Honda BF150 Overheating

[PaulBF150]

Seeking advice regarding subject problem.
Thus far; new water pump, new thermostats (2), new Temp Sensors (4), new pressure relief valve, cleaned internal cylinder block and heads of corrosion.
All resulting with same issue, under load especially attempting to get onto plane throws temp light and alarm and subsequently shuts off motor.
Boat 25ft Grady white with twin BF150's. Age 12 years with 1000hrs. Second engine still running good.
Also tried numerous solutions with water flow and routing. Can discuss further if asked.

Paul

 

[MattFL]

When you say cleaned the block and heads of corrosion, what method was used to clean them and how much did you get out?

 

[PaulBF150]

I had to remove the engine head from the engine block. The Head was cleaned with solvent and compressed air. The cylinder jugs I cleaned with brass brushes. I would say at least a cup full of corrosion. Some port on head were clogged. And as I mentioned around cylinders 3 and 4 were much loose corrosion.

 

[PaulBF150]

Here is the full version of my problem and what was doen to date....

I have read through many of the threads on this topic and concluded they are similar but not hitting the target. So, writing this new thread.



History: Boat is 25ft Grady White with Twin BF150’s. They have about 1,000 hrs and all been in Chesapeake Bay, Maryland (brackish water)

Purchased nearly new (2010). Both engines running like a champ, although more Hp would be nice.

Started to experience the Overheating issue 2 years ago. While getting up to plane with both engines this one triggers the Temp Alarm and engine is shuts down. By chance I do get up on plane I have to throttle back the faulty engine 1,000 RPMs or so, thus keeping engine temps lower.

Over the course of those years have replaced: Water pump, Thermostats [(2) Cylinder and Head), the (4) Temp sensors [cylinder, block, exhaust, and case], pressure relief valve. Past winter opened head and cleaned but cylinder jugs and head of corrosion that settled down around cylinders 3 & 4. Replaced spark plugs as well. Good compression on cylinders (150psi).

Seen thread on Water tube grommet in oil pan, did not replace and don’t believe it is a problem since there is no water in the oil.

Also seen thread on Oxygen Sensor and I have to looking into that a bit more. Any advice would be appreciated. Also check OBD with jumper and count flashes! However, engine runs pretty well and seems happy and MIL light has not illuminated.

So, my thinking thus far is a cooling issue since I instrumented the (4) Temp Sensors and the Cylinder and Block sensors approach 200 degrees. I played with configurations of the thermostats swapping 60C with 50C, also no thermostats with water relief hose pinched a bit but Case temps increases. However, Cylinder, Block and Exhaust are relatively low. But still not the solution.

Injected additional water via wash-down hose port, helps but not the solution.

Now planning to try shutting off Pressure Relief valve so no water is return to the sea!

Anyone have an Idea what next to try to fix this puppy?

If the engine is running hot due to fuel mixture, I have no idea how I would adjust that... Recommendations?

 

[MattFL]

Just thinking out loud, I wonder if some important passage was missed during the manual cleaning? Since you're approaching the point of nothing to lose, have you tried flushing the block with a decalcifier? There are a few on the market such as Rydlyme, Barnacle Buster, etc.. The long and short of it is acids do a fantastic job of dissolving calcium build up, such as salt and hard water deposits. The challenge is acids are also not good on metals such as Aluminum. So the challenge is making an acid that dissolves the bad stuff but doesn't hurt the metal in the motor. That part of the chemistry is beyond my knowledge, but several companies have products that claim to do this, such as the companies mentioned above. If it were my motor, I would flush the block with Rydlyme and see if that solves the problem. I've got a now 23yr old Honda 50 that was starting to show signs of build up so after much research I tried Rydlyme and got a bunch of junk out. Read about it on this forum here: https://forums.iboats.com/threads/descaling-flush-motor-that-stops-peeing.747060/ It was easy to do and I've been using the motor a ton since and so far no issues. What I learned doing research was milder things such as vinegar or CLR were essentially like spitting on a forest fire, technically you could say they might descale but not significantly enough for this situation. The stronger chemicals are required for any real result. Anyway I hope this helps.

