Bravo III overheat issues

[Don S]

Re: Bravo III overheat issues

One of the reasons for the need to go to a thru-hull raw water pickup is if your standard bravo water transfer tubes starts to close up on the transom assembly due to corrosion between the aluminum walls of the outer transom plate and the rubber preformed hose forms like this, 2007 Bravo swivel shaft seal leak, opening a can of worms

Wonder why one wouldn't just replace the hose and clean and paint the hard parts instead of redesigning the cooling system.

It's a 5.0L engine, and there is a lot of engines with a Bravo drive that don't overheat. Nor does every overheat require a through hull pickup.
Find the real problem, and fix it instead of throwing parts at it.
Air leaks on the suction side of the pump will cause your problem, even the drain system type on that model could be the problem and after going to all the problems to install a through hull pickup it would still overheat.

 

[Fun Times]

Re: Bravo III overheat issues

Wonder why one wouldn't just replace the hose and clean and paint the hard parts instead of redesigning the cooling system.

Good question as always, so i did some more investigation work.

Every time i've read about this issue, the fix from either the boat owner or service shop doing the work (Mainly it's sea ray) just seemed to go with the thru-hull raw water pickup vs spending the money on a new transom assembly. Cleaning never seemed to come up as an option until i just read what the inventor of the new Bravo Thru Hull Transom Fitting Assembly had to say about it. His two options were,
YOU HAVE TWO CHOICES.
ONE REPLACE THE HOSE AND PUT BACK ORIGINAL DESIGN HOSE AND EXPECT THE SAME PROBLEM NEXT YEAR OR
TWO USE OUR REPAIR KIT #IM654 AND THE BOAT WILL BE FIXED FOREVER.

So as you can see, cleaning it up would work as well.

 

[Nielsd]

Re: Bravo III overheat issues

Glad to see more input on this, thanks guys. I would like to think when the first repair was done, it was done using the kit, but I doubt it. The marina said they pulled the engine and drive to do the repair, somehow I'm not so sure. This was at a time my girlfriend and I first started dating so I was a little reluctant to get heavy handed with the marina. I DID get to see the impeller when they removed it, and it was fully intact. The 'debris' mentioned was dirt/muck, so the mechanic told me. Given the nature of the way the whole event went down, I can't be sure of too much, in retrospect. That's why I'm looking for information on this nightmare before I go nuts pulling it apart to 'check' things. NO, I am not going to arbitrarily drill a hole in the bottom of a $30,000.00 boat on a guess! When I did driveability diagnosis, fixing cars no one else could, the key was understanding how the system works, and diagnosing it in a logical manner. The problem here is getting the engine to shed heat - and I have a feeling water FLOW is the key. I'll start with the easiest test, and systematically go through the water flow circuit until I know what's wrong. As far as 'checking' the exhaust manifolds - if I go to the extent of pulling them for that, I'll replace them, given their age. A question for those who know - how likely is that amount of corrosion (like you see in the pictures) going to be on a transom plate of a boat with 112 hours on it the has been dry stored all it's life? Just curious. I'll do some checking this weekend and let you all know what I find. Pictures, too, hopefully. Again, thanks for the input and keep it coming!

 

[Don S]

Re: Bravo III overheat issues

Here is an overheat diagnosis for a Volvo drive. They use engine mounted pumps as well, pulling water from the pickups in the drive.
Perhaps the procedures will give you the same results on your Bravo drive and engine pump.

View attachment VP Overheat Diagnosis.pdf

 

[Nielsd]

Re: Bravo III overheat issues

Thanks, Don. Having raw water pump suction and pressure readings is a help. IF the SmartCraft system is giving me good information, I currently have 7.5 psi at idle and 9.5 psi at cruise - wherever the sensor is mounted. After that, who knows. I have low pressure gauges (old A/C set) I can plumb in with adapters if/when I need to.

 

[Nielsd]

Re: Bravo III overheat issues

Household chores took precedence over the weekend so we didn't get to the boat until last evening. I disconnected the hose going into the thermostat housing and started the engine. Here's the result:


So next I crawled over the engine and disconnected the hose going from the raw water pump to the p/s cooler. Couldn't take a picture but when I started the engine there was a solid column of water coming out. Then I put that hose back on and disconnected the outlet side and started the engine again. Same thing. Put the hose back and started the engine one last time and watched what little water came out of the hose going to the thermostat housing. Looks like I have a plugged oil cooler. NOW, I can't even see it, tucked under the exhaust manifold:

Will I be able to get it out without pulling the starboard exhaust manifold? I don't think I'll be able to back flush it to clean it thoroughly, based on prior replies. What do you all think?

 

[HT32BSX115]

Re: Bravo III overheat issues

You should certainly have MORE water flow than that apparently tiny trickle (even at idle)

Will I be able to get it out without pulling the starboard exhaust manifold? I don't think I'll be able to back flush it to clean it thoroughly, based on prior replies. What do you all think?

