Any guess about overheating problem?

[nzfisher]

Finally put the boat in at Newport OR. Tooled around the river to make sure systems normal after a winter of non use in a heated covered shop. At less than 8 knots every thing ok. Headed out to sea through the channel at about 11 knots, 5.7 gph, good oil pressure and got an engine overheat alarm. Thinking this was the same thing that happened last year when I took the boat out the first time when the problem cleared itself, I checked the oil-ok, checked the raw water strainer-ok, blew water out of the washdown and waited for the engine to cool down. Luckily, the wind was not blowing me back towards the rocks. At 200 degrees restarted, temp dropped down very quickly to 184 as hot water must have mixed with cold. Motored out at 3-4 knots to put more distance between shore, temp rose to 207 at low rmp with a steady climb. Stopped engine. Waited for the engine to cool to 185 before restarting, turned on the heater and this kept the heat down to around 190 for a very cautious 3-4 knot ride into the birth. Inside the harbor turned off the heater and brought the boat up to 3400 rmp just to check it out to see if I got lucky with a miracle fix. Temp shot up to 207 very quickly, turned on heater dropped almost immediately to 194. These are the clues, any theorys?

 

[kaiserwe]

Just a few obvious ideas. Is coolant level OK? Have you run water from a hose into the sea strainer and verified significant water is being pulled by impeller/sea water pump? Is the belt tight? Is there any play in the coolant pump pulley? Is the heat exchanger clogged? (Run saltaway/vinegar thru intake?) Is the oil pressure running low? BTW what engine is in your boat?

 

[joempo]

We have a 110 HP Yanmar in our R-25. We also had an intermittent overheating issue - high temp and alarms at high RPMS, followed by lower temps at lower RPMS. I found we were losing coolant, but could not find the source. I eventually borrowed a coolant system pressure tester. Long story short, I discovered a leaking hose connection at the rear of the water heater.
There have been several discussions on this forum. I suggest you conduct a search for "overheating" to learn what others have done.

 

[linedoctor]

I just solved with what I suspect is the same problem...please see the thread.

viewtopic.php?f=5&t=3486

 

[nzfisher]

I neglected a few details in my first overheating post in the fog of disappointment of having more problems with my boat which has been far from trouble free. It is an r25sc with yanmar 150. It has 193 hours on it. The overheat was an exciting 139 before I noticed and shut it off. This was after closely monitering everything for 40 minutes in checking things out. The engine temp rose very fast after the speed was increased to around 11-12 knots. After cool down checked coolant level (full), oil level (full new approved synthetic oil same as previous), water flow through the strainer with the top removed (good), pressure through the wash down (good), signs of fluid in the bilge (none beyond normal water). The fact that turning the heater on brought down the temp leads me to believe I have a clogged something running through something else and using the heater bypasses this clog. Anybody out there have a better guess as a means of attacking the problem? I have checked the site with an engine overheat search and did not find anything particularily germane to my situation but maybe I am missing something. I would prefer not to pull the impeller until I get more definitive information as the engine does cool down by running the heater. I stored the raw water system drained but after flush with non salt water. It was run prior to putting it in water with hose fed fresh water to about 130 degrees for oil change. It took quite a while to bring to 130 so everything seemed ok to launch in salt.

What is a reasonable course of action here from people with more diesel boat experience?

Thanks to those who have already tried to help.
In a conundrum.

 

[South lake]

I'm definitely not an expert but it sounds exactly like what happened with our 4BY2-150 last summer when the impeller went kaput. We were taking the boat out of the harbor into Lake Erie. All of a sudden there were alarms going off to tell me the engine was overheated. We ran it back to the marina and the next day the impeller was changed. The boat only had about 50 hours on it. The mechanic recommended replacing the impeller every 2 years.

Why it went bad after only 50 hours? I don't know. We bought the boat new in January of 2012 and it was a 2010 model that had probably been at the dealers for a year before we got it. Maybe that time had something to do with it.

 

[K7MXE]

I got about 62 hours out of mine. It was past the 50 hour service when I bought the boat six months old and the first service showed up a bad impeller. Did not overheat but was missing one fin. I check it yearly and have found just one fin gone twice now. My guess they are easily broken with normal use. I just put in the spare and order a new one.

