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BF90A 2006 Overheating please help

N

nasser720

New member
Dear All,
I'm facing an issue with my BF90A, when I increase the RPM above 4000 RPM overheating alarm starts beeping. I noticed yesterday when I was cursing around 3500-4000 RPM the pee hole got clogged, it was dipping water slowly "" it happened long time ago this is the second time "" I put my finger in the peeing hole tube to build up pressure after 2 seconds flow got back to normal flow speed.
things been done 2 months ago,
1- new head gasket '' cleand the cylinder water passages were clogged.
2- new valve spring "spring relief"
3- new Impeller.
Any advice how to diagnose the problem?
" I tested the temp sensor if it was giving me fault alarm, sensor is working perfect.
 
Hi nasser720,

Sorry you're having problems. Who performed the aforementioned work?..... You?..... A shop?

Was the work done trying to alleviate this exact problem or was it a bit different the first time?

I see no mention of thermostat in your post. Was it checked? Replaced?

I really don't know what to think about your item 2: new valve spring
"spring relief".....Can you elaborate on that?

You say that the water passages were clogged and that they were cleaned out. What was clogging the water passages? How were they cleaned out? Is it possible that debris is still clogging things up?

You say impeller was changed. I prefer to see people use an entirely new pump replacement kit. Often times simply changing out the impeller alone results in less than optimum pump operation and reduced efficiency.

These are your words:
"I was cursing around 3500-4000 RPM".....YEP! these types of problems would have ANY skipper cursing and not cruising.
(Sorry, I just had to say it ;>).

Anyway, many questions.

You may want take an infrared heat gun and notebook with you and point it at several places on the cylinder head and engine block and record temperature readings. You can develope a baseline chart for hot spots and or overheat conditions.

The one thermostat I see on boats.net parts is supposed to open at approximately 172 degrees Fahrenheit.
 
jgmo said:
Hi nasser720,

Sorry you're having problems. Who performed the aforementioned work?..... You?..... A shop?

Was the work done trying to alleviate this exact problem or was it a bit different the first time?

I see no mention of thermostat in your post. Was it checked? Replaced?

I really don't know what to think about your item 2: new valve spring
"spring relief".....Can you elaborate on that?

You say that the water passages were clogged and that they were cleaned out. What was clogging the water passages? How were they cleaned out? Is it possible that debris is still clogging things up?

You say impeller was changed. I prefer to see people use an entirely new pump replacement kit. Often times simply changing out the impeller alone results in less than optimum pump operation and reduced efficiency.

These are your words:
"I was cursing around 3500-4000 RPM".....YEP! these types of problems would have ANY skipper cursing and not cruising.
(Sorry, I just had to say it ;>).

Anyway, many questions.

You may want take an infrared heat gun and notebook with you and point it at several places on the cylinder head and engine block and record temperature readings. You can develope a baseline chart for hot spots and or overheat conditions.

The one thermostat I see on boats.net parts is supposed to open at approximately 172 degrees Fahrenheit.
Click to expand...

Hey thank you for you help
work was done by me, well long story short I bought the engine used from a friend which was left on a boat for 3 years never been tuned on , when I bought it I bolt it on to my boat cleaned the carbs ,etc.
I started the engine and then I noticed that the pee hole was clogged, well i went a head and changed the impeller, impeller hosing , relief valve, thermostat.
tested the engine agine same issue poor flow from the pee hole.
I suspected that the cylinder head was the problem spot on , I removed the head then I found out that the block was full of caked salt. I cleaned it with salt away, engine cleaner, water then I used air compressor.
I also replaced the head gasket with new one.
: update:
Today I removed the thermostat completely from the engine 4500RMP- 5000RPM no problem at all , no alarm no red light even when touch the cowl wasn't hot at all,
Since you mentioned that boats.net thermostat open at approx 172F would that be the issue because I got mine from them " the one I'm using right now"
 
Well, it sounds as if you know what you're doing and were pretty thorough about everything other than pairing a new impeller with an old housing. But even that is probably not an issue as you probably looked it over before reusing it and you say the engine is cooling well with the stat out..

The fact that it cools with the stat removed could indicate that you may have been sold a defective thermostat. It happens even though the boats.net site sells genuine, Honda packaged replacement parts. The only way to know would be to do the old stove top test and see if it opens at 172f.

