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.