 

[nzfisher]

I guess unless I hear some compelling new information I will be replacing the impeller in a sincerely non user friendly environment. I will make a stab at calling the distributer to see if I can get someone to talk to me. One thing I learned that should be in everyones log book (if they don't already know)- If your engine overheats, turn on the heater. This substantially dropped my engine temp almost immediately and enabled me to bring the boat in with normal operating temps, but a much reduced speed. Could be critical in dire circumstances and it should do no harm otherwise.

 

[baz]

Some thoughts...

1) I'm not 100% sure about this, but I think the cabin engine heater derives its heat from blowing air over a radiator that is fed from the engine's coolant system and not from the raw sea water. If so, this explains why the engine temp drops quickly as the cabin heater is very effective at removing heat from the engine's coolant liquid. When the cabin heater is not running the engine's coolant liquid has to be cooled only by the raw sea water heat exchanger which requires raw sea water to be pumped though it via the raw water impeller pump system. Thus, if just the raw water heater exchanger is the only means for cooling the engine and the engine temp rises this would mean that some portion of the raw seawater engine cooling system is failing to provide sufficient cooling.

2) My Yanmar 4BY2-150 Service manual states causes for "Engine Overheat Problem/Symptom"

-Clogged seawater inlet
-Low coolant level
-Clogged seawater filter (if equipped)
-Clogged hydraulic cooler
-Seawater pump worn or damaged
-Defective sensor / instrument
-Defective thermostat
-Damaged closed coolant pump
-Combustion gas leakage (causes loss of coolant)
-Seawater pump belt slips or pump pulley loose on pump shaft
-Clogged heat exchanger

3) Have you checked that sufficient water is being pushed out from the port side engine exhaust outlet at water level ? Does it seem normal to what you seen in the past ?

4) I would seriously advice that you inspect the raw water impeller system before venturing out again. If necessary have a qualified technician inspect and replace things.

5) Verify that the water impeller's pulley belt is not slipping and/or damaged in some way; did you get any oil on the belt when changing the oil maybe ? It could be the belt starts slipping at higher engine RPM.

6) I wonder if the thermostat is sticking after inactivity during storage ?

Let us know what you find out is causing this issue, and good luck.

 

[baz]

What really bothers me about this and particularly concerning the raw seawater impeller is that the Yanmar Maintenance Schedule calls for the impeller and impeller pulley belt to be checked every 250 engine hours or 1 year and replaced every 1000 hours or 4 years.

So why do people see/have premature problems with the impeller at times significantly less than what Yanmar states for it to be checked and/or replaced ?

This has been discussed at length in this forum and I cannot fathom out any reason why there's such a wide range in the failure reports.

I had my impeller and impeller pulley belt checked last September 17th when engine hours were at around 240 (it was the 250 hr maintenance service called by Yanmar) and they were both in good condition. Neither were replaced.

Replacing the impeller is a DIY job if you care to take the time and are careful. A second pair of hands presumably is also useful. One TugNut posted detailed instructions for the DIY people and I present them below for you...

I just changed my impeller on my R-27. It took me 1.5 hours with the help of another person. Below are the steps I took:

Tools
22 mm socket 3/8 drive
6 mm hex male 3/8 drive
3” extension
3/8 drive ratchet
Long needle nose plier
¼ inch drift pin or Phillips screwdriver of same diameter
Paper towel

