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BF225A4 - Overheat When Getting on Plane The First Time

W

wildebeest

Contributing Member
So, I've got a relatively minor, but strange issue with one of my 2004 225s overheating in a very specific situation.

When I launch, idle out of the marina, then get on plane, I get an overheat alarm when at around 3,000 rpm as I get it up on plane. If I turn off the motor, restart, then try to get back on plane, I've got a 50/50 chance of the alarm going off again, but once I get on plane for the first time during the morning without the overheat alarm I will not get an overheat alarm the rest of the day in any circumstances--cruising, WOT, stopping for a few hours and restarting, etc.

My initial thought, which generated my workaround, was that this engine wasn't heating up as fast as the other engine so the thermostat wasn't open when I first tried to get on plane. So my workaround was to idle for at least 5 minutes, then throttle up to 2,000 - 2,500 RPM for a few seconds then throttle back down probably 3 or 4 times before I tried to really give it throttle to get on plane. This resolves the issue, and if I do this every morning that I launch the boat, I never get an overheat alarm and have no issues. But I have to rev it up and down to avoid the alarm. If I just idle out of the marina to try to warm it up at idle, even for 10 minutes at just idle, I still get the alarm, which makes me think it's probably not really a warm up issue. Not a big deal, and that's what I do every time now, but I'd like to know why or what is really the issue. This engine does idle high at 900 RPM when first starting it up for significantly longer than the other engine before coming down to 650 (which is part of what made me think it was a warm up issue).

New thermostats, new water pump (including housing, gaskets, etc.) didn't affect the issue. And the pressure and Pee stream is always strong. In fact, the pressure and pee stream on this engine are always better than the other engine. The other engine is always about 5 psi less than this engine. For example, the engine with the overheat issue is about 25 psi at WOT while the other is about 20 psi at WOT.

Also, when I've hit the exhaust manifolds with an IR temperature gauge immediately after the alarm and I shut the engines down, both seem relatively normal at about 160-165. Water temperature ranges from 75-85F and air temperature ranges from 70-95F, and neither seem to affect it.

My thoughts are that it might be the pressure relief valve, which gets stuck, but frees up after putting pressure against it a few times by revving up (but I don't really understand exactly how it works or how it could cause this) or the temperature sensor itself is simply faulty (and it somehow resolves after it is warm?).
 
Are you sure it's an overheat alarm, these symptoms are typical of an O2 sensor heater failure.Nothing here makes sense? Best place to start is with DrH to see what sensor is registering an overheat situation
 
Have you pull fault codes? A fault code will pinpoint the heat sensor that is alarming. Code 6 is ECT (block temperature) code 24 is the manifold temp sensor 1 (I think that is the starboard side), and code 25 is manifold temp sensor 2 (port side.) See attached. View attachment MIL Fault Codes Scanned.pdf

If is possible that one or both pressure relief valves are sticking. They are pretty easy to service. Remove the upper cowling. They sit at the bottom rear of the engine compartment base. You can easily see the water hoses going in and out. It looks like it has three bolts holding it down, but only the two outer-most bolts need to be removed to get it out. The bolt in the back just holds together the valve housing.
 
chawk_man said:
Have you pull fault codes? A fault code will pinpoint the heat sensor that is alarming. Code 6 is ECT (block temperature) code 24 is the manifold temp sensor 1 (I think that is the starboard side), and code 25 is manifold temp sensor 2 (port side.) See attached. View attachment 28399

If is possible that one or both pressure relief valves are sticking. They are pretty easy to service. Remove the upper cowling. They sit at the bottom rear of the engine compartment base. You can easily see the water hoses going in and out. It looks like it has three bolts holding it down, but only the two outer-most bolts need to be removed to get it out. The bolt in the back just holds together the valve housing.
Click to expand...

Bill, fault codes only indicate faulty sensors, overheat events are notvstored in the ecm, the only way to identify which sensor is setting the alarm off is by physically watching the temps when alarm sounds using DrH
 
You are correct, of course, now that I think it through. Jeeez- getting too old, I guess.

Sorry about that Wildebeest. But still worthwhile to pull codes and see what you have.
 
