• Untitled Document

    Join us on March 29rd, 7pm EST

    for the CBEC Virtual Meeting

    All EYO members and followers are welcome to join the fun and get to know the guest speaker!

    See the link below for login credentials and join us!

    March Meeting Info

    (dismiss this notice by hitting 'X', upper right)

Oil consumption and running a diesel hard enough

Alan Gomes

Sustaining Partner
In 2017 I replaced my well-running Yanmar 1GM with another 1GM that I got for a steal on eBay. This one had been run only in fresh water (a great thing for a raw water cooled engine), had zero surface rust, and was just too good of a bargain to pass up. So I bought it, tested it in my garage, and then swapped engines in June of 2017. The original engine is in my garage and I plan to rebuild it in my leisure, or just keep it as is for a spare.

Anyway, the "new" engine started right up, had good compression (which I verified with a compression tester), ran very well, but did smoke a small amount. Because of family commitments, I had very little occasion to run it in 2018. But after putting only about 20 of my own hours on the engine, I began to observe that it was consuming some oil. The Yanmar manual says that some oil consumption is normal, being greatest when the engine is brand new and also toward the end of its useful life. However, the numbers I was seeing were more than I was comfortable with. Specifically, I was observing around 0.4 to 0.5 oz./hour. This may not seem like much, but that little engine only holds 1.4 qts. total in its baby oil sump to begin with! Plus, my original engine consumed little if any oil--certainly nothing like this. I was not happy.

Knowing that the compression is good, I was thinking it might be the valve seals, or possibly the oil ring. It was not leaking oil, so the oil had to be going out the exhaust. So even though it was not smoking much, I figured the amount it was smoking had to be enough to account for this amount of consumption.

I was considering swapping back to the original engine and then tearing down this one for a rebuild. But I first decided to give a call to Scott at S&W Diesel in Wilmington to see what he thought. He wondered if perhaps the engine had been run too lightly or not under enough of a load for prolonged periods. He said that he often talks to customers who baby their engines (thinking that's a great thing to do) and then encounter increased oil consumption from things like stuck rings, etc. He mentioned that it's especially bad with generators because it's often difficult to load those up. He said that he will tell such customers to run the crap out of their engine for several hours and see if the problem doesn't fix itself. He mentioned one fellow who did this, motoring from San Diego to L.A. Harbor (I think it was), and by the time he put 10 hours of hard running on it the problem vanished. He suggested I give that a try.

I already knew that a diesel ought not to be babied and I have never done that with any of the ones I've owned. But with this engine I don't really know how the previous owner may have run it in the past. I do know that he used to race his boat and it could be that he just fired it up to get to the starting line and then to get back into the slip. I'm just speculating here, of course. I do not really know the total number of hours on this engine as the previous owner did not have an hour meter on it, nor do I know his usage pattern. It looks to have had light use, and if so, that's not necessarily a great thing.

So, I decided to follow Scott's advice and run the heck out of it. I put a little over 10 such hours on it, running it at about 3300 rpm. This is above its normal cruising rpm but within the continuous rpm rating of the engine, and is about the max I can get with my particular prop in any case. (I am slightly overpropped.) This was a really good, hard run. When I did this, the oil consumption shot up to over 2 oz. per hour! Yikes! But after this I also noticed that the smoke I had been seeing pretty much disappeared when I ran it at a more reasonable cruising rpm (e.g., around 2800). Something clearly had changed.

Since putting those hard-running hours on the engine, I've been running it at 2850-2925 rpm since mid-February. This is a good, stout cruising rpm for this engine and puts it under a decent load. (I confirmed actual engine rpm with an optical tach; my Yanmar tach reads about 200 rpm too low in this range.) I would carefully check the dipstick after every run.

Well, guess what? On April 13, after 27.2 hours, I could finally discern a very slight decrease in oil level on the disptick! So I carefully added a small amount of oil until I brought it right up to the full line again. It took all of 2 oz.! Doing the math, this is only 0.07 oz./hour! And the engine no longer smokes. I can sometimes get a small amount of steam, depending on the outside air temperature/dew point. Sometimes I don't even get the steam. But as for the smoke, it is gone.

Scott's suggestion paid off. I'm guessing there may have been some carbon causing a stuck ring or something. The engine runs great--though to be honest, I would have thought all was well before had I not observed the oil consumption.