• Shut seacock valve
• Turn off engine switch
• Disconnect engine positive wire
• Remove interior panel that has 110 and 12 V outlet. This makes sliding and removing slide panel easier and allows for better vision from side into engine
• Remove Impeller pulley belt – From cockpit side have one person push on belt at bottom of impeller pulley. Have 2nd person in cockpit on port. Reach into crankshaft pulley with 22mm socket, extension and ratchet. Turn engine clockwise (as if you were looking aft) and belt will work off.
• The following work is from cockpit side. Having 2nd person looking from inside helps a bit
• Turn impeller pulley so that pulley slots allow access to hex bolts
• Put a piece of paper towel on male end of extension and force hex socket onto extension. This will prevent the socket from falling off.
• Feel your way to the hex bolt and insert drive into bolt and then attach ratchet. Just loosen bolt, do not remove.
• Do this same procedure for the three remaining bolts.
• Now put a piece of paper towel on the end of the hex drive and force that into the hex bolt. If you loosened your bolts enough you can screw them out with just the extension and no ratchet.
• Once all the bolts are out you can slide the pulley and housing out and the person inside can handle it through the step access.
• Get a good set of straight needle nose pliers and insert them with one end in shaft hole and one end between blades and yank. Once you have it out half way you can turn clockwise while pulling out and you should have it in hand.
• There is a small O-ring type washer on the motor side housing. Mine looked good so I did not replace it.
• Insert new impeller by working it in turning it clockwise and inward pressure. Once started push it in.
• Now insert pulley and shaft assembly. Line up holes using the drift pin in one of the holes.
• Do the paper towel trick, using only the extension and screw in like you would a screwdriver and be careful not to cross thread the bolts. First turn counterclockwise then clockwise so as to be sure you are not cross threading and hand tighten. Do this for the remaining bolts.
• Now remove the paper towel piece in between the 6mm drive and the bolt and now tighten all the bolts using the ratchet.
• Now with the help of the 2nd person. Place the belt around the drive pulley and start it on the impeller pulley at the bottom
• Go back to your removal positions and turn the engine clockwise while the impeller person works the belt on.
• Visually inspect from the inside to be sure belt is on both pulleys appropriately.
• Reconnect engine power cable, turn on engine battery switch and open the seacock.
• Check for any leaks.
• Start engine, check that water is discharging, and look for leaks.
• Hi five and have a beer.

 

[nzfisher]

Baz,

Thanks so much for your very thorough and detailed reply. Of course upon thinking about it the internal cabin heater is heated from the engine coolant not the raw water. This should have been especially obvious to me since this hose were the coolant forks off to the heater, failed.

Your very complete description of removal and replacement should be a great help in the process I will undertake tomarrow. My local Yanmar mechanic is not interested in working on recreational boats, tried to have him replace the other "recall" issue on the engine, (the oil pipe) and it was immediate apparent I should not let this guy work on my boat. Since this looks like it is going to be a yearly replacement issue, do you think removing the stairs would make this easier? I have fair amount of expertise with wood so if it makes fixing the boat easier, more appealing and hence more likely to happen I would prefer to replace the stairs before the impeller.

Thanks again for your help. If we ever meet I owe you a bottle or case of whatever it is you drink.

 

[baz]

nzfisher: Those detailed instructions for replacing the raw water impeller are those of another TugNut forum member. I had tucked them away for future use and simply copy/pasted them into my response to you. I do hope you find what is causing your trouble and sorry to read about your local Yanmar technician being of no help to you... bummer that. 🙁

If the impeller is the problem and you undertake its replacement via the detailed instructions I posted then at least 1/2 the case you mention should go to the TugNut that posted them. Here's the link to the original Post (Title was R-27 Impeller change) that provided the detailed instructions. It was posted by Mike Rizzo (knotflying member).

http://www.tugnuts.com/viewtopic.php?f=5&t=3318&p=24333&hilit=five#p24333

 

[knotflying]

Baz,
Thanks for the credit. Nzfisher, if your impeller is missing vanes hopefully they are within the pump casing, if not you need to get them out of the heat exchanger if they are in there because they can clog up the water flow. It is possible that they may have passed through and aren't there. Hopefully they are in the pump chamber.

Good Luck!!

 

[trailertrawlerkismet]

nzfisher and Barry:

nzfisher please report back if changing your impeller solved your problem. Barry you asked why an impeller may fail prematurely as compared to Yanmars recommended change cycle, which is a fair question. As you and others know an impellers premature failure has to do with a lack of water lubricant. As an example if a plastic bag gets sucked up against the water intake on the hull of a boat, this prevents water intake and therefore the impeller looses its natural lubricant and weakens or fails. This could happen at any time. So lets say someone changes their impeller and goes out for a cruise two days later and while motoring out of the harbor sucks up a piece of plastic....their impeller could fail even thou it may have been just changed or the same thing could happen and the plastic might get knocked off in a matter of a minute or less, the impeller compromised but still works then it fails three months later and we wonder why. Another example is sand. If one cruises in shallow water they could suck up sand, the sand works as an abrasive compound, restricts lubricant and could cause failure.....the longer someone cruises in shallow water the sooner a failure could happen.

A clogged sea strainer restricts water as well and for that reason I clean mine out at least weekly when we're cruising and try to check it every day or two.

A good samaritan practice we apply is to pick floating plastic out of the water when we see it (ice bags and grocery shopping bags are big culprits) for the simple reason it could be our boat it gets sucked up onto.

