Help brainstorm low water flow overheating
 

Hi all,

Hoping to bounce some ideas off you guys and ask for input on an issue with my ‘88 formula 311 w/ 330hp 454s and bravos.

The issue: port side motor runs hot. When puttering around at low speed it sits around 210 degrees while the starboard motor sits at 160.
When on plane it really starts to heat up and can’t run for more than 3 minutes before the temp starts creeping up and the oil pressure starts dropping from the oil cooler not cooling and the oil getting hot.

Pulled the thermostat housing and found the previous owner had removed the thermostat.
Also found that with the housing removed on both motors and both motors running, the port side pumps significantly less water out than the starboard side.

Both port and starboard have new raw water pumps.

So, I’m thinking either the circulation water pump on the front of the port motor is bad or the water pickup on the port bravo leg is somehow clogged up.

One thing to note: on the problem side bravo drive, the water pickup is not the usual 5 or 6 holes in a line on either side of the leg. It has 4-5 holes on the front of the cone in direct line with the prop hub (holes face forward, to suck water in as boat is moving forward).

I’ve ordered transom mount water pickups in anticipation that the problem is a clogged up drive.

I am considering removing the line from the raw water pump to the engine and turning the motor on to see if the water flow from there is slowed up before reaching the engine. Just haven’t gotten to it yet as the hoses are old and hard to remove.

Anything else you guys can thing of to diagnose this? Anything else I should be aware of?

You have one high water pickup drive.
And one DUAL (upper and lower) water pickup drive.

Do you have water pressure gauges? (Invaluable IMHO)
When the boat is idling, in the water, do you have the same amount of water flow out of all four exhaust tips?

Try taping off one pickup or the other. I would start off with the upper holes. I think the problem is you are sucking air with the drive with dual water pickup.

No water pressure gauges. Cannot see the exhaust, these boats have the silent thunder box. I would assume there is less water coming out of the port motor though as it is getting less water pumped into the motor as evidenced by the low water flow coming through the thermostat housing.

Where are the multiple water pickups? I only see the one on the front of the cone. I’m thinking someone along the way closed up the ones on the side. This drive only has holes in the nose cone, nowhere else.

Have you back flushed the engine that runs hotter could be some debris in the coolers

Haven’t back flushed.

But new information.

I just pulled the hose off the raw water pump (which is brand new) and it’s pushing hardly any water into the engine.

So leads me back to some sort of clog pre-raw-water pump.

My mechanic said he doesn’t want to pull the drive off and would rather do the transom mounted water pickups. I’m ok with this and have already ordered them.

But before going that route as the boat will have to come out of the water, are there any options for unclogging that drive while it’s still in the water (I’m guessing no but have to ask)?

Did you buy a marine pump or automotive ? reason Im asking as a marine pump will move water in any rotation, auto won't they are directional

it’s a marine sea water pump.

Additionally, was having overheating issues prior to installing the new pump. Part of why the previous owner removed the thermostat.

good chance the hose is collapsed in the gimble helmet. would have to pull the drive off to check

good info thanks!

so this leads back to just adding transom mount water pickups as a more reasonable fix?

I would rather fix it correctly myself than open another can of worms but that's just me. Search "Bravoitis" lots of info on it.

As stated before, it sounds like Bravoitis to me.

So now I have more perplexing information. After messing around with the pump hoses and pulling the feed line off to see how well the raw water pump was pumping, I put it back together. Then we went out last night for around 2 hours, mostly low wake cruising but on plane a couple times…

https://cimg6.ibsrv.net/gimg/www.off...5c21a8ee1.jpeg
She never went above 140* for 2 hours, oil pressure stayed identical to the starboard motor and was actually running around 20-30* cooler than starboard the whole night.

So now I’m thinking/hoping that maybe there was an air bubble or a kink in one of the hoses or something as it appears the issue is completely solved. Not ready to celebrate yet though so I’ll probably take her out again later today for a while to confirm

I'd check for "bravoitis" on the inside of the boat where the water neck comes off the transom. If that is the problem, the new Mercury hose kits have an improved design that is less prone to having this issue in the future.

https://cimg6.ibsrv.net/gimg/www.off...c7f3432abb.jpg

So another update:
Ran it for about two hours today at low wake and she stayed very cool, then at then end I got her on plane for about 5 minutes and by the end she was starting to heat up again. As soon as I came oof plane the temps dropped back down to 120* but clearly something is still not right.

More research to do.

Ditto on checking Bravoitis. Be aware if you have a Y pipe or anything in the way installation of the new main water inlet hose is going to be damn near impossible with engine in place. Different waterpickup sounds like a new can of worms. Look at the install instruction for the main water inlet hose thru the transom and see if you can access the hard suction line fitting where it passes thru the transom.

Doesn't the Bravo 1 drive benefit from water flow cooling?

Bravoitis.

I have dealt with this on a couple of boats - my old 242 LS and my Cigarette Bullet (when my buddy owned it). One the Bullet we added thru-transom pickups to solve the problem - fortunately the transom was solid so no surprises. The Formula... not so much. The Silent Thunder platform caused leaks and turned the transom into confetti.

The bellhousing needs to come off and you need install a new hose and plastic fitting. The really good way to fix is with a repair kit that has a stainless fitting that feeds into the hole from the engine side. Not the easiest of jobs to do - replace the driveshaft, shift bellows, and the gimbal bearing while you're in there. If you go the route of adding a transom pickup, you'll need to figure out how to add ball valves and sea strainers - hopefully no issues with the transom.

Side note... get rid of the Silent Thunder for sure - that thing is a transom killer.

Google this-
bravo 1 waer cooling thru drive
There are several threads on drive cooling thru the drive via water pickups. I have a dump valve that is spraying a solid stream at speed thru a 3/4 hose at top cap. Reading some of the threads on the cooling I am thinking of finding a way to get that stream directed more towards the side of the upper. Perhaps something on the top cap to just catch the water and direct or let it flow down the sides.
Something like this cap-
https://www.ebay.com/itm/28221628448...waAnweEALw_wcB

So if you go with thru hull pickups for cooling water you will need to provide additional cooling or a way to allow water to flow thu the drive. Seems the simplest solution would be to just repair the Bravoitis. O would suspect using pickups could introduce water pressure problems at speed.

From the pictures you posted in the other thread and the fact you’re keeping it in the water I would almost guarantee, as others have mentioned, that your hose in you transom assembly is corroded, the plastic insert fitting has possibly collapsed and you likely also have growth in the drive.

pull drives, yank motors and install new transom assemblies is the proper way to fix it. I only say replace TA’s because I’m sure the bellows are at end of useful life, gimbal bearings are worn, swivel seals are gone, etc, and as someone who has made the mistake of rebuilding TA’s before it’s not cost/time smart.