Pump Rebuild

[cyphert]

I removed a leaking water pump">raw water pump from a Yanmar 3GM30F and replaced it with new one. I decided to take the old one apart to rebuild it and in doing so 3 parts came off and fell to my workbench before I could identify the order in which they would go back in! They are a lip seal, an o-ring and a plastic tripod.
The pump is a Johnson F4B-903, 10-24509-01. I can't find a diagram for it on-line so has anyone rebuilt this pump and know the order of assembly?

[sailorchic34]

Lip seal, should be the water seal seperating the impeller from the open port. the o-ring may have been on the lip seal (repacing the spring that rusts.

I've never seen a plastic tripod thingy. But only place for that is between the seal and bearing's.

[jamhass]

Yep, plastic thingy is a spacer, usually between seal and bearing. Careful inspection of the wear areas on both the shaft and pump housing will help you ID the correct reassembly order. Note that the lip of the seal is oriented so that the water pressure forces the lip to "expand" and make a tighter seal.

[cyphert]

So, the lip seal has a spring on one side. Is this the side adjacent to the impeller?

[rognvald]

The Yanmar service manual has an exploded diagram of the pump. Good luck and safe sailing.

[cyphert]

Indeed it does but is a different pump than was installed on some Yanmar 3GM30F engines! There was a previous discussion of this anomaly having to do with, I think, the YEU version. In any case it is not clear from this pump diagram the orientation of it's lip seal. It seems logical that the metal spring should not be on the water side of the seal, but then again this is Yanmar. Thank for your help.

[rognvald]

Cy,
Contact Yanmar Marine. They should be able to give you the proper sequence. Good luck and safe sailing.
Home - Yanmar Marine

[bobnlesley]

I have photos, but don't know how to upload, so a description (it's the same for both types of 3GM30F pumps) Beginning from the stern end:
Oil/water seal with open/spring face pointing sternward
Small O ring
Plastic tripod - legs pointing sternward
smaller bearing
circlip
spacer tube
larger bearing.

If you're rebuilding do NOT buy the Yanmar/Johnson kit, the parts you need - better quality and way cheaper - are:
Bigger bearing – S62012RS
Smaller Bearing – S60012RS
Seal – SEAL2-VITON 12-24-7 R23 (double lipped) - Original is a single lip, but this moves the 'wear point' on the shaft and I'm told (never tested it) that if the pump rins dry, a viton seal will survive that ordeal longer.
O-Ring -11 x 2.4mm – 24N0116.

This list is all stainless steel and should cost you less than £25/$30

[Rapanui]

Thats very useful bobnlesley. I have 2 3ym30s on our catamaran which also use a Johnson F4B-903 pump variant. Getting a bit fed up with water spraying all over my lovely engines.
Can I ask how many hours you have run the modified service kit on your engine?

[bobnlesley]

Originally Posted by Rapanui

...how many hours you have run the modified service kit on your engine?

Back in 2014 we had a major problem on a glass-flat run from the Bahamas to Beaufort NC; the water pump began leaking and when I switched it out for our spare - a secondhand unit that'd been sat in a locker for three years - that soon began leaking even worse; we plodged on, mopping up the water until we reached Norfolk Va. by when the 'spare' unit's shaft was completely trashed, so we bought and fitted a brand new Johnson unit - that was when I discovered that other than having different impellers, the two Yanmar/Johnson pump types are directly interchangeable; so why is one almost twice the price of the other?
By the time we'd run up to and around Maine - less than 200 hours - the new unit had already begun leaking, though I might've been partially to blame for the early failure?
During a visit back to England from Maine I'd sourced three sets of those bearings/seals that I listed and had already rebuilt the original pump and so just switched them over and I've been running on that one ever since - almost 900 hours. The second set is in our since unused 'new' pump and the third set I used to rebuild the water pump of a Canadian yacht in the Dry Torugas (were they ever glad to meet us there!) which subsequently went around Cuba, up through the Bahamas and back to Ontario - I got an email to tell me that it'd run leak free the whole way too; no idea of their engine hours, but I know they pretty much ICWed/Hudson Rivered it all the way back north, so they must've been substantial.

[Rapanui]

That's really useful info bobnlesley. Order going in today, as you say the bits cost peanuts but was quite amused by the bearing salesperson trying to save me money by going for a nitrile seal rather than viton.
Did you you keep the stainless gaiter springs in the viton seal or replace with O ring?

[bobnlesley]

I've retained the stainless springs, though I've a good friend who is adamant that they should always be changed for a nitrile O-ring; your choice.

[Jim Cate]

BnL, if you kept the pump with the trashed shaft, most likely it can be revived with a "speedy-seal" or other such sleeve device. These are available at any bearing/seal type vendor, and work a treat. Got one in our Johnson pump with a badly scored shaft and it has been leak free for several hundred hours now!

Jim