Question on 3GM30(F) engine

[davbaker]

My son recently purchased a 1985 sailboat with a Yanmar 3GM30 engine in it, and the water pump is leaking. In the process of figuring out exactly which engine it is to get the correct pump, one of the previous owners wrote down 3GM30F as the model number. It's a saltwater boat and has been for at least the past 15 years. I'm getting a little nervous for him, but he can't find the plate that shows the exact engine type. He's looked behind the oil filter and to the left of the alternator but can't find anything. Any ideas here?

I'm thinking this might not be a good thing without the plating. Can anyone give me any information what's going on in the engine given it's salt water and the engine may be lacking the plating?

Thanks

[Attikos]

My 3GM30F is a later year, but the plate on it is on the front end of the engine, below and to the left of the fresh water pump, behind the v belt. It's not easy to spot without looking closely.

[Wotname]

Originally Posted by davbaker

My son recently purchased a 1985 sailboat with a Yanmar 3GM30 engine in it, and the water pump is leaking. In the process of figuring out exactly which engine it is to get the correct pump, one of the previous owners wrote down 3GM30F as the model number. It's a saltwater boat and has been for at least the past 15 years. I'm getting a little nervous for him, but he can't find the plate that shows the exact engine type. He's looked behind the oil filter and to the left of the alternator but can't find anything. Any ideas here?

I'm thinking this might not be a good thing without the plating. Can anyone give me any information what's going on in the engine given it's salt water and the engine may be lacking the plating?

Thanks

davbaker, welcome aboard CF,

The 3GM30 is a raw water cooled engine while the 3GM30F is a "fresh" or coolant cooled engine. They are fairly easy to tell apart.

The 3GM30F has a coolant water pump (engine driven) and a raw water pump (belt driven). It also has an engine mounted heat exchanger with radiator style cap.

If there is no heat exchanger or coolant pump on the engine, it must be a 3GM30.

The raw water pump is usually the same on both engines. I say usually as it is not always and it is serial number dependant.

Later 3GM30(F) have a model / serial number plate on the front of the high pressure injector pump (front LHS when looking from the front). I'm not sure if it is the same for earlier years of the same engine.
Unfortunately some don't bother with detail and refer to a 3GM30F as simply a 3GM30.

There is also an earlier model - a 3GM which finished production in 1983.

[Peterlsmith]

Originally Posted by davbaker

My son recently purchased a 1985 sailboat with a Yanmar 3GM30 engine in it, and the water pump is leaking. In the process of figuring out exactly which engine it is to get the correct pump, one of the previous owners wrote down 3GM30F as the model number. It's a saltwater boat and has been for at least the past 15 years. I'm getting a little nervous for him, but he can't find the plate that shows the exact engine type. He's looked behind the oil filter and to the left of the alternator but can't find anything. Any ideas here?

Thanks

On the 3GM30, the outermost belt just drives the alternator, while on the 3GM30F , it also drives the fresh water (coolant) pump. Alternatively, if you have a radiator cap on the top with a hose connecting to a coolant reservoir - it's the 3GM30F.

Do you know if the leak is coming from the gasket (back cover) or the seal (around the pulley)?

[davbaker]

Thanks everyone. My son still can't find the plate, but this is indeed a 3GM30F. Is the heat exchanger rated for salt water?

The leak is definitely around the shaft. I have no idea what pump is currently mounted, but do all the various seals and impellers interchange?

Thanks

[Cheechako]

You can usually rebuild the pump/shaft seal rather than buying a very expensive pump. Yes the exchanger is meant for salt water.

[davbaker]

Thanks Cheechako. I can tell the bearings are a bit rusty, so these probably should be replaced. I was contemplating getting an overhaul kit, but I read on a website yesterday that a bench vise was needed to remove and replace some of the parts. Do you know if there is any truth to this?

Thanks

[Cheechako]

Been too long for me, but dont remember needing a vise. many here are up to date you should get an answer pretty quick. Sailorchic would know I bet. Seems I used a wood dowel....?
A kit should have a new "cam", seal and bearing. However, kits are expensive too...

[Matsubob]

It is easy to rebuild the water pump on the 3GM engines. The only thing you need is a pair of "C clip pliers". That makes removal and installation easier. It is always best to replace the seals, bearings, gaskets and impeller while you have it down.
The pump for the "F" model is slightly larger than the raw water setup, so parts will probably be different.

[foufou]

I rebuilt my raw water pump a few years back. On the boat with no vise. New bearings and seals. It still drips but much less. I have been told that replacement pump is made by Johnson at much lower price .

[boeing1]

yes I would rebuild the pump, but if you do not feel like you would want to try, Try the Flying Dutchman, out in Selma OR, 888-595-1110, you can ship him the pump and he will rebuild it and ship it back, I have used his service before he does good work.

[sailorchic34]

Raw water pumps are very easy to rebuild. I just did a full rebuild on mine two days ago (at anchor). Bearings and seals are available on amazon.

Seal is a TC13x28x7 available near about anywhere.

https://www.amazon.com/Grease-TC13x2...70_&dpSrc=srch

Bearings are 6202-2RS, available anywhere.
https://www.amazon.com/6202-2RS-Seal...70_&dpSrc=srch

If the shaft is scored from the seal, light sanding with emery clothe should give you another 1000 hours on the shaft. Seals will go bad every 700-1000 hours, least that's been my experence.

The impeller non yanmar part number is a 22799-0001. It's cheaper if it does not say yanmar on it...

The shaft is available from Depco pump for $150 ish.... OUCH! That and the cam plate (Depco), bearings and seal, and impeller are the wear items.

Odds are the oil seal is the only thing bad. I replaced my oil seal at 1000 hours and again at 1500 hours (blonde installed it backwards.. Doh). At 1900 hours the bearings had noticeable slop, which is why I installed the new shaft and bearings I had on hand (two days ago).

A 12mm socket wrench, screw driver, circlip plyers and a brass drift (very important) and a 2x4 with a 1/2" hole drilled in it is all you need to rebuild it.

BTW seal flat side faces bearings, spring side faces impeller.

I really recommend removing the circlip, inside the boat as one time the darn thing almost flew into the water when it spronged off the plyers while rebuilding it in the cockpit.

Also do not use a hammer to tap the brand new $150's dollar shaft onto the bearings, as the end of the shaft will mushroom a tad. Blonde happens. A drimmel with a grinding stone will fix that blonde moment. A brass drift is highly recommended.

If its the cooling water pump, that's a bit harder and a leak there may be due to too tight a alternator belt.

[Attikos]

Just to be clear, are we talking here about a leaky raw water or coolant pump? The 3GM30F has both.

Rebuilding the raw pump isn't difficult, as Sailorchic describes. One tip I picked up from an earlier thread is to remove the new seal's circular steel spring with a pair of needlenose pliers and replace it with an O ring of similar size. The steel rusts out quickly in contact with the water, so you can extend the life of the seal considerably by doing that.

[davbaker]

Attikos, the fresh water pump is leaking, but while we're doing maintenance, I thought we'd pursue the raw water pump as well. Thanks for the tip - we'll try this out.

[tjandoverguy]

i agree with this
i rebuilt the water pump several times ,still leaked ,replaced wit a pump i beleve from blue water in fl,bolt on .never leaked