4BTA G1503 Raw Water Pump Questions

[Clinton Rowley]

Background:
I recently replaced my port side 4BTA G1503 Raw water pump with a new pump sourced from sbmar earlier this summer when they were in stock. The pump was likely the original pump from ‘05, it was painted white, and I had to cut some carpet to remove a floor board to access, I really think it was never changed or rebuilt before. It is possible that the impeller had been changed before but I don’t know. Boat has always been in salt water, never freshwater flushed, and has 600+ hrs on the ticker. Pump was leaking sea water from the shaft seal into the bilge.

Starboard R/W pump has been replaced, it is not painted white, But I don’t know when. I’ll have to go though the receipts from prior owner.

Questions:
1. I have read the G1503 is a bad design and can cause catastrophic engine failure. What exactly goes wrong to cause catastrophic engine failure? Are we talking sea water leaking past the seal into the crankcase rather than just leaking into the bilge?

2. I want to rebuild the pump I took out. Many forum posts recommend Depco in Florida for having the pump rebuilt. I’m considering learning to rebuild myself. Comments on rebuilding myself, or links to resources, youtube videos or forum write ups are welcomed.

3. Lot’s of opinions out there on how many years between rebuilds is appropriate. Please share your opinion.

Topic

[Clinton Rowley]

Thank all for responding.

My brand new pump is leaking 2 weeks after install. Probably leaked from day one.

It did have support bracket, and I was very careful in my Install. Nothing forced or dropped. Tightened pup flange to engine before tightening support bracket etc.

I do have room to do a front belt drive pump.

[Mark Tripi]

I pulled the 4BTAs from my boat a few years ago so I could work on them. After reading about the Sherwood pump failures and finding the inside of my timing cover with grind marks inside it from the drive gear I would not put the engines back in until I had a replacement pump system in. I looked at a bunch of 6B pumps but none would fit. I then designed a belt driven system using a Jabsco pump from a Cat 3208. A couple of others have now used the same design and we have no problems.

[Dan]

My first pump failure was around 350 hours, oil was leaking badly from the seal.

Ive read the Sherwoods have been known to snap the shaft and drop the gear into the timing cover.

Also leak salt water into the engine.

There is a support bracket on the back end of the pump that attaches to the engine block, hopefully yours are still there, they need it!

[Bob Odell]

The G1503 is crap, but you really have no choice if you want to stay factory.

I’ve seen them lock up hard and get pretty torn up from the flywheel, mostly in boats that are infrequently run. They can tear up an impeller or break a shaft, stopping water flow pretty much immediately.

There’s no magic number to determine how often you rebuild/replace them. It depends on your use, your water, etc. I’ve had them go years and once far less than a year.

Rebuilding them is not hard if they haven’t spun the bearing in the housing. I don’t have any direct YouTube pointers but it isn’t all that different from any other pump.

[Author]

Replies