Leak from impeller shaft Perkins 4-108

[shanegeard]

Greetings,
There is a steady drip from the slot under the impeller shaft housing. I'd appreciate any advice on what is likely to be causing this. An O-ring I'd imagine, but where?

[Diesel Bill]

My guess is a bad shaft seal. Water leaking out between pump and engine. You would have to strip down the pump, remove impeller, press out the shaft then remove old seal
and clean every thing to reassemble with new seal. Others will give more details.

[shanegeard]

Thank you. I have a spare impeller kit that also contains gasket and various O-rings. Hopefully it'll contain the right shaft seals but I'll take the shaft apart and see.

[nigel1]

Sorry to disappoint, but the impeller kit is unlikely to contain the seal you need.
I suspect the pump you have is a Jabsco pump, ( https://www.jabscoshop.com/marine/pu...aded-ports.htm ).

The pump has two lip seals, one on the water side, one on the oil/engine side. Thwe one on the water side has probably worn, and there is a possibility that the shaft may also be slightly grooved where the seal sits.

You should also replace the bearing while you replace the seals.
Bearings and seals are pretty much generic and once you have the pump apart and seals and bearings removed, you can get the replacements from a bearing supplier. To be honest, I have found that Jabsco prices for spares to be very reasonable.

There is a good article on rebuilding water pumps here

Rebuilding A Raw Water Pump Photo Gallery by Compass Marine How To at pbase.com

Although the pump in the article is different to yours, it provides a good insight in how to strip down and rebuild a raw water pump.

[shanegeard]

Excellent, thank you. That's sounds right as the impeller was replaced recently by a mechanic when I bought the boat.

[Mithril Bham]

Most likely lip seal. Looks pretty narly. Pressing shaft out might be difficult. Have had a shaft shatter when doing that before. I would try to find a good rebuild or buy a new pump. Shaft alone is $100.

[Movinon1]

I have the same problem with my 4-108. In talking to my slip neighbor, who rebuilt his 4-108 pump, I remember that for some reason, he had to borrow
an alignment tool when he put the rebuilt back in. Wished I could remember more specifics, but the manual does mention using the alignment tool. I think he said that he had moved something after he had removed the pump, which necessitated using the alignment to put it back on. Good Luck.

Bob

[barnakiel]

It is a seal leak. Bad seal or bad seals. Check and replace.

b.

[Seadoc777]

My Perkins 4-108 the second seal (water to oil) failed allowing the oil pan to fill with sea water. The dip stick obviously showed an excessive oil level.

[Jason Flare]

Originally Posted by Movinon1

I have the same problem with my 4-108. In talking to my slip neighbor, who rebuilt his 4-108 pump, I remember that for some reason, he had to borrow
an alignment tool when he put the rebuilt back in. Wished I could remember more specifics, but the manual does mention using the alignment tool. I think he said that he had moved something after he had removed the pump, which necessitated using the alignment to put it back on. Good Luck.

Bob

I just removed a Sherwood pump from my 4-108, (or possibly 4-107,) and the 4-108 workshop manual said if the adapter plate is removed realignment is necessary. If you only take off the four bolts of the pump realignment isn't necessary.

I had my pump rebuilt then reinstalled it. I sweated the first several hours on the engine because a diesel mechanic told me he ruined a 4-108 once by not aligning the adapter plate.

This adapter plate alignment, as far as I can tell, is only mentioned in the Workshop Manual.

I've put about 65 hours on the engine since pump rebuild and so far OK.

BTW Bob, you bring up a good point about alignment. It's definitely something to watch out for.

[boatman61]

Had one go on my Jabsco raw water pump (Gushing out) when I was bringing my boat back from Malta a couple of years back.. had got to Lisbon/Cascais.. the local shop had nothing and said I'd have to send off to Jabsco for a replacement which would take a while.. they could source none in Portugal for my 80's pump.
Could not afford to leave the boat in the marina for weeks and.. I had a delivery to do later that month so took the pump to the shop and they found me a rubberish ring tap washer of near enough the same dimensions to tightly fit the shaft and almost fit the hole in the casing..
Spent the next 2 days on the anchorage assembling/dissembling the pump as I fitted and removed it trying various dodges to make it work.. finally got it water tight using Sikaflex to seal the gap and lock the ring to the casing.. it got me the remaining 110nm North to Fig da Foz without leaking motoring all the way.
I have since fitted the proper seal and carry a spare..

[Qayaq]

Hiya. CAUTION. been there done that, snapped the ear of the pump drive. When you remove the pump make sure you leave the adapter plate bolted to the engine. Only remove the pump to adapter plate bolts.

I have an alignment tool if you happen to be in NZ. Making an alignment tool is easy if you have a friend with a lathe. It's just a bit of round bar about 3" long. OD the size of the whole in the adaptor plate with a whole drilled in it (using a lathe) the size of the OD of the camshaft drive. Actually just found my tool. 80mm long OD 34.75 mm.ID hole in side 22.25 mm. Depth of hole 25mm.might want to check those dimensions with your engine that was for a 1983 4108.. if you remove the front engine case/Cover like if you are doing a front crank seal, you have to re- align the adapter plate, if not you are then in danger of snapping off a RW pump shaft drive ear which can fall into the drive gears and cause a big load of damage. Other than that it's easy. Good luck with it.
Cheers Simon

[Seadoc777]

The steady drip is from a weep hole to indicate first seal is gone a warning the second seal could go allowing water flow into the engine oil pan.

[Captain Bob]

The leak is almost certainly the lip seal on the seawater side. It is frequently caused by sand particles (silaca) that become imbedded in the soft rubber seal surface and then cut a groove in the pump shaft as it rotates. If there is a groove (you can feel it if you drag a fingernail accross it lengthwise) it can be fixed by installing a jiffy sleeve (made by Chicago Rawhide) over the groove. You will need to make a very accurate measurement (micrometer) of the current shaft diameter for this to work. This is not a job for an ametuer so try to find some qualified help.

[dduresky]

Do not make the same mistake that I did, I ignored it and ran the engine. I got saltwater intrusion into the oil. I ended up having to rebuild the engine. As others have said, you're probably going to have a pretty serious repair on that bearing. While it's not cheep, it's a lot cheaper than the way I went!