Seacock strainer

[jimgram]

My question pertains to a brief grounding on shoal in the Intracoastal waterway. In less than two minutes the water flow shut off to my starboard 6bt5.9 Cummins 210 appears to have cooked it beyond help. This mishap will be covered by insurance (it was a collision). But after being towed 70 miles to a repair marina, other than a burnt engine, there is no evidence of the grounding. No sand in the water pump, no sand or mud in the thru-hull seacock/strainer assembly (Groco). Looking at this unit, it looks like no sand or mud could get through the stainer to the engine. But there is also nothing in the strainer. I think, since the strainer input side is open to the water at the bottom of the boat, most sand or mud would likely drop out as soon.as the engine (and of course, pump) stopped. That draining followed by 70 miles of towing would likely leave an empty strainer. Now, all I need to do is convince my insurer of that. Any thoughts?

 

[STB]

The water flow can be obstructed without the strainer or coolers being clogged by debris. All it takes is for the intake thru hull to be obstructed by the bottom or anything else that doesn't intrude beyond that point.

The tell would be a burned up impeller and, perhaps, associated fouling inside of the raw water pump where the overheated and melting impeller was spinning. There might be other damage to the raw water pump as well, depending upon the details of the situation.

It would probably be helpful to the cause if you have records showing proper maintenance to the raw water pump, e.g. a receipt for the most recently installed impeller. This way it is clear that any observed impeller failure is more likely related to the grounding than lack of maintenance and normal aging.

 

[Comodave]

I agree on the impeller being damaged. What does it look like?

 

[oguidry]

My 1989 GB 36 had twin 6bt5.9 Cummins 210s I left the marina with the engine seacocks closed. Temp alarms went off after about a half mile at idle speed. I slowed worked my to a dock by alternating engines. Both impellers had lost their vanes. I replaced the impellers and returned to the marina. The engines were fine. I am surprised that a short period of no raw water flow cooked an engine. Maybe I got lucky because the engines were not up to operating temp before losing water flow.

 

[Comodave]

I have exhaust temperature alarms on my boat. They will go off much sooner than the engine temperature gauge will show overheating. I got mine at Borel Manufacturing. They are super simple to install.

 

[oguidry]

I also installed the Borel sensors and alarms after my bone headed move of not opening the seacocks.

 

[firehoser75]

+3 on the Borel exhaust alarms. They will alarm before the engine gets toooooo hot (before damage usually), whereas the regular engine overheat alarm may not alarm soon enough to prevent damage.

I also installed an Aqualarm raw water flow alarm. This indicates a no or low raw water flow, allowing for shutdown and investigation of the condition, usually before impeller damage. This can prevent the need to "hunt down" impeller pieces in the downstream coolers and having to perform an impeller change under what could be "bad conditions". Waiting for the exhaust alarm to get hot enough to alarm (with a closed sea cock) may not be in time to "save the impeller"

 

[jgwinks]

Did the tow boat unground you? Their bill should reflect that and you could submit it as supporting evidence.

 

[jimgram]

We went completly over the shoal. A very rough guess is that the shallow water lasted a little over 1 1/2 to 2 boat lengths (36 ft. GB). I continued on while preparing to drop anchor but was approaching state park seawall and ultimately tied up there. Only then did I kill the engines. What I believe is that when I was over the shoal the Groco seacock/strainer filled with sand, etc. which it held until I stopped the engines. Your's is a great suggestion but won't work for me. It really seems that there is little (or no) evidence that I didn't make the whole thing up (I didn't).

 

[STB]

Why won't it work for you? Is your impeller in good condition?

The thing of it is, most impellers are water lubricated and water cooled. If the water flow was stopped for any length of time, it'd likely be fried. It doesn't really matter why it was stopped, just that it lost cooling and/or lubrication.

My memory is that the pump on that engine is gear driven
You could pull it and check the driver gear and the idler or shaft it interfaces with. If there are broken teeth or something like that, it is possible that something sized the pump. Maybe you'll find a piece of metal in the impeller area or something vs sand or mud.

