re: Low oil pressure? No, bad sender!

    Ha i just removed a perfect oil sender to install a gauge and guess what- the **** gauge is faulty---- go figure?
    Paul YM1500 & YM14 MkII

  5. #5
    Veteran Member MJPetersen's Avatar
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    1,255
    Location
    Warsaw, Poland
    Tractor
    YM 1510-D

    Default Re: Low oil pressure? No, bad sender!

    Thanks for the update. I vaguely remember that you had posted about an oil pressure problem, but I could not remember which tractor had the problem and I was too lazy to hunt for it.

    I broke my upper lift arm on my 1510D today. It is cast and I believe it is iron so it would be very difficult to repair it. I am kind of bummed about it. I think that tomorrow I will start a thread about it.

    Mike
    "In all your ways acknowledge Him and He will direct your paths." Solomon
    YM1510D, YM 1202 tiller, The following home made tools: Quick Hitch, KK copy dirt scoop, imitation Gannon rollover box blade, Forks on 3pt, a Rear Blade with gauge wheels and a 1.5 yd dump trailer.

  6. #6
    Gold Member
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    755
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    North Texas
    Tractor
    Yanmar

    Default Re: Low oil pressure? No, bad sender!

    I broke my upper lift arm on my 1510D today.
    Mike,
    Thats pretty common on the stock 1510 lift arms. They are way too light duty for most implements. I dont think they were ever intended to lift anything but a tiller. We have some new lift arms that are MUCH heavier.

    Yanmar Tractor Parts: Upper Lift Arm With Pin

    Aaron
    Hoye Tractor Parts
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    (940)592-0181
    Aaron
    Hoye Tractor Parts
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    Yanmar Tractor Parts

  7. #7
    Super Member California's Avatar
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    Sonoma County
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    Yanmar YM240, YM186D, and another YM186D

    Default Re: Low oil pressure? No, bad sender!

    Quote Originally Posted by MJPetersen View Post
    vaguely remember that you had posted about an oil pressure problem

    I broke my upper lift arm on my 1510D today. It is cast and I believe it is iron so it would be very difficult to repair it. I am kind of bummed about it.
    I don't think it was me who posted about oil pressure before. I'm sorry to hear about that lift arm!

    Quote Originally Posted by HoyeTractor View Post
    Mike,
    Thats pretty common on the stock 1510 lift arms. They are way too light duty for most implements. I dont think they were ever intended to lift anything but a tiller. We have some new lift arms that are MUCH heavier.
    Yanmar Tractor Parts: Upper Lift Arm With Pin
    Wow! Does my YM186D have those light 1510 arms, or stronger ones? I assumed this could lift and carry anything it could get off the ground. I already used the 4 ft Howse mower. It works fine. I was hoping to share the implements I have for the YM240: RS1400 tiller, 5 ft Howse box blade, 4 ft disc, maybe even try the 6 ft disc. (But I won't install the 3pt backhoe!)

    Maybe I should stick to just the 6 ft ditching/grading/snow blade ('Carrington Terracer') that came with the YM186D.

    -p1540082rcarringtonterracer-jpg

  8. #8
    Gold Member
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    Yanmar

    Default Re: Low oil pressure? No, bad sender!

    Wow! Does my YM186D have those light 1510 arms, or stronger ones?
    No, the 186 has the heavy duty arms.

    Aaron
    Hoye Tractor Parts
    Contact Us
    (940)592-0181
    Aaron
    Hoye Tractor Parts
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    Yanmar Tractor Parts

  9. #9
    Super Member California's Avatar
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    Sonoma County
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    Yanmar YM240, YM186D, and another YM186D

    Default Re: Low oil pressure? No, bad sender!

    Quote Originally Posted by HoyeTractor View Post
    the 186 has the heavy duty arms.
    Thanks Aaron. That's one less thing to worry about.

    Back on the YM240 Oil Pressure Sender: I finally got an opportunity to install the new sender. And I put in a 'T' temporarily to monitor the oil pressure.

    35 psi @ 1500 rpm
    -p1550937roilgauge-jpg
    Now no more idiot-light flicker. All it needed was a new sender. Thanks Norm for the good advice!

    Next: since I've verified good oil pressure and the light is working as Yanmar intended, I'll remove the T and my gauge. When the pressure sender is screwed right into the block it will be tucked in where I cant snag its wire on something. (BTDT).

  10. #10
    Super Member bp fick's Avatar
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    Beaver Creek, Northern Michigan
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    Kubota BX2360

    Default Re: Low oil pressure? No, bad sender!

    Back in 1974, I got a Ford 100 with a 300L six cylinder. Yeah, that 6 cylinder. The best industrial engine ever put in a vehicle, but I digress.

    My oil pressure gauge, from the get-go never registered any pressure to speak of. I just didn't believe that engine had pressure that low, so I stopped by an parts store and picked up a new sending unit. Got out a big socket, teflon tape and installed a new unit. Couldn't have been more than a few dollars. Bingo! The dash gauge register correctly. Glad you got yours fixed.

    Man I miss that old truck.
    BP


    "Some chickens, some gardens and a Kubota."

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