Cooling system in 4-107

[Capt Dan]

I have a Perkins-4-107 in my new to me Willard 30 and a question about engine exhaust cooling.* After the salt water has done it's duty to the heat exchanger and oil coolers there is a T in the line before it enters the exhaust riser.** This allows part or maybe most of the salt water to exit thru a thru hull at the water line in the side of the hull.** With back pressure from the diesel, I am not sure any water would ever make it to cool the actual exhaust line.** I have not had this boat in the water and after seeing all the sketchy repairs made by the previous owner hesitate to ask any advice there.

Any help?

 

[FF]

Usually on a tiny engine like the 107 the entire cooling volume can be dumped thru the exhaust with no hassle.

I haVE SEEN THE SETUP YOU HAVE ON MUCH LARGER ENGINES where there is no way the exhaust could handle the water volume.

Usually there is a valve on the overboard side that allows the exhaust to get enough water.

Your exhaust back pressure is minor , probably only a pound or twi, so trying it before modidying might be worth while.

 

[Capt Dan]

Thanks Double F,

I am installing a drip-free stuffing box, PSS shaft seal and I am thinking about running that excess water into the nipple on the shaft seal.* The difference there is that the shaft seal is always below the water line, where as the old thru hull is sometimes.

I have a friend that has a portion of his sea water cooling water go into a T in his cockpit scupper so whenever the engine is running, he can see that there is water pumping.

On a different note, As the Willard has a space for a very high loop in the exhaust, I was also considering having the exhaust run dry for about three feet until it reached the apex of this high loop, then ad the water to cool the rest of the exhaust.* With this I could eliminate the space consuming water lift muffler, and the extra thru hull, and virtually any chance of ever getting water back into the engine.* I would still maintain the T fitting , leading some water to the shaft seal, but the T would be about 2 feet above water.

I would however need to heat wrap the dry part of the exhaust.* Any thoughts?

 

[Nomad Willy]

Hey Willard Man,
My Nomad had a 4-107 before I repowered. My sea water comes through the kingston valve (sea cock) goes through through the oil cooler, through the engine coolant heat exchanger and into the top of the exhaust riser. I have a "T" in the hose just before it gets to the top of the exhaust riser and a SMALL hose that (like yours) goes to the PYI dripless seal. My exhaust riser was made by National Marine Exhaust in Marysville Washington. It's all SS and cost $750. I have a new fiberglass lift muffler about level w the top of my BW gear box. If you run in rivers regularly or other abrasive waters perhaps a filter in line to the PYI seal would keep abrasives out of the stern bearing. So 99% of my sea water goes through the exhaust. It seems to build up for a number of seconds and then purge through the hose beyond the lift muffler and out the stern. I'm 999% positive all W30s came from Willard that were not "owner finnished" w the above described system. Before you start pumping money into the Perkins make sure the cylinder sleves arent leaking. In case your'e not aware the 107 has "wet" cylinder sleeves. They are psycsically separate from the block and the coolant is sealed by rubber "O" rings. You may want to call me and I'm very open to that. We can talk free on a land line. I don't think yours is a Fales and I'm wondering if you know about the Willard Boat Owners site on Yahoo Groups. Glad your'e here.

Eric Henning
Willard Nomad*
Thorne Bay Alaska

 

[Capt Dan]

Thanks Eric,

I won't make any major mods for the upcoming season, except rerouting the extra cooling water, diverting it to the shaft seal.*** The engine owes me nothing at this point.* If it is a problem next year then it will be time to repower.* I can get a complete short block for about $3000.* Or go with a more quiet more modern diesel, if it exists.

Got to go to work and listen to a couple of v12-71s today at my day job.* I'll have more later.

Dan

 

[FF]

I have seen cruising boats where any excess sea water was piped to the galley sink.

Unlimited free hot water makes the first rinse a snap, and is still noticeable if it stops.

 

[Nomad Willy]

Fred,
I really like that one Fred, however, I don't think our little engines in the Willards would heat the Water very much.Just for fun I'll put my hand on the hose just before it dumps into the exhaust and see how warm it is.

Eric Henning

 

[FF]

One gallon of diesel is 160,000 BTU or so.

Since 1/3 is dumped into the cooling system , even at a single GPH (13hp) fuel burn , there will be warm water.

Enjoy,

 

[Chris Foster]

"I am installing a drip-free stuffing box, PSS shaft seal and I am thinking about running that excess water into the nipple on the shaft seal.*"

I'm curious why you're doing that.* My boat has the same thing, but PSS seems pretty explicit that there's no need to do so with slower boats (under 10 knots, I think).*

My undersanding is that the water line is there because with a faster boat there's enough of a vacuum to pull air past the seal and defeat the water cooling.* But with slower boats, there's no need*... and more fittings, complexity, things to break.

I'm thinking about removing it on mine as the setup that the "professional mechanics" created in order to pick off the water for the seal looks like a failure waiting to happen.* But I'm curious if there's something that I'm unaware of (OK, there's LOTS that I'm unaware of, but that's another story...)

