SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: iloveitloud on May 04, 2011, 06:53:10 PM
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Can I use regular graphite impregnated pump shaft seal rope instead of the stuff you get right from Berkeley, or other aftermarket places?
I already have some, and don't want to pay the $15 bucks Berkeley throws on to every order----even if it is literally just "one" screw, or nylon bushing.
Also, do I have to cut it into 5 pieces, and overlap the seams, or can I just wrap a long piece around the shaft a few times, and tighten it up like that? Thanks in advance!
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curious to see what the answers are here, because me and nordic454 pondered this exact same thing...even the whole wrapping it besides just individual pieces...i would almost venture to say that the wrapping would almost be better, and of course the graphite is better
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IMO a packing seal is a packing seal. If you assemble it correctly and understand which way to wind it and why, it will do it's job.
As an alternative, I prefer real seals....the kind made of rubber. HTP sells a nice setup, or a housing could be machined and some off the shel seals installed to get away from the rope seal all together
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When replacing the packing you need to make sure that all of the old packing has been removed.
Install only rings of packing and stagger the joints. Do not coil the packing using only one piece.
Graphite impregnated or teflon impregnated will work in a water pump application.
The main difference between our water pumps and the millions of other water pumps is the variable and higher shaft speed we turn.
A mechanical shaft seal would be nice but they are expensive and very sensative to dirt and grit.
My $0.02
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I can see some logic in useing pieces instead of one long piece coiled up. I am assuming that multiple pieces would be much less likely to bind up, or tighten up, and spin in the housing. Or, am I way off? My pump seal leakes a little bit at speed, and my hand hole cover has a few cracks too, so I need to freshen up those things. I have a JE-A pump, and really don't want to do a full rebuild on it this year, and I am hopeing to nurse it along for one more season.
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Industry standard is to use packing rings. Been done that way for many moons.
When the pump is turning you want a small amoount of water leaking from the packing.
It helps cool and lubricate the shaft and packing.
If you tighten it up to stop all leakage you will damage the shaft and burn the packing.
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So... At normal cruising, my seal leaks about a gallon every 20 min or so. It seems like alot to me, and is a bit of a pain cuz I have to run the bilge pump every little while. Plus, it is always wet under the motor so I always have shop vac out the water that doesn't drain out the plug. I also replaced the gasket on my handhole cover, so I am hopeing that helps the sucktion piece "suck" more, and helps slow down the front seal leak.
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The leakage rate you described is way to much.
You should have minimal leakage, drops not stream of water.
When you dig out all of the old packing, inspect the area on the shaft that the packing rides on.
If it is nolonger smooth, you need to replace that shaft sleeve.
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I also replaced the gasket on my handhole cover
Gasket or o-ring?
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When the pump is turning you want a small amoount of water leaking from the packing.
It helps cool and lubricate the shaft and packing.
I just rebuilt my pump and followed the Berkeley manual when installing and setting the packing rope, I don't have any leaks from mine and I would like to think I did exactly as the Berkeley manual/spec requires. Not sure if I will have any shaft issues but I don't think Berkeley ment to add water into your boat when they designed these pumps, does anyone else have leaky packing after their rebuild or know this was the norm?
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Leakage rate is drops, not a stream.
The problem with tightening the packing gland until there is no leakage is that you may overtighten and burn the packing and damage the shaft sleeve. Once the packing is burned or the sleeve scored, you will keep tightening it until you have no leakage, then the cycle is repeated.
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Industry standard is to use packing rings. Been done that way for many moons.
When the pump is turning you want a small amoount of water leaking from the packing.
It helps cool and lubricate the shaft and packing.
If you tighten it up to stop all leakage you will damage the shaft and burn the packing.
X's 2 this was a good answer , also if you ran a continous piece you Packing gland would be cocked (not square) We buy (and sell) this material in 100 foot rolls likely is a guy could find it in bulk and do the same tom
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I can see some logic in useing pieces instead of one long piece coiled up. I am assuming that multiple pieces would be much less likely to bind up, or tighten up, and spin in the housing. Or, am I way off? My pump seal leakes a little bit at speed, and my hand hole cover has a few cracks too, so I need to freshen up those things. I have a JE-A pump, and really don't want to do a full rebuild on it this year, and I am hopeing to nurse it along for one more season.
dude fix that. I think i have one i will give you.
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An integral part of a quality pump rebuild is to verify shaft straightness, and then take a truing cut (usually several) to the shaft where the rope seal runs. We use a crankshaft polisher and a lathe to polish the shaft to a very fine finish before the shafts reinstallation. If the shaft is only polished and not trued first, the new rope seals life will be shortened because the worn shaft will still not be totally round or true to the shafts center. Remember that the stock stuff lasts 20 or 30 years with proper care and maintenance, but then again the new shaft was true and factory polished. If you don't true and then polish the shaft during the rebuild, in some cases the new rope seal can destroy itself in several outings. Since the rope seals typically last 20 to 30+ years, their replacement with anything else in MY opinion is just an elegant solution to a non-existant problem. Its true, that rope seals do have a few horsepower more loss from drag, but since a jet requires 20 HP per MPH gain anyway, and I am not chasing any national records, I still don't care. You still should true and polish the shaft before using a lip seal retrofit kit to ensure a long service life. Every shop has their own way of doing things, this is how we choose to do it. We have had excellent results. As far as seal material goes, both types work well when installed correctly. We also like billet inducers, real boobs, green eyed redheads, fast cars, motorcycles, boats, and jumping out of perfectly good airplanes. What the heck do I know. Everything here is just an opinion. TIMINATOR
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A packing gland is one of the simplest and forgiving sealing methods in the industry. The one point to be aware of is, always start with the gland on the loose side and adjust from to much liquid leaking to the correct amount. If you start out tight with standard rope packing you can glaze the packing from it running dry and tight. Not to mention possibly damage the shaft. Teflon and graphite impregnated packing is more forgiving in this area but set up right, rope will work well.
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Just put in some new graphite impregnated shaft seal. It is "COLD"---58 degrees,--here again, with rain expected for the next 5-7 days, so it will be a bit before I get to run it, and tighten it up as needed. I did get to run the boat, but I did not touch the old seal since last season, but it did not leak as much as it did last fall. I posted earlier that my hand hole cover had a few cracks, but I meant that the O ring had a few cracks, and I replaced that. I ran the boat Saturday, and was pretty happy with how it launched. I did not try a top end run, but it seemed to have better thrust, with less RPM than it did before I fixed the handhole cover. Also, the mods I did to the diverter worked great, and the rooster tail is really high, and long now.