Sea Water pressures

S

SeaRenity

Member
Mar 31, 2008
200
chesapeake bay / Back river
Boat Info
320 Sundancer 2005
Engines
350 Mag hor.
just changed my raw water pump and it seems my smartcraft water pressure is low and engine running a little hotter.

I have a 350 mag horizon
starboard 4.5 @1500 RPM and 18.2 at 3600
port ( new) 4.4 @ 1500 and 12.3 at 3600

does anyone know if this is acceptable and in range?

thanks
Rich
 
Those are good numbers.

What are your engine temperatures at idle and cruising speed?
 
I would probably start with swapping the water pressure senders and make sure that the port engine is actually flowing less water.

If the numbers remain the same then you probably have a restriction in the heat exchanger. Why did you replace your raw water pump?
 
Cruising in the 3,200-3,500 rpm range I see anywhere from 9-12 psi.

It’s been that way for the last 3 years. In that time I’ve replaced manifolds and risers and also a new raw water pump impeller this year.

Same range before and after.
 
Changed the pump or impeller ? New impeller in one of those easily scored brass pump will do that. A restriction downstream of the pump would make you pressure read higher not lower.
 
Mine stay at 13 to 16.
20190623_101815.jpg
 
+1 on scoflaw - - Restriction downstream increases pressure. Low pressure means pump is starving for water. Check your strainer baskets n make sure clean and sea cock is all the way open. Is/was your pump housing scored bad? This can also cause lower pressure as water leaks by the scores. The problem is before or at the pump. Could also have an obstruction at the intake under the boat (barnacles, paint build up, piece of whatever partially obstructing). The numbers you posted above are good at 1500, but the lower pressure on the port side and with it running a wee hotter indicates not enough volume input (water) to the pump at the higher rpms to get you the adequate pressure to give you the proper flow to cool the engine. Your 3600 rpm pressures should both be in the high teens.
 
Changed pump due to seal failure. Mechanic insisted he installed a new pump, I believe he did but I might have a Sierra not mercruiser.
Thanks for everyone's response
Rich
 
Bravo or Alpha drive? The Bravo's get Bravoitis and the intake tube gets squeezed shut.
 
SeaRenity - If you have Bravo 3 drives as asked above, your problem is most likely Bravoitis. Unless you have had the new tube kits installed in your drives. It is very easy to check. let me know if you indeed have the drives and I will explain how to check it and the options how to fix it. Just went through same thing last season.
 
Korkie said:
SeaRenity - If you have Bravo 3 drives as asked above, your problem is most likely Bravoitis. Unless you have had the new tube kits installed in your drives. It is very easy to check. let me know if you indeed have the drives and I will explain how to check it and the options how to fix it. Just went through same thing last season.
Click to expand...
If you could kindly post the "how to tell" I would appreciate it. I have a Bravo 3, Thankfully no problems on my 2004 5.0 at this point but since Bravoitis is a real thing Id like to know if the previous owner may have already installed new tubes or if I should put it on the to do list after this season. Thanks
 
If you follow your input hose from your sea water pump to the transom, you will see where it goes through. Disconnect it at the transom and if you have Bravoitis it will be obvious.
 
Korkie said:
If you follow your input hose from your sea water pump to the transom, you will see where it goes through. Disconnect it at the transom and if you have Bravoitis it will be obvious.
Click to expand...

Here is a pic of what Bravoitis looks like.
18318.jpeg
 
Ok Thanks, That photo is looking down the hose that passes thru the transom and out to the drive correct?
 
If you have a through-hull water intake Bravoitis isn’t an issue. Check to see if you have one before getting too concerned.
 
Most Stern drives do not have through hull unless added. If you do not have a through hull, adding one is the best fix in my opinion. That is what I did on several recommendations.
 
Korkie said:
Most Stern drives do not have through hull unless added. If you do not have a through hull, adding one is the best fix in my opinion. That is what I did on several recommendations.
Click to expand...
Agreed on the adding part. Sea Ray installed a through hull intake at the factory for my boat. It’s worth checking.
 
You must log in or register to reply here.

Forum statistics

Threads
113,116
Messages
1,426,393
Members
61,028
Latest member
ddbyrd329
Back
Top