My memory is that the pump on that engine is particularly hard to service, leading many people to defer maintenance.
Perhaps if you have receipts to show the maintenance, that will help your case.

Maybe we should back up. I understand that there was an engine failure proximal to a soft grounding. Can you describe the symptoms at the inset of the failure, how you noticed the failure, your actions at the time you noticed, the behavior or symptoms of the engine when you tried to return it to service, and any subsequent diagnosis or findings?

Are we sure the failure was overheating? And if so, relates to the saltwater path vs the coolant loop? Are we sure, for example, itnhadnt been slowly heating up? That the thermostat opened, etc?

Are we sure it overheated? Or could it have ingested water?

Or, maybe the engine is essentially fine and it just blew a head gasket?

I guess I'd like to understand the history of the trip as it relates to that engine, the failure, and the diagnosis.

I'm hoping it is something other than an internal problem.loke a head gasket, etc.

Engines overheated to failure don't usually keep running fine until being stopped at the dock then never run again. Thst sounds more loke water ingested via the exhaust or something.

But, without a boatload of more information, there is. O telling from where I stand.

I'd post all the details and let the folks here wax poetic about the quality of the EOL diagnosis, what caused it, and what to do about it, etc.

 

[jimgram]

The starboard engine had shutdown as I was crossing the shoal or very shortly after. That was the alarms sounding. The port engine was running until we were secured and I rushed to the salon door. First, let our dog out (he travels in the aft cabin), then shut down the port engine and turned off alarms. Smoke in the cabins was very heavy. I lifted the engine room hatch to see if there was any flame (there wasn't). When things settled down, I tried to crank the sb engine - froze solid, no sign of a shaft movement. Tried the port engine and it started right away, but I shut it down quickly assuming there could be debri in the pump. History: My wife and I purhased this GB 36 CLASSIC in Annapolis early 2022. We took it to Daytona via the Intracoastal mid '22 throgh early '24, making stops of one day to a week. We live in the Florida panhandle (Destin area) but decided to keep the boat on the east coast. Jacksonville is an hour and a half closer to our home so we left Daytona heading for a marina on Johns River in Jacksonville. We stopped for 2 days (due to high wind advisories) at Palm Coast. We left PC and ran over the shoal about 30 minutes out. We we're towed to what was going be our final destination.
So far, the tear down shows no damage to the raw water pumps and very little debri in the strainers.
I believe the starboard raw water thru-hull sucked in enough sand to block the coolant flow and since the sand ( or whatever) couldn't move on to the engine (pump, etc.), it simply drained back out as soon as the engine stopped turning or shortly thereafter. Hence other than an engine that is frozen and shows signs of being extremely overheated (the recirculating coolant had boiled out and sprayed the engine room). I'm certain that no other cause for intense over heating will be found through further disassembly.

 

[Bmarler]

Shutting off the raw water will definitely cause overheating, but it takes a couple of minutes. First thing to go would be the exhaust hose. Maybe that was the smoke. But boiling out all the coolant on the fresh water side should have taken several minutes.
Also doesn’t track that the raw water pumps seemed ok. If the overheat was caused by choking off the raw water inlet, it should damage the impeller pretty darn quickly, just like the exhaust hose. If those items seem undamaged, lack of raw water flow wasn’t the issue.
Is it possible that you had a coolant leak go unnoticed and that was the overheat cause that seized the engine?

 

[LarryM]

I have exhaust temperature alarms on my boat. They will go off much sooner than the engine temperature gauge will show overheating. I got mine at Borel Manufacturing. They are super simple to install.

