Yanmar 2 QM 15 Oil Pressure Low

[markwesti]

After warm up it only makes about 8 lbs. @ 2,700 RPM, at low idle I'll get the red light. It has run like this for over 20 yrs. It has 750 hrs. on it.
I have installed a new sending unit and gauge.
I have rigged up a mechanical gauge and it confirms low press.
In the manual it says low pressure is caused by worn out crank and or rocker shaft.( remember 750 hrs.) As long as I have been owner it has had regular service. I use Dello 40 and a Fram filter. It was over heated once for a short time, but after I got that fixed the pressure was no worse for it. It didn't get that hot anyway.
There is a way to boost Press. It has a check ball and spring, you just add shims. I'm a little leary of this because it does make 40 lbs. @ cold start.
Things I think are the problem, out of specification clearance on the crank, rocker shaft, oil pump. Thoughts are appreciated. Thanks.

[delmarrey]

What do the specs say it's supposed to be?

Have you owned the boat for 20 years?

[markwesti]

Hi Delmarrey, I don't have the manual with me It's on the boat. They do have specific specs for the pump. And you can check it with a feeler gauge. But you have to pull the transmission and fly wheel to get to it. As far as the crank and rocker shaft, those specs can be had but obviously a full tear down to check that . And actually I have had my little Westsail 28 for 22 yrs. Thanks!!

[Chuteman]

FWIW - recent Yanmar Diesel class instructor said ONLY use OEM filters
not that other mfg are bad but specs & materials are different and specific for Yanmar requirements
Might not solve this problem but could help prevent for others

Other things to check:
Oil Leak / Oil level?
Clogged oil filter
*** Oil Regulator valve loose / misadjusted
Oil Temp too high
Low viscosity

***Manual - see sec 6.6 for Oil Regulator Valve - Just in case
http://www.yanmarcenter.nl/webwinkel...vicemanual.pdf

[delmarrey]

The Specs, I was referring to was the oil pressure. Here's the manual but no oil pressure specs. >>> http://j30.us/files/2QM15.pdf

But there was some discussion on an engine forum, which suggests your oil pressure is normal.
2qm15 low oil pressure when warm

The boatdiesel forum has some info but one has to be a member to access the info, which I'm not. Same guy asking though....... http://boatdiesel.com/Forums/Yanmar/.../P-7/index.cfm

[delmarrey]

Originally Posted by Chuteman;888455

***Manual - see sec 6.6 for Oil Regulator Valve - Just in case
[url

http://www.yanmarcenter.nl/webwinkel/pdf/manuals/engine_discontinued/service/2qm15_servicemanual.pdf[/url]

There ya go, page 6-3. oil pressure is 35 to 49 @ 3000 rpms. And it appears the pump is mounted to the back of the motor and removable for repair.

Enjoy.............

[markwesti]

It has come up in conversation before, that you should use a Yanmar oil filter. I have never done this , I will now. That was interesting that the guy shimmed his regulator, and saw no change. Also his problems sound much like mine. Here is what I plan to do. Yanmar filter for sure, shim the regulator, stick with the Dello 40/w. Now here comes the good part, I'm going to try a little Lucas oil treatment. Hope this will get me through the summer. Next winter it comes out. I really like this little engine, Its perfect for my boat. I was thinking 5 more hp. 1 more cylinder . But what for, if I can just get the oil press. right. Any how thanks for all the thoughts and links. I'll keep you posted.

[sailorchic34]

The Boat I was on in Florida had a 3qm that started having low oil pressure readings. It turned out to be a cracked casting on one rocker tower under one of the rocker arms. A new tower was only $56 at the time. Could also be a bad spring or seat on the oil bypass (ball and spring thingy)

[rebel heart]

My yanmar 4jh drops pretty low once it's warmed up but the rpm's go back down to idle again. When it's at a good rpm everything is perfect. When it goes back to idle after that the pressure is pretty low. Not the in danger zone, but low.

[Ironhorse74]

Check for diesel in the oil. A lot of diesel will cause a low oil pressure reading. A filter in bypass (clogged) will do it too.

[markwesti]

Cracked rocker tower? I haven't heard of that one. How did you find the crack? Could you just see it? I don't think I'm getting diesel fuel in the oil as dip stick level is always good. But thanks for the tip. That check ball and spring is getting looked at for sure. Thanks!!

[sailorchic34]

well after 8 hours of running at 15 psig pressure the bearing surface on the rocker tower bent which stoped #3 exhaust from opening, so it was blow back in the intake. Lots O noise all of a sudden. That was 20 miles off shore with no wind.. We used a socket, penny and duct tape to make a spacer over #3 exhaust valve and used the decompression level to hold the exhaust valve open, We then ran the engine on 2 cylinders at lower rpm for 4 hours getting back home. That was an exciting day.

It looked to be a bad casting as the bearing surface was fine and the crack was just at the tower where the bearing surface protruded...

Only way to check would be to run the engine without the valve cover on (messy) and look for abnormal oil flow around the valves and rocker towers on the 2qm. Well you could pull the tops of the towers and remove the rocker arms and check for cracks..

[rickster1965]

I have a 2qm20h that runs at just above 20 psi pressure pretty much at all rpm ranges. Does anyone know of a qualified YANMAR mechanic on the west coast of Florida that I could contact about rebuilding my engine just as a precautionary measure? Or atleast have it checked out thoroughly for any possible issues? Preferred area would be Tampa / St. Pete area.

[Compass790]

You absolutely need to check your oil pump. With such low hours it is hard to imagine it's worn out but it happened to our supposedly low hours motor. I've had a long battle getting our YSM8 yanmar oil pump to work properly. It had multiple problems including worn oil pump rotor shaft, worn hole in case where rotor fits, scored inner face that the inner & outer rotors bear against & scored pump cover.In the end I had to fit a priming system to make oil pump work ok as they dont make cases for them anymore but if yours primes itself pump probly not too bad
If it makes 40lb at cold start I'd suspect clearances somewhere outside the oil pump. but by all means check your pressure relief valve & pump first.
Our crank mains,conrod & big end had to be replaced but our pump had failure to prime problems that caused their failure.Your symptoms are different but maybe the consistently low oil pressure has caused accelerated mains & big-end wear. Just speculation on my part but until you check you dont know.
I very much doubt that using a non-Yanmar filter is the cause of your problems. Our oil pressure is 40 cold, 30 hot at 2400rpm & 14lb @ 800rpm idle using 15w-40. Yr 2qm15 is basically 2ysm8's side by side afaik so shud be similar. I changed the original Yanmar metal screen filter to a remote spin on type but it shows no difference in oil pressure.
I machined one of our main bearings with a little too much clearance ( wouldn't pay Yanmars $500 price for 1 bearing) so our oil pressure could be a little better.
Hope that helps

[a64pilot]

First I’d check the oil pressure relief valve, it sounds as if it’s stuck open.
It’s usually not much more than a ball and a spring, oil pressure hits x amount, forces the ball off of its seat and pressure isn’t allowed to go above set point, if it sticks oil pressure stays low of course.