 

[Marin]

Our boat has conventional, flax-packed packing glands but there is a water feed from each engine to its respective shaft log. The reason is that the cutless bearing in the log does not receive enough cooling/lubrication water when the boat is underway because of its recessed position back up in the bottom of the hull. The pick-off from the engine's raw water system ensures that the shaft log cutless bearing runs cool and well lubed. If this cooling feed is lost--- say if the engine has to be shut down for some reason--- the shaft has to be tied off to keep it from freewheeling because if it turns without the water feed the bearing, shaft log, and packing gland get VERY hot VERY fast and severe and expensive damage will result to the log, the bearing, and the shaft. We have run a very short distance with the shaft of a shut-down engine freewheeling and I know how fast the log gets hot. So on our boat--- and many others with similar setups--- the water feed to the shaft log--- even though it has conventional slow-drip packing--- is essential.

I don't know anything about PSS dripless seals so I don't want to hazard a guess as to how critical the water feed to them is or isn't. If our boat had them I would definitely contact the manufacturer to make sure disconnecting the feed was truly okay. If it isn't the learning curve you go through could include buying a new prop shaft.

 

[FF]

the shaft has to be tied off to keep it from freewheeling because if it turns without the water feed the bearing, shaft log, and packing gland get VERY hot VERY fast and severe and expensive damage will result to the log, the bearing, and the shaft

Sounds like you would be first in line for Duramax or its competition!

FF

 

[Chris Foster]

Interesting... PSS seems to feel that 12k is the magic speed, but perhaps it's also a hull shape issue:

"For high-speed vessels it is required that a water supply be plumbed to the PSS for the purpose of cooling and lubricating the seal faces (i.e.,at over approximately 12 knots of speed a vacuum is created in the stern tube and water is drawn away from the PSS resulting in a loss of cooling water that may cause the carbon to over heat)."

If/when I make the change, I'll probably test it first ... do it on one engine only and check the water level in the water line (which becomes a vent line instead of a supply line) to confirm that there's still water to the seal.

 

[Marin]

FF wrote:
Sounds like you would be first in line for Duramax or its competition!

Why?* The issue is very simple--- the prop shafts on a GB twin*exit the hull thorugh slots and the shaft logs and their cutless bearings are at the forward end of those slots where there is very little water flow when the boat is moving forward. So they used a water pick-off from the engines' raw water system to ensure the cutless bearing in the shaft log gets the proper cooling and lube flow.* It's a perfectly workable system used on thousands of boats.*

You just have to make sure not to go very far with the prop freewheeling.* But tying off a shaft is a simple enough procedure--- our boat has heavy-duty brackets mounted above the shaft couplers for exactly this purpose.

It doesn't matter what kind of a seal system you have, fancy or simple, you still have to get cooling water to the shaft log cutless bearing one way or another.



-- Edited by Marin on Wednesday 7th of October 2009 11:36:03 AM

 

[FF]

"It doesn't matter what kind of a seal system you have, fancy or simple, you still have to get cooling water to the shaft log cutless bearing one way or another.

I would disagree,

You are talking about the historic flax or tefflon packing , the Duramax needs no cooling except water contact , it usually only operates* a bit over water temperature.

It id VERY different from the historic packing.

If tieing off the shaft is EZ , fine , but I do not believe its necessary with modern materials.

Usually Duramax* is set up not to drip,which is tighter than flax , and has no heating problem.

FF

-- Edited by FF on Wednesday 7th of October 2009 12:04:53 PM

 

[Marin]

FF wrote:

"It doesn't matter what kind of a seal system you have, fancy or simple, you still have to get cooling water to the shaft log cutless bearing one way or another."

I would disagree,

You are talking about the historic flax or tefflon packing , the Duramax needs no cooling except water contact

Right.* You have to have sufficient contact with coolling water to cool the Duramax.* And that's the issue on a twin GB, or at least an older twin GB.* There apparently isn't enough contact with cooling water when the boat's moving forward*to cool the shaft log--- Duramax or not---* because of the location of the shaft log, hence the need for a water connection.* If you look at the photos and descriptions for the Duramax system, it has provision for a cooling water connection if it's required by the boats shaft log location/hull configuration.

This has nothing to do with what the packing material is made of.* We use flax because the*boatyard we use prefers that to*tefflon,*Gore, etc. for conventional packing glands.* Given that we got*almost ten years out of the last flax packing in the glands, we've seen no reason to switch to anything else.** I'm not saying that teflon or Gore isn't a better material, just that we've had no problems with flax so see no reason to spend extra money when we don't have to.

 

[FF]

" I'm not saying that teflon or Gore isn't a better material, just that we've had no problems with flax so see no reason to spend extra money when we don't have to.
"
You might wish to contemplate hoe Flax dies.

Usually from the heat , lack of lubrication or rusting of the SS shaft the SS will flake off and imbed it self in the packing.

The SS grinds big groves in the shaft , for other reasons Bronze does the same flaking shaft + grooving.

PM is the art of avoiding repairs,

 

[Marin]

FF wrote:

You might wish to contemplate hoe Flax dies.

Usually from the heat , lack of lubrication or rusting of the SS shaft the SS will flake off and imbed it self in the packing.

We don't have heat, lack of lubrication, or rusting of the SS.** So I'm not going to lose any sleep over this one.

*