Thanks, guys. No codes, and the alarm is a solid beep overheat with temp light. This made me think it wasn't an O2 problem, but I don't know exactly how that manifests. My engines are a good 6 inches above the waterline at rest and I rarely turn them off when offshore so didn't really think I would have the issue either. Chawk sent me sb56 last week, and I was thinking about doing it when I was digging in and doing the exhaust anodes in a few weeks. It's about to be spring and I'm excited about fishing so this is when I'm most motivated to work on things. :)

I have a copy of Dr H that came with the boat, but I can't get it to run on my PC despite a year of trying various workarounds, so it may have an issue. Will healtech tell me which sensor is alarming? I was thinking of trying that instead, but understand it doesn't have all the capabilities of Dr H.
 
Sorry,I'm not familiar with heath tech, maybe someone else on this forum can help out here. I have to say this is a tricky one since you say the water pressure is very good. You really need to identify the sensor responsible for setting off the alarm or you will be going in circles
 
Wildebeest, if your issue is with the Dr H software, I can upload a working version which does not require dealer registration.
 
Well, I think I inadvertently found my problem. I think I have a cracked head, but the crack is small enough that it must close up enough not to be an issue when the engine is warm. I did a compression test when hot with 210 in all cylinders except 5 and 6 which, were 190. I figured this was just a carbon issue, so I did a decarb, and when doing a compression test after the decarb, just out of curiosity, took a look inside cylinders 5 and 6 with a borescope to see how clean they got from the decarb... and I saw salt crystals inside cylinder 5 and discoloration on the walls. This is not good, I'm thinking. Saltwater in the combustion chamber is not something I like to see.

I went ahead and did a compression test hot, and cylinder 6 improved to 200, but cylinder 5 is still 190. But a cold compression test gives it away. Testing cold, all cylinders are 200, but cylinder 5 is 160.

I think what happens is that when the engine is cold, the crack allows compression from cylinder 5 into the cooling passages resulting in an overheat. But once it is warmed up, the crack isn't as significant, which is why I can go all day without an overheat once warm--and why compression is significantly better when warm and horrible when cold.

Based on the condition of the cylinder wall where the leak is, this has been going on for some time. The odd thing is that I have none of the normal symptoms of a head/head gasket issue--spark plug not rusted at all or wet after running and looks identical to all my other spark plugs. No oil consumption or water in oil. Engine does not run rough at all. Only issue is the overheat when cold.

I plan to pull the head off next weekend to see if I really have a crack or just a head gasket issue. Here is a photo of where I think the crack is:

Crack-20220618125713933.jpg
 
Also, my pressure relief valve was stuck on this side of the engine and the rubber gasket the valve goes through deformed and cockeyed, but replacing it did not resolve this issue. It was deformed in such a way that I would assume that it was never installed correctly in the first place.
 
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Interesting observation. Most common issues with these heads is a pin hole in the exhaust port, be very interested to hear what you find.
 
Well, I finally got around to pulling the head... after putting another 30 hours on the motor and cylinder 6 eventually hydrolocked in the marina. I idled it over to the gas dock, filled it up, but then when I went to start again, it was hydrolocked. I hadn't detected any water intrusion into cylinder 6, only in cylinder 5, so this was surprising to me. After getting the water out of cylinder 6, the engine ran smooth (for the few seconds I was willing to run it out of the water), and I measured my piston heights to confirm as best as possible that the rod wasn't bent, and it doesn't appear so.

I cleaned up the block a little bit and think the block looks good.

20220723-175657.jpg

20220723-195814.jpg

The head does not look good. I did some measurements, and I have some fairly extensive warpage, greater than .005 inches at several points, and the water jackets, particularly on cylinder 6 were nearly completely blocked. The head gasket is not in good condition, but I can't see where the head gasket was actually blown through to the cylinders, and what I thought was a crack in the head was just carbon. There are no obvious cracks in the head. So I'm really not sure from where the water got into the cylinders. From the pitting on the head at cylinder 6, it looks like it's had a more serious water intrusion issue than cylinder 5.

