Universal M18 leaking oil / low oil pressure

[adamv]

Had the engine out to change the mounts- since putting it back, on a couple occasions now:
* at cruising revs for an hour I noticed the oil pressure steadily drop from 45ish to 20.
* when I drop the revs down to idle the pressure drops to zero and the ignition buzzer comes on
* most important of all, about 2 tablespoons of oil have dripped
* the engine temp looks normal (barely a 3rd up the guage)

I can't see which gasket the oil is coming from- it's the lowest point- the back of the oil pan/ sump.

I did change the oil and filter when the engine was out- I did only tighten the filter a hard hand tight and I don't see any signs of oil dripping from it. I also changed the dipstick tube but this looks clear of oil too

Of course it's difficult to fully tell what the source is- I would need several go pros recording an hour while at high revs to really see what's going on.

Anyone with experience of solving a similar problem? I don't really want to take the engine out yet again only to find the gasket I replaced wasn't the problem one!

 

[adamv]

Oh... and one more question.. has anyone tried Stop Leak such as: https://www.amazon.ca/AT-205-ATP-Re...580e5f41aedd3f21995f879c38830dbb&gad_source=1

 

[kloudie1]

Sounds like your oil is thinning at higher temperature!, your oil should be 15 W 40 diesel oil. If that is what you are using, you can go to 50 wt heavy duty oil to carry you temporarily while ya do more trouble shooting
Best to not use leak stop

 

[adamv]

Sounds like your oil is thinning at higher temperature!, your oil should be 15 W 40 diesel oil. If that is what you are using, you can go to 50 wt heavy duty oil to carry you temporarily while ya do more trouble shooting
Best to not use leak stop

Thanks I am using 15w 40 as specified. From what you're saying am I right in thinking you're believing that the oil is coming out of some relief valve or something rather than a worn gasket? For me, this is key to understanding what's going on - if my engine is faulty I would rather not just try to avoid the circumstances that trigger the problem (as that this does not add to one's inner peace) but to fix the source. Of course if everything is working as expected and I'm just not taking the right course of action or not using the right product or procedure it's a little easier to know what to do.
It feels that using heavier oil than specified isn't addressing any underlying but perhaps I'm thinking wrong?

 

[Ralph Johnstone]

Have you checked the level of oil in the sump ? I'm not a Universal expert but if your lift pump uses a diaphragm, it may be possible that a broken diaphragm is leaking diesel fuel into your sump.

It feels that using heavier oil than specified isn't addressing any underlying but perhaps I'm thinking wrong?

@kloudie1 is suggesting using a slightly heavier oil while you search for the cause of what is "possibly" reducing the viscosity of your oil. Just a safeguard.

* most important of all, about 2 tablespoons of oil have dripped

The loss of two tbls. of oil is of no interest at this time. That will not affect your oil pressure if your oil level is full up.

I also changed the dipstick tube but this looks clear of oil too

Speaking of full up, are you sure your new dipstick tube is the correct length. Are you speaking of the diptube which screws into the block or the actual dipstick ? If you are overfilled, the oil will foam and cause all manner of excitement including a runaway engine.

 

[adamv]

Have you checked the level of oil in the sump ?

Speaking of full up, are you sure your new dipstick tube is the correct length. Are you speaking of the diptube which screws into the block or the actual dipstick ?

The oil level is in the middle of the range every time I checked. I could add more oil but don't see much reason to- its certainly not overfilled

I changed the tube itself( as it was rusty) for a new OEM one. I made a card gasket using regular gasket card I got from an auto repair shop.

One question for everyone- the oil pressure sensor - is my understanding that the name of this really wrong and its a oil viscosity sensor correct? So really a heat sensor for the oil? Would this mean oil escaping through any means Would not actually reduce the pressure? And if it is basically an oil temp guage how could the oil heat up while the coolant stay at temp?

