Stuffing box question

[Ajay73]

I have a 1980 C27 with a 5411 Universal diesel. I need some information from C27 owners with the same engine. My question concerns the stuffing box. On my boat the stuffing box heats up a lot after some time motoring (maybe after 15 minutes running). My stuffing box is very close to the shaft coupling and, of course, the transmission. I'm wondering if the heat I'm feeling in the stuffing box is really coming from the transmission and engine, and not from the stuffing box. The shaft coupling gets hot as well. By hot I mean you can't keep your hand on the packing nut for more than a second. I'm assuming here that all the Universal 5411 C27's are set up about the same with only about an inch to an inch and half of shaft showing between the stuffing box and the shaft coupling.

 

[Blindnavigator]

Is the stuffing box dripping a few times a minute while it's turning? It should be cool to the touch-I'd back it off some, and check the packing. I shoot some Teflon grease into the packing once a year and it seems to last forever.

 

[Ajay73]

Is the stuffing box dripping a few times a minute while it's turning? It should be cool to the touch-I'd back it off some, and check the packing. I shoot some Teflon grease into the packing once a year and it seems to last forever.

I had a diesel mechanic at our marina align the engine at the beginning of the season and he put in new 1/4 inch flax packing. I recently backed the packing nut off a quarter turn and got a drip about once every 2 to 3 seconds with the engine off. I tightened the packing nut slightly until the drip stopped. At this adjustment I don't get a drip while running. The adjustment is so sensitive I can't find a good middle ground where I get a drip while running and no drips when docked. One other question is about the 1/4 inch packing the mechanic put in. The spec for the C27 I think is 3/16 inch. I'm wondering if that is part of the problem. Also, with the stuffing box so close to the transmission wouldn't the stuffing box pick up a lot of heat from the transmission which is obviously hot when running. The coupling, which is a flexibe type is also hot to the touch which I assume is so because of heat transfer from the transmission.

If you would could you check the temperature of your stuffing box after a run to see how hot your box is. I mean just feel how hot the stuffing box is. Thanks for your reply and help.

On second thought I just noticed you have a Pearson 30. I need a comparison with a C27 with my engine.

 

[Don S/V ILLusion]

Re: C27 5411 Universal Diesel Question

I don't know what difference it makes = P 30 vs C27, etc... Many years ago, I had an Ericson 27 with the same transmission and engine as your C27. That was before teflon impregnated packing material existed and we used the old fashioned flax stuffing. The stuffing box was never "hot"; warm, yes - hot, no.

Why don't you measure the diameter of the shaft and the ID of the stuffing box to determine the proper size stuffing?

 

[Ajay73]

I don't know what difference it makes = P 30 vs C27, etc... Many years ago, I had an Ericson 27 with the same transmission and engine as your C27. That was before teflon impregnated packing material existed and we used the old fashioned flax stuffing. The stuffing box was never "hot"; warm, yes - hot, no.

Why don't you measure the diameter of the shaft and the ID of the stuffing box to determine the proper size stuffing?

The difference is because I want to compare apples to apples. The P30 may have a lot more shaft between the stuffing box and and coupler which would effect how much heat is picked up from the transmission/engine. The proper size packing is the 3/16 inch for my 1 inch diameter shaft. How do you know your stuffing box was warm? Did you actually put your hand on it after a run. I suspect that many aren't people don't even consider this is an issue.

 

[Don S/V ILLusion]

Re: C27 5411 Universal Diesel Question

Thermal scanner measurements confirmed by the traditional tactile test, i.e., it felt fine!

Shafts are excellent heat conductors. After heating up, the shaft would be expected to be of uniform temperature throughout that length. I didn't do well in thermodynamics in college but some things must have penetrated my haze.

 

[Ajay73]

Thermal scanner measurements confirmed by the traditional tactile test, i.e., it felt fine!

Shafts are excellent heat conductors. After heating up, the shaft would be expected to be of uniform temperature throughout that length. I didn't do well in thermodynamics in college but some things must have penetrated my haze.

The shaft isn't going to be warmer at the coupling than inside the stuffing box? I once heard an engineer espouse one law of thermodynamics was that heat runs from the higher temp to the lower temp in any medium. Sorry to offend but I'm just trying to get a practical answer to my problem here.

 

[Stu Jackson]

Re: C27 5411 Universal Diesel Question

Try this: you've already put your hand on the box, why not put your hand on the transmission and then on the shaft, too?

 

[Ajay73]

Try this: you've already put your hand on the box, why not put your hand on the transmission and then on the shaft, too?

Is this an attempt at humor? If not they are all very hot.

 

[Stu Jackson]

Re: C27 5411 Universal Diesel Question

Nope, it was just a logical next step to avoid "engineering" and buying a temp sensor. So what do you think that's telling you? Is the heat going from the box to the transmission, or vice versa? Is the engine heating the transmission?

Really, make it simpler: back off the box until it drips and see if it's still hot. But backing off a box is not the right thing to do, so if it was my boat, I'd simply redo the stuffing properly.

Good luck.

 

[jrowan]

Re: C27 5411 Universal Diesel Question

I have a 1980 C 30 with the 5411 & original Hurth transmission as yours.
My packing nut also drips ervery 2 - 3 seconds whether the engine is running or not.
I can't even tighten my packing nut down any further. I want to replace mine with a PSS shaft seal to get a dry bilge, but I know that the packing has to drip some or the shaft will heat up & score it permanently. Sounds like your packing nut is too tight. Try to find a spot in between 2-3 sec. drip and none at all. Without a drip high heat buildup will result. Although to be honest, I've never actually touched the shaft or packing while running the engine. I've had some experience with this tough lil engine, so let us know if you have further questions.