The other possibility is that there is srill some blockage in the head or block and removing the stat is allowing water to bypass the blockage. If the thermostat passes the "pan test" then that is where I would be looking again.
 
jgmo said:
Well, it sounds as if you know what you're doing and were pretty thorough about everything other than pairing a new impeller with an old housing. But even that is probably not an issue as you probably looked it over before reusing it and you say the engine is cooling well with the stat out..

The fact that it cools with the stat removed could indicate that you may have been sold a defective thermostat. It happens even though the boats.net site sells genuine, Honda packaged replacement parts. The only way to know would be to do the old stove top test and see if it opens at 172f.

The other possibility is that there is srill some blockage in the head or block and removing the stat is allowing water to bypass the blockage. If the thermostat passes the "pan test" then that is where I would be looking again.
Click to expand...

Thank agine
I just tested the stat it was opreating as it should be.
One more question, should the water coming from the pee hole be warm or cold ? Because I noticed water temp stays cold no matter what even with the thermostat on
 
Johnnygjr is right. It can get pretty warm but not scalding.
EXCEPT...
...Try not to have your hand in the stream as the engine is being shut off...I've noticed the stream can get VERY hot when the pump stops turning.

If your running it on muffs, it might not get warm but if it's in a test tank or submerged in the lake or bay, it should get warm fairly quickly.

Again, that makes me think that there may still be some blockage causing a "rerouting" of sorts.

I never like suggesting that the power head needs to come out but since the head was so caked up, that may be where your headed to everything flushed out.
 
jgmo said:
Johnnygjr is right. It can get pretty warm but not scalding.
EXCEPT...
...Try not to have your hand in the stream as the engine is being shut off...I've noticed the stream can get VERY hot when the pump stops turning.

If your running it on muffs, it might not get warm but if it's in a test tank or submerged in the lake or bay, it should get warm fairly quickly.

Again, that makes me think that there may still be some blockage causing a "rerouting" of sorts.

I never like suggesting that the power head needs to come out but since the head was so caked up, that may be where your headed to everything flushed out.
Click to expand...


Any thoughts on replacing the OEM thermostat with a lower size one? Like 50c or 60c ?
 
Well,
You COULD try that but to what end? I have a feeling that it will probably do the same thing with a colder stat in there. But, if it did help keep it from overheating, it may have the engine running too cool. That would increase fuel consumption and lower performance while causing carbon to build on the valves and in combustion chamber. Much the same as running it with no stat at all.

I think it has as bad, or worse, salt caking in the block as you found in the head.

But, how could I know for sure? It's just a guess on my part.

You could keep pouring Salt Away in the thermostat passages and into the bypass and see if it helps. If Salt Away is cost prohibitive, as it would be for me, you can substitute a 3 to 1 mix of vinegar to water.

Let us know what you try and what results you get. This is a big problem for poorly flushed salt water outboards.
 
jgmo said:
Well,
You COULD try that but to what end? I have a feeling that it will probably do the same thing with a colder stat in there. But, if it did help keep it from overheating, it may have the engine running too cool. That would increase fuel consumption and lower performance while causing carbon to build on the valves and in combustion chamber. Much the same as running it with no stat at all.

I think it has as bad, or worse, salt caking in the block as you found in the head.

But, how could I know for sure? It's just a guess on my part.

You could keep pouring Salt Away in the thermostat passages and into the bypass and see if it helps. If Salt Away is cost prohibitive, as it would be for me, you can substitute a 3 to 1 mix of vinegar to water.

Let us know what you try and what results you get. This is a big problem for poorly flushed salt water outboards.
Click to expand...

when I replaced the head gasket I cleaned the block and the head cooling ports , I have a feeling that the thermostat is the problem , I try replacing the thermostat today and see.
The reason i didnt go with the OEM one becuase we have a poor dealership where I live. Every single part is not available in stock i have to wait at least 10 bussines days in order to get the part.
I support what you suggested first that I have to pull out the head and check i dont what to go to that setup so lose a part or head gasket or any other gasket and wait 10 days at least to get the parts.
Saltaway came to my mind last week and our local marine shop has it avalible. i think it a good idea to try, I will remove the lower unit clogg the intake port pour for the thermostat port and will leave it for 48h and flush it back with regular water will see if it will make a difference.
 
Last edited:
Ok, I forgot you mentioned that the stat was an aftermarket. Yes, an OEM stat would definitely be a good idea to try. Another Salt Away treatment can't hurt either.

Good luck.
 
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