+1

 

[STB]

The starboard engine had shutdown as I was crossing the shoal or very shortly after. That was the alarms sounding. The port engine was running until we were secured and I rushed to the salon door. First, let our dog out (he travels in the aft cabin), then shut down the port engine and turned off alarms. Smoke in the cabins was very heavy. I lifted the engine room hatch to see if there was any flame (there wasn't). When things settled down, I tried to crank the sb engine - froze solid, no sign of a shaft movement. Tried the port engine and it started right away, but I shut it down quickly assuming there could be debri in the pump. History: My wife and I purhased this GB 36 CLASSIC in Annapolis early 2022. We took it to Daytona via the Intracoastal mid '22 throgh early '24, making stops of one day to a week. We live in the Florida panhandle (Destin area) but decided to keep the boat on the east coast. Jacksonville is an hour and a half closer to our home so we left Daytona heading for a marina on Johns River in Jacksonville. We stopped for 2 days (due to high wind advisories) at Palm Coast. We left PC and ran over the shoal about 30 minutes out. We we're towed to what was going be our final destination.
So far, the tear down shows no damage to the raw water pumps and very little debri in the strainers.
I believe the starboard raw water thru-hull sucked in enough sand to block the coolant flow and since the sand ( or whatever) couldn't move on to the engine (pump, etc.), it simply drained back out as soon as the engine stopped turning or shortly thereafter. Hence other than an engine that is frozen and shows signs of being extremely overheated (the recirculating coolant had boiled out and sprayed the engine room). I'm certain that no other cause for intense over heating will be found through further disassembly.

What did the "smoke" in the cabin smell like? Any chance you blew a head gasket? If there was seet smelling white smoke in the cabin, it sounds like a little could have been a blown head gasket.

I guess the next question would be that were a cause or an effect.

I guess maybe if the engine were really hot to start and then rpms dropped off the impeller could be kept cool enough by whatever water is has that it can't move for longer than an already hot engine can hold out while still making heat and getting no cooling. Dunno'

It seems really rare for an obstructed seawater flow to overheat an engine before overheating an impeller.

 

[Bmarler]

What did the "smoke" in the cabin smell like? Any chance you blew a head gasket? If there was seet smelling white smoke in the cabin, it sounds like a little could have been a blown head gasket.

I guess the next question would be that were a cause or an effect.

I guess maybe if the engine were really hot to start and then rpms dropped off the impeller could be kept cool enough by whatever water is has that it can't move for longer than an already hot engine can hold out while still making heat and getting no cooling. Dunno'

It seems really rare for an obstructed seawater flow to overheat an engine before overheating an impeller.

Or the exhaust hose at the mixer. Very unlikely.

 

[STB]

Or the exhaust hose at the mixer. Very unlikely.

Yeah. A seawater obstruction just doesn't seem to match the fact picture. Not the length of time. Nor the undamaged impeller. Nor the smoke in the cabin, and if the turbo had been spooled up and the exhaust hose was fine, not that either.

I suspect the mechanic will know more as everything gets torn down. Sometimes things are coincidences.

As the old sayings go, "When it rains, it pours" and "Trouble comes in threes."

 

[twistedtree]

This doesn't make sense. Correct me where my understanding goes astray..


You were running fine for 30 minutes. Did you have eyes on the temp gauges during the time? That would be a good confirmation of whether things were working correctly before hand.



Then you ran over the shoal. The stbd engine stalled while crossing the shoal or shortly after. The port engine continued to run. How long was the transit over the shoal? It sounds like it was pretty quick? Seconds? More than a minute?


What makes no sense is for an engine to overheat and seize in such a short time. Even with a complete loss of raw water flow the engine would run for a while before overheating. The exhaust would be the first to go, and there would be unmistakable evidence. Has it been inspected? The hose section immediately after the water injection ring? Seizing of the engine would be the LAST thing to go, not the first.



Also, the engine shut down. I don't know of any overheat alarms that shut an engine down. They make noise, but don't shut down the engine. And again, it would take a while for the alarms to go off, and even longer to seize and engine.


Bottom line is that I suspect there is nothing wrong with your engine, and that it stalled because the prop came into contact with the shoal and stalled the engine. I'll wager that your torsional coupling came apart and is wedged in the bell housing, giving the appearance of a seized motor. The transmission will probably have to be pulled back to get a good look, and certainly to fix it. But there might be access holes or ports through which you can see how things look. A diver should also check the running gear.



