Sherwood water pump

[madhatter66]

Water pump seized up a while back. It was rebuilt using the kit including impeller. Sherwood E35 on 454. Ran last Sunday. 20-30min ride. She ran great. Spent about an hour on anchor (12-15ft of water) we came back in. She started to run hot 15min into the return trip. I noticed no so called gargling (water flow) in the strainer. Did not see any blockage. Shut down and came in on 1 motor. Finally got to look. No blockage in the input/output of the strainer. I took a video shows gargle water flow however there's a slight dribble of water from pump. Is that normal to cool off the bearings? This was a lil after 5min from cold start. The drop of water from the pump every 3 secs.

 

[ageless]

What was the condition of the old impeller? How does the exhaust flow look, strong or weak?

There should not be any leaks, could be that your pulling air from the leak

 

[rustybucket]

The leak indicates a bad seal (usually). Pump may have cooked the seal and needs to be rebuilt again.

1. How is the exhaust water flow?

2. How long has it been since the HEX's were cleaned?

3. How long has it been since the exhuast manifolds were replaced (elbows and manifolds)

4. Is the engine full FWC or are the manifolds and risers RWC?


My gut feeling (based on very little info) is that your exhaust manifolds and elbows are clogged and need to be changed. This clogged situation is leading to the water pump being overloaded/overheated due to lack of flow through it (water flow through the pump also serves to cool/lubricate the pump). In this scenario the water pumps failing are just a symptom and not the actual problem.

My second gut feeling is that you are sucking air pre-pump somewhere. Could be the strainer lid gasket? Could be a hose connection? Any pvc or non-metal barbed nipples involved anywhere? Worth pulling the hoses off them for inspection.

IF it's manifolds be sure to inspect the exhaust hose when you pull them, usually when you have a clogged manifold or elbow the inside of the exhaust hose gets cooked and swells/folds/bubbles inwardly blocking exhaust gas.

Just my $.02, take it at face value but may give you some direction in trouble shooting.

 

[Scarlett]

One simple thing, some seals have a orientation another words an up or down side, if not done correctly they will leak a little. John

 

[madhatter66]

The impeller was good and intacted when the pump seized. I replaced the impeller in the beginning of last season. 2018

Water flow is good.

No issues prior to seized pump. She ran a consisted 155-165 sometimes 170 degrees.

Manifolds/ Elbows have not been replaced. I've had her for the past 6yrs.

 

[Boatsb]

5 years on manifolds and risers is about it. They rust up and leak back into the cylinders

 

[rustybucket]

The impeller was good and intacted when the pump seized. I replaced the impeller in the beginning of last season. 2018

Water flow is good.

No issues prior to seized pump. She ran a consisted 155-165 sometimes 170 degrees.

Manifolds/ Elbows have not been replaced. I've had her for the past 6yrs.

Are the manifolds/elbows FWC or RWC? If they are RWC they are absolutely due for replacement. may want to check out skidim.com for the manifolds/elbows.

 

[madhatter66]

Manifolds are FWC

 

[rustybucket]

Manifolds are FWC

Elbows?

 

[oscarvan]

For the interested observer.... FWC RWC ?? Assuming forward or rearward .... but what? Thanks.

 

[rustybucket]

For the interested observer.... FWC RWC ?? Assuming forward or rearward .... but what? Thanks.

FWC = Fresh Water Cooled, as in antifreeze/coolant circulates through the part.

RWC = Raw Water Cooled, as in sea water or lake water circulates through the parts.

Most of us with diesels everything is FWC except the heat exchangers which of course have a raw water loop in them.

Lots of gas engines are RWC or at least partially RWC. For instance a lake boat who only sees good clean freshwater is fine being RWC whereas that same boat that sees saltwater really needs to be FWC or at least partially FWC. Partial FWC engines have coolant circulating in the block and heads (and possibly exhaust manifold) then to a heat exchanger. The risers or elbows are almost always RWC, meaning sea water passes through them and out of the boat through the exhaust system.

The exhaust manifolds and elbows can both be included in the FWC side or RWC side. If either of them are in the RWC side they need to be looked at as a maintenance part and be replaced on a 5yr interval. Even if flushed regularly they WILL (being a cast iron part) start to flake/swell/rust internally and restrict cooling passages leading to all sorts of weird cooling/temp issues.

 

[dsharp]

The elbows on a gas engine are raw water cooled to cool the rest of the exhaust system. It’s very easy to chip the ceramic seal on the raw water pump. Like previously stated you’re running on borrowed time with 6 years (at least) on the risers.

 

[rustybucket]

The elbows on a gas engine are raw water cooled to cool the rest of the exhaust system. It’s very easy to chip the ceramic seal on the raw water pump. Like previously stated you’re running on borrowed time with 6 years (at least) on the risers.

Yup, what dsharp said. NOTHING will kill an engine quicker than an elbow/riser failure, basically dumps seawater directly into the cylinders causing a hydrolock and all kinds of bad stuff happens at that point.

Last time I changed a set of risers I want to say they were only $100/ea on a 350 vortec, should be similar for the big block.