Yanmar 4JHTE Low Oil Pressure Reading

[VVD]

It seems that my lube oil pressure gauge is giving me very low pressure when I run the engine on 1100 RPM, a little above zero and when I rev it up to 2300RPM he meter seems to go up but not higher than 4, the beginning of the green bars. Should I be worried? The dipstick reads ok, but I will change the oil anyway. What should I check?

[rebel heart]

- Are you running it under load?

- How long are you running it for?


I've seen some odd stuff in my Yanmar 4JH2E when it comes to oil pressure, but when I'm doing what it's designed to do (2K-4K rpm), the temperature and oil are exactly where they're supposed to be. Come to think of it, I think at 1100 it's pretty dead on mine to.

[capngeo]

check it with a mechanical gauge threaded into the oil gallery on the engine

[perchance]

Originally Posted by VfvanDoorn

It seems that my lube oil pressure gauge is giving me very low pressure when I run the engine on 1100 RPM, a little above zero and when I rev it up to 2300RPM he meter seems to go up but not higher than 4, the beginning of the green bars. Should I be worried? The dipstick reads ok, but I will change the oil anyway. What should I check?

How many hours on the engine and did this happen suddenly or has the pressure been declining over time? Is the pressure near normal when cold then drop when the engine heats up? Start with the obvious as capngeo says; a pressure gauge screwed in where the sending unit goes and work from there.

[emcmia]

I have a pair of 4JH3E mains with less than 1200 hrs. Over the last couple of weeks one of the engines has had an intermittent oil alarm at idle. Checked oil level and found ok. Yesterday, when I started that engine, the alarm was continuous even at higher RPMs. Shut down engine; rechecked oil level and then pulled the oil pressure sensor. Cranked the engine - no oil. Although thinking oil pump had gone bad was very low probability, I pulled the timing case cover, unbolted oil pump and found clearances to be within specs. Hoisted engine and dropped oil pan. Surprize! Found the oil pickup pipe had failed (i.e. broken off) at the weld joint to the base which bolts to the block and feeds oil to pump. Very strange.

[Laidback]

In the Manual -- Chapter 5 - Para 4.1 and Para 4.2
The Pressure should be between 49.78 and 64.00 psi
Check the pressure regulating spring.

[Hudson Force]

My Yanmar 4JH3E oil pressure sensor (part # 119773-91501) has been the most frequently replaced item on my engine, discounting filters. With 5,050 hours on my engine, the oil pressure sensors have had an average "life span" of 1,400 hours. I have no explanation of their poor performance, but this has been my observation.

[sailorboy1]

I had this oil pressure problem last year. Was the wire going to the sensor.

Start with the easy stuff first!

[meyermm]

Strongly recommend doing as suggested check with master gauge. If it is low something like the oil pick up pipe problem mentioned is more likely, although in theory the pressure relief valve sticking could be the cause, this is most unlikely worth a check but plan for the worst.

[GordMay]

Measure Resistance from Dark Blue Sender Wire to Ground.
American Press. Sender: 240 Ohms @ Zero Pressure, or 33.5 Ohms @ Full Pressure (80 psi)
European Press. Sender: 10 Ohms @ Zero Press., & 180 Ohms @ Full Press. (150 Bar)

See ➥ http://www.cruisersforum.com/forums/...sting-645.html

And:

➥ Testing Engine Gauges - See also Wiring Diagram & Sender Resistances Cruisers & Sailing Photo Gallery

➥ Testing Engine Gauges (2) - See also Wiring Diagram & Testing Instructions Cruisers & Sailing Photo Gallery

➥ Engine Gauge Wiring Diagram - See also Gauge Testing Diagrams Cruisers & Sailing Photo Gallery

[VVD]

Thanks everybody, I have changed the oil and oil filter and it the reading is now a lot better, I am still surprised because I took as much out as I put in. Now I am dealing with lots of white smoke that started to appear a while ago.....

[cfarrar]

Our 4JH3E w/ 1700 hrs has experienced two failed oil pressure sensors.

[Jon Hacking]

We have a pair of 4JH2CE Yanmars, & they've always reported different oil pressure. Swapped the wires around & they reported the same, so I decided the gauges were a bit wonky. OK, they're now 15 years old, with 6,000 hours.

[noelex 77]

Originally Posted by VfvanDoorn

Thanks everybody, I have changed the oil and oil filter and it the reading is now a lot better, I am still surprised because I took as much out as I put in. Now I am dealing with lots of white smoke that started to appear a while ago.....

The most common reason for your symptoms would be a fault with the oil pressure sender, but "lots of white smoke" suggests a real problem rather than a sender problem.
I would assume there is a real oil pressure problem (which will destroy an engine quickly) until it is proven otherwise.
I think it may be time to call in the professionals.

[meyermm]

I second that your problem would not have been just old oil and filter under any conditions I have seen. Maybe the old oil was diluted as a result of your other problem.