455 Oil Pressure

cef2lion · Oct 11, 2011

My 455 with just over 500 hours has the oil pressure light flickering at idle. When you increase the RPMs the light goes out. I replaced the sensor switch. No change. I changed oil and filter. Still same issue. I have no gauge to check the pressure.

I was wondering if anyone else has had the same issue with this type engine? I have been reading the shop manual and it takes about checking the oil pressure regulator for wear. Not sure how you would do that. If the regulator is stuck I assume it could cause the low oil pressure. Can it be cleaned or it needs to be replaced. Don't want to just toss parts at it. I have always used JD oil and filters and it has been well taken care of.

Craig

beenthere · Oct 11, 2011

I've a 455 and so far not a problem. Don't know how you would check out the pressure, or if it has ok oil pressure but just faulty detector/warning parts.
However, until I knew I'd not leave it idle.
I very rarely idle mine as it is either working or off.

cef2lion · Oct 11, 2011

Manual says to remove oil pressure sender. Which I have replaced already. Install adapter and pressure gauge. Oil pressure range is 43-64psi. Need to locate a pressure gauge that will fit and get some readings.

If low pressure confirmed the manual says to check the oil pressure regulator first. Then the oil pump. I had thoughts of a too low idle causing the issue. I don't have a tach to test that. If I bump up the throttle a bit the light goes out. Slow idle is listed at 1650. I think best to check idle speed first then move on to an oil pressure test.

cef2lion · Apr 4, 2012

I wanted to update this thread in case it helps anyone else. I replaced the oil pressure regulator valve. It appears to have solved the oil light flickering at idle. You take off the oil filter and remove the filter mounting plate. The valve is in the mounting plate. I took the valve apart and the spring inside didn't meet specs listed in the service manual. It was short uncompressed. You have to replace the entire valve. I got a gasket and O-ring for the valve to put it back together. So far after mowing for an hour and then sitting at idle. No more oil light.

beenthere · Apr 4, 2012

cef2
Thanks for the update. Glad to hear you made a change that worked out for you.
I'll keep an eye out for that problem, and glad to know there is a reasonable fix.

TimS · Apr 4, 2012

Thanks for the update. My 455's oil light does not flicker at idle, but I have noticed over the last 4 or 5 months that the light is a little slower to go off at initial startup than it was - used to be instantaneous, now it takes a second or two. I'm wondering if that spring is getting soft on mine too - just turned 500 hours, which seems like a major coincidence.

The valve isn't cheap, but it's probably cheaper to replace it than track down a pressure gauge or take it to a dealer. Replacing the valve looks pretty straightforward - did you run into any difficulties?

I'm thinking to maybe replace it to avoid any chance of running with low pressure. Guess I could just buy the gasket and O-ring first, and then take it off and measure.

Tim

cef2lion · Apr 4, 2012

I found a new JD oil pressure valve on ebay for half what the dealer wanted and it included shipping. I got the gasket and O-ring from the dealer. They had to order the gasket.

No real issues changing the valve. Before you take the plate off the engine after removing the oil filter. Loosen the big nut under the oil filter. Its on tight and I had to put plate back on the engine to crack the nut free. Valve then threads out of the plate from the back side. You then take the cap off the end of the valve to get the spring out.

Before you take the valve apart look at it and see if its dirty or being held open. I put a punch in the end and pressed to open the valve. I put the spring on the work bench and measured it uncompressed with a digital caliper. Spec says it should be 43.50-48.50mm. Mine was more like 35mm. The shorter the spring the quicker it would open or be fully closed and allow oil to bypass back in to the oil pan. I'm thinking at higher RPMs the oil pump produced enough pressure to keep the light out.

Its not a hard thing to check if you changing oil. The gasket might come off clean and you could reuse. I got a new one anyway. If you take the valve apart and reuse. put the valve back in the way it came back out. Followed by the spring and endcap. Make sure endcap is on tight. Diagram says to stake cap to valve body. I'm guessing to make sure it doesn't turn loose. Marking it with small cold chisel should do.

Something I learned on the gasket. I didn't use gasket sealer. When cleaning the old gasket off put some type tape over hole into block to keep gasket from going in there. I broken off a part of my scraper blade and glad I did or broken part could have gone into the block.

You might be ok with your issue but might be a good idea to check the spring. Too bad they don't sell the spring by itself. Manual talks about shims you can adjust to adjust the oil pressure up. Not sure where you would get those.

I also got a digital tach to check and set the idle. You put a peice of reflective tape on the flywheel and aim the tach at it. I was below 1650 by altitle. I got it set pretty close now.

Running good now and no oil light. Glad it wasn't anything else.

Hope this helps,

Craig

TimS · Apr 5, 2012

Thanks Craig!

I'm a little on the fence as to whether to open it up and check the spring -hate to tear into something that's working and create a problem! Seems like yours had compressed significantly though, and that's got be a function of age more than anything else. Maybe I'll hold off until the next oil change.

