BF 150 Overheat **FIX**

Hi all,

i have a 2013 BF150 with about 600 hours that recently started to go into limp mode with an overheat alarm to go with it. If I left it on, it would shut down after about 20 seconds, but if I turned it off and back on again it would run. After a bit of testing, I concluded that it would happen at any temperature, but only over 4500 rpm.

After reading through all the posts on here, I changed the thermostats and the 4 temp sensors even though they tested fine. I cleaned the poppet valve (which incidentally can be done with only the cowl removed) and of course I replaced the impeller.

The reason for this post however is because I couldn’t find any info on how to change the grommet at the top of the water pipe, which eventually is what fixed the overheat issue for me.

The water pipe has 3 grommets on it. One is on top of the water pump, one is right up inside the leg and there is one in the middle. The middle one just locates the pipe so it can stay there, but the top one needs to be changed.

You can can access the top grommet with only the gearbox removed. On my 25” leg, I needed about 14” of extension on my ratchet with a 10mm socket, but it was relatively easy to get to the bolt and the retainer. Pull down on the pipe and push it out of the way. I could grab the flange and remove the grommet pretty easily and after cleaning out the gunk, I put it all back together. The extension case stayed on, and the side covers stayed on.

One thing to be careful of - make sure you lube the splines on the shifter and the driveshaft, and put a heap of lube on the whip bearing that’s about 8” above the water pump. Put a bit on the locating pins as well so it doesn’t get stuck next time.

So so there it is. Pretty easy job and doable in your driveway. Solved my problem, hope it helps someone.

good luck!

Leo

Great post. Thanks.

Thanks for the info

I just printed that out--thank you for that!

I don't know how I miss seeing this one before but I'm hopeful it will me to the solution that I am facing now with similar symptoms as you had. Can you expand on how you found this grommet problem and why the grommet would cause the problem?

I am also puzzled in how the grommet enables engine overheating. The way I see it the pump output tube is mounted up into oil pan and extends into water area around where the Poppet or Pressure relief valve is located. If it was leaking in or around that area water would be in the oil (in my case it is not). Also in my case with lower unit removed I hooked up submersible pump to that water tube (to circulate water in the engine during troubleshooting, no leaks). The service manual does not address or show the tube (at least I couldn't find it).

PaulBF150 said:

I am also puzzled in how the grommet enables engine overheating. The way I see it the pump output tube is mounted up into oil pan and extends into water area around where the Poppet or Pressure relief valve is located. If it was leaking in or around that area water would be in the oil (in my case it is not). Also in my case with lower unit removed I hooked up submersible pump to that water tube (to circulate water in the engine during troubleshooting, no leaks). The service manual does not address or show the tube (at least I couldn't find it).

Click to expand...

Paul, with the submersible pump hooked up to the water tube did you confirm no leaks by visually looking at The Grommet area? I asked this because there should be a lot of water coming down through that area as I think all of the exhaust water ends up coming down through that area. There potentially could be leaking there at The Grommet but you may not be able to see it until the pressure gets amped up.. the pressure you would expect to see at 4,000 to 5,000 RPMs from the impeller. I don't expect that Submersible pumps generate very much pressure. However I agree that this particular grommet does not look like a likely candidate for causing an overheating situation, so I would still like to hear from the op why he feels this solved his problem.
I am hoping to add a water pressure meter or sensor to an appropriate place on the engine so that I can be aware of what pressure is normal and what pressure is indicative of the impeller going bad. Does anyone have any suggestions on where an existing Port is that I could tap into to measure the water pressure?

Also paul, can you share where the locations are for the four or five temperature sensors? I need to make sure I am testing and replacing all of them

On theBF150 the Exhaust sensor at rear top side of exhaust manifold, near O2 Sensor.
Cylinder Head and Cylinder Block on top of motor where big hose is connected.
Case Temp sensor on starboard side of engine in area where the oil filter and oil sensor are located.

I'll see if I see any water leakage at grommet. I'll just pinch off the 3 hoses. Also note when engine is running in the bay, there is a good stream of water coming out the 2 exhaust hoses and the main large hose. I have them all routed directly out of the engine (not routed thru exhaust pipe).