Bottom of gasket:

20220723-173009.jpg

Top of gasket:
20220723-173028.jpg

Cylinder head itself (after spraying it down with parts cleaner and wiping it down):
20220723-173034.jpg
 
Hi wildebeest,

Ha ha, yeah! "Relatively minor" this ain't!

I've been following your thread with interest. I have a question:
Is the "bottom" combustion chamber in the photos you posted cylinder #6?

I ask because the heads of the valves look quite a bit different than the two chambers above that one. A sort of "washed off" look if you will.

Another question not neccessarily aimed at you:
I wonder if the bad pressure relief valve had something to do with this problem or are the two totally unrelated?

Just geeking out a bit.

Hope you get it patched up and back out there soon!
 
jgmo said:
Hi wildebeest,

Ha ha, yeah! "Relatively minor" this ain't!

I've been following your thread with interest. I have a question:
Is the "bottom" combustion chamber in the photos you posted cylinder #6?

I ask because the heads of the valves look quite a bit different than the two chambers above that one. A sort of "washed off" look if you will.

Another question not neccessarily aimed at you:
I wonder if the bad pressure relief valve had something to do with this problem or are the two totally unrelated?

Just geeking out a bit.

Hope you get it patched up and back out there soon!
Click to expand...

Yes, the bottom combustion chamber is 6. It is, from top to bottom, 4, 5, 6, on this bank. You can't see it well in the photos, but the head on 6 has a lot of pitting in the combustion chamber if you feel it with your finger. And the two intake valves on 6 are pretty pitted and rusty. Also, if you look at the photo of just the head, in between 5 and 6, and the side that is closer to 5, on the mating surface for the gasket those black spots are actually pits you can feel with your fingernail. I think that must have been the leak point into number 5.

With that corrosion in the combustion chamber and the warpage (.005 to .007 when the spec is .002), I'm kind of thinking this head is trashed. Maybe this can all be machined out, cleaned up, and pressure tested to confirm it is operational, but I'm looking at some used heads and may try to pick one of those up. I'm not ready to spend multiple thousands on a new head for an 18 year old motor.

This may have to do with the bad pressure relief valve, but I'm really not sure. I don't really understand how the pressure relief valve operates. I think it lets water bypass the block and go straight out of the engine when there is enough pressure and it opens up. The pressure relief valve was basically stuck closed, so I would think it would have allowed excess water pressure in the block. I don't know what the consequences of that are.

Anyone know what the spec is for when the pressure relief valve should open? My other engine runs at about 20 psi at cruise (3,800 rpm), and this engine typically ran at 25 psi at cruise. However, my pressure gauge is on the starboard side at the thermostat, when all this overheating and the bad pressure relief valve was all on the port side of the engine, so it may have affected my readings.
 
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The pressure relief valve allows a higher water flow rate through the engine at higher rpm. There is no spec on the pressure listed anywhere.
 
Hi, I have the same issue with my 2011 BF 150A4 , i replace thermostats, temperature sensor but the problem keeps coming back.I would you like to use Dr Honda ,could you direct me on where to find it? thanks
 
I finally got this engine put back together with a used head. The first cold compression test was 90-120... but I ran it for 30 minutes, and it checked out between 195-210. Cylinder 5, with the slight cylinder wall damage is the 195 cylinder, so I assume I'll just have to live with that. Sea conditions will probably be bad the next month, so it will probably be a while before I get to do a full water test under load.

I do think the bad pressure relief valve contributed to this, and potentially an improperly installed exhaust manifold gasket. I didn't check for any non visible cracks in the old head yet so that may have been an issue. The head gasket itself was not blown. The warpage on the head was pretty massive, though, which makes me think it was running very hot frequently.

Putting this back together made it clear that all my exhaust manifold gaskets on both engines are installed upside down and on the wrong side, so the restrictive sides of the gaskets are on the wrong side of the manifold. I have new internal anodes and gaskets so will fix all those when I do the anodes. I'm not sure how much of an effect this had, though, on my head temperatures.
 
wildebeast,

The 195 to 210 compression spread shouldn't be a problem...that's about 7% difference and, although not ideal, I call anything under 10% good with anything above 15% suggestive of reseal time.

You just need to hope that cylinder doesn't erode further in the damaged area.

Thank you for the update.
 
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