alignment - stuffing box issues

[Marty Levenson]

Installing our MMI rebuilt and aligned the engine to the prop shaft as I have done successfully before.

This time, once it was bolted on, the stuffing box started to leak (without the engine running) at about a drip per six seconds. I believe I had the mating surfaces straight (feeler gauges), but about 1/16th inch apart before bolting together. Wondering if tightening the bolts pulled the stuffing box forward a tiny bit?

I unbolted the output coupling and went back the next day to look at it....the leak had stopped. Left it unbolted as I was excited to get the new engine running, and fired her up. (Ran fantastically: 3000 RPM without pushing at all...I'm sure it will go higher. Our tired old A4 had never got past 2600 on a good day). The output coupling must have been just brushing the prop shaft, as the shaft started to slowly spin. After shutdown the leak had returned, but only one drip per 16 seconds.

Another possible cause is that during removal the output coupling hung up on the shaft connector and suddenly released with a thunk....ouch. Could that be the cause of the current leak? It didn't leak after that until reinstall a week later.

So, what to do now. Simply tighten the stuffing box, align again (after shoving the engine aft 1/16"), and see? Put her on the hard (ouch - almost ready to head to our mooring) and repack the stuffing? Hasn't been touched in at least 15 years....but never leaked AT ALL till now. If I do simply tighten her up, what can I clean the stuffing box with that won't cause any harm: looks quite green and crusty.

This is new territory for me, so any guidance appreciated.

Marty

[BunnyPlanet169]

Hasn't been touched in at least 15 years....but never leaked AT ALL till now. If I do simply tighten her up, what can I clean the stuffing box with that won't cause any harm: looks quite green and crusty.

A gentle wire brushing will get you to clean wrench flats, and a little tightening will probably stop the drip, but this is a long time for zero maintenance.... How's the rubber hose and hose clamps on the shaft log look?

[JOHN COOKSON]

One drop ~ every 15 seconds sounds about right to me.
The packing is water lubricated so an occasional drop ensures that the packing is lubricated and not overheating. If you tighten the packing nut so tight that there no drips you risk burning out the packing and burning the shaft.
How long has the boat been in the water? Maybe the packing needs to rehydrate a bit.
For the time being I'd just keep my eye on it.

TRUE GRIT

[Marty Levenson]

Thanks

Appreciate the guidance.

Rubber hose was inspected and reclamped about five years ago....look good and no leaks there. Maybe align, tighten to no drips, repack next spring at haul out?

To be clear: the drips are when the engine is not running. Never used to drip at all.

Boat lives in the water: just out each year for a power wash, re-coat anti fouling every other year.

[JOHN COOKSON]

You might try tightening the packing nut just a bit. Packing will wear and the drip rate will change over time. This is normal.
The drip rate is a personal thing so set it how you like it. Speaking for myself, I have the drip rate set at 1 drop every ~ 15 seconds when the shaft is turnung. There is a very rare drop when the shaft is not turning.
If you mark the packing nut with a drop of paint before moving it the fine adjustment will be easier.

TRUE GRIT

Edit: Give the packing and lock nuts a shots of PB blaster for a few days before you try to loosen them.

[MikeB.330]

Unless you're talking about a dripless stuffing box and I don't think you are, 1 drip per second is correct for a traditional packing gland with shaft NOT turning. I'd probably tighten the nut a bit if I were seeing 1 drip every 16 sec but not much.

cheers
Mike

[Mo]

Marty, the drop every 16 seconds is neither here nor there. The fact that the stuffing box hasn't been done in 15 years...and you are dropping in a new engine! Replace the packing my friend...just do it and have it done. I'll give you one guarantee right here right now...that packing isn't lasting the life of your new engine and it would have been wise to replace it while you could crawl in there with the old engine removed...without an engine in the way. So, short story...replace stuffing box packing....

All the best.

[Marty Levenson]

what's the plan?

Wow - thanks for all the replies. Quite a range of viewpoints.

My short term plan is to re-align the engine and tighten the stuffing box until no leak when not running.

Mike B: you are right...not a dripless stuffing box.

John: Is PB Blaster okay to use there? Won't harm the stuffing inside? Have read it can dissolve engine seals.

Mo: totally agree the stuffing box is overdue for repacking. Never gave it much thought when it wasn't even dripping....ever. Hindsight is 20/20: wish i had redone it when the engine was out. That space is TIGHT. Now it ill be my fall priority, unless cleaning and tightening reveals deeper issues that need work now.

Many thanks,
Marty

[Mo]

Marty, I was told by an marine engineer a few years back: "don't mess with a stuffing box until it starts leaking and tightening the nut doesn't stop it." It is certainly something that doesn't need to be done yearly or bi-yearly. Rick, who was chief engineer on 600ft long tankers said they never messed with a stuffing box until it needed doing.

[Skywalker]

Marty,

If you are going to mess with it, remove the wooden partition in the port locker for easy access.

I used to be able to get to mine from the quarter berth, but the plumbing for my FWC is now in the way.

Chris
T27 249

[Marty Levenson]

access

Hey Chris - that's a great idea....I've never removed that. I do have my heat exchanger in the star locker (and holding tank in the port), but I still think it will be easier than through the quarterberth.

-Marty

[Skywalker]

How large is your holding tank? That's a long run from the head. I have a 10 gallon under the port V berth, but there is room for a larger one. I'll get to it one day...

The port side access has been helpful with the fuel tank, too. If you ever have to remove/change out the tank, that's the way to go. When I first got my boat, the neck of the original Monel tank had broken away. I didn't know what Monel really was, so I cut it out with good tin snips, make a mock up tank that would fit out of cardboard, and had a tank made. I can remove it for cleaning without any difficulty.

One warning. The hardest part of working through that space is the slope of the hull. You will have to get creative with how you wedge yourself in there! I'm a small guy, 5'7", 150, so there is plenty of room for me. But it is a challenge to keep from sliding head first!

Chris

[roadnsky]

John: Is PB Blaster okay to use there? Won't harm the stuffing inside? Have read it can dissolve engine seals.

Marty-
YES, PB Blaster WILL destroy engine seals as well as the rubber hose on your shaft log. Be careful using it.

A good tutorial on Stuffing Box re-packing is:

http://www.pbase.com/mainecruising/stuffing_box

or

http://www.captfklanier.com/articles/art17.htm

[Marty Levenson]

PB Blaster

Thanks Jerry - I have read the maine cruising site many times: great information on lots of topics. He suggests never spraying PB Blaster, but instead applying it with a q-tip exactly where you want it.

-Marty

[Marty Levenson]

hockey puck?

People keep telling me about a teflon (I think) hockey puck that gets installed aft of the output coupling. Supposed to reduce vibration. Is that a good idea for the A4 on our Tartan 27?

Thanks!
Marty