My plan is to run it at WOT for an hour or two here and there, to keep everything blown out. I've also added a nice solar panel setup so I can keep up with my electrical loads without having to idle the engine. (As I mentioned, I didn't tend to do that too often before anyway, but now I'm being very punctilious about avoiding that completely.)

I hope this info may be helpful to someone else.
 
Last edited:

Frank Langer

1984 Ericson 30+, Nanaimo, BC
I'm sure this will be an interesting discussion! I asked a local mechanic about this for my universal 16 hp 5416 diesel engine. He said it should be run at cruising rpms, idled as little as possible though enough to warm it up before putting a load on it, and run it at least once a month. I told him that a fellow sailor had heard that one should run diesels hard "like you just stole it", and he said no, that's hard on the engine. He said to use it respectfully.

So now I cruise at 2250 rpm (max is apparently 2800 so I aim for 80% of that) avoid idle except to warm it up, and run it regularly. The engine has 2,480 original engine hours on it, runs well and doesn't burn any oil (judging by the dipstick level). I change oil twice per year, about every 75 engine hours, which is a bit more often than the manual suggests. I have had the injectors serviced and a valve adjustment done at about 1800 hours, both for preventive reasons rather than for any problem.

I'll be interested in what you experts suggest.
Frank
 
Last edited:

Alan Gomes

Sustaining Partner
I'm sure this will be an interesting discussion! I asked a local mechanic about this for my universal 16 hp 5416 diesel engine. He said it should be run at cruising rpms, idled as little as possible though enough to warm it up before putting a load on it, and run it at least once a month. I told him that a fellow sailor had heard that one should run diesels hard like you just stole it, and he said no, that's hard on the engine. He said to use it respectfully.
So now I cruise at 2250 rpm (max is apparently 2800 so I aim for 80% of that) avoid idle except to warm it up, and run it regularly.
I'll be interested in what you experts suggest.
Frank
Thanks for your thoughts on this, Frank.

Just so we're comparing apples to apples, the Yanmar 1GM is a high RPM engine. It is rated for 3600 rpm max with a "continuous" rating of 3400. So my running it for 10 hours at around 3300 is certainly within its rated rpm. My favored cruising rpm of 2900 is about 80% of max.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks for that clarification, Alan. I'm aware that different engines have different rpm ranges, so that makes sense to me. I guess the question is still whether one should run diesels really hard as some suggest, or more moderately (though high enough rpms to avoid becoming a soot factory). Also, whether one should race the engine briefly before shutting it down to blow out any soot/carbon as some people suggest (my universal manual cautions against racing the engine at all, but doesn't say why).
Frank
 

supersailor

Contributing Partner
Diesels like to run at about an 80% load at a constant RPM. Gasoline engines like to run at about a 23% load with varying RPM. This makes diesels ideal for boats and gasoline engines ideal for cars.. Run the RPM's up there and forget the throttle. You need a larger displacement with a gasoline engine to keep the load down. Diesels do not like to be idled and run at low load factors. They soot and carbon up. Blowing them out does work as long as the carbon hasn't hardened up, particularly on the injectors.

Running the engine harder certainly hasn't murdered fuel economy. Terra Nova has averaged out at .42 gallons a hour over the last 4 years.
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
A very thought-provoking post. It makes me think I've "babied" my M-25 a bit too much in the last 2+ years I've owned it.

It brings up what is probably a related inconsistency in how many of us (from what I've read here) operate our engines. My M-25 manual says that normal operating temperature is 165-190 degrees (the Ericson E32-3 manual says 175-185 deg). With the standard 160 degree thermostat, operating at 160 or below means the engine is probably never really warmed up (and, possibly, more prone to carbon buildup). But, I've grown comfortable operating it like that because I can still reach near hull-speed. At higher rpms, the sterns just squats lower in the water, I don't pick up much additional speed, and the temperature rises to about 185 or higher, where I feel the constant need to monitor it to ensure it doesn't overheat. I usually back down on the throttle shortly thereafter. Sounds like I should probably just let her run, for a long time, as long as the temp stays below 200 degrees or so.

I'm no engine mechanic, but the idea of running hard to burn off deposits make sense--high rpms, high temperatures, large quantities of air and fuel coursing through the valves and cylinders, metals expanded due to high forces and temperatures, and material deformations pushed outside their normal wear patterns. Sounds like this is how you would shake-out old, crusty engine deposits.

