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Old 12-28-2019, 10:27 AM   #1
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GB36 Water Cooled Stuffing Glands

One of my engines has recently suffered from overheating (under the previous owner) after consulting with a couple of mechanics one of the suggestions was to reduce the diameter of the hose from the salt water cooler to the stuffing box. This would increase the water flow through the coolers and to the exhaust, the original hose was 1/2" and the new hose being 3/8".

While removing the hose fitting from the stern gland it literally collapsed as soon as tension was applied in order to unscrew it. As you can see from the photos the fitting was in terrible condition, boat owners with this arrangement might want to have a close look at their fittings.

I managed to get the remnants of the old fitting out and retap the gland in order to install a new hose fitting but am concerned about the integrity of the stuffing gland, it appears to have suffered from electrolysis over the years with the bronze leaching from the unit, there is definitely a pink tinge to the gland.

My question is, does anyone have any idea where I can order new fittings of the same design, the only ones I can find are of the standard design with no cooling water fitting.
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Old 12-28-2019, 11:29 AM   #2
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Buck Algonquin, now Hyddrosearch Recreational makes them. See https://catalog.hydrasearchrecreatio...ning-spud-type

Jamestown Distributers among other dealers, sells their products. Pack the new one with GFO packing and once adjusted right, you will never have to touch it again more than likely.

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Old 12-28-2019, 11:41 AM   #3
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Hi Oil Gypsy,

I must confess this is a new one on me. Never seen a water-cooled conventional stuffing box, although David M has pointed to a Hyddroresearch source for same.

From your pictures, it appears that, yes, the existing stuffing box (and I'm assuming there's two) looks to be wasted, and in need of replacement. But why introduce water downstream from the packing? That part of the gland is flooded with the boat in the water anyway.

Any insight would be appreciated.

Regards,

Pete
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Old 12-28-2019, 11:44 AM   #4
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The old hose adapter fitting might have been brass instead of bronze and that could be why it had weakened.
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Old 12-28-2019, 12:04 PM   #5
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DavidM, thanks for the quick response, thats perfect, I see there are various fittings for different size hoses, which would overcome the requirement to wrap the fitting with fibreglass to match the hose diameter, which is the current arrangement.

Jungpeter, This is the first time i have seen this arrangement as well, I cant say I really like it as there is no valve or isolation, failure of the hose or fitting could result in unrestricted waterflow into the boat. I only changed the arrangement on one engine, the second is still as original, I tested the temperature of both stuffing boxes with a laser sensor and there was a difference of about +5 degrees on the side with the 3/8" hose 26C as opposed to 21C on the original (tested on a cold winters day in the PNW). The stuffing gland is about 2ft from the point where the shaft exits out of the hull, I can only assume that it is a way of introducing waterflow into the area around the stuffing box.
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Old 12-28-2019, 12:20 PM   #6
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Glad you found a replacement, I can bookmark this for when I may need it.
I would like to know why an engine overheat is related to the hose size to the stuffing box.
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Old 12-28-2019, 12:46 PM   #7
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Soo-Valley,

Both mechanics I asked suspected that the 1/2" hose was allowing too much water to bypass the cooler, the outlet to the shaft gland is on the seawater inlet end of the heat exchanger. When I took it all apart I also found that the exhaust riser was significantly blocked with sediment which again was restricting water flow. Personally I've come to the conclusion that the overheating was caused by several factors.
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Old 12-28-2019, 12:59 PM   #8
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I'm guessing the fitting was brass. The stuffing box does appear to have a lot of verdigris and it looks as though you have wire brushed it. I would file down one of the flats to remove the pink surface. If pink color extends below surface then they must be replaced.

3/8" is adequate and would result in more flow to exhaust elbow which should run a few degrees cooler as you have measured. Engine overheating would be more likely from a plugged heat exchanger. Mechanic may have cleaned it at the same time.

I have the same setup and I am not thrilled with the lack of a shutoff. It's only 3/8" and I'm guessing the bilge pumps would keep up with the est. 150 gph (plus another WAG 150 gph if water pump is running) so I'm not going to change it but I should add a bilge pump warning light to the dash. I do ensure that hoses are in excellent shape via inch by inch inspection.
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Old 12-28-2019, 01:05 PM   #9
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Quote:
Originally Posted by Oil Gypsy View Post
Soo-Valley,

Both mechanics I asked suspected that the 1/2" hose was allowing too much water to bypass the cooler, the outlet to the shaft gland is on the seawater inlet end of the heat exchanger. When I took it all apart I also found that the exhaust riser was significantly blocked with sediment which again was restricting water flow. Personally I've come to the conclusion that the overheating was caused by several factors.
Well I agree the riser restricted flow before the hose to stuffing box. maybe even the exchanger itself. I have replaced one so far and the other soon after the rad shop said it would cost too much to fix with no guarantees. My outlet hose to packing is at the end where the engine heated water enters the exchanger into the inside tubes off course. They are suggesting that inflow of salt water leaves the exchanger before it cools the freshwater. As long as plenty of water is exiting the tail exhaust it is cooling the fresh water. IMO, not a mechanic but I did stay at a holiday inn.
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Old 12-28-2019, 02:06 PM   #10
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I too have never seen a packing gland with a water cooling hose and fitting. But almost all dripless shaft logs (the ones with mechanical seals) have water hose cooling to them and they seem to do all right, although I would like to have a shut off valve near the source if the hose fails.

