3GM30F overheating, with lube oil in the coolant.

BCC Forum
1

After three years without a problem our 3GM30F began to overheat while mortorsailing on the third day of a run down the coast from Cape Fear to Ft. Pierce. No noticable loss of power or other obvious symptoms other than;

  1. Slight loss of coolant, mabe 8 oz. with no sign of leakage.
  2. Lube oil in the freshwater coolant, a little at first, then more and more.

We shut down each time the alarm went off and did not overheat the engine - no scorched paint, hot smells or painful to the touch engine surfaces.

Once at Ft. Pierce we pulled the head and found signs of a leaking head gasket around the center #2 cylinder. And, steam cavitation pitting on the head’s combustion chamber and exterior surface of the injector! It appears that there has probably been some head gasket leakage here for quite a while - loss of compression may account for the somewhat difficult starting when cold we have been having?

Questions:

  1. How would oil be getting into the cooling system from this location? Or may we be faced with two unrelated problems-- a leaking head gasket, plus a leak of oil into the coolant from some other location?

  2. How much pitting on combustion chamber surfaces is tolerable before performance is affected?

  3. Now that the head is off, what other potential problems should we be looking for or preventative maintenance items taken care of before fitting the new gasket and putting her back together and hoping that the problems have been fixed?
    I cross-posted this to the yanmarhelp.com forum but don’t yet know how active it is.

Thanks for any suggestions,
Scott

PS. Apart from and despite the engine problem we had a fine run offshore from Cape Fear to Ft. Pierce, Four and a half days and four nights close reaching with starry nnights and lots of dolphins accompanying us from time to time. Wind veered the last day and a half so we did some hard motorsailing into headwinds and swell to make Ft. Pierce before nightfall and with favorable tide in the inlet.

After we get the engine back together we are heading across Okeechobee to the Gulf Coast for a while then to the Bahamas. Anyone have a suggestion for a good do-it-yourself tolerant yard in the Ft. Myers - Sarasota vicinity whwew I can haul and fit a new rudder? Or a cheap place to leave Itchen for a couple of weeks while we take care of things at home?

TIA, Scott

2

Oil in coolant from blown head gasket is not uncommon, with gasket failure, sometimes you get oil in the coolant, other times you get coolant in the oil, would rather have the former. Have the cylinder head rebuilt, if the rebuilder doesn’t have a problem with the level of corrosion in the cylinder head don’t worry about it, heads are expensive. Check precombustion chamber in head for concentricity-these get washed out with use, worn chambers will do more to adversely affect operation than minor pitting. Make sure you take your head to someone who specializes in diesel rather than gas, the gas folks don’t have a clue. Have head magnafluxed for cracks and surfaced as necessary.

Marty Chin

BCC Forums bccforums@samlmorse.com wrote:
Author: Itchen
Username: Itchen
Subject: 3GM30F overheating, with lube oil in the coolant.
Forum: BCC Forum
Link: http://www.samlmorse.com/forum/read.php?5,4406,4406#msg-4406

After three years without a problem our 3GM30F began to overheat while mortorsailing on the third day of a run down the coast from Cape Fear to Ft. Pierce. No noticable loss of power or other obvious symptoms other than;

  1. Slight loss of coolant, mabe 8 oz. with no sign of leakage.
  2. Lube oil in the freshwater coolant, a little at first, then more and more.

We shut down each time the alarm went off and did not overheat the engine - no scorched paint, hot smells or painful to the touch engine surfaces.

Once at Ft. Pierce we pulled the head and found signs of a leaking head gasket around the center #2 cylinder. And, steam cavitation pitting on the head’s combustion chamber and exterior surface of the injector! It appears that there has probably been some head gasket leakage here for quite a while - loss of compression may account for the somewhat difficult starting when cold we have been having?

Questions:

  1. How would oil be getting into the cooling system from this location? Or may we be faced with two unrelated problems-- a leaking head gasket, plus a leak of oil into the coolant from some other location?