It makes less sense to me (as was described in a related post) to rev the engine before shutdown, but after it has cooled down from operating temperatures. Once the engine has cooled down, it's hard to see how revving up it up just prior to shutdown is much different from revving it after start, before it's been fully warmed up. But, either way, revving an engine under no-load is obviously different from revving one with resistance on the crankshaft. I would guess that the quicker accelerations and lack of counter-forces are what can damage an engine under no-load revving. I also wonder if it's bad for the transmission.
 
Last edited:

Alan Gomes

Sustaining Partner
A very thought-provoking post. It makes me think I've "babied" my M-25 a bit too much in the last 2+ years I've owned it.

It brings up what is probably a related inconsistency in how many of us (from what I've read here) operate our engines. My M-25 manual says that normal operating temperature is 165-190 degrees. With the standard 160 degree thermostat, operating at 160 or below means the engine is probably never really warmed up (and, possibly, more prone to carbon buildup). But, I've grown comfortable operating it like that because I can still reach near hull-speed. At higher rpms, the sterns just squats lower in the water, I don't pick up much additional speed, and the temperature rises to about 185 or higher, where I feel the constant need to monitor it to ensure it doesn't overheat. I usually back down on the throttle shortly thereafter. Sounds like I should probably just let her run, for a long time, as long as the temp stays below 200 degrees or so.

I'm no engine mechanic, but the idea of running hard to burn off deposits make sense--high rpms, high temperatures, large quantities of air and fuel coursing through the valves and cylinders, metals expanded due to high forces and temperatures, and material deformations pushed outside their normal wear patterns. Sounds like this is how you would shake-out old, crusty engine deposits.

It makes less sense to me (as was described in a related post) to rev the engine before shutdown, but after it has cooled down from operating temperatures. Once the engine has cooled down, it's hard to see how revving up it up just prior to shutdown is much different from revving it after start, before it's been fully warmed up. But, either way, revving an engine under no-load is obviously different from revving one with resistance on the crankshaft. I would guess that the quicker accelerations and lack of counter-forces are what can damage an engine under no-load revving. I also wonder if it's bad for the transmission.
A couple of thoughts, Ken: (1) The reason your Universal engine has a 160-deg. T-stat is for the health of the heat exchanger. If you ran it hotter, salt would precipitate out and clog the exchanger. But you are correct, I believe, in saying that the engine would be happier at 190. (2) If your engine temps are varying above the thermostat setting then this tells me that your heat exchanger is clogged and/or undersized, or there is some other issue in your cooling system. You should be able to run that engine at any rpm and never have it go above 160 (if that's what the T-stat is). I had a Universal M-18 and an M25XP in previous boats, and they both had 165-deg. (I think) thermostats in them. They would not run hotter than that no matter how hard I ran the engine. I know that some of the M25 engines were fitted with a 2" exchanger, and that proved inadequate because even the slightest degradation in the water passages would cause what you are describing. For that reason many people upgraded them to 3" exchangers. Catalina also went with 3" exchangers for that engine later in their production run, if I'm not mistaken. If your engine has a 2" exchanger then I'd suggest you do the same. If it's a 3" exchanger then it might be time to get it cleaned out. In any event, this is not normal and ought to be addressed.

Edit: Check this out (from the Catalina Direct site): https://www.catalinadirect.com/shop...5xp-m-35-3quot-dia-wbrackets/?SearchResults=1
 
Last edited:

Mark Roberts

E34-200 Kingston, Ontario
First let me preface to say I am still in the novice stage when it comes to diesel engines. But I would like to share a perspective from Nigel Calder who is an expert. I attended an all day seminar of his on diesel engines at the Toronto Boat Show. One of the many excellent comments he made is relevant here. He said that many of us are slowly killing our diesel engines. We start them at the dock, motor out to our sailing grounds and then shut them down. If this distance is short, as it is in my case, you will not push your engine under load or get it to a healthy operating temperature. He said diesel engines like to be pushed under load. So now in my case I make sure to motor further and at higher RPM's before I shut down to sail.

This is paraphrasing Nigel, but you get the idea. It agrees with what Alan has been advised and experienced.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
Since my other thread about spitting soot, the last two days I've gone out I've "floored" it out of the marina for a while, hitting max RPMs of 3200 on my M-25. Since doing this I haven't noticed the light surface coating of soot on the water, and I don't smell the diesel burning while cruising quite as much.

Also, redlining it tells me that my cruising RPMs should be around 2500, which is higher than I have been going at 2100-2300 or so. My tach is wobbly so I don't trust it too much, and have erred on the low side. This likely contributed to the buildup of soot that I noticed.

