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Old 06-14-2015, 12:20 PM   #161
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Marin,
Not if the thermostat was functional.
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Old 06-14-2015, 12:37 PM   #162
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It wont affect engine temp. It will overload the exhaust. The HX is large enough to handle the flow but if she dumps all of the water into the exhaust it will compete with the exhaust gas for available space, the water will win. Bad juju for engine. A gate valve after the HX and befor the muffler is the fix, just like on most older sporties, just adjust the valve until you get the flow out of the exhaust that you want. Again, not rocket science. I would lower the rpm of the pump with a bigger pulley. Does Janice not have "the book", Boat Owners Mechanical and Electrical etc. or the other must have mechanical systems book (drawing a blank) by ???.
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Old 06-14-2015, 12:45 PM   #163
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Marin,
Not if the thermostat was functional.
Yes, I guess I answered my own question in my own post, didn't I?. Thanks.
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Old 06-14-2015, 01:41 PM   #164
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Putting more raw water through the engine's heat exchanger is analogous to driving a car fast and getting more air flow over the radiator. No harm because it is the thermostat on the engine's cooling system that regulates engine temperature. Once you get enough flow to carry away the heat, more doesn't help or hurt.


As you note some engines have other heat exchangers with raw water feeding them that are not regulated such as the transmission in your boat. Those will get cooler with more flow. But that little Kubota doesn't have these.


And to put it in perspective your 5.8 liter engine needs a 1" pump. I am suggesting a 1/2" pump for the little Kubota which should produce 1/4 the flow of a 1". The Kubota engine is about 0.7 liters, so it sounds a bit big at 1/4 the flow for 1/8 the liters. The pump also needs to be matched to the mixer and I think that the Yanmar mixer that I referenced uses a 1/2" pump.


The basic requirement for a raw water pump is to put enough water through the heat exchanger to carry away the heat at wot and completely fill the spray nozzle holes in the mixer at idle so you get a good spray pattern. Any more is wasted although most engines I suspect have twice the flow required to meet these criteria to allow for marine growth and busted impeller vanes.


But you realize, all of this interesting technical discussion is probably wasted.


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Old 06-14-2015, 02:03 PM   #165
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Driving the car faster to get more air to cool better only works to a point of diminishing returns. Eventually the speed requires more power generation (heat) than the radiator can suplant, regardless of airflow. Oh, I think I left a window open, I'm feeling a drift
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Old 06-14-2015, 02:40 PM   #166
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A little birdie told me it might be just easier to do a T-bypass for excess pump flow...pretty common on genset installs was the reference point...


here is the comment...


"As far as the exhaust system is concerned, simply teeing off a bypass valve before the mixer or spray ring will assure proper performance of the mixer and the lift muffler. That is a common means to regulate exhaust water flow to control backpressure and prevent flooding the lift muffler or water separator. We do that all the time. It is far far more practical than trying to calculate pulley size or pump capacity."


To be fair....without more explanation or taken too much out of context might not answer all possibilities...but this sounds like a simple, realistic approach too.




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Old 06-14-2015, 03:23 PM   #167
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Yes a bypass would work, but it depends on the skill of the operator to adjust it right and keep it that way ;-).


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Old 06-14-2015, 03:31 PM   #168
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And guessing the heat removal and exchanger size is just as much as a gamble without the designer specs.
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Old 06-14-2015, 04:32 PM   #169
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It wont affect engine temp. It will overload the exhaust. The HX is large enough to handle the flow but if she dumps all of the water into the exhaust it will compete with the exhaust gas for available space, the water will win. Bad juju for engine. A gate valve after the HX and befor the muffler is the fix, just like on most older sporties, just adjust the valve until you get the flow out of the exhaust that you want. Again, not rocket science. I would lower the rpm of the pump with a bigger pulley. Does Janice not have "the book", Boat Owners Mechanical and Electrical etc. or the other must have mechanical systems book (drawing a blank) by ???.
Mechanic had discussed a gate value and adjusting the speed of water flow with same.

Of course I have Calder's. And it's well thumbed. I even recall the first day I could put the thing away -- nothing to fix!!! -- and how I made phone calls to friends afloat.