I appreciate the helpful commentary and the picture.

Tim

cef2lion · Apr 5, 2012

No problem Tim. Just wanted to post my results in case it could help someone else. Been hunting this issue since last fall and glad it was such as easy fix. I'm thinking as you. That age was the factor in the spring falling out of spec. I really like the 455 as a mower and how easy it is on fuel so I want to keep it in top shape.

Craig

bootsnixon · May 11, 2012

Just started having a similar problem with my oil pressure light on my 455. Thanks for the advice cef2lion and coming back to post your cure.
Boots

cef2lion · May 14, 2012

Thanks for the comments. Thats whats good about these forums. Good reference for issues that other might have already seen. It is nice when an issue is posted as well as a follow-up solution.

The 455 is a great mower and I'm glad I got this issue taken care of. Been mowing a lot with it and at idle no oil light anymore.

TimS · Jun 3, 2015

Craig, just finally got around to doing this job - it was pretty simple, thanks to your instructions. When I disassembled the original valve, my spring, like yours, was way shorter than the minimum spec. The oil light now goes off immediately, and although I have no means of measuring the oil pressure, I am sure it is better.

Seems like this should go under routine maintenance for the Yanmars, after 10 years or so.

Thanks again!

Tim

cef2lion · Jul 10, 2015

Glad to hear it worked out. Not an issue with my oil light since the fix.

ribouk · Aug 4, 2019

Sorry for resurrecting an old thread !

How did you guys remove the end cap off the oil relief valve ?

There are some flat parts on the cap and the valve which I had a 17mm spanner and an adjustable on, but I've now managed to round the flats on the cap and it hasn't budged. Is it actually threaded or is it pressed on? Wondering if it could be hammered out with a punch from the oil filter end somehow?

BTW, the reason I'm trying to take it apart is that I've just added an oil pressure gauge and it looks to be reading lower than the spec, at least according to the gauge which is saying 42 psi when full throttle when 'cold' but drops to 30 psi maybe when fully up to temperature, and is showing near 0. Oil light doesn't come on though.

beenthere · Aug 4, 2019

ribouk
:welcome: to TBN

end cap off the oil relief valve

Do you have a reference or pic of this "end cap"? I don't find it yet in jdparts.

Is this part referenced earlier in this thread?

Are you planning to pull out the hydraulic pressure valve behind the oil filter and replace that spring ?? or something else?

Amvcane · Aug 4, 2019

Guessing you already have this page from the manual. Step 3. remove cap and add shims.
Not sure what “stake to valve body” means. Could there be a pin through it or is it crimped on. Can you post a pic of it? Don’t be embarrassed by any damage you may have done, we’ve all been there.

ribouk · Aug 4, 2019

beenthere said:
ribouk
:welcome: to TBN

Thanks!

beenthere said:
Do you have a reference or pic of this "end cap"? I don't find it yet in jdparts.

I believe they only sell the entire "Hydraulic pressure valve" as AM880983, which is everything, spring, cap, and valve body - quite expensive list price at my dealer at about $120.

beenthere said:
Is this part referenced earlier in this thread?

Yes the part in the diagram earlier in the thread.

beenthere said:
Are you planning to pull out the hydraulic pressure valve behind the oil filter and replace that spring ?? or something else?

Yes that's the plan, the manual has measurements for the spring in compressed and uncompressed states. So I was going to measure and check if it's within the specifications, and if not then see if I can find a suitable compression spring... or worst case replace the whole thing.

But I'm stuck being unable to remove the cap right now.

Amvcane said:
Guessing you already have this page from the manual. Step 3. remove cap and add shims.

Yes, saw that. Doesn't explain how to remove the cap, no reference to the flats on it, and the guys on the thread haven't mentioned that bit.

Amvcane said:
Not sure what éƒ½take to valve body means. Could there be a pin through it or is it crimped on. Can you post a pic of it? Don't be embarrassed by any damage you may have done, we've all been there.
View attachment 615805

Nor me. Yes sure; here's a few photos of it, with the damage I've done to it !

You can see where I've chewed up the thread on the 'cap' part. The flats on the main part fit a 17mm spanner, but the cap flats were smaller than that... slightly larger than 15mm hence the adjustable. Any thoughts on how it's removed?

You can also see the Yanmar part number for the housing... using that I did a bit of detective work and I *think* that the valve unit is Yanmar part number 119225-35300 which I can get cheaper at $72 (assuming that it really is the exact same part !).

But I'd still like to check the spring length, and try to find just a spring before replacing it. I've also ordered another oil gauge in case it's a bad pressure reading on my existing gauge.

ribouk · Aug 4, 2019

Just tried pushing the canister/valve part by pushing a bolt through the oil filter end. It pushes down against the spring maybe 10mm or so and then stops... so I'm thinking it might be possible to hammer/push the cap off from the inside that way, but not sure if it'll damage the valve depending on the force needed.