My temp gauge never gets above 130, though. I don't know if Puget Sound is just THAT cold, or (more likely) that my heat gauge in the cockpit is crappy. I think bgary has noted a similar issue on his 32-3, and he is also a Puget Sounder.

I guess my main fear with the "italian tuneup" is that while I may be blowing carbon and soot out, pushing it too hard might cause other deferred maintenance items I haven't thought of to blow out as well...
 

supersailor

Contributing Partner
Your thermostat is stuck and needs replacing. Mine was stuck also and replacement solved the temp problem. I went with a 180 degree thermostat. The engine runs better. I pull the ends on the heat exchanger every six months and have noticed no buildup in the exchanger. The hot water tank is also warmer which makes the other half happier.
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
A couple of thoughts, Ken: (1) The reason your Universal engine has a 160-deg. T-stat is for the health of the heat exchanger. If you ran it hotter, salt would precipitate out and clog the exchanger. But you are correct, I believe, in saying that the engine would be happier at 190. (2) If your engine temps are varying above the thermostat setting then this tells me that your heat exchanger is clogged and/or undersized, or there is some other issue in your cooling system. You should be able to run that engine at any rpm and never have it go above 160 (if that's what the T-stat is).

Good points Alan. I hadn't thought of the effects of higher temps on the heat exchanger. But this is why I called it an "inconsistency;" Kubota built the engine and then Universal "marinized" it by adding a water heat exchanger. If Universal installed a 160 degree thermostat, how could they claim normal operating temperature is 165-190? Would they really design it that way to protect a $300 heat exchanger at the expense of an $8000 engine?
 

Kenneth K

1985 32-3, Puget Sound
Blogs Author
Good points Alan. I hadn't thought of the effects of higher temps on the heat exchanger. But this is why I called it an "inconsistency;" Kubota built the engine and then Universal "marinized" it by adding a water heat exchanger. If Universal installed a 160 degree thermostat, how could they claim normal operating temperature is 165-190? Would they really design it that way to protect a $300 heat exchanger at the expense of an $8000 engine?

And, you are correct, I have the original 2" heat exchanger. But it was thoroughly boiled out, with new injection elbow, exhaust riser/mixer and all hoses replaced in 2017.
 

bgary

Advanced Beginner
Blogs Author
... many of us are slowly killing our diesel engines. We start them at the dock, motor out to our sailing grounds and then shut them down.

Well, crap, now I gotta add that to my list of things to worry about. That's EXACTLY what I do...

I start the motor at the dock, let it warm up for a few minutes, idle out to the fairway, throttle up a little (1500-2000 rpm) down the channel, about 3/4-mile, and then... if there's wind, I raise sails and shut it down. If no wind, I usually run the motor at 2300-2400 rpm which pushes the boat comfortably above 6 knots. More than that, it doesn't seem to produce additional speed, just more noise and vibration and - as Kenneth notes - buries the transom in the quarter-wake.

One of the things on my list of things to do this spring is to borrow a handheld tach and see if my tachometer readings are close to what the engine is actually doing. At this moment I have no idea, although it is more of an intellectual exercise than a critical bit of info, IMO.

My temp gauge never gets above 130, though. I don't know if Puget Sound is just THAT cold, or (more likely) that my heat gauge in the cockpit is crappy. I think bgary has noted a similar issue on his 32-3, and he is also a Puget Sounder.

Yup. When the boat was new-to-me, temp at cruising speed ran around 165-170F. Seems pretty normal. In 2017, I replaced the coolant pump, and replaced all the hoses in the raw-water cycle, plus added a raw-water strainer. Since doing that, temp at cruising speed has been a rock-solid 145F. I don't know why. The only substantive changes were a new fresh-water pump and new raw-water hoses (albeit, up a size from 1/2" to 5/8", and the old ones were pretty crudded up, so effectively they were probably less than 1/2"-equivalent).

I've flashed an infrared thermometer at the side of the manifold, it says the outer wall of the manifold is just about 145F, so that seems to corroborate the gauge.

I don't think it's because the water in the Sound is cold. My guess is that mine is running cooler because more water is going thru the raw-water circuit than before, making the heat-exchanger more efficient. Dunno.

I also don't know if running at 145F will, in some way, cause long-term harm to the motor. It "seems" healthy and happy, but... that's just uninformed subjectivity talking.

