YM2000b oil pressure

[zoomzoom-HT]

I have a 2000b that i have owned for about 18 years. 4 years ago my wife was bushhogging a field that had a lot of grass seeds and overheated the engine when the radiator became clogged. I cleaned the radiator and the tractor ran fine but over the next year i smelled antifreeze and noticed bubbles around the head when running -but the tractor ran cool and i put off changing the head gasket for about another year. Last year while using my tiller the oil pressure light started to flicker ,I shut it down replaced the sender and added a guage.The tractor when started has pressure of about 52 pounds after a hour of running at 2000 rpms the pressure is down to 30-if i throttle back to 1000 the light flickers and guage shows less than 10 psi. If i run the tractor at 1000rpms it will run for several hours before the pressure drops.I have changed the oil-the pressure relief valve-new yanmar filter and checked for metal in the oil and the tractor does the same thing.The tractor runs cool and runs great but when the oil gets hot the pressure drops-been using the same oil since i bought it John deere the same as recomended for a jd850.I am out of ideas thinking of tearing it down and replacing the bearings and rings but it runs too good--any ideas?

 

[Norm-HT]

A couple of things come to mind. I can't think of any reason to run at 1000 rpm for long periods, (not good). Are you sure it's the oil light and not the low coolant, or low battery water light? The oil light only comes on at about 3 psi. Don't know from JD850, but are you using 15w-40 wt. oil?

 

[zoomzoom-HT]

Using deere 15w40 oil-my dad has 2 john deeres made by yanmar a 850 and 1050 and i use the same oil--the gauge shows the pressure is low so that cant be the other lights-and when i let it idle at 1000 or 1200 rpm when first started it has 45 psi of oil pressure---i shimmed the oil pressure relief valve with one small washer and the pressure showed 75psi when cold and replaced the relief valve with a new one from hoye and that gets me 52 psi-but when the oil gets hot the pressure drops but it takes a hour or so

 

[winston-HT]

Sounds to me like you have excess bearing clearances.

 

[Norm-HT]

With cold engine I crank my 2000B, with compression release engaged, until the oil light goes out, about 3 to 5 seconds. how long does yours take?

 

[zoomzoom-HT]

Bearing clearances are what i have been thinking too--but was hoping for a easier fix--Does anyone know which bearings wear the most rod or mains? And does anyone know how the oil flows through the engine -does it go to the mains first and then the rods or is there a oil passage through the block?

 

[alan-HT]

Doesn't take hours for the oil to get hot; it's something else but I'm not sure what.

You changed the HG and there's no more bubbles, and the pressure drops more than normal after several hours of running and/or at idle. Is that the situation? I ask because I can't see bearings explaining that kind of drop. Is is sudden or gradual?

 

[Norm-HT]

Have had my 2000B for 12 years and all I know about the oil pressure is that it stays above 3psi. That's where the light goes out on initial cranking, and stays out. Perhaps your sender wire is frayed and shorting somewhere. The last place to get oil is the rocker arms. If it's slinging oil there I would look for other reasons for a blinking oil light. Definitely do more troubleshooting before tearing into a good-running engine. When you had the head off, if there were no marks on pistons from hitting valves, your rod bearings should be ok. Only a few thou." clearance there at best. There are oil passages and tubes throughout the block, maybe a shot of air.

 

[Carey-HT]

<QUOTE author="Norm"><s>

</s>With cold engine I crank my 2000B, with compression release engaged, until the oil light goes out, about 3 to 5 seconds. how long does yours take?<e>

/e></QUOTE>

This is the way I start mine and pretty much the same on the oil pressure coming up on a Cold Start. No mention of this. But have you Checked the Oil Pickup Screen.

