Yanmar YSB8 Oil Spin Filter

[1629dill]

Thanks

[delta_shawn]

Hello, I discovered this thread/forum trying to troubleshoot my YSM8, so please excuse me for blatantly asking with a first post...

I recently had my oil spin filter replaced/serviced on my new to me YSM8. I didn't do the service and have little knowledge of engines. There is now a steady drip of oil from somewhere on the lookers left of the oil spin filter, and a little towards the top, as far as I can determine. This engine is under the V berth in a 1980 25' yamaha, so access is a little weird, though I can stick my head down there to view the spin filter.

Reading this most helpful thread it seems that the O ring does all the sealing inside of here, and upon my initial inspection the spin filter bolts are quite secure and snug. The engine runs fine, but the leak is significant enough to drain the oil pan after (4-5) hours of moderate RPMS.

I'm running the boat out from the slip to the sailing grounds and back, about a fifteen minute trip (2 miles) at low RPMS but am hesitant to motor sail or go any distance with a leak of this nature.

Some more details... The boat didn't have an oil leak before the service, so something could have been damaged or improperly installed during the service. However, this engine only had 31 hours when I bought it and immediately after the service, I sailed it 20 miles from SF bay to its new home in the Delta where I ran the motor pretty hard, or at least much harder than its been run in a long while, and perhaps ever. So the service could have been legit and my heavy use could have caused the leak.

Again, I don't know **** for engines, except what I've learned in the last few days trying to troubleshoot this issue. Someone told me the filter bolts could have been cross threaded, which could be really hard to re-tap or fix considering the tight access (about maybe 8-10 inches to the forward engine room bulkhead from the cylinder side), but the bolts seem really snug.

Looking for your guesses as to the likely culprit here, and also more advice or warnings about running this engine with the current leak. My current plan is to motor on low RPMS with absorbent pads under everything and several quarts of oil....which isn't always possible considering wind and tides etc... I doubt I can get this fixed soon by a mechanic, and not before the best of the sailing season is over here. Also, I would like to try fixing it myself, or perhaps be talked out of this plan

Much thanks in advance...

[Wotname]

Welcome aboard CF, delta_shawn.

Your spin oil filter housing may be sealed by an Oring as described upthread or it may be sealed with gasket material.

If it is leaking from under the cover, I would pull it and replace the Oring (if fitted) or replace the gasket material.

The pictures shown what might be the under the filter cover. Yellow is a gasket and red is an Oring.

Personally I have found a gasket along with some gasket sealing compound works better than an Oring but each to their own!

Ignore the broken bolt in the picture!!!

[delta_shawn]

THx wotname. after seeing your pic of the old gasket material, that seems a good place to start. presumably I replace the gasket, like as a part I can order, or is this gasket something you have to customize or apply?

[Compass790]

I too have a YSM8 & have a lot of experience with the oil pump & filter.
I'd have to disagree with Wotname about the o-ring I prefer them as they are less hassle.
BUT that does not mean you cannot replace with a gasket & sealant if you wish.
ONLY do that on the filter tho not on the oil pump cover as the rotor clearances are critical.
I would say that the oil leak most likely the fault of the "service" or perhaps lack of service. The person who did it should fix the leak at no charge.
However if they dont get a 1/4" drive ratchet with a 10mm socket & take the filter out & examine o-ring & sealing face.Oil will come out when you remove filter, maybe 1/2 cup.If o-ring is damaged you should get a replacement from any bearing supply place. No need to go to Swensens
The bolts should not need to be very tight, they are only little bolts into an aluminium case & if some ham handed mechanic has stripped them you are in a world of hurt considering your access.
My advice is use threadlocker on every bolt, Loctite 242 is my usual but there are others. If you dont you run the risk of vibration loosening them.
If you PM me your email address I can send you the service manual if you want to know more about the engine.
They are noisy shakey, not very powerful beasts ( dont try fighting tide up San Joaquin lol) but they are simple, easy to maintain & if you feed them clean fuel & change the oil as recommended they should last a fair while.
Ours is 40 years old & I reckon it's got another 25 years minimum after its reco job.

As for running whilst leaking as long as you keep the oil level above the minimum mark on the dipstick you'd probably be ok but I recommend installing a pipe tee where the oil pressure sender fits on top of that case & installing an oil pressure gauge to work in tandem with the oil pressure alarm.
Much better to fix leak, it should not be difficult. If you have any buddys that are mechanically minded get them to help.
Can't believe the low hours on that engine! I'm jealous

[Compass790]

CORRECTION:
After thinking on your problem a little more its possible the o-ring is a bit perished. What happens if you motor for a long time the oil gets hot so therefore thinner & it can leak easier. So I might have been a bit hasty blaming the serviceman. After 40 years the compound of the o-ring (nitrile?) may have deterorated. Quite likely.
Hard to judge from 5000 miles away.
Knowing what I know I would replace the o-ring any way & you can fit a gasket as well if you choose. Dont make the gasket too thick as the filter outlet needs to align with the passage leading to the crank & bearings. Probably a bit of tolerance there but need to measure to know.
Ask any questions you want.

[Rod B]

If you use a sealant like RTV or similar, make sure that mating surfaces are as clean as possible and use only a light smear. Excessive amounts get squeezed into the oil passages causing blockages which have killed many engines. Best of luck with the fix.

By the way, if you use an o-ring, use a little o-ring lube, it really helps them seal plus it helps to keep them in place while you do the reassembly. Available from anywhere that sells o-rings.