I did not confess why I was so chipper. Putting away Calder's was the cause. I think I even wrote about it in the Log Book.

Another question came up... A good friend of mine has a classic Hatteras. He swears that the reason his Detroit diesels are still running well is because after each run he flushes the cooling system with fresh water. It's a raw water boat.

Would something like that abate the potential damages from salt water in that SS box of mine? Simply at the end of the day run the motor sucking fresh water for five minutes to replace the salt water...

Is that something that in your view would help?

And thanks for your patience. I'm getting out Calder's now. Third Edition.
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Old 06-14-2015, 04:37 PM   #170
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P.S.- I know the exhaust elbow is the Ideal Solution. I'm wondering if what I have can be used in the interim successfully for a longer duration with a fresh water flush.

Ditto the elbow. My friend in St. Pete says that's the first thing I should do once I'm there.

I won't have that done here (Job scope creep)
But soon? It sure does sound like a Good Idea to me.
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Old 06-14-2015, 04:56 PM   #171
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Good question Janet,
I can't remember .. is the seawater pump issue solved? Has it got a rubber impeller? With that problem solved you can run the engine. Lots of vibration and heat but if the "heat exchanger" dosn't fall off or come apart you should be able to limp along. How long and how far is a very open question.
I don't see what the flushing has to do w it unless you're thinking of running the engine w seawater circulated by the engines coolant pump .. How would you prime it? Could work if the engine was below the WL. It's at least questionable if the engines water pump would be able to pump through all the additional places like the exhaust and the seawater intake. Is that what you're thinking?
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Old 06-14-2015, 05:32 PM   #172
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Don't use a gate valve to throttle fluids. The gate rattles in the seats until something (the stem or gate, usually) breaks.

Use a globe valve or ball valve.

Of course throttling the suction or discharge of a positive displacement pump is not a great idea anyways.

Yes, you have an over sized pump. Consider a pump return loop or outlet branch to another discharge.

Yes, you have too large of a heat exchanger. Bypass or plug tubes.

Yes you have a 2 bolt flange on the manifold inlet. Might need to play with different gaskets or seal externally.

Yes, schedule 40 316 pipe will not provide great heat transfer to the exhaust going through it. The "manifold" is, ahem, unusual

Yes, the "manifold" might chloride stress corrosion crack. Might. Might not.

Yes, the U bend of the pipe seems shallow. Use an injection nozzle to direct raw water inlet downwards.

Yes, the pretty welds are on the outside of the box, instead if on the inside, where they need to be.

But. I think you just need to finish it off and run it. It will either fail quickly, or it may just work. Hopefully long enough to go somewhere else. Monitor and fix everything later. As Voltaire said, the best is the enemy of the good.

It may not be engineered (it is not), but you aren't going to know how well or poorly it is going to work unless you run it.
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Old 06-14-2015, 06:08 PM   #173
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There is no shop manual that I can find for the Kubota 720-40. I've looked. Once I find something that will suffice, I'll buy it or have it printed if it's a digital version. I need paper versus screen time when studying something like this.

Janet - Your engine (less the marinized bits) is the same as the Beta 20.

You can find a manual for them here:
Beta 20 - Beta Marine
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Old 06-14-2015, 06:46 PM   #174
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Inserted below, in bold text.

Quote:
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Good question Janet,
I can't remember .. is the seawater pump issue solved? Has it got a rubber impeller? With that problem solved you can run the engine.

I asked about that and was told it's a Jabsco. (variable pulley)
Also, the numbers on the top say 6523-8000


Picture here:


Lots of vibration and heat but if the "heat exchanger" dosn't fall off or come apart you should be able to limp along. How long and how far is a very open question.

There is a cradle built for the heat exchanger. It's already mounted to the forward bulkhead in the engine room. It is above both the manifold and the Vernier lift water muffler.

This is a much smaller one than I had on the Beast. Then I had two large Centek tube-types.

Pictures will be forthcoming however since the new $130 A/C unit is due in tomorrow I'm waiting until then before bilge diving...


I don't see what the flushing has to do w it unless you're thinking of running the engine w seawater circulated by the engines coolant pump ..