 

[PaulBF150]

Just thinking out loud, I wonder if some important passage was missed during the manual cleaning? Since you're approaching the point of nothing to lose, have you tried flushing the block with a decalcifier? There are a few on the market such as Rydlyme, Barnacle Buster, etc.. The long and short of it is acids do a fantastic job of dissolving calcium build up, such as salt and hard water deposits. The challenge is acids are also not good on metals such as Aluminum. So the challenge is making an acid that dissolves the bad stuff but doesn't hurt the metal in the motor. That part of the chemistry is beyond my knowledge, but several companies have products that claim to do this, such as the companies mentioned above. If it were my motor, I would flush the block with Rydlyme and see if that solves the problem. I've got a now 23yr old Honda 50 that was starting to show signs of build up so after much research I tried Rydlyme and got a bunch of junk out. Read about it on this forum here: https://forums.iboats.com/threads/descaling-flush-motor-that-stops-peeing.747060/ It was easy to do and I've been using the motor a ton since and so far no issues. What I learned doing research was milder things such as vinegar or CLR were essentially like spitting on a forest fire, technically you could say they might descale but not significantly enough for this situation. The stronger chemicals are required for any real result. Anyway I hope this helps.

thanks Matt,
Actually, did that when I broke down the engine. With lower end off hooked up sump pump to the water tube and pump in barrel and cycled the cleaner for days. Did wash out about tablespoon amount in each flush. Also did go with adding some HCL in water mix.

 

[MattFL]

thanks Matt,
Actually, did that when I broke down the engine. With lower end off hooked up sump pump to the water tube and pump in barrel and cycled the cleaner for days. Did wash out about tablespoon amount in each flush. Also did go with adding some HCL in water mix.

Interesting that you're still having overheating issues... what cleaner did you use, and what concentration of HCL? Was it squeaky clean looking when done? I guess the next step would be figuring out which specific sensor is tripping the overheat alarm and verifying that it's reporting accurate data. Also see if you can check the water pressure inside the block while under way, just to be sure the pump is really working as expected with no obstructions. I wouldn't think that running lean would cause an overheat alarm, but did the spark plugs that came out all look OK (anything to indicate an overly lean cylinder)? How are the valve clearances? An overly tight valve that hangs open can cause extra heat... also double check the cam timing for the same reason.. how is the oil pressure? Maybe try a leak down test, perhaps a leak or crack somewhere is allowing combustion gasses to displace water inside the block. On a closed loop cooling system, you could do a chemical test of the coolant for hydrocarbons to diagnose this type of leak, but that's going to be difficult on an outboard... maybe try to tap into the cooling system as close to the end as possible, take a sample while under heavy throttle out in open water and try testing that perhaps, but I'm not sure the result could be trusted. Did you take pictures during reassembly, maybe double check that the head gasket was installed correctly. I don't know if this will apply to your specific motor, but on some motors there are holes in the head gasket to control water flow and if the gasket is installed flipped-180 the water flow can be wrong, causing some areas to heat up. Maybe run something like a metal wire snake up the inlet tube to check for obstructions, such as a piece of old impeller. Just grasping at straws now...

 

[PaulBF150]

Interesting that you're still having overheating issues... what cleaner did you use, and what concentration of HCL? Was it squeaky clean looking when done? I guess the next step would be figuring out which specific sensor is tripping the overheat alarm and verifying that it's reporting accurate data. Also see if you can check the water pressure inside the block while under way, just to be sure the pump is really working as expected with no obstructions. I wouldn't think that running lean would cause an overheat alarm, but did the spark plugs that came out all look OK (anything to indicate an overly lean cylinder)? How are the valve clearances? An overly tight valve that hangs open can cause extra heat... also double check the cam timing for the same reason.. how is the oil pressure? Maybe try a leak down test, perhaps a leak or crack somewhere is allowing combustion gasses to displace water inside the block. On a closed loop cooling system, you could do a chemical test of the coolant for hydrocarbons to diagnose this type of leak, but that's going to be difficult on an outboard... maybe try to tap into the cooling system as close to the end as possible, take a sample while under heavy throttle out in open water and try testing that perhaps, but I'm not sure the result could be trusted. Did you take pictures during reassembly, maybe double check that the head gasket was installed correctly. I don't know if this will apply to your specific motor, but on some motors there are holes in the head gasket to control water flow and if the gasket is installed flipped-180 the water flow can be wrong, causing some areas to heat up. Maybe run something like a metal wire snake up the inlet tube to check for obstructions, such as a piece of old impeller. Just grasping at straws now...

