Engine Runs hot coming off plane

I replaced the raw water pump with the Harden Stainless Steel pump today. Seems to have fixed the issue. Cruises at 158° and didn’t go any higher than 176 at idle after a 3500 rpm ride.

The wear plate on the rear pump cover has some scoring. The inner surface, the pump body itself was heavily scored.

Pump pressure is just a little higher but I guess that made a difference.
 
Be interesting to see some inside pictures of the old pump!
 
I’ll get some. May not be able to see the grooves but I can definitely feel them.

I didn’t take any of the plate in the rear cover before I reinstalled that with the new Harden pump.
 
Espos4 said:
I replaced the raw water pump with the Harden Stainless Steel pump today. Seems to have fixed the issue. Cruises at 158° and didn’t go any higher than 176 at idle after a 3500 rpm ride.

The wear plate on the rear pump cover has some scoring. The inner surface, the pump body itself was heavily scored.

Pump pressure is just a little higher but I guess that made a difference.
Click to expand...

Very nice ! When you have no obstruction in the circuit even a small increase in pressure may mean a significant increase in circulating water volume .
 
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I have a 2005 single 496HO with Bravo X1. Bought new, always fresh water. I had a low water pressure issue (1 psi at idle). Temp. running 165F to 190F at 3500 rpm. Water was flowing out both exhaust. Did the following checks.
- Replace water pressure gauge (new one showed zero)
- Installed manual pressure gauge (showed zero)
- Put original gauge back in. (1 psi)
- Replace sea water pump with Hardin Marine Gen 7 HD pump. (no change)
- Checked all hose connections and ran water over each one while watching pressure. (no change)
- Checked both exhaust drains with camera and found white ball checks intact with no rust.

Found my problem!
- Removed 1 1/4" suction hose at transom gimbal housing to check for Bravoitis. Found the red 1 1/4" suction hose collapsed close to the hose connection housing. The collapsed part of the hose was facing down and could only be seen with the hose removed. No Bravoitis found using camera through hose connection housing. Replaced hose and all is good! Looked like the hose may have been slightly twisted when originally installed and it took 18 yrs to collapse.
 
Auto said:
View attachment 149470 View attachment 149471

I have a 2005 single 496HO with Bravo X1. Bought new, always fresh water. I had a low water pressure issue (1 psi at idle). Temp. running 165F to 190F at 3500 rpm. Water was flowing out both exhaust. Did the following checks.
- Replace water pressure sensor (new one showed zero)
- Installed manual pressure sensor (showed zero)
- Put original gauge back in. (1 psi)
- Replace sea water pump with Hardin Marine Gen 7 HD pump. (no change)
- Checked all hose connections and ran water over each one while watching pressure. (no change)
- Checked both exhaust drains with camera and found white ball checks intact with no rust.

Found my problem!
- Removed 1 1/4" suction hose at transom gimbal housing to check for Bravoitis. Found the red 1 1/4" suction hose collapsed close to the hose connection housing. The collapsed part of the hose was facing down and could only be seen with the hose removed. No Bravoitis found using camera through hose connection housing. Replaced hose and all is good! Looked like the hose may have been slightly twisted when originally installed and it took 18 yrs to collapse.
Click to expand...
 
Strecker25 said:
I’d pull the elbows and get a good look at the risers and manifolds first. That’s a lot of time of them and maybe they’re clogged enough to slow water flow at particular RPMs
Click to expand...
Looks like you were right.
The overheating coming off plane has returned. I did install a new Harden raw water pump and on a few trips after that temps would climb from 160 to 174 coming off plane. Then on an 8 mile trip last week temps rose to 168 while cruising. Coming off plane it spiked to 220. Oddly enough, the elbows were cold. Back at the dock, I removed the hoses and drain valves from under the exhaust manifolds. This is the only way hot water leaves the boat and it was clogged. No water drained from the manifolds. I cleared the blockage and got some water flow from the manifold. Now it stays at 156-160° all the time.

New manifolds and elbows are on order.
 
This past weekend I was pulling the grands on a couple of tubes, so running pretty hard swinging them around, my son pulled up on his jet ski about the time one of the kids fell off, so I shut her down for a couple of minutes, when I went to start back up, I got a temp alarm, looked down and my temp was 220. It came right down after starting. It has never done this before, and never did it again through the weekend. I have no idea what caused it that one time
 
Espos4 said:
Looks like you were right.
The overheating coming off plane has returned. I did install a new Harden raw water pump and on a few trips after that temps would climb from 160 to 174 coming off plane. Then on an 8 mile trip last week temps rose to 168 while cruising. Coming off plane it spiked to 220. Oddly enough, the elbows were cold. Back at the dock, I removed the hoses and drain valves from under the exhaust manifolds. This is the only way hot water leaves the boat and it was clogged. No water drained from the manifolds. I cleared the blockage and got some water flow from the manifold. Now it stays at 156-160° all the time.

New manifolds and elbows are on order.
Click to expand...

glad you caught it! Usually won't be too long from a clog to a full-on leak into the exhaust, so the timing is good.
 
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