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BF150 Overheating Continues

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PaulBF150

Contributing Member
Assume everything known to man was done.
The past season engine still overheats, but did find later in season when water temperature dropped 10 degrees engine would not shut down at high RPMs (as it did when water temperatures were higher).
So considering placing water scoops facing forward over water inlet on engine. To force more water into pump/engine.

Seeking opinions on that.

Had already installed electric water pump onto exhaust manifold, bringing cool water into exhaust. It had some improvement, but still have engine shut down.

A real far-fetched thought would be water chiller. Just haven't figure out how yet. Another thought was to close off the water flow in engine and use antifreeze with some sort of radiator. Incorporating a fan is still in the thought mode.
 
Hi Paul,
sorry you're still having problems there.

Well,
You obviously like the engine and how it runs to be willing to go to those lengths. Not to mention all that you've already done.
But, if it were mine, I would be looking for a way to just get it cleaned out instead of doing a bunch of "re-engineering".

If it were all cast iron you could just disassemble and put it all in a."hot tank" to dissolve the minerals that are coating the cooling passages. But, with aluminum, I don't think that would work well.

I would definitely consult with a high end machining/engine rebuild center to see what is reasonable to do other than just swapping out block, head and exhaust manifold. There might be some new "magic" methods available. I don't know but maybe worth a conversation anyway.

Just my 22 cents...(Bidenomics)

Good luck.
 
jgmo, Thanks for the 2 cents worth!

Thing is I believe I have ample water flow throughout the motor. I have had it apart 3 times now and everything I check water flow through the "accessible ports". The first time apart did find a bunch of corrosion and junk in around cylinder jugs and in the head. In the other 2 times apart there were little deposits were present.

Maybe I should look into head gasket design. Honda uses the gasket as means to restrict water passage. If I remember correctly there was only 2 holes in the gasket aligning with 2 of the head water ports around the cylinder area. All the other passenges somethig like

What throws me for a loop is the recent findings, that is engine ran well up on plane when water temperature the boat was running on was at least 10 degrees cooler. This making me think there isn't a blockage or restriction in cooling system.
 
Well, it was $0.22 actually. Adjusted for bidenflation.

Your comment about enlarging the head gasket holes sort of makes my point in this discussion.

Honda wanted those holes a specific size to SLOW the water down. This is because water rushing past a hot surface won't have time to absorb and then carry away the heat from that metal.

Forcing the coolant to "linger" in specific areas will actually aid in heat transfer.
Enlarging the head gasket holes would be a mistake IMO.

I think that poor heat transfer is at least part the problem here.

These "raw water" cooling systems suffer from the "plating out" of minerals (specifically calcium and magnesium) onto the metal surfaces. This "coating" effect drastically interferes with heat transfer in the system. I can't recall the exact numbers but a very thin mineral coating, say 1/32", in a coolant passage could inhibit the transfer of heat near the same as a solid plate of 3/8" steel. Actually I think it's closer to 1/2" plate but I can't find the example at the moment.

Some waters are worse than others as it has to do with the amount of these "total dissolved solids" that the water you operate in contains.
Add salt to the equation and heat transfer goes down even more.

That's why I suggested finding an effective method of cleaning the deposits from inside the passages.

I don't recall if you've already tried the test tank vinegar flush yet but, if not, you might want to consider it.
 
I did have the thought about heat transfer (why I was thinking antifreeze). So, it makes more sense that my issue is not water flow but heat transfer.
I understand the point of establishing a dwell time so water can absorb the heat, but I also thinking more water passing thru engine will carry that heat out as well, thus thinking more water!

I been flushing the engine each year with a solvent for that purpose and having low end removed recirculate the solution in a 55 gallon drum with sump pump (24/7). Stuff does come out in the wash. However, each year engines still overheat despite the flushing, no golden goose!

This part stumps me, I have a twin 150 with same hours on it with no overheating and haven't opened it up to inspect. That handles pushing the boat when the other engine alarms and need cooling down.

Today tested and recorded 3 of the 4 sensors (the computer app supports 3 sensors only Engine Head, Case and Exhaust). I wanted to retest trip points on each sensor. Faking computer with a resistor box. it reports an alarm at about 160 degrees F, with subsequent shutdown. However, case temp can be well over 200 degrees F and does not trigger the alarm. The Block is not monitored in the program but the resistance of about 400 ohms that causes the head to trigger is the same for the block, so temp likely the same. Not sure why honda set it for that.