  2. How much pitting on combustion chamber surfaces is tolerable before performance is affected?

  3. Now that the head is off, what other potential problems should we be looking for or preventative maintenance items taken care of before fitting the new gasket and putting her back together and hoping that the problems have been fixed?
    I cross-posted this to the yanmarhelp.com forum but don’t yet know how active it is.

Thanks for any suggestions,
Scott

PS. Apart from and despite the engine problem we had a fine run offshore from Cape Fear to Ft. Pierce, Four and a half days and four nights close reaching with starry nnights and lots of dolphins accompanying us from time to time. Wind veered the last day and a half so we did some hard motorsailing into headwinds and swell to make Ft. Pierce before nightfall and with favorable tide in the inlet.

After we get the engine back together we are heading across Okeechobee to the Gulf Coast for a while then to the Bahamas. Anyone have a suggestion for a good do-it-yourself tolerant yard in the Ft. Myers - Sarasota vicinity whwew I can haul and fit a new rudder? Or a cheap place to leave Itchen for a couple of weeks while we take care of things at home?

TIA, Scott

3

Thanks Marty, this is VERY helpful and reassuring. I’ve been staring at the head with a Yanmar service manual opened to the pages showing oil and water circulation passages and neither I nor the marina mechanics could for the life of us see how oil could get into the water side via a leaky head gasket. Location of coolant and oil passages and pressure differences just did not seem to add up. Water in the oil would be easier to explain, but the oil is water-free, thankfully.

I guess the pitting is potentially serious - we will have to have a close look at the pre-combustion chamber. Will this be obvious to an experienced Yanmar mechanic, or is it more subtle and a maybe ok, maybe not ok sort of situation? Or better yet, should it be obvious to a reasonabley knowledgable layman backyard & dockside mechanic who knows what to look for?

Sounds as though instead of just slapping it back on with a new gasket that checking and resurfacing the head face is indicated.

Thanks,

Scott
SV Itchen (BCC #73)

Shamrock Wrote:

Oil in coolant from blown head gasket is not
uncommon, with gasket failure, sometimes you get
oil in the coolant, other times you get coolant in
the oil, would rather have the former. Have the
cylinder head rebuilt, if the rebuilder doesn’t
have a problem with the level of corrosion in the
cylinder head don’t worry about it, heads are
expensive. Check precombustion chamber in head for
concentricity-these get washed out with use, worn
chambers will do more to adversely affect
operation than minor pitting. Make sure you take
your head to someone who specializes in diesel
rather than gas, the gas folks don’t have a clue.
Have head magnafluxed for cracks and surfaced as
necessary.

Marty Chin

BCC Forums
<bccforum&
#115;@samlmor
;se.com> wrote:
Author: Itchen
Username: Itchen
Subject: 3GM30F overheating, with lube oil in the
coolant.
Forum: BCC Forum
Link:

After three years without a problem our 3GM30F
began to overheat while mortorsailing on the third
day of a run down the coast from Cape Fear to Ft.
Pierce. No noticable loss of power or other
obvious symptoms other than;

  1. Slight loss of coolant, mabe 8 oz. with no sign
    of leakage.
  2. Lube oil in the freshwater coolant, a little at
    first, then more and more.

We shut down each time the alarm went off and did
not overheat the engine - no scorched paint, hot
smells or painful to the touch engine surfaces.

Once at Ft. Pierce we pulled the head and found
signs of a leaking head gasket around the center
#2 cylinder. And, steam cavitation pitting on the
head’s combustion chamber and exterior surface of
the injector! It appears that there has probably
been some head gasket leakage here for quite a
while - loss of compression may account for the
somewhat difficult starting when cold we have been
having?

Questions:

  1. How would oil be getting into the cooling
    system from this location? Or may we be faced with
    two unrelated problems-- a leaking head gasket,
    plus a leak of oil into the coolant from some
    other location?