 

[kloudie1]

I didn't mean too suggest that heavier oil would fix anything, rather it might marginally help while you get more information.. Low oil pressure can come from many causes.. worn engine and connecting rod bearings are some of the biggest price wise to fix.. Some other causes of low oil pressure would be an oil pressure relief (control) valve that would have a spot of debris in it, a bad oil filter, a worn oil pump,
Your oil leak is most likely a worn rear main oil seal.. requires pullling the gearbox and flywheel to access.. that can happen with age but also with a worn rear main bearing which allows too much shaft movement.. That leak itself is not a cause of low oil pressure.
On page 13, item 15 is the oil pressure valve..it can be easily removed and checked for debris or a broken spring or..??
200139 (westerbeke.com)
EDIT : I think that engine is a Kubota D 600 block and parts (non-marinized parts) can be a lot less expensive and easier to find through them
Cross Reference for M18 to Kubota Parts | Sailboat Owners Forums

 

[adamv]

thanks @kloudie1 ! It would seem strange that i have two independent oil issues at the same time. I did take the engine out and the coupler was very rusty and took a lot of pursuading to get the bolts out with a hammer. My fear at the time was that something would be affected. I also had a situation earlier in the year where the coolant had drained (hose issue) and i ran the engine for 15 mins with too little and the engine became very hot.
It does look like the oil is dripping from the rear edges of the oil pan (on both sides) - the bell housing sits lower and more rearward so i would expect oil to be dripping from further back if this was the cause.

My total guess is that its one of:
* oil pan gasket
* oil relief valve or something
* dipstick tube

When installing the dipstick tube, i did just use card - no anti-sieze. Perhaps i should have used some silver or some other adhesive? Again, i dont see any sign that the oil is ineed coming from this area but it would make sense if that is indeed needed

but this/these theories it seems dont really explain the oil pressure....

could another theory be that a sump / pan gasket has been old and ready to go for some time, that there's some problem circulating, regulating or cooling the oil? this means it gets hot and reduces the viscoity - it seeps through holes it can now get through. If this were the case, how could the engine (i.e. coolant) temp show as normal but the oil get very hot and low viscous? Are there any other pump or sensor failures that could explain this scenario? Perhaps the faulty sensor or blocked value is, as you described @kloudie1 the most likely culprit - i wonder if other explainations could fit too though?
Thanks

 

[Ralph Johnstone]

One question for everyone- the oil pressure sensor - is my understanding that the name of this really wrong and its a oil viscosity sensor correct?

100% incorrect. Looking back on my refinery instrumentation, I can't remember anything that measures viscosity directly. The sensor measures pressure using a bellows.

On page 13, item 15 is the oil pressure valve..it can be easily removed and checked for debris or a broken spring or..??

This should be your next item to check because :

1. It's a more likely cause
2. It's free to check. Always work from the cheapest to more expensive as you look for a cause of a problem.

 

[adamv]

okay i think the hive mind here was absolutely correct... i spotted some oil on top of the transmission - it looks like its dripping from above and it appears that there is some after market external box... for the pressure sensor to live in (at least i very much assume this is what it is given that the small hose that the 45 degree elbow feeds from loops back under the manifold and into where the sensor is supposed to live.

Ive wiped this flat surface clean this surface a few times- i believe the oil is coming from here.

This part doesnt appear in the technical manual so i assume its after market. Any idea what it would be called?

It also appears to me that this box has been soldered to repair it. maybe? Maybe also its damaged and thats why its leaking?

If anyone knows what part this might be perhaps i can order a replacement for it and the sensor?.. (BTW - i believe this is a sender as im 99% this goes to a guage and buzzer - not just a light)
Thanks so much - and apologies for making you look at the dirty end of the engine!

 

[Tally Ho]

Hard to tell what that tubular device is without some detailed photos on any connections.

My first thought was a heat exchanger, but too small and not in the typical orientation.

Maybe an oil cooler?

Greg

 

[smokey73]

I'm a little confused on which problem we are trying to solve? The apparent "low oil pressure," or the slight oil leak. Of course the slight oil leak should be checked and fixed, or you live with it and an oil absorber pad and while troublesome, is not catastrophic. Find it & fix it or live with it. I can think of NO situation where a small oil leak would lead to low oil pressure until you let it go for such a long time and don't check and fill up the oil and end up with the oil level so low the pump looses suction. Anyone with a Land Rover or Fiat will tell you they leak oil, live with it. It is hard to believe that any reasonably sized leak would be of sufficient volume to result in a low oil pressure switch to trigger unless you saw a nearly solid stream of oil coming out.