No salt water will ever enter Betsy. The whole complication with this manifold system was as a direct result of making sure that salt water won't get into my motor. She'll have a closed system with the coolant running from the heat exchanger, through the manifold then back through the engine. Repeat.

Raw water (salt) will come in at the sea strainer and flow through the heat exchanger. From there, some will be injected into the pipe just prior to it exiting the stainless manifold. That (theoretically) will cool the pipe enough that the hose (runs from there to the water lift muffler) will be undamaged.

Here, I've read that too much water is either a bad thing or nothing to worry about. The boys in Carrabelle had talked about adjusting the water flow for when I'm running.

I specifically asked if this was something I would have to mess with when underway. It was stated that once the adjustment was made it was "lifetime" and I would not have to touch it again.

There was much discussion here (Carrabelle) about the merits of a radiator, fans and more. A dry exhaust too came into the arguments. Ditto Keel Cooler though I was not in favor of a keel cooler.

I've been known to test the depth with my skeg. And too, I just don't like 'em. Ditto the dry exhaust. Here, in the south that won't work on a boat as small as Seaweed.


How would you prime it? Could work if the engine was below the WL. It's at least questionable if the engines water pump would be able to pump through all the additional places like the exhaust and the seawater intake. Is that what you're thinking?
I must not have explained myself well. I wondered if running a gallon of fresh water through the salt side of the cooling system would abate any issues of salt and hot gasses at the exit of the SS box.

If I understood it correctly, a friend has a hose gizmo tee-d off his sea-strainer. Just prior to shutting down the engine he turns on the fresh water and shuts the thru-hull. Thus his risers(?) do not have salt water sitting in them between runs.

Since one of the parts that was brought up previously in this thread was the point of salt water at that nipple inside the SS manifold (corrosion at the weld) I wondered if fresh would abate any possible damage.

As for another comment regarding the welds outside being spectacular and those inside questionable... mechanic was there and saw inside. He states it's just as good inside as out.

Of course, as has been pointed out, there's no way to monitor that because of the nipple location being hidden. I would not know when failure was imminent.

And I don't want salt water in the engine. For now, I am hoping that they mechanic actually follows through and has the worker here this week. Hopefully on Tuesday.

Once again, thank you for all the input. I'm learning. And I will be printing this out (hint M!!!) for inclusion in my stuff about the motor. For the Kubota 720-40 (what I have) thus far I have not found a shop manual. Nor a repair manual.

I've got Calder's but am looking for the Real Deal. Even if it's a PDF, I can have it printed and bound at a UPS store. They do that stuff quite reasonably.

I've got the one from my BOB engine and will sell it on eBay at some point. Unless someone here has an MD2 and needs a shop manual. Printed on decent quality paper with a plastic cover, spiral bound it lays flat and is pretty doggone nifty.

Pictures will be coming once I'm sitting in air-conditioning...!

And thanks again.
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Old 06-14-2015, 06:59 PM   #175
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Janice,

Do you have a drawing showing the flow of water i.e. what hoses run to where? I attempted a guess in post #142.
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Old 06-14-2015, 10:29 PM   #176
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Do you have a drawing showing the flow of water i.e. what hoses run to where? I attempted a guess in post #142.


It's pretty close to what you have... There is no hot water heater. The hoses have not been attached but as I understand it, you're correct. The hoses are next, and then the final adjustments for cooling.

From the SS box, we go downward to the Vernier water-lift muffler (to quiet the sound) then up (loop) and down (out side of boat)... the exit thru-hull is about a foot above the waterline on the starboard side.

Oh, and the support for that SS manifold has to be cut out. The pattern is in the shop. No work here on Mondays. The shop is closed.

Also my bigger alternator needs to be mounted on the engine. The little one that came with the engine has been removed.

I see hope. Thanks to AusCan, I've got a manual. It's already been sent to the printer so by the end of the week I'll have a repair manual, and associated goodies. Thanks so much to him. That will be a big help.

It included wiring diagrams and more.
There are sections on wet exhaust and dry, keel coolers and more. It looks fascinating. There are even checklists. I like my lists.