  2. How much pitting on combustion chamber surfaces
    is tolerable before performance is affected?

  3. Now that the head is off, what other potential
    problems should we be looking for or preventative
    maintenance items taken care of before fitting the
    new gasket and putting her back together and
    hoping that the problems have been fixed?
    I cross-posted this to the yanmarhelp.com forum
    but don’t yet know how active it is.

Thanks for any suggestions,
Scott

PS. Apart from and despite the engine problem we
had a fine run offshore from Cape Fear to Ft.
Pierce, Four and a half days and four nights close
reaching with starry nnights and lots of dolphins
accompanying us from time to time. Wind veered the
last day and a half so we did some hard
motorsailing into headwinds and swell to make Ft.
Pierce before nightfall and with favorable tide in
the inlet.

After we get the engine back together we are
heading across Okeechobee to the Gulf Coast for a
while then to the Bahamas. Anyone have a
suggestion for a good do-it-yourself tolerant yard
in the Ft. Myers - Sarasota vicinity whwew I can
haul and fit a new rudder? Or a cheap place to
leave Itchen for a couple of weeks while we take
care of things at home?

TIA, Scott

4

Scott:

I re-read Marty’s post and he certainly knew what to check. His support of the BCC is priceless.

Rod

5

Yanmar recommends periodic head re-torque, most owners never do it, even if done, gaskets never last forever. See owners manual for your models recomended torque interval.

Essentially what you have is a compression leak into the water jacket when the engine is warm, combustion pressures are considerably higher than the 7-14 PSI of the cooling circuit, therefore oil draining down through the push rod galleries can be forced through the gasket to the cooling water, usually a high temp expansion leak.

Oil can also be drawn into a cylinder on the downward stroke of the piston before the inlet valve opens via the head gasket, oil tube o-ring, between head and block leaks, also happens when the inlet valve oil seal fails and valve guides are work.

Some times this happens and the cooling water never enters the oil, take luck where you can get it.

Cheers,

Marty Chin

BCC Forums bccforums@samlmorse.com wrote:
Author: Itchen
Username: Itchen
Subject: Re: [BCC Forum Post] Itchen: 3GM30F overheating, with lube oil in the coolant.
Forum: BCC Forum
Link: http://www.samlmorse.com/forum/read.php?5,4406,4408#msg-4408

Thanks Marty, this is VERY helpful and reassuring. I’ve been staring at the head with a Yanmar service manual opened to the pages showing oil and water circulation passages and neither I nor the marina mechanics could for the life of us see how oil could get into the water side via a leaky head gasket. Location of coolant and oil passages and pressure differences just did not seem to add up. Water in the oil would be easier to explain, but the oil is water-free, thankfully.

I guess the pitting is potentially serious - we will have to have a close look at the pre-combustion chamber. Will this be obvious to an experienced Yanmar mechanic, or is it more subtle and a maybe ok, maybe not ok sort of situation? Or better yet, should it be obvious to a reasonabley knowledgable layman backyard & dockside mechanic who knows what to look for?

Sounds as though instead of just slapping it back on with a new gasket that checking and resurfacing the head face is indicated.

Thanks,

Scott
SV Itchen (BCC #73)

Shamrock Wrote:

6

Rod, (and Marty - thanks!)
Agreed, no substitute for practical experience with the specific engine in question. The “oil in the water” with no obvious way for it to get there had eveyone here scratching their heads. For an additional insight into its source there is the possibility that it is not lube oil but instead, unburned fuel and soot from the malfunctioning cylinder getting into the coolant via the leaking head gasket. This was suggested by the local service manager, and just now, by the very responsive man who staffs the Yanmar help forum. I was unaware of that forum but found it while doing an internet search. I won’t quote it all here but those with Yanmar GM30F’s might be interested in checking out his site. I also posted some photos of the head & gasket damage there. The URL is <http://www.freeboards.net/index.php?mforum=yanmarhelp&showtopic=522&st=0&

This is slightly different from but still generally consistent with Marty’s analysis. I just saw Marty’s more recent post and yes, I think the advice to periodically retorque the head bolts is very good advice. We were pushing hard when the gasket failed but no harder than had been done many times in the past. But it certainly happened at an inconvenient time! Better to discover these things during periodic maintenance than offshore . . … It didn’t take all that long to pull the tappet cover and get to the head bolts and in fact two or thre of them were less tight than the others. Checking the torque could have been done from start to finish in less than an hour, including assembling the tools and cleaning up. Much faster & cheaper than pulling the head!