Jim

 

[baz]

Jim: Thanks for that explanation of why the impeller can fail prematurely. It sure makes sense and is akin to why auto air filters need changing more frequently if the auto is driven in dusty conditions such as along logging trails or in windy coastal areas where sand can be present in the air.

I wonder if our Yanmar 4BY2-150/180 engines or its pre-ignition system primes the raw seawater piping and impeller housing with water before the engine is cranked ? That would avoid the impeller from being starved of water during its initial operation. I believe this aspect has been discussed before. If the boat has been in dry dock such as during a winter storage this seemingly would mean the impeller has been 'high and dry' for maybe several months. Starting the engine when boat is returned to water presumably means the impeller will initially start rotating before seawater has had a chance to lubricate it. This then will place undue loads on the dried out impeller vanes leading to premature failure. How can this condition be avoided ?

My understanding from my Yanmar technician is when you turn the engine ignition key to the ON position and wait until the siren alarm stops that during this 'siren' sounding period some form of engine system priming is being done such as the fuel pump stirring into action to prime the fuel system. In fact, if you listen carefully you can hear the fuel pump whine as it spins up to pressurize the fuel system. I also believe a series of other pre-ignition engine tests are performed to ensure it's safe to start the engine -- not sure what all these are mind you.

In nzfisher's case I wonder if there are engine diagnostic codes that might reveal the root cause or provide clues as to what his engine cooling problem is ?

Does anyone know how to get the engine diagnostic codes to display, say on the Yanmar engine display ? (Andrew or Kenny might know ?????? )

 

[nzfisher]

I suppose there could be something to this. However, whenever I run the boat out of the water, I run a hose to the raw water strainer sump and adjust the pressure so that the sump stays full prior to and while the engine is running. Unless there is an air pocket in the system (which would be hard not to consider as a design flaw), the raw water system never is run without water.

In one of Baz's responses I think he mentioned a raw water filter, I think in a quote from the manual. I am not aware of a raw water filter other than the strainer. Am I missing some critical piece of the puzzle?

 

[baz]

nzfisher: I don't believe our Yanmar engine systems employs a seawater filter. The manual qualifies this with "if equipped". All we have is the seawater strainer -- the globe-like contraption with the see-through screw down plastic covering.

 

[Kenny Marrs]

Baz: you need an OBD II tester to read the codes.

Jim: thanks for the help explaining why an impeller can fail prematurely.

nzfisher: please email me direct if you have any further questions kennymarrrs@rangertugs.com. emails will go to my phone, however i don't get tugnut post alerts. Please let me know if the impeller change fixes the issue.

Thanks,
-Kenny

 

[baz]

Kenny:

So I do have an OBD II device that I use to extract codes from my Volvo XC70 T6 auto engine.

The Yanmar Operational Manual for 4BY & 6BY engines states

Diagnostic Trouble Codes
When certain faults occur, or when certain limits have been exceeded, the engine ECU may generate a "Check Engine" warning or turn on a check engine light (if equipped). Some of these faults may also generate a DTC or Diagnostic Trouble Code and an audible alarm. If a DTC is generated, the engine ECU will store that code or codes for reference. To read the DTC codes, a special tool is used by the technician. The technician then can use a list to more quickly find the cause of the fault and correct it.

Some conditions will produce an alarm but do not generate a trouble code. An example is engine overheat (over 108ºC, 226.40ºF) -- 'I provided the ºF conversion') caused by an obstructed seawater inlet. The overheat alarm will sound and the engine torque will be reduced to protect the engine, but no code will be set.

Under some conditions, the warning alarm will sound until the fault code is checked and corrected. Under other conditions, the alarm will be canceled if the engine is turned off and then restarted.

The DTC codes range from P0001 to P2617 and U0001 & U0426 in a following table.

Can the OBD II extract these P and U codes ?

I'm curious... Where does the OBD II cable connect to on the engine as a search on all my Yanmar engine manuals for "OBD" shows NULL ?

 

[baz]

Baz: you need an OBD II tester to read the codes.

Jim: thanks for the help explaining why an impeller can fail prematurely.

nzfisher: please email me direct if you have any further questions kennymarrrs@rangertugs.com. emails will go to my phone, however i don't get tugnut post alerts. Please let me know if the impeller change fixes the issue.

Thanks,
-Kenny

N.B. One too many "r"s in Kenny's Email addr. :roll: