BF150 Overheating (New Issue)

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?

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.

Should check out my thread on 2014 Honda BF150 overheats. Turned out to be a thrust washer thrown and down between the plates near the shift linkage. I'll be happy to answer any questions as I did a rebuilt myself with a new short block.

Steffannalin

First thanks for reply.
Second I looked for your post but only found one with low oil pressure
What be exact title?

It is unclear to me that a thrust bushing is the cause of my problem. Unclear where the 2 plates are. What is purpose of thrust washer?

Paul

Steffannalin

Okay read more into your low oil pressure thread an found where you discuss the thrust washer. Not sure their function though and how failure of them effect overheating.
You mention a few pictures.
Also mentioned about some wear I guess on the timing chain and alternator sprocket.
What was that exactly?

Did the short block come with pistons and crankshaft?
When you had engine apart were you able to see water routing in case. Say from water pump tube into block and case? I seen the one going to head at bottom of block but wondering where I might have restrictions and picture in manual is not very informative.

Ok, third time trying to reply. Damn this site:

Thrust washer holds the crank from walking up and down out of the block. The main caps hold the crank against it's rotational force, and the thrust washers (sometimes called bearings) hold in the axial force, that up and down movement. If they aren't there the crank rubs the block..which is what I had. Why it gave overheat I don't know, as the head and block never overheated...though the oil likely got very hot with the crank rubbing the block like it did.

The wear on the crank case (the top of the engine under air baffle/silencer) was from the crank pulley rubbing when the crank was walking up and down. It also partially melted the crankshaft position sensor (CPS), and since they are so expensive and mine was still good, I used some Yamabond Marine 4 and reused it. Doesn't leak and works fine. The grooves in the case weren't that bad, but definitely a result of a missing thrust washer.

Short block comes ready to install sans the head. Pistons, rods, bearings, crankshaft and unique 'main cap' bottom part of engine is assembled.

Water routing is pretty straight forward, but you obviously can't see the passages in the block and head. When I thought I was just overheating, due to blockage or similar, I did the extreme and easy way to flush. Bought a sump pump, $90 at the hardware store. Couple hoses, a T, a large tote and a quart of salt away rounded out my effort. Took off the lower unit, took out the thermostats and the pressure relief valve. First hooked up the hose and T on the top at the thermostat housing. Put tote full of water and appropriate amount of salt away under the engine and start flushing top down. It's a foam party, and I ran it this way for about 3 hours. Shut down, changed water. Lots of little hard deposits and sandy like crap. Let it sit a bit, then reversed the process to flow UP and out from the bottom water tube. Took out the T and reconnected the engine water hose at the thermostat housing. Flushed another couple house with fresh water and salt away, got a little more gunk. Then flushed one more time from the top to allow gravity to do her thing. The water passages were in damn good shape for almost 800 hours all in salt when I tore it down.

Steffannalin,

Thanks for reply.
First, I have the same failure that manifested with alternator pulley rubbing on the CPS and housing. When I had it apart for cleaning the head, I noticed that up and down movement but figured that was a design flaw.

So how do I replace that puppy (throw out washer/bearing)? Do I need to get into oil pan or is it accessible otherwise?

As for cleaning the engine I basically did the same as you over the past winter. Cleaning I used salt away and mild HCL acid. Same means with sump pump in barrel recycling cleaner (that is with lower end off and connecting to pump tube) and for days.

Now Since I closed off the water pressure relief valve engine is cooler, however NOW appears I have fuel flow issues. Can't get it above 3000 RPM and fuel consumption meter is show 2.5gal/hr (normally underway around 12 gals/hr. Fuel is getting to low pressure pump but not sure about high pressure pump. I ordered a high-pressure gauge and waiting on delivery. So, I fix one thing and another pops up??? Also, at times I'm blowing smoke (oil burning), not sure from where, yet. Thinking since I see the case temp in excess of 200F, that the oil is boiling or something like that. Also noticed oil level might be high especially when engine is tilted down. So going to attempt to remove oil and see if smoke goes away. Otherwise at low RPMs say 2000 engine runs relatively nice. Just no POWER!! Now.

Then figuring engine is not overheating of throwing alarm since can't get RPMs up to 4000 -5000. That is something for another day.

To replace the thrust washers you will need to do a complete disassembly, and you'll want the shop manual to do so. I gave mine to the new owner. A seal, gasket and o-ring kit is needed as well. The oil pan has to come off to get to a few of the bolts that hold the block to the transom plate/bracket. It's quite an undertaking.

Should do an oil analysis on the oil you take out. If your crank was running up and down and rubbed the case, then your crank likely has been rubbing the block...and those filings of metal get into EVERYTHING. It took a lot of doing to get the cam shafts empty of the fines, and the gasket/screen on the opposite side of the VTEC actually blew out the screen it was so clogged with metal filings. That axial flow back and forth of the crank surely didn't do the main bearings any good either.

Fuel wise I'm not sure...your set up is different that mine was I'm pretty sure. Not sure when they added the electronic sensor water separator and fuel filter under the hood...plus one on the fuel canister/high pressure pump. I do know that mine had a float inside it, and it could be sticking if you have a float.

If you can find a parts engine...or a recent take off where someone went YAMAHA or even (HACK) MERCURY, then I would do a swap. Or, if you can find one, get a new short/long block and start there.

Steffannalin

Okay found the thrust washers at bottom of crank. Are they placed below the crank bearing? Suppose I should ask, do I have to pull crankshaft out to R/R the washers? Can't see in diagrams their exact placement.
As for oil status, I haven't seen any large amounts of metal on the drain plug.


Paul

Only way I can imagine being able to change them would be to remove the bottom part of the block, the main caps are incorporated into it. Remember even if the plug is magnetic, I don't think mine were, a magnet won't collect non ferrous metals...of which most everything in the engine is made up of. About the only iron is the crank, rings and liners...and the crank rubbing the block will pretty much only erode the block.

Good Point there Steffannalin!

I guess this winter I will be doing a deep dive on motor, unless I take a long walk off a short pier before then.

BTW I purchased an external oil cooler and installed today. Does lower case temperatures but still having overheat alarms. My sensor is saying exhaust temp now.
I need to figure means to figure exactly which sensor is unhappy. Posted another thread on that but no answers.

I guess the experts out there don't wish to comment...

Thanks again Paul
PS: if you are still around this fall-winter (in Maryland area), I might seek a lifeline on engine work.