Only you can determine that. I can get to mine but I have more room back there on that side. You may not be able to......If that cooler is crammed with impeller debris and other "stuff" a back-flush might not get it all and I wouldn't trust it unless I could look inside......

As far as 'checking' the exhaust manifolds - if I go to the extent of pulling them for that, I'll replace them, given their age.

The main thing to check is the riser-manifold gaskets. If even one of them leaks, it can allow small amounts of salt (or fresh flush) water to run back into an open exhaust valve after shutdown. If that's the shutdown before storage, then it sits on top of a piston until you "de-winterize" next Spring or Summer! (Draw your own picture here!! )

While you are replacing the gaskets and cleaning up the gasket surfaces, you can look into the manifold and riser water-jacket areas to determine how clogged they are with rust. They eventually clog completely or rust through.........But are designed to clog before they rust through. (some have rusted through before completely clogging though.....)

Some people even try to "clean" out the rust to clear the passages enough to improve flow. (this is very dangerous. because the interior walls of the cast iron manifolds get thinner and thinner as the rust inside gets thicker & thicker...........you WANT it to clog!.............. an over-heat doesn't usually destroy an engine...........Salt water on top of a cyl DOES!!)

Fresh water manifolds and risers can last as long as 20 years (or more)..... Salt water? Some have to replace after only 5 years or so...... I would pull them and at least replace the riser gaskets......(because you destroy the old gaskets taking them apart to inspect)

If they're even a little questionable, replace them.

 

[TilliamWe]

Re: Bravo III overheat issues

I don't think I'll be able to back flush it to clean it thoroughly, based on prior replies. What do you all think?

I would certainly try very hard to backflush it, before I pulled components off! As you have found out, it's easy to test.

 

[HT32BSX115]

Re: Bravo III overheat issues

I would certainly try very hard to backflush it, before I pulled components off! As you have found out, it's easy to test.

I wouldn't. Only because I could have done that with my completely clogged oil cooler before, and it might have removed *some* of the "stuff" clogging it, but not all of it.

If you cannot look in there and VERIFY it's all gone, some may still be left in there....... the flow would be greatly improved, but with some of the fragments left in there, it could easily clog again with other "stuff" that makes it through the water pick-up.

I would vote for either removing it and cleaning it or at least disconnecting it and using a bright light and a mirror etc, to ENSURE that it's cleared of obstructions.....

 

[TilliamWe]

Re: Bravo III overheat issues

In a perfect world I agree with you Rick. But if he just can't see it or it's WAY too hard to remove it, I'd flush it. If it improved the flow A LOT, then I'd be satisfied. If it improved the flow a little, or none at all, I'd be disappointed. And if it improved the flow A LOT, then later it got clogged again, I'd flush it again. Whatever it took to not have to diassemble stuff (and spend the $$$$$ on gaskets and such.)

 

[Fun Times]

Re: Bravo III overheat issues

That's plenty of room to get down in there for a eep:.

The part/tube that's down there between the two hoses is called a Fitting Drain Tee, it should have a royal blue drain plug on the bottom of the fitting that you should be able to reach down there and remove to see how much water comes out. Using a mirror may help.

That fitting should be wide open with no small numerous holes to impede with small debri.

If you or your girlfriend can't get down there, Maybe you could try pulling both the outlet side of the p/s cooler and thermostat housing side and running a drain snake down it to see if that helps out any, then flush that hose section and retest.

Item #12,
Mercruiser, Mariner, Mercury Outboard Parts, Inboard & Sterndrive Parts Online, OEM Parts Online at MercuryParts-Direct.com

Good luck.

 

[Nielsd]

Re: Bravo III overheat issues

Not for nothing, what does the inside of the oil cooler look like? Anyone got pictures inside of the inlet and/or outlets so I have a better idea what I'm dealing with? I did decide I'm going to try a backflush first, IF I'm lucky whatever is in there is soft and will come out.

 

[HT32BSX115]

Re: Bravo III overheat issues

Not for nothing, what does the inside of the oil cooler look like? Anyone got pictures inside of the inlet and/or outlets so I have a better idea what I'm dealing with? I did decide I'm going to try a backflush first, IF I'm lucky whatever is in there is soft and will come out.

There's a couple of types. If it's an engine oil cooler (which I am not sure any 5.7L engine came with stock) it's got a small 5/8" inlet/outlet for water that tapers to the larger diameter of the cooler (1-3" diameter) If that's the case, no amount of lfushing will push that stuff out of it. (As I said earlier, I had to pick the pieces out with needle-nose pliers!)

Do a google search for "mercruiser power steering cooler" then click images and you see how many different types of coolers there is and what they look like....There's also a few cooling system schematics there....

Mercruiser usually puts them in the raw water circuit prior to the t-stat or main engine heat exchanger (if closed cooled) and NOT before the raw water pump.



Some of them are combined type heat exchangers. I.E., both engine oil and PS oil are cooled in their own separate chambers in the main (copper) tube. Mine has a separate oil cooler for the engine and PS.