With no signs of damage to the cooling system, I think it's very unlikely that there is any engine damage.


Just as a baseline side story, when I was a kid, pre drivers license, I had a junker Dodge Dart that I drove around in our fields for kicks. After some repair, I left it full of water rather than a mix of antifreeze, probably because I didn't have the money to buy antifreeze. It got really cold, the water froze, and cracked the block. That was the end of the car, so decided to see how long it would run with no coolant, so off we went. And I drove the piss out of it - no trawler speed operation back then. I was going for a spectacular lockup of that engine. Well, it took a LOT longer than I expected. Probably a good 10-15 minutes, well past billowing coolant (what little remained), almost to the point of boredom for a 14 year old kid. Lesson learned - it takes a lot of abuse to seize and engine.

 

[STB]

Also, the engine shut down. I don't know of any overheat alarms that shut an engine down. They make noise, but don't shut down the engine. And again, it would take a while for the alarms to go off, and even longer to seize and engine.

If the engine stalled, as you suggest below, they'd go off as (or just after) the engine stalled and oil pressure dropped. Could be easy to confuse the order of events

Bottom line is that I suspect there is nothing wrong with your engine, and that it stalled because the prop came into contact with the shoal and stalled the engine. I'll wager that your torsional coupling came apart and is wedged in the bell housing, giving the appearance of a seized motor.

This is a very good thought!

With no signs of damage to the cooling system, I think it's very unlikely that there is any engine damage.

Well, there is the smoke that was reported to be filling the cabin, but I don't think we've gotten any more detail about its character to try to figure if it was exhaust or coolant or something else.

 

[twistedtree]

If the engine stalled, as you suggest below, they'd go off as (or just after) the engine stalled and oil pressure dropped. Could be easy to confuse the order of events

Exactly. The engine will alarm (low oil pressure) if it stalls.

Well, there is the smoke that was reported to be filling the cabin, but I don't think we've gotten any more detail about its character to try to figure if it was exhaust or coolant or something else.

I don't have an explanation for that, but it seems there are lots of possibilities, including burned rubber from the damper.


Also the report of no or low coolant in the stbd engine remains a mystery. I can't explain that either.


But I do think there is zero possibility of an engine overheating to the point of seizure in seconds (max a minute), let alone with no signs of damage to the raw water impeller and/or exhaust hoses.

 

[kapnd]

Groko does make strainers that are called self cleaning, is that what is in your boat?
If not, it’s very unlikely that the strainer cleared itself after shutdown.

 

[jimgram]

This doesn't make sense. Correct me where my understanding goes astray..


You were running fine for 30 minutes. Did you have eyes on the temp gauges during the time? That would be a good confirmation of whether things were working correctly before hand.



Then you ran over the shoal. The stbd engine stalled while crossing the shoal or shortly after. The port engine continued to run. How long was the transit over the shoal? It sounds like it was pretty quick? Seconds? More than a minute?


What makes no sense is for an engine to overheat and seize in such a short time. Even with a complete loss of raw water flow the engine would run for a while before overheating. The exhaust would be the first to go, and there would be unmistakable evidence. Has it been inspected? The hose section immediately after the water injection ring? Seizing of the engine would be the LAST thing to go, not the first.



Also, the engine shut down. I don't know of any overheat alarms that shut an engine down. They make noise, but don't shut down the engine. And again, it would take a while for the alarms to go off, and even longer to seize and engine.


Bottom line is that I suspect there is nothing wrong with your engine, and that it stalled because the prop came into contact with the shoal and stalled the engine. I'll wager that your torsional coupling came apart and is wedged in the bell housing, giving the appearance of a seized motor. The transmission will probably have to be pulled back to get a good look, and certainly to fix it. But there might be access holes or ports through which you can see how things look. A diver should also check the running gear.