So that leaves us with low oil pressure. The actual potential catastrophic point of failure if it is really true. It could be an instrument problem or could be something causing a real condition of low oil pressure, such as a relief valve that opens when it shouldn't, oil diluted with diesel fuel or a blown head gasket leaking water into the oil (should be foam in the oil if that is the cause,) worn bearings, etc. The first thing to do is to figure out if it is an instrument problem. From you description, it appears you have an oil pressure gauge (reading pressure) AND a low oil pressure switch independent of the pressure gauge. Normally the low oil pressure light and buzzer come from the low oil pressure switch, not the gauge. This would be at first blush to say that it is really some sort of actual low oil pressure condition since both are telling you the pressure is low.

So, you need to sort this out before you go much further. An easy and relatively simple way to check this is to replace the oil pressure sender unit with a manual pressure gauge and see what you have. (check to see if the threads are NPS or BPT) A manual gauge should tell you a lot. I had something similar (except my low oil pressure buzzer never came on). I was concerned so I replaced my oil pressure sender unit and gauge and also installed a manual pressure gauge teed off the same sensing point. Turned out I did not have a low oil pressure problem, just a failing oil pressure sending unit.

To paraphrase the rules from Gibbs on NCIS - RULE 1 - BELIEVE YOU INDICATIONS!

 

[Ralph Johnstone]

i spotted some oil on top of the transmission - it looks like its dripping from above

Why are you so obsessed with this bloody oil leak ? It isn't worth mentioning. It has nothing to do with the low oil pressure problem.

Get back to reality, man ! You may have a REAL PROBLEM with low oil pressure that has the potential to destroy your engine. As in permanently destroy, as in fork over $8-10K for a new engine, installed. It doesn't take more than a few seconds to lose oil pressure at full load and permanently DESTROY you engine. Are you even aware of this ?

Is there something we don't see here ?

 

[adamv]

Why are you so obsessed with this bloody oil leak ? It isn't worth mentioning. It has nothing to do with the low oil pressure problem.

Cool your jets! its significant because A)the two problems started at the same time and B) a suddenly leaky sensor seems EXACTLY the kind of culprit, doesnt it to you? C) It even looks very much like the PO has done a bodge job trying to fix an external housing around the sensor using either solder or some sort of araldite. Ive not found any references online to this kind of external housing so its hard to know whether i should look for an OEM sender or something else to replace it with.

 

[Ralph Johnstone]

Awright, jets on cool.

Do you have a Universal M18 maintenance manual from this site yet ? I'm too lazy to look for one because as I said, I'm a Yanmar guy. Without a manual handy, I'm pretty sure I'm in the right ballpark in saying this is the oil pressure switch :

A pressure switch in not a pressure sensor. It doesn't give you a pressure readout, it only opens and closes an internal switch at a dangerously low oil pressure (about 5 PSI). Any small oil leaks in this area will not affect the pressure supplied to the sensor element by virtue of the the relatively large cross sectional area of the pipes and tubes feeding the inlet to the pressure switch. Next :

The adjacent tube shown above looks interesting if you can tell us where it leads to with a picture of the termination.

@Stu Jackson , any chance you could supply a manual to indicate what the block is that the pressure switch sites on ?

 

[Ralph Johnstone]

One more suggestion is to clean up the wires on the pressure switch. They look to be in bad shape and they may be hiding a problem (or not).

 

[adamv]

Thanks @Ralph Johnstone ! Yes the m18 technical manual and parts list just shows an oil switch screwing directly into the kubota z600 block under the manifold, unlike my engine where this is placed near the heat exchanger - as I mentioned I've not come across anything like this external box. This is the OEM part the parts list calls for- Universal, Switch, Oil, 298663
As its a switch, i am assuming the PO didn't like not having a guage and added the box as an upgrade that later failed catastrophically (note the wobbly reconstructed side)

So i think i should replace this whole box and pressure sender. Could this be with a 3 pin sender which sends pressure signal and a 8 psi warn? Assuming not any will do?

 

[smokey73]

First question to clarity. Do you have both a pressure gauge of some sort (reading actual sensed pressure) AND a pressure switch operating the low oil pressure buzzer? If you do where are these sensed? You indicated that the oil pressure went to zero (indicating something indicating oil pressure) AND the oil pressure buzzer sounding so it sounds like you do. It is not likely that one sensor would provide both signals but I guess it is possible.