Marty, do you agree with the Yanmar helpdesk man that it would be wise to relap the valves before reassembling the engine? At this point I don’t plan to pull th pistons to check the rings - much to big a job and not cost/time effective under these circumstances, I think.

Regards, Scott

IDUNA Wrote:

Scott:

I re-read Marty’s post and he certainly knew what
to check. His support of the BCC is priceless.

Rod

7

It defys logic, but oil can finds it’s way into the cooling water as well, but more often than not it is exhaust gasses blowing past he head gasket forming a carbon sludge, yes it will feel oily. The oil slick on the water is probably from worn valve guides and valve seal.

Marty Chin

BCC Forums bccforums@samlmorse.com wrote:
Author: Itchen
Username: Itchen
Subject: Re: 3GM30F overheating, with lube oil in the coolant.
Forum: BCC Forum
Link: http://www.samlmorse.com/forum/read.php?5,4406,4411#msg-4411

Rod, (and Marty - thanks!)
Agreed, no substitute for practical experience with the specific engine in question. The “oil in the water” with no obvious way for it to get there had eveyone here scratching their heads. For an additional insight into its source there is the possibility that it is not lube oil but instead, unburned fuel and soot from the malfunctioning cylinder getting into the coolant via the leaking head gasket. This was suggested by the local service manager, and just now, by the very responsive man who staffs the Yanmar help forum. I was unaware of that forum but found it while doing an internet search. I won’t quote it all here but those with Yanmar GM30F’s might be interested in checking out his site. I also posted some photos of the head & gasket damage there. The URL is Scott:

8

Hi Scott,

Sorry about the engine trouble - I’m fighting with a single cylinder Yanmar in my old Hunter (hey, it’s a boat and I’m only 18!); looks like it’s time for a rebuild here. Hopefully all will be well and it won’t be a reoccurring problem for you though.

As for a tolerant, do-it-yourself yard on the west coast, there are two great ones up in Charlotte Harbor (mid-way between Sarasota and Fort Myers). They are both really in South Gulf Cove which is closer to Englewood than Pt. Charlotte.

 All American Covered Boat Storage

10450 Winborough Dr
Port Charlotte, FL 33981

(941) 697-9900

 Charlotte Harbor Boat Storage Incorporated

13101 Appleton Blvd
Port Charlotte, FL 33981

(941) 828-0216

I suggest Charlotte Harbor Boat Storage as they seem to handle more sailboats than All American. However, AABS is generally slightly less expensive and less crowded. I chose it for the lower amount of traffic; I was taking my topsides and bottom down to the glass in many areas and patching much of the gelcoat, then doing a barrier coat and all, so it seemed easier to work in that lot as there was a lower risk of someone coming up and saying “Hey! You got a bit of sanding dust on the gravel! I’m telling!!!” Again though, I stress that the guys at CHBS seem generally more knowledgeable about sailboat handling; that was a non-issue for me and my $2k restore-or-sink Hunter.

If you decide to come to the area and need a lift or something, let me know. I’m going off to do a study abroad program on Feb 3rd (SEA, Sea Education Association) but my folks are about ten minutes from the yards (which are right next to one another) and would probably be more than willing to give you a ride to the airport, a hardware store or whatever.

Good luck with the diesel!

Aaron Norlund

9

Aaron,
Thanks for the boatyard info (I’ll check them out) and the offer of transportation help. We’ll probably spend some time cruising around the Pine Island Sound/Charlotte Harbor/Venice-Sarasota area before or after doing the boatyard work. Arrival time there is unkown but most likely after you leave for The Sea Association study abroad - when do you get back? We hope to have the engine back together Monday or Tuesday and then will head for Ft. Myers. What’s the problem with your Yanmar?