Bruce
 

Alan Gomes

Sustaining Partner
Since my other thread about spitting soot, the last two days I've gone out I've "floored" it out of the marina for a while, hitting max RPMs of 3200 on my M-25. Since doing this I haven't noticed the light surface coating of soot on the water, and I don't smell the diesel burning while cruising quite as much.

Also, redlining it tells me that my cruising RPMs should be around 2500, which is higher than I have been going at 2100-2300 or so. My tach is wobbly so I don't trust it too much, and have erred on the low side. This likely contributed to the buildup of soot that I noticed.

My temp gauge never gets above 130, though. I don't know if Puget Sound is just THAT cold, or (more likely) that my heat gauge in the cockpit is crappy. I think bgary has noted a similar issue on his 32-3, and he is also a Puget Sounder.

I guess my main fear with the "italian tuneup" is that while I may be blowing carbon and soot out, pushing it too hard might cause other deferred maintenance items I haven't thought of to blow out as well...
I'd suggest investing both in a digital laser tach and in an infra red laser thermometer, so you can double check your engine's gauges. Harbor Freight has these quite inexpensively.
 

Alan Gomes

Sustaining Partner
Your thermostat is stuck and needs replacing. Mine was stuck also and replacement solved the temp problem. I went with a 180 degree thermostat. The engine runs better. I pull the ends on the heat exchanger every six months and have noticed no buildup in the exchanger. The hot water tank is also warmer which makes the other half happier.
Since you're not getting buildup in the exchanger it sounds like the 180-deg thermostat is really the way to go. I'll bet that the reason Universal specified a 165-deg. T-stat is because most users are not on top of things like you are and may never open up their heat exchangers. Since you are inspecting yours every 6 mos. you'll catch any possible buildup before it becomes an issue.
 

Alan Gomes

Sustaining Partner
Good points Alan. I hadn't thought of the effects of higher temps on the heat exchanger. But this is why I called it an "inconsistency;" Kubota built the engine and then Universal "marinized" it by adding a water heat exchanger. If Universal installed a 160 degree thermostat, how could they claim normal operating temperature is 165-190? Would they really design it that way to protect a $300 heat exchanger at the expense of an $8000 engine?
Well, sometimes companies do funky things. But perhaps they were thinking that if the HE clogged and the engine overheated catastrophically, you'd damage the engine. I dunno. But Bob's idea of going with a 180-deg. thermostat, which definitely makes the engine happier, coupled with regular inspections of the HE, seems like the best way to go to me.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
I'd suggest investing both in a digital laser tach and in an infra red laser thermometer, so you can double check your engine's gauges. Harbor Freight has these quite inexpensively.

Funny you should mention that!
I have purchased both in the last couple of years.

I used the tach to verify the accuracy of the tach on our new engine last year, (it was spot on) , and the laser-pointer temp meter is great for everything-- from stuff in the fridge to parts of the engine, to whatever you have the nerve to point it at....

BTW, that point-and-read thermometer was the "final' diagnostic tool as we approached the replacement of our original Universal diesel and both of the taped-over 'trailer connectors" for that old wiring harness were reading at least ten degrees above ambient.
As they say in the internet: "Yikes".
 
Last edited:

Alan Gomes

Sustaining Partner
And, you are correct, I have the original 2" heat exchanger. But it was thoroughly boiled out, with new injection elbow, exhaust riser/mixer and all hoses replaced in 2017.
I think the point with the 2" exchanger is that it can work when it and the rest of your cooling system is in optimal condition. But there's no reserve, whereas the 3" HE gives you a bit of a safety margin.
 

JPS27

Member III
How best to read temp on diesel

As a relative novice, this thread is very informative. I do not have a temperature gauge to read actual temp of the diesel. I do take readings, mostly out of curiosity only, with a handheld infrared thermometer taking reading at various spots on the engine. The readings are never high enough to cause alarm. Higher in some spots lower in others. Where is the most reliable place(s) to take these readings on the engine?
 

Alan Gomes

Sustaining Partner
As a relative novice, this thread is very informative. I do not have a temperature gauge to read actual temp of the diesel. I do take readings, mostly out of curiosity only, with a handheld infrared thermometer taking reading at various spots on the engine. The readings are never high enough to cause alarm. Higher in some spots lower in others. Where is the most reliable place(s) to take these readings on the engine?
I've always aimed it at the thermostat housing. Perhaps some people like to measure other locations as well?
 
Top