With no signs of damage to the cooling system, I think it's very unlikely that there is any engine damage.


Just as a baseline side story, when I was a kid, pre drivers license, I had a junker Dodge Dart that I drove around in our fields for kicks. After some repair, I left it full of water rather than a mix of antifreeze, probably because I didn't have the money to buy antifreeze. It got really cold, the water froze, and cracked the block. That was the end of the car, so decided to see how long it would run with no coolant, so off we went. And I drove the piss out of it - no trawler speed operation back then. I was going for a spectacular lockup of that engine. Well, it took a LOT longer than I expected. Proably a good 10-15 minutes, well past billowing coolant (what little remained), almost to the point of boredom for a 14 year old kid. Lesson learned - it takes a lot of abuse to seize and engine.

The engine hasn't been delved into yet. Speculation is good though because I have an insurance company chomping at the bit for an out. Trouble is that there was LOTS of snoke from the engine room and the paint is literally burned off of the exhaust manifold. I hope the idea that the engine stalled and the seizing of the engine was due mechanical, not temperature issues.

 

[Kit_L]

As STB wrote,

It seems really rare for an obstructed seawater flow to overheat an engine before overheating an impeller.

I re-read the thread—had you pulled and inspected the impeller yet?

 

[jimgram]

The impellers look good - old, but OK. The smoke and excessive heat I believe was limited to the exhaust manifold so maybe the choking off of raw water before the engine shut down was pretty brief. Could be the engine survived (I hope)

 

[Kit_L]

We all hope so!

 

[Nautica]

Yes, this is sounding less & less like a water blockage. A GB has a keel, the intake would not have been very close to the shoal, but the prop would/ could have been. The overheated exhaust manifold implies (but does not prove) blocked raw water flow. The raw water impeller being OK implies no water blockage. The possibility of two seperate incidents exists. I think it needs more initial investigation as others have suggested.

 

[twistedtree]

An overheated manifold would be cause by a loss of coolant, not a loss of raw water flow. Loss of raw water flow would fry the impeller and the rubber exhaust host after the raw water injection point.


I think you mentioned a significant, if not total loss of coolant from the stbd engine?


All the pieced still don't fit together here in any understandable way.

 

[psneeld]

Yes ...maybe a sand blockage as I have had plenty of those on multiple boats...but I agree with others...doubtful they would clear themselves even after a tow..

Maybe associated with the grounding could be a broken spring from the dampner plate. It could partially at some point start rubbing the inside of the bell housing causing friction and eventual engine freeze up. The friction on my boat when my dampner started coming apart was enough to cause enough smoke to set of smoke alarms in the engine room.

On my boat that happened several times without the engine seizing, but it finally did when a spring part from the dampner wedged more thoroughly, but waited to do so almost 500 miles or so later.

That can explain a lot but not the burnt manifold.... that without a water stoppage seems really strange....especially if the impeller isn't destroyed.

 

[Nautica]

An overheated manifold would be cause by a loss of coolant, not a loss of raw water flow. Loss of raw water flow would fry the impeller and the rubber exhaust host after the raw water injection point.

.

No, manifolds are cooled by raw water which then exits down the exhaust pipe, not by coolant.

 

[jimgram]

No, manifolds are cooled by raw water which then exits down the exhaust pipe, not by coolant.

Correct - raw water runs first heat exchanger -at least one post mentioned an incident when sand associated with a grounding was only found in the heat exchanger. From the exchanger water enters tge exhaust manifold then out through the exhaust.

 

[STB]

Right. It isn't that one can't use a coolant-cooled manifold in a marine application. One can. And, some engines do. It's just that if you've got seawater cooling your coolant via a heat exchanger, doing so is less efficient.

The manifold will transfer the heat to whatever fluid is going through the jacket. In the case of a seawater system, the heat then gets flushed away with the seawater.

If coolant is running through the jacket, that heat ultimately needs to be transferred again by a heat exchanger to get it into the seawater for the flush. That isn't a small load.