The PS coolers are usually not a radiator-type cooler but a bit of tubing inside a larger tube. it would take large pieces of debris to get stuck in there. If that's the case, those pieces might probably have passed right on through into the t-stat housing (and plugged it up!!) or are stuck in your block, heads, manifolds or risers or if you're lucky, just went overboard by now!



If it's a cooler like most oil coolers, (or you have an engine oil cooler) the holes for the water to pass through are small (1/4" or so) those pieces WILL NOT pass through............ and with enough of them, any other debris will be in there with them.

If it were me, I would want to know (for sure) that all the debris in the raw water circuit are gone.

 

[TilliamWe]

Re: Bravo III overheat issues

It's also possible that it's the Cool Fuel cooler?

 

[HT32BSX115]

Re: Bravo III overheat issues

It's also possible that it's the Cool Fuel cooler?

I don't know what they look like "inside", but if they're anything like a regular oil cooler with the tiny little "radiator-core" honeycomb like water passages, it would absolutely clog with anything bigger than the holes.....

 

[Fun Times]

Re: Bravo III overheat issues

It's also possible that it's the Cool Fuel cooler?

Since Nielsd boat is an 2007 with a 5.0 MPI with a Bravo III drive, Nielsd does not have the 11.6" in Length & 1.25" for OD hose fittings, brass tube, gen II fuel cooler.

Like the drain tee fitting mentioned above, the main inner flow part of the tube is open.

Nielsd has the new gen III fuel module that is mounted next to the bravo sea water pump assembly which for the most part, this system has changed a few items around on the water flow system to accommodate the new system.

 

[makonnen]

Re: Bravo III overheat issues

Bad choice on my part I know. I had a proper seacock on it but I didn't like the way it "looked" so replaced it ... hindsight right?

 

[makonnen]

Re: Bravo III overheat issues

Makonnen - thank you for sharing your project with us. As a 'fabricator' myself (and retired master auto tech) I have to say your work is impressive! I found your thread from some time back during a search before I posted this, and flagged it for future reference, as I'm sure if we keep this boat I'll be needing to do this conversion. Pains me to think of drilling a hole in the bottom of a fairly new Sea Ray tho.

TilliamWe - thanks for letting me know I didn't fry the impeller.

We live in southwest Florida - all of our boating is salt and brackish water. WE have never run the boat aground or dug the leg into muck or sand, but we don't know about the prior owner. As I've pondered this, a few thoughts have come to mind. We had an event last year when, right after the 'big' overheat repair was done, the engine developed vapor lock issues. The repair was to clean out the Cool Fuel heat exchanger - we were told it was plugged with debris. Huh. Yes, I've considered the manifolds may be plugged, and I realize we are on borrowed time with them. I'd hate to replace them if I don't have to yet, and not fix the overheating. Thinking about previous suggestions..... about cooling water flow - it goes from the raw water pump, through the PS cooler, then oil cooler, then into the engine itself. What if one of those two coolers is partially restricted? If I AM drawing air into the system, one test should bear it out: I'm going to take the hose coming from the oil cooler to the intake off, hold it somewhere safe, and start the engine. If all is well, I should have a strong stream of water coming out, shouldn't I? And, if I am drawing air, I should be able to splice in (temporarily) a piece of clear reinforced hose and observe air in the water, yes? Give me your thoughts on this, if you would guys - I'll be trying this out this weekend. Thanks again for your input.

My merc dealer is a real believer in this conversion (raw water bypass). The lead technician whom I trust tells me they sell it on approximate 50% of the bravo services that they do. I'm guessing what they mean by that is when a customer comes in for a major outdrive service (bellows, gimbal bearing etc...) they also try and sell the raw water bypass. They had all the parts in stock including various selections of clam-shell pickups, seacocks etc...

Good luck!

 

[makonnen]

Re: Bravo III overheat issues

Ok, so let me see if I understand. Fastimz and Makonnen both think drilling a large hole in the bottom of your boat is what you should do, before you diagnose the problem? Anyone else think that too? Or am I the only one that thinks he should know the problem first? And then if the solution is the hull pickup, install one?

Good point, I'll admit.

Diagnose it first.

As for my modification, I wasn't fixing a problem, just making improvements. Plus I like projects like that.

 

[makonnen]

Re: Bravo III overheat issues

Wonder why one wouldn't just replace the hose and clean and paint the hard parts instead of redesigning the cooling system.

It's a 5.0L engine, and there is a lot of engines with a Bravo drive that don't overheat. Nor does every overheat require a through hull pickup.
Find the real problem, and fix it instead of throwing parts at it.
Air leaks on the suction side of the pump will cause your problem, even the drain system type on that model could be the problem and after going to all the problems to install a through hull pickup it would still overheat.

This is true, I probably should have read the OP message a bit closer. Bad habit of mine to read the title and respond.

I wasn't fixing a problem, I just bought a new hole saw kit and needed to try it out.