Data collected today is going into the "thinking mill" so that I can make heads or tails with it.
 
Well, I agree....160°f seems WAY low for an overheat sensor. Especially on a fuel injected engine.
What temperature are your t-stat set points?
Have you measured the resistance on a new one?

Sorry, no answer. Just a couple of thoughts.
 
Paul, what did you use for the flushing process? I’ve used vinegar in very high concentrations but I know there are other good products.

I have a 1999 130 hp which is a 2354cc car block 4 cylinder used in the accord, crv, etc. In the cars, it’s called the 2.4 and I have a 2013 CRV with a 2.4. The CRV has had problems with a clogged heater core and Honda issued a TSB for flushing the core with CLR, they even supplied a pump, hose, filter, and bucket setup and a mix of CLR to tap water for a 1.5 hour flush. I’ve wondered if the CLR flush would work in an outboard to remove salt and mineral deposits?
 
Jgmo
The figure of 160 is measured by Honda Marine Diagnostic S/W test device. Cylinder Head T-Stat is set for 50C and Cylinder Block is 60C.
The sensors run about 1.8k ohms (engine off). then drops the hotter it gets.
++++++++++++++++++++++++
NSDON,
I'm using CRC Salt & Corrosion Terminator. But at this point can also try Calcium, Lime & Rust Remover (CLR).

At this point investigating what is available to "polish" internal parts. Likely wishful thinking.
 
Does this motor have a poppet valve in the cooling system? If it's like a Mercury OB, it may. Connect a blow gun to an air line from your compressor and blow into the port for the water stream at the back of the motor shroud- if you hear a click, it was stuck.
 
jimn
Yes, it does, and I have had it apart several times, plus replaced it once. Also disabled it totally to prevent any water from going back to the sea! Thought was here if I had a blockage or restrictions higher pressure may clear things. Presently I have it closed off and putting my own valve on the dump hose so I can regulate amount of dump water when engine is at the higher RPMs.
++++++++++++++++++
NSDON,
Will give it a try. Won't know if effective until next spring though.
Thanks Paul
 
PaulBF150 said:
jimn
Yes, it does, and I have had it apart several times, plus replaced it once. Also disabled it totally to prevent any water from going back to the sea! Thought was here if I had a blockage or restrictions higher pressure may clear things. Presently I have it closed off and putting my own valve on the dump hose so I can regulate amount of dump water when engine is at the higher RPMs.
++++++++++++++++++
NSDON,
Will give it a try. Won't know if effective until next spring though.
Thanks Paul
Click to expand...
It should cool as it came from the factory- how would you monitor the water flow and how would you control it in normal use?

What do you mean by "disabled it to prevent any water from going back into the sea"? The cooling water came from the body of water that you're on- why would you want to contain it in the motor indefinitely? Even if it had a heat exchanger, water would need to enter and leave the system.
 
From what I have determined the Pressure Relief/Poppet valve opens and bleeds off excessive water into the exhaust pipe. This happening at higher RPMs. Closing it off entirely.

Meanwhile water entering cooling system branches off to fee water to block and block has 2 holes that enable water passing into the head and regulated by 2 small holes in head gasket. As engine heats up the thermostats on top of engine Head and Block open dumping hot water into exhaust pipe. Even when the thermostats are closed there are little channels in the valve that allow some water to flow through. Also water that enters the engine heads over to the exhaust manifold traveling up and around exhaust ports. That water is routed out of the engine by small tubes at top of the exhaust manifold. Bottom line water is continuously moving through the engine.

What I am doing is to increase water flow. I also integrated and Oil heat exchanger connected at oil filter to external cooling radiator that sits in the water. Also introduced another water source via another water pump to inject cool water into exhaust manifold inspection ports. (That was when I thought the overheating was in the exhaust manifold). Also routed all water outlet hoses directly out of engine rather than dumping into exhaust pipe. Each of these things improve cooling but the Golden Goose!
 
PaulBF150 said:
From what I have determined the Pressure Relief/Poppet valve opens and bleeds off excessive water into the exhaust pipe. This happening at higher RPMs. Closing it off entirely.