WoW looks like more homework!
Answers inserted into your text in ( )


What cleaner did you use (not sure now)

What concentration of HCL? (Used Muriatic Acid, and just dumped say a cup full into 5 gallons of water)

Was it squeaky clean looking when done? (No, still corroded looking).

I guess the next step would be figuring out which specific sensor is tripping the overheat alarm and verifying that it's reporting accurate data. (When engine normally configured it appears to be the Cylinder Sensor (I have computer with A/D converter measuring voltage and converting to degrees F.) {{A}} Yesterday I tried a test with no thermostats installed and pinching off vent tube a bit to provide some restriction, then pumped wash-down pump water into other end of vent tube into exhaust that water supply. Result shifted to increasing Case Temperature but the other 3 sensors were reading about 150F. )

Also see if you can check the water pressure inside the block while under way, just to be sure the pump is really working as expected with no obstructions. (not sure where to hook into it, maybe in line to oil cooler.)

I wouldn't think that running lean would cause an overheat alarm, but did the spark plugs that came out all look OK (anything to indicate an overly lean cylinder)?

Spark plugs were pretty clean (normal look) AS I mention no MIL alarm so guessing O2 sensor is happy, thus mixture is good)


How are the valve clearances? An overly tight valve that hangs open can cause extra heat.(Well I did have to check clearances since last year the overheating caused the 2 exhaust valves in cylinder 1 to warp [no compression in cylinder 1]. Replaced this winter and lapped each valve and adjusted clearances)

Also, double check the cam timing for the same reason. (There is a timing sensor that monitors that and no MIL faults).

How is the oil pressure? (Well no Oil Light, however no numeric value)

Maybe try a leak down test, perhaps a leak or crack somewhere is allowing combustion gasses to displace water inside the block. On a closed loop cooling system, you could do a chemical test of the coolant for hydrocarbons to diagnose this type of leak, but that's going to be difficult on an outboard... (not sure how to conduct that, could air pressurized cooling system and close any openings but will have to do after boat is out of the water)

Maybe try to tap into the cooling system as close to the end as possible, take a sample while under heavy throttle out in open water and try testing that perhaps, but I'm not sure the result could be trusted (think I did this, but injected water). Going to try maybe before closing off water pressure valve is a spinoff of {{A}} above. Reinsert thermostats however force them to be open, still vent water directly out of engine and use wash-down pump to inject water into vent hose into exhaust, then see what temperature the case goes too. Logic thinking to see if enough water is getting into case [not sure how the water flows from pump tube to block, I have manual diagram but unclear where passages are])

Did you take pictures during reassembly, maybe double check that the head gasket was installed correctly? I don't know if this will apply to your specific motor, but on some motors, there are holes in the head gasket to control water flow and if the gasket is installed flipped-180 the water flow can be wrong, causing some areas to heat up.

(Head gasket has 2 pins holes for mating pins at top of the engine, can’t reverse gasket)

Maybe run something like a metal wire snake up the inlet tube to check for obstructions, such as a piece of old impeller. Just grasping at straws now...

(Will do this fall, and also pack the water tube with C4)

 

[PaulBF150]

Today I closed off the Pressure Relief valve, so no water is return to the sea! Not getting Overheating alarm even under extreme acceleration. Also reconfigured the 2 thermostats so they stay open. Going to replace them with the proper ones 50C and 60C. See what happens.

 

[ragnad]

Did you resolve this?

"Seen thread on Water tube grommet in oil pan, did not replace and don’t believe it is a problem since there is no water in the oil."

I did all the same things you did, and it still overheated. Then I found the thread about the grommet.

Absolutely, definitely, replace or reseat the grommet. Mine was crumpled up and blocking the riser tube. I wasn't getting water in my oil. In addition to the bunched up grommet, mine had more than a tablespoon of salt and calcium buildup.

Without question, fixing the grommet solved my overheat problem.