Regards,
Scott

10

Scott,

Great question about the Yanmar. In short, we’re not completely sure. Wayne over at Certified Diesel thinks that oil is seeping past the piston rings into the crank case and slowly thinning it out. The effect is an engine that, quite randomly, glow plugs. Sometime we can run it for an hour straight near the top of its RPMs range and it’ll be fine, while other times it’ll “wig out” after two minutes of running at 1500 RPMs.

That is why I say Wayne “thinks”; his theory makes sense, but it’s counteracted by the intermittence of the problem. It looks like we’ll have to get it pulled and torn down for the culprit to be pinned. Till then, I make it a point to run it just long enough to get out into the harbor from in by Millers Marine (or whatever it’s called today).

I’ll be back for about four days in March (~18th-23rd), then I have to get down to the Keys to board the ship for the sea portion of the program. Six weeks on board - down, around Granada and back up to the Keys.

Have you visited this area before?

Cheers!
Aaron N.

11

Is your engine making oil, oil level rising, or in some cased oil level lowering more rapidly than normal?

If you start out with a fresh oil change, recheck your oil level after an hours run time if you notice your oil level has increased, no water in the oil; a common problem with Yanmar is a perforated diaphram in the fuel lift pump. The lift pump cam lever axle is staked into the body, the axle slips to one side and the cam lever twists and ruptures the diaphram; on one side of the diaphram is the inlet and outlet valves, on the other side is the open air cavity in which the cam lever leads to the cam shaft which operates the pump. A rupture of the diaphram, even a pin hole from a rupture or normal wear, will allow fuel to be pumped into the engine block, which causes an increase in the oil level.

Initially the fuel will gradually thin the oil, oil consumption will increase, crankcase oil volume will increase; eventually the volume of fuel to oil will increase to where you have more fuel than oil in your crankcase.

Initially, thinned oil is not completely recovered by the piston oil control rings, oil consumption goes up, crankcase volume goes up; as the oil continues to thin, more fuel/oil escapes past the rings and is expelled out the exhaust, eventually there is very little oil lubricating the cylinders, mostly fuel. Which explains oil on the water and erratic and abnormaly high RPMS.

Advanced cases result in runaway, engine RPMS go to MAX or beyond, advanced cased are termed a cook-off, the engine gets so hot it begins to glow…RUN!!!

Read a case in Austraia where mechanics were attempting to trouble shoot a runaway problem on a new BUKH, started the BUKH but could not stop it; they cut the fuel lines and it continued to run, the RPMS went beyond maximum, all they could do was hide and wait to see what would happen next. Forget about stuffing a rag over the intake, they were afraid it was going to shatter into a million pieces any second. The engine eventually cooked off all it’s paint, glowed a cherry red, then siezed with a bang, must have ran out of fuel/oil to burn. Yet another exciting day at the boat yard.

Cheers,

Marty Chin

BCC Forums bccforums@samlmorse.com wrote:
Author: honkinsailor
Username: honkinsailor
Subject: Diesel in the crank case?
Forum: BCC Forum
Link: http://www.samlmorse.com/forum/read.php?5,4406,4417#msg-4417

Scott,

Great question about the Yanmar. In short, we’re not completely sure. Wayne over at Certified Diesel thinks that oil is seeping past the piston rings into the crank case and slowly thinning it out. The effect is an engine that, quite randomly, glow plugs. Sometime we can run it for an hour straight near the top of its RPMs range and it’ll be fine, while other times it’ll “wig out” after two minutes of running at 1500 RPMs.

That is why I say Wayne “thinks”; his theory makes sense, but it’s counteracted by the intermittence of the problem. It looks like we’ll have to get it pulled and torn down for the culprit to be pinned. Till then, I make it a point to run it just long enough to get out into the harbor from in by Millers Marine (or whatever it’s called today).