J

Oh, and I'll take pictures once it's cool. Hopefully that will be tomorrow. The UPS driver was called and if my a/c is here, he'll deliver it right to Seaweed. Yeah.

That will be mighty fine. When it's this hot I simply wilt.

My get up and go wants to do nothing. I'll tell you how bad it is: I have a stand for my kindle and don't even hold it when reading. I do reach out and tap the page advance button all by myself. Only because I don't have a way to do it automatically.

When the a/c arrives I fully intend to install it immediately. Then I'll turn it on high, grab Skipper and take my kindle to bunk. When I wake up, life will be better, or at least cooler
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Old 06-15-2015, 03:17 AM   #177
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Hi Janice aboard Seaweed.

Shipmate I have no advice for you as your experience aboard boats far exceeds my own.

All I have to offer you is good wishes in your endeavours to motorize your beloved craft.

Fair Winds and Calm Seas. Follow your own counsel and course.

Good Luck Madam. [ with the greatest respect ].

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Old 06-15-2015, 08:35 AM   #178
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Quote:
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Janet - Your engine (less the marinized bits) is the same as the Beta 20.

You can find a manual for them here:
Beta 20 - Beta Marine

Quote:
Originally Posted by janice142 View Post
I see hope. Thanks to AusCan, I've got a manual. It's already been sent to the printer so by the end of the week I'll have a repair manual, and associated goodies. Thanks so much to him. That will be a big help.

It included wiring diagrams and more.
There are sections on wet exhaust and dry, keel coolers and more. It looks fascinating. There are even checklists. I like my lists.

If that Beta 20 manual also shows the water pumps, heat exchangers, and exhaust elbows and so forth that they routinely use... it might be giving you a shopping list of parts (and part numbers) for future improvements.

-Chris
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Old 06-15-2015, 08:43 AM   #179
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Another question came up... A good friend of mine has a classic Hatteras. He swears that the reason his Detroit diesels are still running well is because after each run he flushes the cooling system with fresh water. It's a raw water boat.

Would something like that abate the potential damages from salt water in that SS box of mine? Simply at the end of the day run the motor sucking fresh water for five minutes to replace the salt water...

Is that something that in your view would help?

Quote:
Originally Posted by janice142 View Post
P.S.- I know the exhaust elbow is the Ideal Solution. I'm wondering if what I have can be used in the interim successfully for a longer duration with a fresh water flush.

Quote:
Originally Posted by janice142 View Post
I must not have explained myself well. I wondered if running a gallon of fresh water through the salt side of the cooling system would abate any issues of salt and hot gasses at the exit of the SS box.

If I understood it correctly, a friend has a hose gizmo tee-d off his sea-strainer. Just prior to shutting down the engine he turns on the fresh water and shuts the thru-hull. Thus his risers(?) do not have salt water sitting in them between runs.

Since one of the parts that was brought up previously in this thread was the point of salt water at that nipple inside the SS manifold (corrosion at the weld) I wondered if fresh would abate any possible damage.


I know lots of gas guys use a fresh water flush -- sometimes, occasionally, after every run, whatever -- and I think that's primarily because their exhaust elbows (and risers and so forth, if equipped) are cast iron.

The Detroits in your bud's Hatt may be running well more because he pays beaucoup attention to his engines (witness: incessant flushing) rather than because of the flushing itself.

Still, probably can't hurt... but I'm not sure I'd say it'd extend the life of good stainless enough to be worth the time. Others here would know better...

FWIW, Groco makes a "flush adapter" that many use for easy flushing. Check their website for pics and details.

-Chris
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Old 06-15-2015, 08:53 AM   #180
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Gate valves are used almost exclusively in this type of situation. once it has been correctly adjusted (by taking temp readings from the exhaust under max load) it is never touched again, thereby corroding into being unmovable. Its been done this way for many years, it works. A rubber impellor pump is not really a positive discharge. DO NOT plug tubes in the HX, it wont matter if its to large, it wont affect (overcool) the engine. Thermostat thingy, ya know !! Realistically, to get to where she needs to go Janice could just point the exhaust pipe straight up, run raw water thru the engine and dump it overboard and be on her way. No harm done, short term anyway.
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