 

[Ralph Johnstone]

Sorry to Add Thermodynamics to This ..................

....................... but perhaps the following may give you some insight as to who's adding heat to who.

As you've correctly stated, it's temperature that causes heat to flow. Whoever has the higher temperature is the culprit (source of heat) here.

The experiment runs as follows:

1. Start with the engine, shaft, and stuffing box cool and at the same temperature.
2. Further cool the coupling with a block of ice you've tailor made in your freezer. Make the block big enough so it lasts for a good while.
3. When the coupling is cold, get your lab partner (first mate) to start the engine. You get to stay down below and make the observations.
4. Keep the ice on the coupling.
5. After 30 seconds, remove the ice and run the engine up to cruising speed. Doing this once in its life isn't going to kill the engine. The reason for the rapid run up is that we want the transmission and box to start off approximately together. We don't want the engine heating the transmission much in advance of the shaft starting to turn in the box.
6. After about five minutes of running, have the engine placed in neutral and touch the coupling, shaft and box ASAP to see which one is warmer. An infrared sensor would work far better but as you don't have one ..........................
7. Have the engine placed back in gear, run up to cruising speed and repeat the temperature measurements at longer intervals.

This MAY enable you to tell which one is heating up first. It's dirty and it's crude because you're using your sense of feel to determine the relative temperatures. You also have to keep stopping in order to feel the coupling. If you were to use an infrared gun, you'd have a definite answer in very short order.


Let us know what you find if you try this method.

 

[Ajay73]

I see that these infrared thermometers are not that expensive. I'm going to pick one up today and start checking temps.

 

[Maine Sail]

Sounds like you are possibly using the wrong size packing. Most of the Catalina's take a 3/16" packing.. Occasionally, when their supplier could not ship the packing glands, they came out of the factory with a box that could take 1/4" but these were rare compared to the 3/16" boxes..

 

[71175]

If the box is setup properly you shouldn't get any heat from it. The trans will get very warm/hot.....( make sure fluid level is correct), Engine without a doubt will give off allot of heat. If the stuffing box drips a little more then it should that's not a bad thing....you definitely don't want to run it dry.

 

[Steve Walsh]

The stuffing box on my Universal M-18 has teflon packing. The stuffing box and nut stay pretty much abient temp, though it is slightly warm after 3 hours of motoring. Trans is very warm, but not too hot to keep my hand on it. Coupling is warm, shaft is same as stuffing box. No drips in slip, running it drips 2-3 a minute. Obviously, I test these temps when the engine is off. Agree with the others, sounds like you have the wrong size packing.

 

[CalebD]

When comparing 1/4" to 3/16" packing the difference is obviously 1/16" but since the packing is wrapped around the shaft the difference is actually doubled so 1/4" packing provides 1/8" wider packing overall. The wide packing will constrict water flow and chafe the inside the stuffing box and the shaft.
Pull out the 1/4" packing material and re-pack with the correct 3/16" size packing.

 

[Michael D]

A few thoughts. There are two types of stuffing. One is dripless and will not let water pass through. One allows the passage of water. My system is supposed to be dripless but a lot of the problems, such as you described, disappeared when I adjusted for allowing those drips to occur.

Second what is hot? For example what is hot or just hot enough at the stuffing box, cutlass bearing, stern gland etc. ? My manual faliled to address that.

Third you are in northern waters still quite cold. Down here it cools to warm in the night (Sea of Cortez) so thats bound to cause a difference.

Fourth is the boat loaded down for use. Often we cruisers pack a lot of stuff since we're away from home for a long while and the engine drive train prop are pushing a much heavier load.

Heat is at the source and the ambient heat transferred from one part of the system to another. Using that infrared thermometer will help a lot. Using the intake out take as a comparison check raw water in, exhaust water out, intake and outlet at the heat exchanger or intercooler, engine block where the temperture sensor is located, transmission and stern gland. Also water temperature before and after the pump. Those spots will tell you a lot. We fouond one collapsed hose from the transmission back to the water pump as a result of that little gadget. it had been trimmed and shortened one too many times.

Beyond adding those comments I'm enjoying the thread and it's a great return to sailboatowners cruising forum.

Michael D.
Se Langt
San Carlos/Guaymas, Mexico

 

[Ajay73]

I see that these infrared thermometers are not that expensive. I'm going to pick one up today and start checking temps.

Picked up IR thermometer from Lowes, a General for $40 this morning. Ran the engine in gear at the dock probably for 15 to 20 minutes maybe a little longer. Took several readings. The engine block topped out at about 153 F, the water intake hose just above the seacock was read at 125 F(my system recirculates water until temperature rises and the thermostat opens), the transmission got to about 100 F and the stuffing box at the part just forward of the edge of the hose was at 142 F. The packing nut read about 135 F. That's obviously too high. Before I started the engine I further loosened the packing nut until I was getting a drip once every 20- 30 seconds. After starting it I didn't get any drips while the boat was in gear and the shaft turning. One of the things I wondered about was the position of the water leak. It seemed to be coming out of the rear portion of the packing nut. Should I see water coming out of the forward edge of the packing nut by the shaft?

 

[Ajay73]

When comparing 1/4" to 3/16" packing the difference is obviously 1/16" but since the packing is wrapped around the shaft the difference is actually doubled so 1/4" packing provides 1/8" wider packing overall. The wide packing will constrict water flow and chafe the inside the stuffing box and the shaft.
Pull out the 1/4" packing material and re-pack with the correct 3/16" size packing.

I kind of agree with you in that I think the larger size greater restricts water flow. That 1/4 inch is 33% bigger than the 3/16. I called another diesel mechanic that works in the area and he said he didn't think it made that much difference. He also said that the stuffing boxes do get hot and was indicating that just getting warm was not the normal case.