Meanwhile water entering cooling system branches off to fee water to block and block has 2 holes that enable water passing into the head and regulated by 2 small holes in head gasket. As engine heats up the thermostats on top of engine Head and Block open dumping hot water into exhaust pipe. Even when the thermostats are closed there are little channels in the valve that allow some water to flow through. Also water that enters the engine heads over to the exhaust manifold traveling up and around exhaust ports. That water is routed out of the engine by small tubes at top of the exhaust manifold. Bottom line water is continuously moving through the engine.

What I am doing is to increase water flow. I also integrated and Oil heat exchanger connected at oil filter to external cooling radiator that sits in the water. Also introduced another water source via another water pump to inject cool water into exhaust manifold inspection ports. (That was when I thought the overheating was in the exhaust manifold). Also routed all water outlet hoses directly out of engine rather than dumping into exhaust pipe. Each of these things improve cooling but the Golden Goose!
Click to expand...
How are you using this, racing?

What is the un-cooled exhaust doing to the exhaust path?
 
Surely not racing it can nearly get my Grady white up on plane before I get alarms.

Not sure I understand. Exhaust gases exit from valves through exhaust manifold into exhaust pipe. Meanwhile the Exhaust manifold circulates cool water up through it and out the top of it is the heated water. Out a hose back into exhaust pipe ( prevents hot water spray out of the engine in the air.
 
PaulBF150 said:
Surely not racing it can nearly get my Grady white up on plane before I get alarms.

Not sure I understand. Exhaust gases exit from valves through exhaust manifold into exhaust pipe. Meanwhile the Exhaust manifold circulates cool water up through it and out the top of it is the heated water. Out a hose back into exhaust pipe ( prevents hot water spray out of the engine in the air.
Click to expand...
Which model of boat, how much does it weigh and how old is the motor? If the motor is sized appropriately, it shouldn't overheat.
 
jimn said:
Which model of boat, how much does it weigh and how old is the motor? If the motor is sized appropriately, it shouldn't overheat.
Click to expand...
It is a Grady White Sailfish 1990. It was equipped with two honda 150's and worked good for several years
These were new 2010 although I purchased boat in 2012. Only one of them overheat.
 
PaulBF150 said:
It is a Grady White Sailfish 1990. It was equipped with two honda 150's and worked good for several years
These were new 2010 although I purchased boat in 2012. Only one of them overheat.
Click to expand...
And you want to modify it, even though the other doesn't overheat.....do you have a service manual?

I saw a resistance number for the the thermostat- did you test it out of the motor, to see if it opens at the correct temperature?
 
Yes I do have the service manual.
No I haven't tested the thermostats. I replaced them at least twice. They are definitely working on motor since I have clear hose on their output and can see the result when they open.
I'm going to check good engine values and tripping points ( temp when ecm triggers the alarm). Going to also put thermocouples in output hoses on overheating engine to get Real output water temps.
As stated above if thermostat opens at 140F and ECM alarms at 160F (per Dr H) just does give much margin. Think jgmo indicated top temp should be around 200F.
 
Bottom-line

Tested both engines with Dr H and Thermocouples in exhaust water output and water output from combined Cylinder Head/Block. In around 155F reading from thermocouple and Dr H reports 158F

Engine alarms and subsequently shuts down. So, both engines computers are responding the same just that Starboard engine gets to 160F faster than the Port Engine.

So, I guess I could try faking engine say 10F such that it may extend shutdown point but increases overall head temp.
 
Paul, I am amazed at your persistence and appreciate your personal commitment to fixing this. Has noted elsewhere I think I have a very similar problem to what you have, and everything I have done so far has not eliminated the motor going into Guardian mode.
I think in your results you mentioned that you use a resistor box Network to simulate resistive values for each sensor, and you are able to trigger Guardian mode for each of the four sensors.. is that correct?

I don't have access to a variable resistor box but I I'm planning on trying the following method to determine exactly which sensor is triggering Guardian mode and at what temperature.. knowing what sensor is consistently causing this problem will help me Focus on that particular part of the engine.