I would doubt that reducing the size of the hose and therefore forcing more raw water through the main heat exchanger is going to make much difference. Those heat exchanger systems have at least a two fold safety factor in them to allow for fouling, etc. Keep the heat exchanger clean and you should be fine with 1/2" or 3/8" hose.

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Old 12-28-2019, 03:39 PM   #11
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I'm going to toss in my tome about overheating causes. It may not cover absolutely everything but will address many or most causes.

I also agree that whether the hose to the stuffing box from the exchanger was 1/2 or 3/8 that amount of water would not cause an overheat. It won't help but it will not cause it.
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Old 12-28-2019, 04:00 PM   #12
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Pete. My DeFever has water-cooled boxes as I believe all DeFevers do. I suspect many boats do have them.
Quote:
Originally Posted by jungpeter View Post
Hi Oil Gypsy,

I must confess this is a new one on me. Never seen a water-cooled conventional stuffing box, although David M has pointed to a Hyddroresearch source for same.

From your pictures, it appears that, yes, the existing stuffing box (and I'm assuming there's two) looks to be wasted, and in need of replacement. But why introduce water downstream from the packing? That part of the gland is flooded with the boat in the water anyway.

Any insight would be appreciated.

Regards,

Pete
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Old 12-28-2019, 04:12 PM   #13
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My stuffing box is different than yours but I also have a water cooling hose going to the stuffing box. I attached a poor photo of it. I am redoing most of the hoses and painted the bilge so the photo is somewhat outdated.
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Old 12-28-2019, 04:56 PM   #14
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Dave, someone stole your engine! Are you still working on your tanks ?

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Old 12-28-2019, 05:01 PM   #15
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I took the engine out and then my back flared up again so I decided that I had better not take the tank out because I might not be able to get the new one back in. I have had about 8 procedures on my back this year. I guess that I should have done the tanks the last 2 years... I am doing a lot of cleanup on the wiring, new hoses, paint the bilge, new aft head, more LED lighting in the engine room and a Sweettank on the holding tank. A lot of this stuff would not have been doable with the engine in so I guess I will have to be satisfied with this work.
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Old 12-28-2019, 08:26 PM   #16
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That stuffing box should be replaced most likely due to the pinking indicating loss of the alloying metal leaving only a weakened copper matrix, not a solid metal anymore..

I forgot to suggest that the brass fitting used to reconnect the hose should not be relied upon long term. It has become very near impossible to find real bronze in small fittings so brass may need to be used.

But a big caveat, Install a new one every year as it will corrode MUCH more quickly than the stuffing box it is mounted to.

The options instead of brass are SS 316 or a high quality Nylon GLASS reinforced fitting. I would still check the SS ftg every year although with moving water it should last reasonably well. Just keep checking it every year.
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Old 12-28-2019, 09:26 PM   #17
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C lectric is correct. The new hose to pipe elbow shown in the second picture is yellow brass. It won’t last long in that application.

There is no easy replacement. I think you could do it with a Bronze Street Elbow, a bushing and a 1/8” pipe nipple. Just cut the threads off one end of the nipple and double clamp the hose on the smooth part of the nipple. It won’t come off.
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Old 12-28-2019, 09:35 PM   #18
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I forgot to suggest that the brass fitting used to reconnect the hose should not be relied upon long term. It has become very near impossible to find real bronze in small fittings so brass may need to be used.

Agree completely yellow brass and seawater don't mix long term. I bought red (naval brass) nipples, cut the in half, and turned barbs into the smooth end turning them w/ drill against a triangular file. 3/8" hose goes well over 1/8" NPT nipple and 1/2" hose on 1/4"NPT nipple. (1" hose on 3/4" NPT too) This kind of brass will stand up to seawater.

Plastics... not for me below waterline.
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Old 12-28-2019, 09:38 PM   #19
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Defender has bronze fittings. They have a 1/2” street ell and a NPT to hose barb fitting. The only problem is the hose barb is 3/4” so you would have to reduce the pipe to a smaller size.
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Old 12-28-2019, 10:57 PM   #20
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One thing that I didn't mention was that after removal of the old fitting I had to tap out the threads on the gland, the thread turned out to be 1/4" NPT. One thing that I've wondered about is whether the hose size is critical as the fitting size would act as a restrictor. Is this correct.
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