I agree with @Ralph Johnstone that a small oil leak will not cause an actual low pressure condition. See my post #12. Ralph jets were on fire because he was concerned that the focus on the leak was directing your attention away from the potential catastrophic failure that can come from true loss of lubrication to critical parts of your diesel and the resultant cost to repair. (How is that for diplomacy?) It may leak at the sensor but the leak is not the problem you need to address FIRST. By the way, that looks like JB Weld at the fitting you are concerned about. While the two may have started at the same time (leak and low oil pressure) that does not mean that one is the cause of the other. That line that Ralph asked about looks an awful lot like a sensor line for a manual oil pressure oil pressure (non electric). Follow that line and see where it ends.

For the moment, forget the leak and determine FOR A FACT that you DO or DO NOT have an oil pressure problem.

Once you've solved the oil pressure conundrum, attack the leak and decide if it is something you need to address quickly to avoid a future catastrophic failure or if it something you can let ride and work on later, while you enjoy your boat. If that is JB Weld or something like it I'd be concerned that it might suddenly fail and then you would see a sudden loss of oil pressure followed quickly by a seized engine.

 

[smokey73]

Reading over your post #10 again. It indeed looks like this "after market" block was added by the PO since it is fed from a hose where the oil pressure switch is supposed to be attached. With that in mind, I would bet that the solid tube with a bend that @Ralph Johnstone identified in post #15 is a feed line for a pressure gauge that directly measures pressure (non-electric sensor type). Trace that and you will probably find it leads to the oil pressure gauge that the PO has installed. Where is that gauge installed? It does not appear to be located on the standard instrument panel shown in the link from @kloudie1. Find that gauge and see if it has a solid line, not an electrical wire, feeding it.

If all of the above is correct and the pressure on the gauge behaves as you have stated (drops slowly from 45 to 20 pounds as the engine heats up) and drops to 0 when at idle after that and the buzzer comes on that indeed, it is most likely you have a REAL low oil pressure situation. Two different indications, one electrical and one mechanical gauge both say you have low pressure - Believe your indications. In my business we call that "two unrelated simultaneous failures" since they use different sensing methods. A small leak like a drip of a few tablespoons of oil will not cause this problem.

Others have identified what could cause the low pressure, like relief valve lifting, worn out oil pump, worn bearings, oil contamination and possibly others. Sounds like a worn out oil pump to me but that is just a wild guess.

It should be very easy to screw in a mechanical gauge at the point of the low pressure sensor or the mechanical gauge to confirm what you really have. If it were me, I'd hook up the temporary gauge to the where the electrical sensor is installed so you cold compare it to the PO installed pressure gauge. In any case shut off the engine immediately if the pressure actually drops dangerously low on either gauge.

Best of luck and don't smoke your engine.

 

[Richard19068]

Reading over your post #10 again. It indeed looks like this "after market" block was added by the PO since it is fed from a hose where the oil pressure switch is supposed to be attached. With that in mind, I would bet that the solid tube with a bend that @Ralph Johnstone identified in post #15 is a feed line for a pressure gauge that directly measures pressure (non-electric sensor type). Trace that and you will probably find it leads to the oil pressure gauge that the PO has installed. Where is that gauge installed? It does not appear to be located on the standard instrument panel shown in the link from @kloudie1. Find that gauge and see if it has a solid line, not an electrical wire, feeding it.

If all of the above is correct and the pressure on the gauge behaves as you have stated (drops slowly from 45 to 20 pounds as the engine heats up) and drops to 0 when at idle after that and the buzzer comes on that indeed, it is most likely you have a REAL low oil pressure situation. Two different indications, one electrical and one mechanical gauge both say you have low pressure - Believe your indications. In my business we call that "two unrelated simultaneous failures" since they use different sensing methods. A small leak like a drip of a few tablespoons of oil will not cause this problem.

Others have identified what could cause the low pressure, like relief valve lifting, worn out oil pump, worn bearings, oil contamination and possibly others. Sounds like a worn out oil pump to me but that is just a wild guess.

It should be very easy to screw in a mechanical gauge at the point of the low pressure sensor or the mechanical gauge to confirm what you really have. If it were me, I'd hook up the temporary gauge to the where the electrical sensor is installed so you cold compare it to the PO installed pressure gauge. In any case shut off the engine immediately if the pressure actually drops dangerously low on either gauge.

Best of luck and don't smoke your engine.

I think Smokey73 is spot on with this analysis. The box is simply an aftermarket way to tee off the stock oil pressure sender port so the PO could have both electrial and mechanical pressure indicators. My M-18 has a similar setup but just uses a simple brass tee instead of a box like that.

The leak is a red herring. Figure out the low pressure issue first and then worry about the leak.