I’ll be back for about four days in March (~18th-23rd), then I have to get down to the Keys to board the ship for the sea portion of the program. Six weeks on board - down, around Granada and back up to the Keys.

Have you visited this area before?

Cheers!
Aaron N.

12

Shamrock Wrote:

Is your engine making oil, oil level rising, or in
some cased oil level lowering more rapidly than
normal?

Yes, the oil level seems to be a little erratic now that you mention it. This is my first small diesel, so I wasn’t terribly sure how finicky I need to be about oil level. We’ve had a Volvo Penta 230 which seemed to vary by about a millimeter on the stick either way. We seem to have hit a happy median recently though - it doesn’t seem to have changed at all the last five or so times I’ve run the engine, though you must understand that I rarely run it for more than ten minutes; out into the harbor, back in through the bayou to the dock. After doing some research on Yanmarhelp.com, I realize that my running patterns could be part of my overall problem

A common problem with Yanmar is a
perforated diaphram in the fuel lift pump.
…
A rupture of the diaphram, even a pin
hole from a rupture or normal wear, will allow
fuel to be pumped into the engine block, which
causes an increase in the oil level.

When we first bought the boat and ran the engine, I changed the oil about every two hours at first because the engine had been sitting for a few years without being started. I was told to run the engine for a bit with fresh oil and Seafoam, then to change it and put fresh oil in with more Seafoam and let it run. Well, it turned into having to change it about six times as we were mysteriously getting diesel in the case. However, on the last oil change (which was done mid-trip after a glow plugging incident between Ft. Myers and Boca Grande, FL) we didn’t seem to get any more diesel in the oil. We had planned on having to change the oil again before making it to drydock, but after checking it every half an hour or so for more then five hours, we didn’t find anything out of place.

Have you ever heard of diesel getting into the oil of a dirty engine that has been sitting, but then stopping after it had been run for a while?

Initially the fuel will gradually thin the oil,
oil consumption will increase, crankcase oil
volume will increase; eventually the volume of
fuel to oil will increase to where you have more
fuel than oil in your crankcase.

This is what initially happened, but it has ceased - no sign of diesel in the oil over the last fifteen or so hours of use.

Which explains oil on the water and erratic and abnormaly high RPMS.

What about soot on the transom? I seem to get a fairly high amount of black muck around the exhaust pipe, or it seems to be a lot to me. Like I said, I’ve never had a small diesel engine before this, so I’m still climbing the learning curve. The soot quantity seems to have decreased as we’ve run the engine. We have a new prop on the boat, but no RPM gauge by which to judge engine performance. It seems to run well, though I don’t trust it at all.

It’s a YS12 series engine.

Thanks for your help,
Aaron N.

13

Here’s an update on our 3GM30F problems and their esolution. After taking .005" off the warped head, and grinding and lapping the valves we put it back together yesterday, flushed the oily coolant residue out of the block and fired her up. Started in six seconds and ran smoothly and after givng plenty of time to warm up, ran with and without load for an hour, with no overheating problems. This morning repeated the above, this time checking engine temperatures with an infrared sensor and verifying RPR with a strobe device. Temperature was stable at all RPM’s and light and heavy loads – for the tachometer situation see my other post of a few minutes ago. Huge tachometer error was the big surprise.

Today we ran against a stiff headwind all afternoon down from Ft. Pierce to the St. Lucie River and had nary a problem. Started in 5 seconds this morning, much faster than anytime in the past couple of years. Diagnosis: Compression problems frpm leaky head gasket and maybe one exhaust valve and also a missing (!) copper seal washer between the two halves of the precombustion chamber on #1 cylinder! Engine ran pretty well all that time with all these problems, but certainly runs a lot better now. A tough little engine able to function pretty well even with those problems. Now I have my fingers crossed and hope that no more surprises await when we cross Okeechobee. Thanks to all for good advice.

Scott