Oil pressure question

Outbackfarm · May 27, 2005

Hi everyone I have a Jinma 284 (we call her Jinny) and I had something interesting happen today, I decided to till up the garden and did the usual before starting her up checked the fluids and connections and everything was normal except that I had overfilled the motor oil when I changed it, the level sits about ¼” above the top mark on the dipstick this has not caused me any grief up to now and I never got around to draining off the excess. She fired right up oil pressure in the middle of the range and off I went.
A bout ½ hour latter I looked back at the gauges and to my surprise the oil pressure was just above the redline on the pressure gauge. I shut the engine down quickly and tried to figure out what was going on. I checked the oil and it was right were it was when I started motor I removed the sending unit from the motor and installed a standard mechanical gauge, I started the engine and the oil pressure was 35 PSI . (Engine had cooled while I installed the gauge). Breathed a sigh of relief and went back to work tilling. I kept a close eye on the gauge and I noted that the pressure slowly worked it way down to about 19 -20 PSI at 1800 RPM, the needle on the gauge fluctuated rapidly . The oil in the engine was chevron 30W detergent. Outside temperature was 93 in the shade, about 102 in the sun where we were working. This pressure seems low to me even though the RPMs were only at 1800. The facts are as follows

#1 slightly over filled oil in engine, 30W chevron with some residual original oil (I did not change the filter when I changed the original oil)

#2 Engine RPM 1800 (I need to adjust the linkage on the pump as this is full open)

#3 Outside temperature 93, 10 degrees warmer in the sun

#4 Hours on motor 7 (Seven)

#5 Oil pressure 19 -20 PSI

#6 Engine temp in the middle of the gauge (green zone)

Any thoughts ?

Thanks everyone. /forums/images/graemlins/confused.gif

RonMar · May 27, 2005

Use a multiweight oil. single weight oils thin out more noticibley when hot and a 90 degree day is pretty warm. I bet if you go start her in the evening after she and the air temp have cooled down the pressure will be right back up to normal.

Soundguy · May 28, 2005

I agree.. a 15w40 diesel rated oil is the 'usual' spec for many modern diesel tractors.

Also.. that 19 psi hot.. don't worry too much about that... I've got old fords that start with 18 and drop to 12.. I've seen guys that go down to 6psi at hot idle and not much more at throttle.. and those tractors still plow fields every day.

Soundguy

hbaird · May 28, 2005

With about 6 hours on my JM200LE I had the same problem. I replaced the OEM oil with Rottella T 15/40 and fixed the situation. The manual shows the pressure can be very low at idle, .05 MPA. The JM200LE guage now shows .4 MPa at full power and .2 MPa at idle. I had a similar problem with the throttle. The fuel filter and the Fiberglass cowl both were interfering with the Throttle linkage. I turn the fuel filter a little and filed away some Fiberglass for clearance.
Harold

greg_g · May 28, 2005

( I had a similar problem with the throttle. The fuel filter and the Fiberglass cowl both were interfering with the Throttle linkage. I turn the fuel filter a little and filed away some Fiberglass for clearance. )
Me too - on one of my JM254s - except all I did was pull a couple of the little clevis pins and re-arrange the linkage itself.

//greg//

bluechip · May 28, 2005

I'll confirm what the others have said. In short "a little above the red" on the gage is still OK, but 15W40 will give you better results, wouldn't hurt to change the filter.
You should be able to get to the green mark on the tach so checking thre linkage carefully should reveal the reason.

Outbackfarm · May 31, 2005

Thanks every one, I drained the old oil and put in the 15W-40 Rotella oil and a new filter. The oil pressure was in the “green” all day on Monday when I gave it a hard work out tilling the neighbor’s big garden that had not been cultivated for 4 years. So problem fixed, I went over the linkage for the throttle and found 2 loose bolts on the main bracket that holds the throttle linkage up and adjusted the linkage, no problems now I can fully open her up.

I decided to drain the front drive and install new oil, For the front drive I went with a 85-140W non foaming oil. Had lots of problems getting the drain bolts loose (1/4” square drive plug) finally had a brain storm and decided to use a tap wrench out of one of my tap and die sets, This grabbed the square end securely with out rounding the corners. I was able to get two of them out using this wrench but the 3rd plug was impossible finally had to drill and use an easyout to remove the plug, Broke the first easyout off and spent ½ hour digging out the broke end , redrilled with a ¼ “ bit and used a larger easyout finally with the application of heat it came out. Had about a 1/3 teaspoon of water in the right side drive and about 4 quarts of something that looked like an oil / brake fluid mix ( nasty stuff) . Purchased hex headed brass plugs to replace the original steel plugs and flushed out the drive with diesel and refilled with 4.2 quarts of 85-140W non foaming oil.

On another note I noticed that one web site for Chinese tractors claimed that Rotella oil eats the copper out of the bearings and should not be used on Jinma tractors. I do not believe every thing I read and I know that it was recommended by the members of this forum and went with Rotella anyway.

Have a great day and thanks for your help.

Scott /forums/images/graemlins/smirk.gif

hbaird · May 31, 2005

The Rotella web site forum says Rotella T does not corrode copper and must pass tests to demonstrate this. Copper is a part of the bearing compound Babbit, widely used for main and rod bearings.
hbaird

greg_g · May 31, 2005

( The Rotella web site forum says Rotella T does not corrode copper )

Rotella T however, is engine oil. The question at hand concerned gear oil and yellow metals.

Broadly stated, GL4 is considered "kinder" to yellow metals than is GL5. Something to do with sulfur content, I think. If you elect to use GL5 anyway, it's a simple matter of making sure the label specifies it's safe for use with yellow metals.

//greg//