[Compass790]

Thinking some more ( lol )I still think the leak was probably the fault of whoever did the service. Never heard of those filters being a leak problem.
You probably cant get a gasket for the ysm8 as it is meant to be sealed by an o-ring. You can make one or buy one for a yse8 which uses the same filter except for the o-ring. I'd make one with a bit of gasket paper & put a thin even smear of silicone on both sides of the gasket.
If you take the filter off & find a stripped bolt report back for more ideas.

[delta_shawn]

Funny you should mention powering against the flood upwind on the river, tried that...found some weed beds, too, and the mud, all of which strained the engine no doubt. Now that I realize the limitations of the engine, I’m far more cautious in my explorations... good news is having a handicapped engine is making me a better sailor, and now I’m learning about engines

Great info...so, do I need to pump out all the oil to remove the spin filter? Probly won’t try this until I have a gasket or o ring on hand other wise. I will report back with my findings. Oh and there are no alarms as the wires to the speaker are either not present or disconnected...I think the black circle on the engine panel is a speaker... anyways, there are two lights on top of the engine control panel that come on and remain on, and thats the way the PO said it was...the bottom light I believe is the oil pressure light and that has never worked. I will be pm’ing you, compass70, for that manual....

As for the mechanic who ‘serviced’ me, still not ready to blame the guy, but also really don’t want him back on my boat. perhaps his intent was teaching me to 🐠 rather than setting me up for dependency ...ah...life is really the greatest teacher...and it is also quite a mystery.

[Compass790]

No you don't need to drain oil to remove the filter. As I said in earlier post only about 1/2 a cup comes out, the oil pump needs to be running to flood the chamber that the filter sits in.
Its concerning that the alarms aren't wired up, you need those alarms. If you have any electrical skills it would be a good idea to fix them asap. I'm suspicious as to why they are disconnected. The lights should go off once the engine starts.

You could just remove the filter & slather the sealing faces to the outside of the o-ring ( not on the o-ring) with silicone & just tighten it up loosely let it go off overnite & then tighten a bit more when its gone off. Again you shouldnt put much force on those little bolts, just enough to make the silicone bulge out. I'm confident this would work if you are used to doing this ( I've done it hundreds of times ) but if you have no engine experience you need to be careful. The thing is it's leaking anyway you can always redo it.

When running the motor hard out dont use so much throttle that it blows black smoke. That black smoke is unburnt diesel & it washes the oil off the cylinder walls so it's best to throttle back until it no longer blows black smoke

Did the "mechanic" check the oil pressure when he "serviced" it?

[delta_shawn]

alas, there was no o-ring. not sure how it was overlooked, but the thing is, his mishap led to me familiarizing myself with my boat's engine, which was necessary and is a positive development. I found an o-ring at the auto parts store that fit into the recessed area on the spin filter, installed it and so far that has fixed the issue. Other thing I discovered was a 'made in India' sticker on the engine hrs meter, the wiring to the meter is clearly quite new and doesn't match up with the other wires to the nearby controls. I doubt this engine had only 31 hrs on it when I purchased it. I blindly assumed a 30 year old engine had 31 hrs on it...yeah pretty naive on my part.

Could've been the guy removed the old spin filter and destroyed the old o-ring trying to pry it out and didn't bother telling me. or he could've just not put it in out of sheer forget-fullness, or he could've been deliberately trying to sabotage my boat? I'll likely never know...but as the buddhists say, to rest in not-knowing is where you'll find true knowing...

What I do know is that compass 70 provided some excellent pro-tips and was super helpful in sending me the repair and operating manuals...as have others chimed in above...much gratitude.

Next step is hooking up the water cooling lamp, the wires are disconnected in the engine room. As far as I can tell the charge lamp, and oil pressure lamps are working properly, they turn off after starting. After running the engine moderately for 30 minutes, the block is hot to the touch, but not so hot I can't keep my hand on it... not sure if this is normal. When I bought the boat, and prior to the 'service' the boat choked out black smoke under even low throttle...it's no longer doing that....so this is good.

I have noticed a very slight leak of clean oil, but I need to consult the repair manual to identify the exact area it's coming from, and I will post back. So far it hasn't affected the reduction/reverse gear oil levels, which is where I think it's coming from...

[Wotname]

Originally Posted by delta_shawn

............
Next step is hooking up the water cooling lamp, the wires are disconnected in the engine room. As far as I can tell the charge lamp, and oil pressure lamps are working properly, they turn off after starting. After running the engine moderately for 30 minutes, the block is hot to the touch, but not so hot I can't keep my hand on it... not sure if this is normal. .............

Being a raw water cooled engine, it's operating temperature (water) should be around 50C. This temperature is about the same that stuff feels too hot touch by hand.

I suspect it is running at the correct temperature but you should confirm the overheat switch and wiring is functional.

The overheat switch can be removed and heated in a pan of water. The contacts are open when cold and close around 60C. The process is in the manual provided by Compass790.

The manual also describes the method for checking the thermostat.

[Compass790]

Excellent that it no longer blows black smoke after service so at least he got that right.
Did he clean the exhaust elbow? as that is a common thing to clog up with carbon.
Good news too that your oil pressure alarm is working, the oil pump rotors can wear down into the case & cause problems. You should be ok if the oil pressure light goes off in a few seconds after starting.

[marth]

Happened to read this discussion and wanted to mention my YSM8 had an oil leak from the filter. It became apparent quite suddenly and the leak was significant. The replacement of the O-ring fixed it. Just took the filter out and went to the local store where they gave me a new O-ring. It looked quite ok inside as the oil has been changed every year while the motor is used for 20-50h a season.

[Sherpa17]

It's common to wipe an o ring or filter gasket with oil before tightening to seat a gasket properly.