 

[PaulW-HT]

<QUOTE author="Carey"><s>

</s><QUOTE author="Norm"><s>

</s>With cold engine I crank my 2000B, with compression release engaged, until the oil light goes out, about 3 to 5 seconds. how long does yours take?<e>

/e></QUOTE>


i was also thinking this as dad had an old Holden that after running for and hour or so it ould do the same thing, oil light come on at idle but only on warmer days. pulled the sump off and it was full of crud and pick up was blocked up. cleaned it all up and no more problem.

 

[zoomzoom-HT]

The drop is gradual -but when the oil gets hot it drops-When it is cold the light goes out as soon as you hit the starter and the pressure goes to 52psi on the mechanical guage-I haven't checked the pickup-but i did pull the valve cover to see if oil was getting to the top end -and it is-.I have used it with a scraper blade for a couple of hours below 1600 rpm and the pressure stays above 35psi but i am watching the guage constantly-Thanks to everyone for the help

 

[zoomzoom-HT]

Today I pulled the oil pan on the tractor to check the oil pickup. The engine was spotless inside no sludge and the pickup was clean- i put it back together filled it back up with oil and took it out in field with the scraper blade and used it about 90 minutes at 1800rpm--the pressure stayed above 35psi for at least 75 minutes the dropped to 20 and if i throttled back to 1000 the pressure guage goes below 10psi and the light flickers--so ordered a shop manual to see how to tear the engine down to replace the bearings

 

[winston-HT]

The pan off would have been a great time to plastigauge a rod bearing. You need to check before going head on or at least I think so.

 

[Carey-HT]

Doesn't take hours for the oil to get hot; it's something else but I'm not sure what.

Alan has a good point and I'm still thinking this also. If it was me I would add a pressure gauge were the Oil pressure switch is or T in a test gauge also. Then you can see What the actual oil pressure is on a "known" good gauge. And what it is if the light starts blinking. If the Gauge starts showing the pressure droping and the electrical warning light starts flickering then No Doubt you have a problem. Even if you just put a Manuel test gauge were the switch is temperarily and it drops as your discribing you can pretty much count on it that there's a prob. With most all motors that has bottom end Crank shaft or Bearing wear is why you have low Pressure. You should also have Metal shavings,chips. or black Sediment/Burnt oil in the pan. No mention of it. That way atleast you can assure yourself if there is or isn't a problem.

 

[PaulW-HT]

<QUOTE author="winston"><s>

</s>The pan off would have been a great time to plastigauge a rod bearing. You need to check before going head on or at least I think so.<e>

/e></QUOTE>


that first and then check over the oil pump incase it has a problem but i believe they are very reliable.

 

[Aaron-HT]

Could it be just a bad oil pressure switch? They do go bad- maybe the overheating helped it along?? I don't remember any of the service manuals giving a low idle oil pressure. Just, like Norm said, that the light comes on around 3-6psi. It may be that 10psi is normal at that RPM. I know my old work truck would idle with the oil pressure gauge just <B><s></s>barely<e></e></B> off the 0psi stopper. It ran that way for 100,000 miles before I traded it off... still running great.

 

[zoomzoom-HT]

When I added the oil pressure guage i also put on a new oil pressure sending unit hoping that was the problem--The guage confirms that my pressure is low when the light flickers.I like the plastiguage idea that is why i bought the repair manual because i dont know the clearances--i'm hoping i can change the rod bearings and that would raise my hot oil pressure.There is no metal flakes in the e ngine -I even cut open the oil filters looking for metal-But worse case I'll tear into it -i would rather replace bearings than destroy the crankshaft

 

[Carey-HT]

<QUOTE author="zoomzoom"><s>

</s>When I added the oil pressure guage i also put on a new oil pressure sending unit hoping that was the problem--The guage confirms that my pressure is low when the light flickers.<e>

/e></QUOTE>

Your pretty much have to Plastiguage it. My bet your be ordering new bearings. Hopefully you cought it and didn't damage the crank journals. I think you cought it before you ended up with serious damage

 

[floridaboy-HT]

I have a ym155 I have not piked it up yet will next month , But in the mean time I bought a 155 for parts not running.I have been taking parts off it and sorting them out
i started reading the posts on this low oil pressure issue First I requested info on a remote oil filter mount ,to make a long story short there are enough experts on this board that I am sure you will get there help to solve your problem.

 

[Norm-HT]

I'm confused. are you working on your non-running parts tractor for an oil pressure problem?

 

[floridaboy-HT]

don't be confused Norm , to remove the oil pressure regulator the engine could not be running Unless you know of a way to pull the filter and remove the pressure regulator while it is running . Please advise me how you do it. I am stateing what I have seen in the pressure regulator , if you have removed the regulator and found nothing wrong thats one with no problem , lets see how many people with low oil pressure check theres and do not find a problem and write it up on this web site. Thanks for your responce

 

[Norm-HT]

<QUOTE author="floridaboy"><s>

</s>don't be confused Norm , to remove the oil pressure regulator the engine could not be running Unless you know of a way to pull the filter and remove the pressure regulator while it is running . Please advise me how you do it. I am stateing what I have seen in the pressure regulator , if you have removed the regulator and found nothing wrong thats one with no problem , lets see how many people with low oil pressure check theres and do not find a problem and write it up on this web site. Thanks for your responce<e>

/e></QUOTE>




I see, so you are assuming the non-running engine has low oil pressure and you have cured the oil pressure problem on the YM155.

 

[floridaboy-HT]

no when I bought this spare 155 I asked if the engine was any good and was told No it has No oil pressure

 

[Norm-HT]

<QUOTE author="floridaboy"><s>

</s>no when I bought this spare 155 I asked if the engine was any good and was told No it has No oil pressure So I checked the regulator and found a fault. Have you removed the regulator and checked yours??? I hope some one will ,and confirm what I am saying.. if you know anything about internal combustion engines the oil pump pickes up the oil from the crankcase (as long as its not a dry sump system) the oil goes to the regulator then to the filter then to the bearings . Thats a universal design. now what damage do you think would result if a regulator went to 3 psig .maybe main bearing wear , maybe connecting rod bearing wear , maybe cam shaft bearing
lockup and breaking cam shaft. All questions about this matter are good ones and all advise is good advise. But what is causeing premature pressure loss ?? everything else is the result
worn or seized engine bearings or camshaft .What does your experance tell you Norm could have caused the problem. Norm please don't play devils advocate with me .I am only stateing what I have done so far the proof will be when I test it on a running engine thats true.But if some one on this board is going to change the oil filer on there engine it cost nothing to check out what I am saying an post the results on the board I cauld be wrong , lets see if Iam<e>

/e></QUOTE>

Since the problem seems to be common only to the YM155, I would have to assume it was, as you said, a design problem. Yanmar apparently also thought so, as they issued a factory mod for it years ago, (so it is said).

 

[floridaboy-HT]

Norm if you come accross that mod please let me know. also I think the 1200 also has same problem , I would guess all the 2 cylinder engines have the problem the way they sound like a bucket of bolts could also cause a hormonic vibration causeing the regulator spring to jump over itself and shortin .I will see I might get this engine running as soon as I get the new starter which is on the way ,in the mean time I hope a few of the people on this board checks it out and posts there results . Thanks for your input Bill <E>:mrgreen:</E>

 

[floridaboy-HT]

zoomzoom as to the oil flow thru engine.flow is from crankcase to pump internal cast line to regulator and filter from filter thru banjo fitting to crank shaft thru main bearing thru crankshaft to rod bearings also from banjo fitting to camshaft in seperate cast oil line hope that helps
at least that is the oil routing on a 2tr13a engine

 

[mesologgitis-HT]

I have attached the lub system of probably the most 2 cyl. Yanmar engines, also according to Yanmar manual the is one more probable cause of low pressure you haven't mention and that is "excessive oil escaping from rocker arm support". Hope i helped a little.