I need a fifth known good temperature sensor to do the testing. Then, for each of the four sensors, one at a time, I first disconnect the sensor plastic connector and connect to my 5th sensor and put it in a small safe glass jar that has maybe an inch of warm water in it along with a meat thermometer that will show me what the actual water temperature is. I keep adding additional hot water.. probably close to 200° Fahrenheit.. and watch the meat thermometer increase in temperature until the engine goes into limp mode. I record the temperature on the meat thermometer and remove the sensor from the hot water and let it cool somewhat hopefully to terminate the guardian mode. If it stays in Guardian mode when I cool that sensor it may mean that a different sensor caused this. I'll probably repeat the test one more time and then move on to another sensor. Sooner or later I will hit the sensor of the original four that is at fault for triggering the guardian mode. I'll know this because when I cool off the 5th sensor, which is plugged into the cabling for the 'guilty 'sensor the guardian mode will go away , or should anyway.
If I run these tests on a cold engine I should be able to trigger Guardian mode on each of the for sensor positions because I am heating up One sensor at a time.. the 5th sensor.. until it triggers Guardian mode. At a minimum this procedure will tell me at what temperature each of the sensors triggers Guardian mode. And if I run the procedures with a hot engine it should tell me which sensor is the guilty party because that sensor will not be hooked up and the guardian mode will be under the control of the 5th sensor.
 
Paul, did you say that you shut off the relief valve? If so did that have any notable effect? as it should increase water flow through the engine since the valve will not be dumping water into the exhaust.

I have not had my head off to clean internal passages but a few months ago I did remove the lower unit and pumped vinegar water up the water tube for an hour or more. However I still got Guardian mode. I will probably repeat that flushing exercise and make sure to remove the two thermostats so that water will flow easily. Further, I plan to hook up a one horsepower pump to force the water up the water pipe and hopefully create enough turbulence in the head and block to dissolve much of the scale that is probably there. I'll report on that when I do it.
It's killing me that Dungeness crab season is open here in central California and the commercial crab season has been postponed until the whales leave and I can't get my boat in the water to get the easy crab limits:-(
 
Through the two thermostat holes you can see some distance down into the head and block. It's occurred to me that I may be able to get a thin pressure washer tube running at 2000 PSI down in there to do whatever scrubbing is possible. Can anybody suggest why that may not be a good idea? I might also be able to get a narrow video tube down in those two holes and perhaps some other holes that will enable me to see what the corrosion looks like.
 
PaulBF150 said:
jimn
Yes, it does, and I have had it apart several times, plus replaced it once. Also disabled it totally to prevent any water from going back to the sea! Thought was here if I had a blockage or restrictions higher pressure may clear things. Presently I have it closed off and putting my own valve on the dump hose so I can regulate amount of dump water when engine is at the higher RPMs.
++++++++++++++++++
NSDON,
Will give it a try. Won't know if effective until next spring though.
Thanks Paul
Click to expand...
So Paul, you have disabled the relief valve/poppet valve. Have you run the boat since then to see if that has any Improvement associated with it? Did you keep the spring from compressing or turn it upside down to disable it?

Thanks, wheeler Paul
 
iang6766 said:
That is a good idea, yes, can't do any harm
Click to expand...
Thanks Ian. Since I would be blowing debris backwards through the system is there any issue with the openings of the water channels being too small to accommodate the size of debris that might come from a high pressure spray?
 
Sorry for not responding sooner.
As for Pressure relief valve basically took spring portion off and sandwiched 2 washers with a pop rivet. Kept the rubber portion to maintain a seal.
I did see a little improvement, not enough to write home about!
As for forcing water into thermostat holes. The Head hole access the water jacket around the piston cylinder tops. thing is the head gasket has 2 small holes to meter water flowing from the Block to the head. In my case when I had the head off, corrosion was throughout the water jacket in the head. Also, in the block around Cylinder 3 & 4 was a buildup. Two holes at bottom of block near cylinder 4 jug gets water from main water input (somehow). So, water builds up around the cylinder jugs and then routed thru those 2 holes in gasket for the head. Block also routes water at top of it to the block thermostat. Likely forcing water from top and bottom would be best for the block. As for the head water going in from top basically has nowhere to go, just those 2 holes in head gasket.

As for Dungeness crab, did not know they were down to central California. I caught some in Oregon waters.
 
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