496 bravo 3 3000 RPM plus overheat

[mr300z87]

Yesterday I help my friends launch their 2004 Formula 31PC with twin 496 mag Bravo 3. They are closed cooling, with about 400+/- hours. Raw pump impeller was new last season he was told by the mechanic who used to work on it for PO the Exhaust was new and never run when they bought the boat in fall 2019 We had a 5 - 6 mile cruise. We were running about 3000 RPM when the starboard engine hit 188 degrees and set off the smartcraft alarm. He pull back to idle, the alarm stopped and the engine cooled down. Back up on plane at 3K temp falls off to about 172 degrees then with in a couple minuets climbs back up and sets alarm again. Port engine had no alarm but was running around 180 degrees. My last I/O boat was raw cooled and my current it inboard, so I am not familar with the correct safe operating temps of this set up, but I assume with a 160 dergee Thermostat the 170 - 180 is OK.

My friend and I both work on our own boats and I was hoping some one here can point us in the right direction. He is hoping Bravoitis is not the issue since getting behind the engine to replace the pickup hose from the drive is near impossible with the engines in place. I was thinking to start with a raw pump flow test and them move to cleaning the HEx and last checking the elbows. Another thought was to probe with a thermo gun looking for hot spots on the HEx and elbows.

The good news is it will cruise a low speed all day long so then can at least get out on the water for some R and R at this hang out spot this weekend.

All have a great Holiday weekend. As always any advice is greatly appreciated.

Mike

 

[Bondo]

Ayuh,..... Yer plan of attack sounds reasonable,....
188* seems low for an over-heat alarm, especially with closed coolin',....
I'd think 190 / 195* would be more appropriate,....

While heat exchangers lessen the damage of saltwater, it also allows runnin' hotter, for better motor efficiency,.....

 

[mr300z87]

Thanks for the response, we decided not to do any troubleshooting this weekend. Our NJ forecast is for beautiful 70s and sunny. Better to have partially usable boat then stuck at the dock.

 

[tpenfield]

Yes, to all those things. The IR heat gun can ID where things are going awry. Don't be surprised if it is Bravotis. It is an easy thing to check . . . harder to fix though.

 

[mr300z87]

Yes, to all those things. The IR heat gun can ID where things are going awry. Don't be surprised if it is Bravotis. It is an easy thing to check . . . harder to fix though.

Thanks for the reply Ted, last night after speaking to my marina manager who said sounds like bravoitis I read through your thread on fixing it and since I used to own a 7.4L bravo I know how tough access is. The way the 04 PC 31 is set up I'm not sure if it's even possible to do with engines in. I would have to agree with some of the posts in your thread about through hulls being easier. I think there is plenty of room in front of the engines. This was also the recommendation I got from the marina manager.

Happy boating this weekend

 

[tpenfield]

Often the thru-hull is the preferred solution. I remember considering a 31 PC as a next boat . . . thinking the rear of the engines were nearly impossible to gain access to. As I recall the aft deck extended over the rear portion of the engines.

Also, keep in mind that marine growth (shells, etc) can get lodged in the intake hose at the bell housing, giving similar symptoms as Bravoitis. I lived through a summer of that with my Formula 330SS.

 

[mr300z87]

We have had no time to do any troubleshooting but my friend is in denial that this is Bravoitis. I told him we need to check water flow first. He want to drain the cooling system and rod the HEx? We had the port drive off for some other maintenance but not the Starboard drive which is one having issues, maybe there is a blockage? These are 20 yr old drives and transom assemblies used in salt water their entire life. I post more when we had time to work on it. I am glad my boat is inboards, even if they are V-drives. LOL

Have a great day

 

[kenny nunez]

If you finally end up going through the hull just tie the drive incoming water to the through the hull with “Y” pipe arrangement.

 

[tpenfield]

You could try some 'descaler' solution in through the raw water side and let it sit overnight. It only takes a couple of years in salt water to block many of the tubes within the heat exchanger. This might be easier than disassembling things. I run a descaler every other year, just to try to stay ahead of it.

As for 20 years of usage (Seasonal, I assume) in salt water, the possibility of Bravoitis is quite real. Usually it can be addressed without removing the engine, but certainly the gimbal ring & bell housing need to come off.

 

[kenny nunez]

I saw the insides of a Bravo where the mating water passages were eroded to a point that exhaust gasses were entering into the incoming water.

 

[dubs283]

Bravoitis is quite real. Usually it can be addressed without removing the engine, but certainly the gimbal ring & bell housing need to come off.

Bell housing off yes, gimbal ring no.

Through transom barb fitting/passage hose can be replaced with the ring still in place. Really helps to remove the power steering actuator to access the bilge side of the transom assembly ime

 

[alldodge]

Bravoits can only be seen with transom raw water fitting removed. If not removed this is will not be seen behind fitting

 

[dubs283]

Bravoits can only be seen with transom raw water fitting removed. If not removed this is will not be seen behind fitting
View attachment 380481

I like this. Shows a frustrating issue that can be difficult to troubleshoot properly

Raw water cooling system blockages are real and annoying.

 

[mr300z87]

Update! Saturday we took the end caps off the HEx and rodded as many tunes as possible, soom the casting prevents the stiff 1/8 rod we were using from fitting. We were doughtful this was going to work but was relatively in expensive to try. Did a test run in pretty snotty conditions at 3k RPMs did not see any higher than 177 on smart craft gauge. At 3400 starboard engine did not through an alarm I don't recall the temp. However port engine set an alarm at the higher speed and got close to 190 before it cooled down. Later this week we will rod the port HEx. I'm not 100% sure we got it but it is definitely better.

Another note right after entering the no wake zone I took some temp readings. One encuraging thing was the center of the starboard HEx was 10 degrees cooler than the port HEx. Fingers crossed they will have a happy boating season.

 

[mr300z87]

One other comment if it is bravoitis through hull is the only way to go. After poking my head in there the other day even with the exhaust off I don't think there is a way to replace the pickup hoses without at least 1 engine coming out.

 

[alldodge]

I've done the replacement and know of no way to do it without removing the drive and bell housing. The motor does not need to be removed but then again I was able get to the back of the connection even though very tight

If you can remove the fitting that connects to the raw water pump hose and look, this would verify if its Bravoits. It looks like this

 

[tpenfield]

Here is my thread on fixing Bravoitis. My outdrives were not too bad, but more in the early stages.

https://forums.iboats.com/threads/bravoitis-fix.689156/

 

[mr300z87]

Thanks Ted, I read through your bravoitis thread. I found most of your threads useful as the engine in my last boat was the same Gen 6 7.4L as your SS except mine was carbed.
If it is possible to do this job on the 03 PC31 it's got to be by someone alot younger and skinnier than either of us. Pulling drive and bell housing is the easy part. To be honest I would never own this boat.
At this point we still need to rod the port HEx, he got the parts today. Then more testing. We will go from there.

Have a great evening

 

[mr300z87]

AD, thanks for your post as well your knowledge is always welcome. I saw in your signature file a new boat did you get rid of the Formula and the other boat you had
, can't remember what it was? Haven't been on much. Loving life with inboards.

 

[alldodge]

AD, thanks for your post as well your knowledge is always welcome. I saw in your signature file a new boat did you get rid of the Formula and the other boat you had
, can't remember what it was? Haven't been on much. Loving life with inboards.

Yes, I sold the Formula to a guy in Naples FL. He has been enjoying it, and I was just real tired of hanging upside down to change impellers and other things. Having OB's it should be much easier for this old guy

Here is my Bravoits fix but then again I never had the issue being in fresh water
https://forums.iboats.com/threads/bravo-itis-fix.680176/